2012-2013 Final ReportCOASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
NEW HANOVER COUNTY WATER QUALITY MONITORING PROGRAM
2012-2013
FINAL REPORT
Prepared by:
Coastal Planning & Engineering of North Carolina, Inc.
Marine Scientist: Brad Rosov, M.Sc.
Prepared For:
New Hanover County, North Carolina
Recommended Citation: Rosov, B., 2013. New Hanover County Water Quality Monitoring
Program: 2012-2013 Final Report. New Hanover County, North Carolina: Coastal Planning &
Engineering of North Carolina, Inc. 57p.
July 2013
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
EXECUTIVE SUMMARY
This report represents the results of the New Hanover County Water Quality Monitoring
Program between July 2012 and June 2013. Nineteen (19) monitoring stations within seven (7)
creeks in New Hanover County were monitored on a monthly basis for physical, chemical, and
biological parameters of water quality. The results presented in this report are described from a
watershed perspective.
In order to provide a quick-glance assessment of the water quality within a particular sampling
station and watershed, a rating system has been established for a number of parameters. This
quantitative system assigns a rating of “GOOD”, “FAIR”, or “POOR” to a sampling station
depending on the percentage of samples exceeding the State standard for dissolved oxygen,
turbidity, chlorophyll-a, Enterococci, and fecal coliform bacteria. If the recorded value of a
parameter exceeds the State standard less than 10% of the times sampled, the station will receive
a “GOOD” rating for the parameter. A “FAIR” rating is assigned when a parameter exceeds the
State standard 11-25% of the times sampled. Parameters measured that exceed the State
standard more than 25% of the sampling times are given a “POOR” rating.
As displayed in the tables below, turbidity and chlorophyll-a were determined to be “good”
within all watersheds throughout the study period. Dissolved oxygen was deemed to be “good”
in all creeks with the exception of Pages Creek and Prince Georges Creek where their levels, on
average, was considered to be “poor". Generally, Enterococci was problematic within a number
of these watersheds. Five of the watersheds were rated as “poor” including Barnards Creek,
Motts Creek, Pages Creek, Prince Georges Creek, and Smith Creek. Futch Creek and Lords
Creek were deemed “good” and “fair”, respectively. Fecal coliform, another indicator of
bacterial contamination, was assessed monthly within Pages Creek and Futch Creek. These
creeks generally exceeded the State shellfish standard for fecal coliform bacteria resulting in
“poor ratings”.
Ratings by Watershed
Parameter Barnards
Creek
Futch
Creek
Lords
Creek
Motts
Creek
Pages
Creek
Prince
Georges
Creek
Smith
Creek
Turbidity GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD GOOD GOOD POOR POOR GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Enterococci POOR GOOD FAIR POOR POOR POOR POOR
Fecal Coliform N/A POOR N/A N/A POOR N/A N/A
Long Term Trends
Using data collected on a monthly basis since at least November 2007, the long term trends of
select water quality monitoring parameters were assessed in this report as well. In general,
dissolved oxygen, turbidity, and chlorophyll-a levels oscillate on a seasonal basis. Water
quality, as it relates to these parameters, generally decreases during the warmer months when the
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
water temperatures increase. However, during the cooler months, when the water temperature
drops, these parameters improve.
Since 2007, dissolved oxygen levels exceeded the State standard within surface samples 37%,
29%, 21%, and 10% of the time within Prince Georges Creek, Pages Creek, Futch Creek, and
Motts Creek, respectively. Dissolved oxygen levels were better within Smith Creek and Lords
Creek as both creeks exceeded the dissolved oxygen standard 4% of the time. Barnards Creek
breached the standard only 1% of the times sampled.
Enterococci bacteria has been a chronic problem within several of the creeks monitored in this
study. Since November 2007, samples collected within Motts Creek, Barnards Creek, and Smith
Creek exceeded the State standard for Enterococci 52%, 46%, and 41% of the time, respectively.
Prince Georges Creek exceeded this standard 31% of the time while Pages Creek exceed the
standard 27% of the time. The least amount of exceedences were observed in Lords Creek and
Futch Creek which exceeded the standard 9% and 1%, respectively.
Turbidity and chlorophyll-a were not problematic in any creeks. Since sampling began, only 16
exceedences of the chlorophyll-a standard were observed of the 1325 samples collected.
The turbidity standard was only breached three times in total; two from within Smith Creek and
one within Pages Creek.
Source Tracking
As a supplement to the regular monthly water quality monitoring, a separate sampling effort was
undertaken to determine the source of bacterial contamination within four sites that had
demonstrated chronic high levels of enterococcus bacteria. These sites included Motts Creek at
Normandy Drive (MOT-ND), Smith Creek at Candlewood Drive (SC-CD), and Pages Creek at
Bayshore Drive Upstream and Bayshore Drive Down Stream (PC-BDUS and PC-BDDS).
Six sampling events were conducted through the course of this study, all following significant
rain events. A trio of Bacteroides-based molecular markers were quantified in order to assess the
potential for the presence of human fecal contamination at the four sites studied. In this study,
88% (21 of 24) of the site/storm dates yielded strongly positive results for at least two (2) of the
three (3) human fecal contamination markers indicating that there is a strong likelihood for the
presence of human fecal contamination within the four sites tested.
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
NEW HANOVER COUNTY WATER QUALITY MONITORING PROGRAM
FINAL REPORT
Table of Contents
1.0 Introduction .................................................................................................................................1
1.1 Parameters .............................................................................................................................4
1.2 Standards ...............................................................................................................................6
2.0 Methods.......................................................................................................................................8
2.1 Physical Parameters ..............................................................................................................8
2.2 Biological Parameters ...........................................................................................................8
2.3 Source Tracking ....................................................................................................................9
3.0 Results .........................................................................................................................................10
3.1 Rating System .......................................................................................................................10
3.2 Barnards Creek .......................................................................................................................10
3.3 Futch Creek ...........................................................................................................................12
3.4 Lords Creek ...........................................................................................................................17
3.5 Motts Creek ...........................................................................................................................20
3.6 Pages Creek ...........................................................................................................................23
3.7 Prince Georges ......................................................................................................................27
3.8 Smith Creek ..........................................................................................................................31
3.9 Comprehensive Rating by Watershed ...................................................................................36
3.10 Long Term Trends ..............................................................................................................37
3.10.1 Dissolved Oxygen ...................................................................................................37
3.10.2 Turbidity .................................................................................................................41
3.10.3 Chlorophyll-a ..........................................................................................................44
3.10.4 Enterococci .............................................................................................................47
3.11 Source Tracking ..................................................................................................................50
4.0 Discussion ...................................................................................................................................53
5.0 Literature Cited ...........................................................................................................................56
List of Figures
Figure No.
1 Map of New Hanover County and watersheds included in this study ...................................3
2 Water Quality Sites within the Barnards Creek Watershed ...................................................11
3 Dissolved Oxygen at BC-CBR ..............................................................................................12
4 Enterococci at BC-CBR ........................................................................................................12
5 Water Quality Sites with the Futch Creek Watershed ...........................................................14
6 Dissolved Oxygen at FC-4 .....................................................................................................15
7 Dissolved Oxygen at FC-6 .....................................................................................................15
8 Dissolved Oxygen at FC-13 ................................................................................................... 15
9 Dissolved Oxygen at FC-FOY ............................................................................................... 16
10 Enterococci and Fecal Coliform at FC-4 ............................................................................... 16
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FINAL REPORT
Table of Contents
11 Enterococci and Fecal Coliform at FC-6 ...........................................................................16
12 Enterococci and Fecal Coliform at FC-13 .........................................................................17
13 Enterococci and Fecal Coliform at FC-FOY .....................................................................17
14 Water Quality Site within the Lords Creek Watershed .....................................................18
15 Dissolved Oxygen at LC-RR .............................................................................................19
16 Enterococci Levels at LC-RR ............................................................................................19
17 Water Quality Sites within the Motts Creek Watershed ....................................................21
18 Dissolved Oxygen at MOT-CBR .......................................................................................22
19 Dissolved Oxygen at MOT-ND .........................................................................................22
20 Enterococci at MOT-CBR .................................................................................................22
21 Enterococci at MOT-ND ...................................................................................................23
22 Water Quality Sites within the Pages Creek Watershed ....................................................24
23 Dissolved Oxygen at PC-BDDS ........................................................................................25
24 Dissolved Oxygen at PC-BDUS ........................................................................................25
25 Dissolved Oxygen at PC-M ...............................................................................................26
26 Enterococci and Fecal Coliform at PC-BDDS ..................................................................26
27 Enterococci and Fecal Coliform at PC-BDUS ..................................................................26
28 Enterococci and Fecal Coliform at PC-M .........................................................................27
29 Water Quality Sites within the Prince Georges Creek Watershed .....................................28
30 Dissolved Oxygen at PG-CH .............................................................................................29
31 Dissolved Oxygen at PG-ML.............................................................................................29
32 Dissolved Oxygen at PG-NC .............................................................................................30
33 Enterococci at PG-CH .......................................................................................................30
34 Enterococci and Fecal Coliform at PG-ML .......................................................................30
35 Enterococci at PG-NC .......................................................................................................31
36 Water Quality Sites within the Smith Creek Watershed ....................................................32
37 Dissolved Oxygen at SC-23 ...............................................................................................33
38 Dissolved Oxygen at SC-CD .............................................................................................33
39 Dissolved Oxygen at SC-CH .............................................................................................34
40 Dissolved Oxygen at SC-GR .............................................................................................34
41 Dissolved Oxygen at SC-NK .............................................................................................34
42 Enterococci at SC-23 .........................................................................................................35
43 Enterococci at SC-CD........................................................................................................35
44 Enterococci at SC-CH........................................................................................................35
45 Enterococci at SC-GR........................................................................................................36
46 Enterococci at SC-NK .......................................................................................................36
47 Long term surface dissolved oxygen data within Barnards Creek ....................................38
48 Long term surface dissolved oxygen data within Futch Creek ..........................................38
49 Long term surface dissolved oxygen data within Lords Creek..........................................39
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FINAL REPORT
Table of Contents
50 Long term surface dissolved oxygen data within Motts Creek..........................................39
51 Long term surface dissolved oxygen data within Pages Creek..........................................40
52 Long term surface dissolved oxygen data within Prince Georges Creek ..........................40
53 Long term surface dissolved oxygen data within Smith Creek .........................................41
54 Long term surface turbidity data within Barnards Creek...................................................41
55 Long term surface turbidity data within Futch Creek ........................................................42
56 Long term surface turbidity data within Lords Creek ........................................................42
57 Long term surface turbidity data within Motts Creek ........................................................43
58 Long term surface turbidity data within Pages Creek ........................................................43
59 Long term surface turbidity data within Prince Georges Creek ........................................44
60 Long term surface turbidity data within Smith Creek .......................................................44
61 Long term chlorophyll-a data within Barnards Creek .......................................................45
62 Long term chlorophyll-a data within Futch Creek ............................................................45
63 Long term chlorophyll-a data within Lords Creek ............................................................45
64 Long term chlorophyll-a data within Motts Creek ............................................................46
65 Long term chlorophyll-a data within Pages Creek ............................................................46
66 Long term chlorophyll-a data within Prince Georges Creek .............................................47
67 Long term chlorophyll-a data within Smith Creek ............................................................47
68 Long term Enterococci data within Barnards Creek..........................................................48
69 Long term Enterococci data within Futch Creek ...............................................................48
70 Long term Enterococci data within Lords Creek ...............................................................48
71 Long term Enterococci data within Motts Creek ...............................................................49
72 Long term Enterococci data within Pages Creek ...............................................................49
73 Long term Enterococci data within Prince Georges Creek ...............................................50
74 Long term Enterococci data within Smith Creek ..............................................................50
75 Concentrations of molecular microbial source tracking markers in Motts Creek .............51
76 Concentrations of molecular microbial source tracking markers in Pages Creek .............52
77 Concentrations of molecular microbial source tracking markers in Pages Creek .............52
78 Concentrations of molecular microbial source tracking markers in Smith Creek .............53
List of Tables
Table No.
1 List of Sampling Sites ............................................................................................................2
2 North Carolina Water Quality Standards ...............................................................................7
3 Single sample standards for Enterococci as determined by the US EPA ..............................7
4 Single sample standards for Enterococci as determined by the NC DENR Recreational
Water Quality Program ..........................................................................................................8
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Table of Contents
5 Tier Classification for New Hanover County Water Quality Monitoring Sites ....................8
6 Mean values of select parameters from Barnards Creek .......................................................11
7 Ratings of parameters within sampling stations within Barnards Creek ...............................12
8 Mean values of select parameters from Futch Creek .............................................................14
9 Ratings of parameters within sampling stations within Futch Creek ....................................17
10 Mean values of select parameters from Lords Creek .............................................................19
11 Ratings of parameters within sampling stations within Lords Creek ....................................19
12 Mean values of select parameters from Motts Creek.............................................................21
13 Ratings of parameters within sampling stations within Motts Creek ....................................23
14 Mean values of select parameters from Pages Creek .............................................................25
15 Ratings of parameters within sampling stations within Pages Creek ....................................27
16 Mean values of select parameters from Prince Georges Creek .............................................29
17 Ratings of parameters within sampling stations within Prince Georges Creek .....................31
18 Mean values of select parameters from Smith Creek ............................................................33
19 Ratings of parameters within sampling stations within Smith Creek ....................................36
20 Ratings of parameters within each watershed ........................................................................37
List of Appendices
Appendix No.
A Photographs of Sampling Sites
B Raw Data
C Source Tracking Report
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
1.0 INTRODUCTION
The creeks in New Hanover County, North Carolina provide a wide range of recreational
activities for thousands of local citizens and visiting tourists each year. Tidal creeks are rich
areas in terms of aquatic, terrestrial and avian wildlife and can support complex food webs
(Odum et al, 1984; Kwak and Zedle, 1997). Protection of the water quality within these creeks is
a high priority for New Hanover County. As growth and development continue within the City
of Wilmington and the County, water quality has been increasingly threatened due to many
factors including aging infrastructure, increased impervious surface area and subsequent
stormwater runoff. Furthermore, the County’s population in 2012 was estimated to be 206,359
and is expected to grow at a rate of 1.2% over the next 5 years (NC Division of Commerce,
Labor, and Economic Analysis Division, 2013). To address these issues that impact water
quality, the County, since 1993, has administered a long-standing water quality monitoring
program designed to assess the water quality within the creeks located within the County.
Coastal Planning & Engineering of North Carolina, Inc. began monitoring seven (7) tidal creeks
within New Hanover County on a monthly basis in November 2007. The information presented
in this report represents the results of this monitoring between the months of July 2012 and June
2013. The creeks included in this study are Pages and Futch Creek, which drain into the Atlantic
Intracoastal Waterway (ICW) and Lords, Motts, Barnards, Smith, and Prince Georges Creek,
which drain into the Cape Fear River (Figure 1) (Table 1). Thirteen (13) of the nineteen (19)
sampling sites were previously monitored by the University of North Carolina at Wilmington. In
order to assess any changes to historical trends within individual sites and entire watersheds, data
provided by UNCW has been analyzed and incorporated into the results and discussion section
of this report. Photographs of each sampling site are found in Appendix A.
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Table 1. List of Sampling Sites
Creek Name Site Name Site Code Latitude Longitude
Motts Creek Carolina Beach Road MOT-CBR 34° 08.610 77° 53.830
Motts Creek Normandy Drive MOT-ND 34° 08.373 77° 54.580
Lords Creek River Road LC-RR 34° 05.185 77° 55.275
Barnards Creek Carolina Beach Road BC-CBR 34° 09.522 77° 54.712
Smith Creek Castle Hayne Road SC-CH 34° 15.541 77° 56.325
Smith Creek 23rd Street SC-23 34° 15.472 77° 55.178
Smith Creek Candlewood Drive SC-CD 34° 17.438 77° 51.332
Smith Creek North Kerr SC-NK 34° 15.744 77° 53.256
Smith Creek Gordon Road SC-GR 34° 16.639 77° 52.037
Prince Georges Creek Marathon Landing PG-ML 34° 21.088 77° 55.349
Prince Georges Creek Castle Hayne Road PG-CH 34° 20.675 77° 54.217
Prince Georges Creek North College PG-NC 34° 20.331 77° 53.607
Futch Creek 4 FC-4 34° 18.068 77° 44.760
Futch Creek 6 FC-6 34° 18.178 77° 45.038
Futch Creek 13 FC-13 34° 18.214 77° 45.451
Futch Creek Foy Branch FC-FOY 34° 18.405 77° 45.358
Pages Creek Mouth PC-M 34° 16.209 77° 46.270
Pages Creek Bayshore Drive Down Stream PC-BDDS 34° 16.685 77° 47.673
Pages Creek Bayshore Drive Up Stream PC-BDUS 34° 16.623 77° 48.104
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
Figure 1. Map of New Hanover County and watersheds included in this study
The State of North Carolina has employed a series of classifications that apply to all waters in
the State including streams, rivers, and lakes (NC Administrative Code, section 15A NCAC 2B
.0200). These classifications are meant to protect the specified uses within waterbodies. These
include aquatic life survival and reproduction, secondary recreation, primary recreation,
shellfishing, and water supply. The classifications that apply to the creeks examined in this
study are:
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C Sw: Freshwater that is protected for aquatic life and secondary recreation uses. The
“Sw” supplemental classification indicates that these are swamp waters, and so are likely
to have lower dissolved oxygen and pH than non-swamp streams due to natural
conditions. However, a majority of the sites, including Lords Creek, Motts Creek,
Barnards Creek, Smith Creek, and Prince Georges Creek, designated as C Sw by the
State, are tidally influenced and have a brackish salinity range.
SA: Saline water bodies that are protected for shellfishing uses. This use requires a more
stringent standard for fecal coliform. Areas protected for shellfishing are also subject to
the protection requirements for the less stringent classifications of SC and SB, which
include aquatic life, secondary recreation, and primary recreation. This designation
applies to Futch Creek and Pages Creek.
1.1 Parameters
Physical, chemical, and biological water quality monitoring data are currently being collected for
this study. Physical parameters include temperature, salinity, conductivity, pH, turbidity, and
dissolved oxygen. Chemical parameters monitored in this study include orthophosphate and
nitrate/nitrite. Biological parameters include Chlorophyll-a and two suites of fecal indicator
bacteria: Enterococci and fecal coliform bacteria. Due to limited funding, fecal coliform
samples were only collected from sampling sites located within Futch Creek and Pages Creek.
Temperature:
Thermal pollution can result in significant changes to the aquatic environment. Most aquatic
organisms are adapted to survive within a specific temperature range. Thermal pollution may
also increase the extent to which fish are vulnerable to toxic compounds, parasites, and disease.
If temperatures reach extremes of heat or cold, few organisms will survive.
Thermal pollution may be caused by stormwater runoff from warm surfaces such as streets and
parking lots. Soil erosion is another cause, since it can cause cloudy conditions in a water body.
Cloudy water absorbs the sun's rays, resulting in a rise in water temperature. Thermal pollution
may even be caused by the removal of trees and vegetation which normally shade the water
body. In addition to the direct effects of thermal pollution on aquatic life, there are numerous
indirect effects. Thermal pollution results in lowered levels of dissolved oxygen, since cooler
water can hold more oxygen than warmer water.
Salinity:
Salinity is a measure of the amount of sodium chloride ions dissolved in water. This is important
to monitor since changes in the levels of salt concentration can impact the ability of salt sensitive
species to survive. An estuary, such as the lower Cape Fear River, usually exhibits a gradual
change in salinity throughout its length, as freshwater entering the estuary from tributaries mixes
with seawater moving in from the ocean. Salinity levels control, to a large degree, the types of
plants and animals that can live in different zones of the estuary. Freshwater species may be
restricted to the upper reaches of the estuary, while marine species inhabit the estuarine mouth.
Some species tolerate only intermediate levels of salinity while broadly adapted species can
acclimate to any salinity ranging from freshwater to seawater.
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Conductivity:
Specific conductance is a measure of the ability of water to conduct an electrical current.
Similar to salinity, it measures the amount of dissolved ions (including sodium chloride) in the
water.
pH:
The pH of water is a measurement of the concentration of H+ ions, using a scale that ranges from
0 to 14. Natural water usually has a pH between 6.5 and 8.5. While there are natural variations
in pH, many pH variations are due to human influences. Unanticipated decreases in pH could be
indications of acid rain, runoff from acidic soils, or contamination by agricultural chemicals.
Turbidity:
Turbidity is the amount of particulate matter that is suspended in water. Turbidity measures the
scattering effect that suspended solids have on light: the higher the intensity of scattered light,
the higher the turbidity. During a rainstorm, particles from the surrounding land are washed into
the river making the water a muddy brown color, indicating higher turbidity.
Dissolved Oxygen:
Dissolved oxygen (DO) refers to the volume of oxygen that is contained in water. Oxygen enters
the water as rooted aquatic plants and algae undergo photosynthesis and as oxygen is transferred
across the air-water interface. The amount of oxygen that can be held by the water depends on
the water temperature, salinity, and pressure.
Rapidly moving water, such as in a flowing stream, tends to contain a lot of dissolved oxygen,
while stagnant water contains little. Oxygen levels are also affected by the diurnal (daily) cycle.
Plants, such as rooted aquatic plants and algae produce excess oxygen during the daylight hours
when they are photosynthesizing. During the dark hours they must use oxygen for life processes.
Bacteria in water can consume oxygen as organic matter decays. Thus, excess organic material
in waterbodies can cause oxygen deficits. Aquatic life can become stressed or die in stagnant
water containing high levels of rotting, organic material in it, especially in summer, when
dissolved-oxygen levels are at a seasonal low.
Chlorophyll-a:
Chlorophyll-a is a green pigment found in plants. It absorbs sunlight and converts it to sugar
during photosynthesis. Chlorophyll-a concentrations are an indicator of phytoplankton
abundance and biomass in coastal and estuarine waters. High levels often indicate an algal
bloom which can induce the depletion of oxygen in the water column due to the microbial
degradation of plant cells. Chlorophyll-a concentrations are often higher after rainfall,
particularly if the rain has flushed nutrients into the water. Higher chlorophyll-a levels are also
common during the summer months when water temperatures and light levels are high because
these conditions lead to greater phytoplankton numbers.
Fecal Coliform:
Fecal Coliform bacteria are present in the feces and intestinal tracts of humans and other warm-
blooded animals, and can enter water bodies from human and animal waste. If a large number of
fecal coliform bacteria are found in water, it is possible that pathogenic (disease- or illness-
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
causing) organisms are also present in the water. Pathogens are typically present in such small
amounts it is impractical to monitor them directly. High concentrations of the bacteria in water
may be caused by septic tank failure, poor animal keeping practices, pet waste, and urban runoff.
In order to adequately assess human health risks and develop watershed management plans, it is
necessary to know the sources of fecal contamination.
Enterococci:
Enterococci are distinguished from fecal coliform bacteria by their ability to survive in saltwater,
and in this respect they more closely mimic many pathogens than do the other indicators.
Enterococci are typically more human-specific than the larger fecal streptococcus group. EPA
recommends Enterococci as the best indicator of health risk in saltwater used for recreation and
as a useful indicator in freshwater as well. In 2004, Enterococci took the place of fecal coliform
as the new federal standard for water quality at public beaches. It is believed to provide a higher
correlation than fecal coliform with many of the human pathogens often found in sewage (Jeng,
et al., 2004). Results indicated that Enterococci might be a more stable indicator than fecal
coliform and, consequently, a more conservative indicator under brackish water conditions.
1.2 Standards
Water quality standards have been established legislatively for a number of these parameters
(Table 2). Many of the water quality standards are described in the NC Administrative Code,
section 15A NCAC 2H .0100. The water quality standards for Enterococci bacteria are
described by the US EPA (US EPA, 1986) and in the NC Administrative Code, section 15A
NCAC 18A .3402. The US EPA standards for Enterococci bacteria are based on incidents of
gastrointestinal illness following contact with bathing waters. Bacterial contamination is
quantified by “colony forming units” or CFU. Single sample maximum allowable Enterococci
density is 104 CFU/100ml, 158 CFU/100ml, 276 CFU/100ml, and 501 CFU/100ml for
designated beach areas, swimming areas with moderate to full body contact, lightly used full
body contact swimming areas, and infrequently used full body contact swimming areas,
respectively (Table 3). When at least five samples are collected within a 30 day period, the US
EPA recommends utilizing a geometric mean standard of 35 CFU/100ml. Geometric means are
often useful summaries for highly skewed data, as are often found with bacteriological datasets.
The North Carolina Recreational Water Quality Program (RWQ) adopted similar standards for
Enterococci bacteria, also determined by the frequency of swimming activity. As defined by
RWQ, Tier I swimming areas are used daily during the swimming season, Tier II swimming
areas are used three days a week during the swimming season, and Tier III swimming areas are
used on average four days a month during the swimming season. Single sample standards for
Tiers I, II, and III are 104 CFU/100ml, 276 CFU/100ml, and 500 CFU/100ml, respectively
(Table 4). A geometric mean of 35 CFU/100ml within Tier I swimming areas may also be
utilized if at least five samples are collected within 30 days. The creeks included in this study
have not been classified within the RWQ tier system; however an analysis of accessibility as an
indicator of swimming and boating usage has been performed (Table 5). Based on this analysis,
of the nineteen (19) sampling sites, two (2) could be considered Tier II and seventeen (17) could
be considered Tier III.
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
Table 2. North Carolina Water Quality Standards
Parameter Standard for SA Waters Standard for C Sw Waters
Dissolved Oxygen 5.0 mg/l 4.0 mg/la
Turbidity 25 NTU 50 NTU
pH 6.8-8.5 6.0-9.0b
Chlorophyll-a 40.0 ug/l 40.0 ug/l
Fecal Coliform Geometric Mean (5 samples within
30 days) <14 CFU/100ml; or 10%
of samples <43 CFU/100ml
Geometric Mean (5 samples within
30 days) <200 CFU/100ml; or single
sample <400 CFU/100ml
Enterococci c Geometric Mean (5 samples within
30 days) <35 CFU/100ml
Geometric Mean (5 samples within
30 days) <35 CFU/100ml
(a) Swamp waters may have lower values if caused by natural conditions (b) For swamp streams, pH may be as low as 4.3 if caused by natural conditions (c) See Table 4 for single sample standards based off the tiered system employed by NC DENR Recreational Water
Quality Program
Table 3. Single sample standards for Enterococci as determined by the US EPA
Single sample maximum
Designated beach areas < 104 CFU/100ml
Swimming areas with moderate full body contact < 158 CFU/100ml
Lightly used full body contact swimming areas < 276 CFU/100ml
Infrequently used full body contact swimming areas < 501 CFU/100ml
Table 4. Single sample standards for Enterococci as determined by the NC DENR
Recreational Water Quality Program
Single sample maximum
Tier I, swimming areas used daily during the
swimming season <104 CFU/100ml
Tier II, swimming areas used three days a week
during the swimming season <276 CFU/100ml
Tier III, swimming areas used on average four days
a month during the swimming season <500 CFU/100ml
Table 5. Tier Classification for New Hanover County Water Quality Monitoring Sites
Site Name
Proposed
Tier
Classification
Accessible
for
Boating or
Swimming Comments
MOT-CBR Tier III No Adjacent to culvert off Carolina Beach Road
MOT-ND Tier III No Adjacent to small bridge on Normandy Drive
LC-RR Tier III No Adjacent to bridge on River Road
BC-CBR Tier III No Adjacent to culvert off Carolina Beach Road
SC-CH Tier III No Adjacent to bridge on Castle Hayne Road
SC-23 Tier III No Adjacent to bridge on 23rd Street
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COASTAL PLANNING & ENGINEERING OF NORTH CAROLINA, INC.
SC-CD Tier III No Narrow, shallow. Adjacent to Candlewood Drive
SC-NK Tier III No Adjacent to bridge on North Kerr
SC-GR Tier III No Adjacent to culvert on Gordon Road
PG-ML Tier III No Small boat launch site on private property
PG-CH Tier III No Adjacent to culvert on Castle Hayne Road
PG-NC Tier III No Adjacent to culvert on North College Road
FC-4 Tier III No Private docks are the only means of direct access
FC-6 Tier III No Private docks are the only means of direct access
FC-13 Tier III No Private docks are the only means of direct access
FC-FOY Tier III No No clear access points (no docks on Foy branch)
PC-M Tier II Yes Direct access via docks and boat ramp at Pages Creek Marina
PC-BDDS Tier III No Private docks are the only means of direct access
PC-BDUS Tier II Yes Public boat ramp off Bayshore Drive
2.0 METHODS
The seven creeks included in this study were selected by County staff and individual sampling
sites were selected by County staff in consultation with Coastal Planning & Engineering of North
Carolina, Inc. These seven creeks are primarily located in the unincorporated portion of New
Hanover County. Sampling sites were accessed from land, generally near a bridge or culvert
crossing, or by boat. Each site was sampled one time per month during a high ebb tide. Tides
were determined utilizing the National Oceanic and Atmospheric Administration’s (NOAA)
Tides and Currents website (http://tidesandcurrents.noaa.gov/).
Due to time constraints, monthly sampling events were conducted on three subsequent days each
month. Lords Creek, Motts Creek, and Barnards Creek were visited on the first sampling day
while Smith Creek and Prince Georges Creek were visited the second day. Futch Creek and
Pages Creek were visited on the third day. Rainfall totals for the 24 hours prior to each sampling
event were obtained from observations recorded at Wilmington International Airport as reported
by NOAA’s National Weather Service web site (http://www.srh.noaa.gov/data/RAH/RTPRAH).
2.1 Physical Parameters
All physical measurements (temperature, salinity, conductivity, turbidity, dissolved oxygen, and
pH) were taken in situ utilizing a 6820 YSI Multiparameter Water Quality Probe linked to a YSI
650 MDS display unit. The YSI Probe was calibrated each day prior to use. Physical
measurements were taken from the surface at all sites (depth = 0.1m) and near the creek bottom
at sites with depths greater than 0.5m. Following each sampling trip, the YSI Probe was post-
calibrated following each sampling date to ensure that the physical parameters measured were
within an acceptable range.
2.2 Biological Parameters
Water samples were obtained for the laboratory analysis of biological (Enterococci, fecal
coliform, and Chlorophyll-a) parameters. These grab samples were collected in sterile bottles
during a high ebb tide from the surface at each site (depth = 0.1m). Water samples were placed
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on ice immediately following collection and were delivered in coolers to Environmental
Chemists, Inc. of Wilmington, North Carolina for analysis. All analyses performed by
Environmental Chemists, Inc. were conducted utilizing the following standard EPA approved
methods:
Chlorophyll-a: SM 10200H
Fecal Coliform: SM 9222D
Enterococci: EnterolertE
2.3 Source Tracking
Water samples were collected at each of the four sites during or directly following six storm
events. Subsamples were collected for the quantification of Enterococci bacteria and for batch
analysis using well described molecular methods to determine the source of the bacteria.
Samples of 100ml were filtered in triplicate through 0.45 µm polycarbonate filters and frozen at -
20 C and delivered to UNC Chapel Hill IMS within two weeks of sample collection. The filters
were subjected to the following molecular analyses:
1. Fecal Bacteroides qPCR (Converse et al. 2009)
2. BacHum analyses (Kildare et al. 2007)
3. Human specific marker for Bacteroides (HF183, Layton et al. 2013)
Quantitative polymerase chain reaction (qPCR) methods were used to conduct the Bacteroides
assays:
Fecal Bacteroides qPCR assay (Converse et al. 2009) relies on Taqman chemistry and all
the reagents are in a liquid formulation, except the OmniMix. The assay quantifies a
cohort of bacteria found in high concentrations in the human gut, including Bacteroides
thetaiotaomicron, Bacteroides distastonis, and Bacteroides fragilis. However, the method
is not human specific. The assay has been tested against a range of different fecal
samples types, and has been shown to be capable of quantifying over a wide range of
concentrations, and to be sensitive at concentrations relevant to water quality source
tracking studies. When using the qPCR approach for fecal Bacteroides, strong
relationships have been observed with a wide array of human sewage collected from
areas on both east and west US coastlines. The assay is highly sensitive and the target
bacteria that are enumerated have been shown to be a predictor of human health in both
sand and recreational waters (Wade et. al. 2011, Heaney et al. 2011) during large-scale
EPA-run epidemiology studies. This is a fully quantitative qPCR-based assay that is
being used in an array of studies in stormwater contaminated areas and that, with the use
of other additional confirmatory methods, can be used to both identify potential hot spots
of human fecal contamination (Converse et al, 2009).
BacHum Human Marker: A separate qPCR assay was utilized to quantify the BacHum
molecular markers reported by Kildare et al., 2007. The assay has been widely tested for
specificity against a range of fecal sample types and has shown high capacity for
discrimination against human and animal fecal types (Ahmed et al., 2009).
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HF (human fecal) 183: Human specific marker by qPCR has been conducted previously
by Bernhard and Field (2000) and updated by Seurinck et al., 2006. This assay is specific
to a region of ribosomal rDNA within the Bacteroides spp. that is found almost
exclusively in human feces. The assay has been tested repeatedly in a range of different
environments for cross reactivity with other types of fecal material, and various
researchers have found either a 90 to 100% ability to discriminate between human and
animal feces when using this assay. The assay, however, can be problematic when used
alone, because the target copy concentration in fecal material contributed to receiving
water environments can be quite low due to dilution and the assay has a relatively low
sensitivity.
3.0 RESULTS
The results described in this report represent the physical, biological, and chemical data collected
from all sampling sites on a monthly basis between July 2012 and June 2013. These results are
organized by watershed. All raw data, including parameters not summarized in this section, are
included in Appendix B.
3.1 Rating System
In order to provide a quick-glance assessment of the water quality within a particular sampling
station or watershed, a rating system for a number of parameters has been employed. This
quantitative system assigns a rating of “GOOD”, “FAIR”, or “POOR” to a sampling station
depending on the percentage of samples exceeding the State standard for dissolved oxygen,
turbidity, Chlorophyll-a, Enterococci, and fecal coliform bacteria. If the recorded value of a
parameter exceeds the State standard less than 10% of the times sampled, the station will receive
a “good” rating for the parameter. A “fair” rating is assigned when a parameter exceeds the State
standard 11-25% of the times sampled. Parameters measured that exceed the State standard
more than 25% of the sampling times are given a “poor” rating.
3.2 Barnards Creek
The Barnards Creek watershed includes 4,953 acres and is located in the southwestern portion of
the County, just along the City line. The watershed drains portions of Carolina Beach Road at its
headwaters and flows towards River Road before entering into the Cape Fear River. Zoning
within the watershed is comprised of a mix of residential and commercial uses. The land is
classified as a mix of transition, urban, and conservation according to the CAMA land use plan.
This watershed contains approximately 16.9% impervious surface coverage (Hume, 2009).
Sampling was conducted at one site (BC-CBR) within the Barnards Creek watershed (Figure 2).
Dissolved oxygen within BC-CBR ranged between 5.0 mg/l and 10.0 mg/l with a mean value of
7.4 mg/l (Table 6). These values were within an acceptable level above the State standard of 4.0
mg/l for C Sw waters during all sampling events at both the surface and near the bottom of the
water column (Figure 3).
Chlorophyll-a ranged between 1.0 ug/l and 6.0 ug/l with a mean value of 3.0 ug/l at BC-CBR
(Table 6). These values did not approach the 40ug/l standard.
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Enterococci ranged between 41 CFU/100ml and 1467 CFU/100ml with a geometric mean value
of 292 CFU/100ml, which is above the NCDENR standard of 500 CFU/100ml for Tier III waters
(Figure 4, Table 6). Four (4) of the twelve (12) samples collected during this period exceeded
this standard.
Turbidity values were generally good ranging between 0 and 32 NTU with a mean value of 10
NTU (Table 6). No observations exceeded the State standard of 50 NTU for C SW waters.
Table 7 depicts the ratings for these parameters for the watershed.
Figure 2. Water Quality Sites within the Barnards Creek Watershed
Table 6. Mean values of select parameters from Barnards Creek. Range in parentheses.
Parameter BC-CBR
Turbidity (NTU) 10 (0-32)
Dissolved Oxygen (mg/l) 7.4 (5.0-10.0)
Chlorophyll-a (ug/l) 3.0 (1.0-6.0)
Enterococci (#CFU/100ml) 292 (41-1467)1
(1)Enterococci values expressed as geometric mean
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Figure 3. Dissolved Oxygen at BC-CBR
Figure 4. Enterococci at BC-CBR
Table 7. Ratings of parameters within sampling stations within Barnards Creek
Parameter BC-CBR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci POOR
3.3 Futch Creek
Futch Creek is located on the New Hanover-Pender County line and drains into the Intracoastal
Waterway. The Futch Creek watershed encompasses approximately 3,136 acres extending from
Scotts Hill Loop Road and Highway 17 on the north and east, to Porters Neck Road on the south.
Zoning within the Futch Creek watershed is predominately residential with a small business
district along Highway 17. The land within the Futch Creek watershed is classified as watershed
resource protection or transition in the CAMA land use plan. This watershed contains
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approximately 11.0% impervious surface coverage (Hume, 2009). Sampling was conducted at
four (4) sites (FC-4, FC-6, FC-13, and FC-FOY) within the Futch Creek watershed (Figure 5).
Dissolved oxygen within Futch Creek ranged between 3.1 mg/l and 11.3 mg/l with a mean value
of 6.8 mg/l (Figures 6-9, Table 8).
Chlorophyll-a ranged between 1.0 ug/l and 26.0 ug/l with a mean value of 3.0 ug/l (Table 8).
None of these values approached the 40ug/l Chlorophyll-a standard.
Enterococci ranged between 5 CFU/100ml and 474 CFU/100ml with a geometric mean value of
28 CFU/100ml. No samples collected within Futch Creek exceeded the NCDENR Enterococci
standard of 500 CFU/100ml for Tier III waters (Figures 10-13, Table 8).
The geometric mean of fecal coliform in Futch Creek was 28 CFU with a range of 5 to 3800
CFUs. This geometric mean was above the NCDENR Shellfish Sanitation single-sample
standard of 14 CFU/100ml (Table 8). Thirty-eight percent (38%) of all samples analyzed for
fecal coliform levels exceeded 43 CFU/100ml. The State standard requires “no more than 10%
of samples shall exceed 43 CFU/100ml)”.
Turbidity values were generally low ranging between 0 and 28 NTU with a mean value of 4
NTU (Table 8). One observation exceeded the State standard of 25 NTU for SA waters.
Table 9 depicts the ratings for these parameters for the watershed.
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Figure 5. Water Quality Sites within the Futch Creek Watershed
Table 8. Mean values of select parameters from Futch Creek. Range in parentheses.
Parameter FC-4 FC-6 FC-13 FC-FOY
Turbidity
(NTU) 4 (0-19) 2 (0-7) 6 (0-28) 5 (0-22)
Dissolved
Oxygen (mg/l) 7.2 (4.3-11.3) 7.1 (3.8-10.8) 6.4 (3.1-10.0) 6.6 (3.3-9.8)
Chlorophyll-a
(ug/l) 3.0 (1.0-6.0) 3.0 (1.0-6.0) 4.0 (1.0-26.0) 3.0 (1.0-6.0)
Enterococci
(#CFU/100ml) 22 (5-156)1 15 (5-150)1 55 (5-474)1 35 (5-323)1
Fecal Coliform
(#CFU/100ml) 16 (5-637)1 14 (5-154)1 79 (5-3800)1 35 (5-590)1
(1)Enterococci and Fecal Coliform values expressed as geometric mean
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Figure 6. Dissolved Oxygen at FC-4
Figure 7. Dissolved Oxygen at FC-6
Figure 8. Dissolved Oxygen at FC-13
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Figure 9. Dissolved Oxygen at FC-FOY
Figure 10. Enterococci and Fecal Coliform at FC-4
Figure 11. Enterococci and Fecal Coliform at FC-6
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Figure 12. Enterococci and Fecal Coliform at FC-13
Figure 13. Enterococci and Fecal Coliform at FC-FOY
Table 9. Ratings of parameters within sampling stations within Futch Creek
Parameter FC-4 FC-6 FC-13 FC-FOY
Turbidity GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD GOOD FAIR
Chlorophyll-a GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD
Fecal Coliform GOOD POOR POOR POOR
3.4 Lords Creek
The Lords Creek Watershed is located in the southwestern portion of the County and
encompasses approximately 3,047 acres. Zoning within the watershed is completely residential.
This watershed contains approximately 12.6% impervious surface coverage (Hume, 2009).
According to the CAMA land use plan, the land in the watershed is classified as a mix of
conservation, transition, watershed resource protection and a small natural heritage resource
protection designation. Sampling was conducted at one (1) site (LC-RR) within the Lords Creek
watershed (Figure 14).
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Dissolved oxygen LC-RR ranged between 3.0 mg/l and 10.8 mg/l with a mean value of 7.5 mg/l
(Table 10). All surface samples were within an acceptable level above the State standard of 4.0
mg/l for C Sw waters during both the surface and near the bottom of the water column (Figure
15).
Chlorophyll-a ranged between 11.0 ug/l and 31.0 ug/l with a mean value of 11.0 ug/l (Table 10).
One sample exceeded the State standard of 40ug/l for Chlorophyll-a.
Enterococci ranged between 10 CFU/100ml and 2420 CFU/100ml with a geometric mean value
of 173 CFU/100ml (Table 10). Two samples contained high levels of Enterococci beyond the
NCDENR standard of 500 CFU/100ml for Tier III waters.
Turbidity values were generally moderate ranging between 2 and 17 NTU with a mean value of 8
NTU (Table 10). No observations exceeded the State standard of 50 NTU for C Sw waters in
Lords Creek during the study period.
Table 11 depicts the ratings for these parameters for the watershed.
Figure 14. Water Quality Site within the Lords Creek Watershed
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Table 10. Mean values of select parameters from Lords Creek. Range in parentheses.
Parameter LC-RR
Turbidity (NTU) 8 (2-17)
Dissolved Oxygen (mg/l) 7.5 (3.0-10.8)
Chlorophyll-a (ug/l) 11 (3.0-31.0)
Enterococci (#CFU/100ml) 173 (10-2420)1
(1)Enterococci values expressed as geometric mean
Figure 15. Dissolved Oxygen at LC-RR
Figure 16. Enterococci Levels at LC-RR
Table 11. Ratings of parameters within sampling stations within Lords Creek
Parameter LC-RR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci FAIR
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3.5 Motts Creek
Motts Creek watershed encompasses approximately 2,389 acres and is located in the
southwestern portion of the County, just below Sanders Road. The Creek drains portions of
Carolina Beach Road at its headwaters and then drains toward River Road before entering into
the Cape Fear River. Zoning in the watershed is predominately residential with commercial
business districts along Carolina Beach Road. Land in the watershed is classified as transition,
conservation or wetland resource protection according to the CAMA land use plan. This
watershed contains approximately 12.6% impervious surface coverage (Hume, 2009). Sampling
was conducted at two (2) sites (MOT-CBR, MOT-ND) within the Motts Creek watershed
(Figure 17).
Dissolved oxygen within Motts Creek ranged between 4.7 mg/l and 9.7 mg/l with a mean value
of 7.0 mg/l (Figures 18 and 19, Table 12).
Chlorophyll-a ranged between 1.0 ug/l and 16.0 ug/l with a mean value of 4.0 ug/l (Table 12).
These values did not approach the 40ug/l standard.
Enterococci ranged between 35 CFU/100ml and 2420 CFU/100ml with a geometric mean value
of 563 CFU/100ml (Table 12). MOT-CBR each exceeded the NCDENR standard of 500
CFU/100ml for Tier III waters during seven (7) of the twelve (12) times it was sampled. MOT-
ND exceeded this standard ten (10) of the twelve (12) sample events (Figures 20 and 21).
Turbidity values were generally good ranging between 1 and 12 NTU with a mean value of 7
NTU (Table 12). No turbidity observations exceeded the State standard of 50 NTU for C Sw
waters.
Table 13 depicts the ratings for these parameters for the watershed.
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Figure 17. Water Quality Sites within the Motts Creek Watershed
Table 12. Mean values of select parameters from Motts Creek. Range in parentheses.
Parameter MOT-CBR MOT-ND
Turbidity (NTU) 7 (0-12) 7 (3-10)
Dissolved Oxygen (mg/l) 7.0 (4.7-9.7) 7.0 (4.9-9.4)
Chlorophyll-a (ug/l) 5.0 (1.0-8.0) 4.0 (1.0-16.0)
Enterococci (#CFU/100ml) 420 (35-2420)1 753 (77-2420)1
(1)Enterococci values expressed as geometric mean
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Figure 18. Dissolved Oxygen at MOT-CBR
Figure 19. Dissolved Oxygen at MOT-ND
Figure 20. Enterococci at MOT-CBR
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Figure 21. Enterococci at MOT-ND
Table 13. Ratings of parameters within sampling stations within Motts Creek
Parameter MOT-CBR MOT-ND
Turbidity GOOD GOOD
Dissolved Oxygen GOOD GOOD
Chlorophyll-a GOOD GOOD
Enterococci POOR POOR
3.6 Pages Creek
Located in northeastern New Hanover County and encompassing 2,044 acres, Pages Creek
watershed drains into the Intracoastal Waterway, north of Middle Sound Loop Road. Zoning
within the Pages Creek watershed is predominately residential, with commercial zoning along
Highway 17. The land within the Pages Creek watershed is predominately classified as
watershed resource protection and conservation, with a small portion classified as transitional
according to the CAMA land use plan. This watershed contains approximately 23.2%
impervious surface coverage (Hume, 2009). Sampling was conducted at three (3) sites (PC-
BDDS, PC-BDUS, and PC-M) within the Motts Creek watershed (Figure 22).
Dissolved oxygen within Pages Creek ranged between 2.2 mg/l and 12.4 mg/l with a mean value
of 6.5 mg/ (Table 14) (Figures 23 through 25).
Chlorophyll-a ranged between 1.0 ug/l and 37.0 ug/l with a mean value of 6.0 ug/l (Table 14).
No samples exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 5 CFU/100ml and 24196 CFU/100ml with a geometric mean value
of 184 CFU/100ml (Figures 26-28, Table 14). While samples collected from PC-M did not
contain high levels of Enterococci, six (6) and nine (9) samples from PC-BDDS and PC-BDUS,
respectively, contained levels higher than the NCDENR standards.
Fecal coliform levels ranged between 5 CFU/100ml and 35,000 CFU/100ml with a geometric
mean of 199 CFU/100ml (Table 14). Fecal coliform levels exceeded the NCDENR Shellfish
Sanitation single-sample standard of 14 CFU/100ml on eleven (11) and twelve (12) sampling
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events at PC-BDDS and PC-BDUS, respectively. This standard was breached at PC-M on three
(3) occasions (Figures 26 through 28). Seventy-two percent (72%) of all samples analyzed for
fecal coliform levels exceeded 43 CFU/100ml. The State standard allows “no more than 10% of
samples shall exceed 43 CFU/100ml”.
Turbidity values were generally good ranging between 0 and 21 NTU with a mean value of 6
NTU (Table 14). None of the observed turbidity values exceeded the State standard of 25 NTU
for class SA waters.
Table 15 depicts the ratings for these parameters for the watershed.
Figure 22. Water Quality Sites within the Pages Creek Watershed
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Table 14. Mean values of select parameters from Pages Creek. Range in parentheses.
Parameter PC-BDUS PC-BDDS PC-M
Turbidity (NTU) 9 (3-21) 5 (0-11) 5 (0-20)
Dissolved Oxygen (mg/l) 6.0 (2.9-12.0) 6.3 (2.2-12.4) 7.1 (4.1-12.4)
Chlorophyll-a (ug/l) 8.0 (1.0-37.0) 5.0 (1.0-12.0) 3.0 (1.0-7.0)
Enterococci (#CFU/100ml) 1124 (10-24196)1 534 (10-14136)1 10 (5-52)1
Fecal Coliform
(#CFU/100ml) 1718 (163-3500)1 294 (10-17000)1 16 (5-560)1
(1)Enterococci and fecal coliform values expressed as geometric mean
Figure 23. Dissolved Oxygen at PC-BDDS
Figure 24. Dissolved Oxygen at PC-BDUS
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Figure 25. Dissolved Oxygen at PC-M
Figure 26. Enterococci and Fecal Coliform at PC-BDDS
Figure 27. Enterococci and Fecal Coliform at PC-BDUS
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Figure 28. Enterococci and Fecal Coliform at PC-M
Table 15. Ratings of parameters within sampling stations within Pages Creek
Parameter PC-BDDS PC-BDUS PC-M
Turbidity GOOD GOOD GOOD
Dissolved Oxygen POOR POOR FAIR
Chlorophyll-a GOOD GOOD GOOD
Enterococci POOR POOR GOOD
Fecal Coliform POOR POOR FAIR
3.7 Prince Georges
Prince Georges Creek drains into the Cape Fear River. The Prince Georges Creek watershed is
approximately 14,589 acres and drains most of Castle Hayne, extending eastward across I-40
into the Blue Clay Road area. Zoning within the Prince Georges Creek watershed is
predominately residential with some business and light industrial districts within Castle Hayne.
Most of the land within the Prince Georges Creek watershed is classified as aquifer resource
protection, conservation or transition according to the CAMA land use plan. This watershed
contains approximately 10.1% impervious surface coverage (Hume, 2009). Sampling was
conducted at three (3) sites (PG-CH, PG-ML, and PG-NC) within the Prince Georges Creek
watershed (Figure 29).
Dissolved oxygen within Prince Georges Creek ranged between 0.6 mg/l and 9.8 mg/l with a
mean value of 4.8 mg/l (Table 16). Surface dissolved oxygen values at PG-CH and PG-NC were
below the State standard of 4.0 mg/l for C Sw during three (3) and six (6) sampling events,
respectively. PG-ML was below the standard on two (2) occasions (Figures 30 through 32).
Chlorophyll-a ranged between 0.0 ug/l and 20.0 ug/l with a mean value of 4.0 ug/l (Table 16).
No samples from PG-CH exceeded the 40ug/l standard.
Enterococci ranged between 35 CFU/100ml and 2420 CFU/100ml with a geometric mean value
of 563 CFU/100ml (Table 16). During this study, six (6) and seven (7) samples from PG-CH
and PG-ML, respectively, contained Enterococci levels above the NCDENR standard of 500
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CFU/100ml for Tier III waters. Two (2) samples from PG-NC exceeded this value during the
same time period (Figures 33 through 35).
Turbidity values were generally good ranging between 0 and 39 NTU with a mean value of 6
NTU (Table 16). No observed turbidity values exceeded the State standard of 50 NTU for C Sw
waters.
Table 17 depicts the ratings for these parameters for the watershed.
Figure 29. Water Quality Sites within the Prince Georges Creek Watershed
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Table 16. Mean values of select parameters from Prince Georges Creek.
Range in parentheses.
Parameter PG-CH PG-ML PG-NC
Turbidity (NTU) 7 (1-20) 2 (0-5) 10 (2-39)
Dissolved Oxygen (mg/l) 5.3 (2.1-8.3) 5.7 (3.2-8.8) 3.9 (0.6-9.8)
Chlorophyll-a (ug/l) 4 (1.0-20.0) 4.0 (0.0-13.0) 4.0 (1.0-14.0)
Enterococci (#CFU/100ml) 579 (150-7,000)1 1008 (308-
33,270)1 198 (37-1733)1
(1)Enterococci values expressed as geometric mean
Figure 30. Dissolved Oxygen at PG-CH
Figure 31. Dissolved Oxygen at PG-ML
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Figure 32. Dissolved Oxygen at PG-NC
Figure 33. Enterococci at PG-CH
Figure 34. Enterococci and Fecal Coliform at PG-ML
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Figure 35. Enterococci at PG-NC
Table 17. Ratings of parameters within sampling stations within Prince Georges Creek
Parameter PG-CH PG-ML PG-NC
Turbidity GOOD GOOD GOOD
Dissolved Oxygen POOR POOR FAIR
Chlorophyll-a GOOD GOOD GOOD
Enterococci POOR POOR FAIR
3.8 Smith Creek
Located in north-central New Hanover County and containing approximately 14,665 acres, the
Smith Creek watershed drains into the lower northeast Cape Fear River, just north of the Isabelle
Holmes Bridge. The watershed drains land within the City limits and the unincorporated
County, including the Wilmington International Airport. Zoning within the Smith Creek
watershed is a mix of industrial, residential, and commercial. The land within the watershed is
predominately classified as urban and transition, with a small portion classified as conservation.
This watershed contains approximately 21.9% impervious surface coverage (Hume, 2009).
Along with increased development and impervious surfaces, water quality in Smith Creek has
declined in recent years. High bacteria levels have been reported, as well as low dissolved
oxygen levels. As a result, Smith Creek has been listed on the 303(d) list for impaired waters
due to impaired biological integrity. Sampling was conducted at five (5) sites (SC-CH, SC-23,
SC-NK, SC-GR, SC-CD) within the Smith Creek watershed (Figure 36).
Dissolved oxygen within the creek ranged between 3.6 mg/l and 11.4 mg/l with a mean value of
7.5 mg/l (Table 18). Dissolved oxygen levels within SC-CH and SC-NK fell below State
standard of 4.0 mg/l for C Sw waters on one occasion. No other sampling sites within Smith
Creek below the standard (Figures 37 through 41).
Chlorophyll-a ranged between 0.0 ug/l and 43.0 ug/l with a mean value of 6.0 ug/l (Table 18).
One sample exceeded the State Standard for chlorophyll-a.
Enterococci ranged between 41 CFU/100ml and 60000 CFU/100ml with a geometric mean value
of 526 CFU/100ml (Table 18). A number of samples exceeded the NCDENR standard of 500
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CFU/100ml for Tier III waters including ten (10) from SC-CD and nine (9) from SC-GR. Five
(5) samples from SC-NK exceeded the standard while four (4) samples and three (3) samples
exceeded the standard from SC-CH and SC-23, respectively (Figures 42 through 46).
Turbidity values were generally good ranging between 0 and 66 NTU with a mean value of 10
NTU (Table 18). One observation exceeded the State standard of 50 NTU for SW class C
waters.
Table 19 depicts the ratings for these parameters for the watershed.
Figure 36. Water Quality Sites within the Smith Creek Watershed
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Table 18. Mean values of select parameters from Smith Creek. Range in parentheses.
Parameter SC-23 SC-CD SC-CH SC-GR SC-NK
Turbidity
(NTU) 12 (4-26) 4 (0-29) 20 (3-66) 9 (0-37) 4 (1-8)
Dissolved
Oxygen (mg/l) 7.2 (4.1-10.4) 8.4 (6.6-10.4) 7.6 (3.6-11.4) 8.1 (6.5-9.8) 6.7 (3.9-11.1)
Chlorophyll-a
(ug/l) 9.0 (2.0-23.0) 2.0 (0.0-12.0) 4.0 (1.0-13.0) 3.0 (1.0-13.0) 12.0 (2.0-43.0)
Enterococci
(#CFU/100ml) 189 (41-1,333)1 1362 (143-60,000)1 267 (41-2200)1 1217 (179-2420)1 483 (136-3100)1
(1)Enterococci values expressed as geometric mean
Figure 37. Dissolved Oxygen at SC-23
Figure 38. Dissolved Oxygen at SC-CD
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Figure 39. Dissolved Oxygen at SC-CH
Figure 40. Dissolved Oxygen at SC-GR
Figure 41. Dissolved Oxygen at SC-NK
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Figure 42. Enterococci at SC-23
Figure 43. Enterococci at SC-CD
Figure 44. Enterococci at SC-CH
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Figure 45. Enterococci at SC-GR
Figure 46. Enterococci at SC-NK
Table 19. Ratings of parameters within sampling stations within Smith Creek
Parameter SC-23 SC-CD SC-CH SC-GR SC-NK
Turbidity GOOD GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD GOOD GOOD GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD
Enterococci FAIR POOR FAIR POOR POOR
3.9 Comprehensive Rating by Watershed
When combining all results from each site within individual watersheds, it is possible to obtain a
“snapshot” of water quality within each watershed (Table 20). Smith Creek, Motts Creek, and
Barnards Creek demonstrates “good” water quality with the exception of Enterococci, which was
in the “poor” category. Lords Creek was deemed “good” for all parameters with the exception of
“fair” for Enterococci. Pages Creek and Prince Georges Creek demonstrated “good” ratings for
turbidity and Chlorophyll-a along with “poor” ratings for dissolved oxygen and Enterococci.
Futch Creek contains “good” ratings for all parameters with the exception of fecal coliform
which, along with Pages Creek, was determined to be “poor”.
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Table 20. Ratings of parameters within each watershed
Parameter Barnards
Creek
Futch
Creek
Lords
Creek
Motts
Creek
Pages
Creek
Prince
Georges
Creek
Smith
Creek
Turbidity GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD GOOD GOOD POOR POOR GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Enterococci POOR GOOD FAIR POOR POOR POOR POOR
Fecal Coliform N/A POOR N/A N/A POOR N/A N/A
3.10 Long Term Trends
Water quality data has been collected within New Hanover County since the mid 1990’s.
Several of the historical monitoring sites continue to be utilized for the ongoing monitoring
effort. In order to assess the long term trends in water quality, a database has been created to
include the all data collected within the seven (7) tidal creeks under current investigation. Prior
to 2007, UNCW collected data within three (3) of the tidal creeks included in the present study.
These include Pages Creek, Futch Creek, and Smith Creek. Accordingly, the data from these
three creeks dating to 2004 has been incorporated in the analysis of long term trends. The long
term trends from the remaining creeks (Motts Creek, Lords Creek, Prince Georges Creek, and
Barnards Creek) have been derived from data obtained between November 2007 through June
2013.
For each parameter examined, data was plotted on a line graph over time and a trend line was
created. Trend lines, also known as regression lines, can be used as a way of visually depicting
the relationship between the independent (x) and dependent (y) variables in the graph. In this
case the independent variable is time and the dependent variable is the water quality parameter.
A trend in water quality is defined as an increase or decrease in a particular constituent
concentration over time. Statistical analysis was not performed; therefore the significance of
these long term trends should be interpreted with caution.
3.10.1 Dissolved Oxygen
Figures 47-53 depicts the long term trends in dissolved oxygen within the seven (7) creeks
examined within this study. The figures illustrate a distinct seasonal pattern including higher
dissolved oxygen during the cooler winter months and lower dissolved oxygen during the
warmer summer months. Generally speaking, the dissolved oxygen levels within each creek
have not changed drastically from year to year. The apparent increasing trend line associated
with Smith Creek is not necessarily representative of an actual improvement in dissolved oxygen
levels due to the fact that sampling was only conducted seasonally between 2004 and 2006
thereby skewing the data. Since 2007, dissolved oxygen levels exceeded the State standard
within surface samples 37%, 29%, 21%, and 10% of the time within Prince Georges Creek,
Pages Creek, Futch Creek, and Motts Creek, respectively. Dissolved oxygen levels were better
within Smith Creek and Lords Creek as both creeks exceeded the dissolved oxygen standard four
(4%) of the time. Barnards Creek breached the standard only one (1%) of the times sampled.
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Figure 47. Long term surface dissolved oxygen data within Barnards Creek
Figure 48. Long term surface dissolved oxygen data within Futch Creek
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Figure 49. Long term surface dissolved oxygen data within Lords Creek
Figure 50. Long term surface dissolved oxygen data within Motts Creek
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Figure 51. Long term surface dissolved oxygen data within Pages Creek
Figure 52. Long term surface dissolved oxygen data within Prince Georges Creek
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Figure 53. Long term surface dissolved oxygen data within Smith Creek
3.10.2 Turbidity
Figures 54-60 depict the long term trends in turbidity within the seven (7) creeks examined
within this study. In general, the long term trend of turbidity has remained fairly constant within
each creek on an annual basis, however seasonal patterns emerge. This includes higher turbidity
observations during the warmer months and lower turbidity during the cooler months. The
trends within Futch Creek, Lords Creek, Motts Creek, and Smith Creek have demonstrated a
slight decrease in turbidity over time while turbidity in Prince Georges Creek has increased
slightly. Turbidity within Barnards Creek and Pages Creek have maintained roughly the same
level of turbidity since 2007, however, these long term turbidity trends have not been verified to
be statistically significant. Turbidity has remained within the State standard within all sampling
sites included within this long term analysis.
Figure 54. Long term surface turbidity data within Barnards Creek
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Figure 55. Long term surface turbidity data within Futch Creek
Figure 56. Long term surface turbidity data within Lords Creek
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Figure 57. Long term surface turbidity data within Motts Creek
Figure 58. Long term surface turbidity data within Pages Creek
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Figure 59. Long term surface turbidity data within Prince Georges Creek
Figure 60. Long term surface turbidity data within Smith Creek
3.10.3 Chlorophyll-a
Figures 61-67 depict the long term trends in chlorophyll-a within the seven (7) creeks examined
within this study. In general, the long term trend of turbidity has remained fairly constant within
each creek. Similar to the trend observed with dissolved oxygen, chlorophyll-a levels appear to
increase during the warmer months and decrease during the cooler months. Since sampling
began, only 16 exceedences of the chlorophyll-a standard were observed of the 1325 samples
collected.
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Figure 61. Long term chlorophyll-a data within Barnards Creek
Figure 62. Long term chlorophyll-a data within Futch Creek
Figure 63. Long term chlorophyll-a data within Lords Creek
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Figure 64. Long term chlorophyll-a data within Motts Creek
Figure 65. Long term chlorophyll-a data within Pages Creek
Figure 66. Long term chlorophyll-a data within Prince Georges Creek
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Figure 67. Long term chlorophyll-a data within Smith Creek
3.10.4 Enterococci
Figures 68-74 depict the long term trends in Enterococci within the seven (7) creeks examined
within this study. Motts Creek, Smith Creek, and Prince Georges Creek have all maintained a
relatively high level of bacteria over time. Pages Creek and Barnards Creek contain levels of
bacteria which have apparently increased within recent years. The opposite trend was observed
within Futch Creek and Lords Creek where relatively low Enterococci levels appear to have
decreased over time. High levels of Enterococci have persisted within Prince Georges Creek,
Smith Creek, and Motts Creek over time. Since November 2007, samples collected within Motts
Creek, Barnards Creek, and Smith Creek exceeded the State standard for Enterococci 52%, 46%,
and 41% of the time, respectively. Prince Georges Creek exceeded this standard 31% of the time
while Pages Creek exceed the standard 27% of the time. The least amount of exceedences were
observed in Lords Creek and Futch Creek which exceeded the standard 9% and 1%, respectively.
Figure 68. Long term Enterococci data within Barnards Creek
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Figure 69. Long term Enterococci data within Futch Creek
Figure 70. Long term Enterococci data within Lords Creek
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Figure 71. Long term Enterococci data within Motts Creek
Figure 72. Long term Enterococci data within Pages Creek
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Figure 73. Long term Enterococci data within Prince Georges Creek
Figure 74. Long term Enterococci data within Smith Creek
3.11 Source Tracking
In this study, 88% (21 of 24) of the samples collected yielded strongly positive results for at least
two of the three human fecal contamination markers indicating that there is a strong likelihood
for the presence of human fecal contamination. Methodological limitations prevented accurate
quantification of the HF183 in a few instances, because the water sample collected and purified
had to be diluted in order to gain a proper qPCR signal from the sample. This is called “qPCR
inhibition”. Inhibition is typically caused by large high molecular weight molecules such as
humic and fulvic acids, which are present in high quantities in the Creeks studied here. Even
though there was inhibition of the samples, 13% of the site/storm dates studied yielded positive
results for all three of the human markers tested. Motts and Pages Creek (Figures 75, 76, and 77)
were the locations (both upstream and downstream) that dominated the Fecal Bacteroides spp.
concentrations with concentrations reported at both sites in excess of 100,000 CE/100 ml.
Smith Creek was the only location for which the HF183 marker concentration exceeded 1000
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gene copies/100 ml (Figure 78). Two locations showed positive HF183 concentrations, although
weak, within Smith Creek and the Upstream site at Page’s Creek (Figure 77 and 78). Even when
the HF183 marker was measured, it was measured at very low concentrations throughout this
small study. For the BacHum based marker (see Kildare et al. 2007 for details), 96% of the
samples were positive, ranging in concentrations from 53 to 102,881 gene copies/100 ml. Motts
Creek exhibited some of the highest BacHum marker concentrations, along with the highest
concentrations of this marker being observed during the April 29, 2013 storm event for all three
sites. There was no statistical relationship between Bacteroides-based molecular markers and the
Enterococcus concentrations or total rainfall, but this study includes a small sample size, upon
which it is often difficult to conduct statistical analyses appropriately (p > 0.05, correlation
analysis). This is a small study, and the sites were selected based upon previous historical data
showing contamination. All of the sites indicate that human fecal contamination has the
potential to pose a serious problem to these receiving waters. The storm on March 12, 2013
posed a methodological problem because the storm was so strong that the landscape was scoured
resulting in high amount of inhibition in the water samples collected. This can be viewed as
inhibition of the qPCR reaction conducted. To remedy this situation, the samples require either
further purification or dilution to conduct full quantification. With dilution of the sample comes
not only dilution of the inhibitory compounds, but also of course, dilution of the intended target,
making it likely that false negatives can be reported when the samples could have contained
some of the marker. Indeed, even with dilution of the sample to 1/125 of its original strength,
inhibition was still being observed in the qPCR reaction.
Based upon the data generated, and especially the concentrations of Fecal Bacteroides spp. and
BacHum marker present during smaller rainfall events, it appears that all three Creeks exhibit the
propensity to be conduits of human fecal contamination but delivery mechanisms for each of the
creeks have not been elucidated. The patterns observed indicate a risk to public health.
Figure 75: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Motts Creek at Normandy Drive. Note axis is
on logarithmic scale.
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Figure 76: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Pages Creek at Bayshore Drive Up Stream.
Note axis is on logarithmic scale.
Figure 77: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Pages Creek at Bayshore Drive Down Stream.
Note axis is on logarithmic scale.
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Figure 78: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Smith Creek at Candlewood Drive. Note axis
is on logarithmic scale.
4.0 DISCUSSION
Water quality is an important issue in the region due to the fact that there are many economic and
recreational opportunities that are supported by the aquatic resources in and around these
waterways. One of the greatest threats to water quality in this area is stormwater runoff created
by increased impervious surface coverage (Mallin et al., 2000). Due to many of the
contaminants found in stormwater runoff, adverse effects can be imposed upon plants, fish,
animals and people. Excess nutrients can cause algal blooms while bacteria and other pathogens
can wash into swimming areas and create health hazards. New Hanover County has experienced
rapid growth and development over the past several decades. In 1990, the population within the
County was 120,284. By 2006, the population grew over 50% to 182,591 (U.S. Census Bureau,
2006). The County’s population in 2012 was estimated to be 206,359 and is expected to grow at
a rate of 1.2% over the next 5 years (NC Division of Commerce, Labor, and Economic Analysis
Division, 2013). Along with this population growth came increased stormwater runoff, increase
in septic tanks, aging wastewater infrastructure, and other issues that potentially impacted the
water quality within the County’s creeks. With this in mind, it is important to monitor the water
quality of these local systems to determine potential impacts to both human health and ecosystem
function.
Typically, water quality degrades as the water temperature increases and oxygen is not as readily
dissolved in the water column. This was observed while investigating the long term trends of
water quality in this study. The dissolved oxygen along with chlorophyll-a and turbidity levels
increased during the warmer summer months. Furthermore, longer days allow for increased
photosynthetic activity allowing for an increase in phytoplankton blooms. While often more
problematic in the summer months, algal blooms are less common in the fall and winter when
water temperature decreases. High levels of chlorophyll-a and nutrients along with increases in
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pH and turbidity may indicate the presence of an algal bloom. Throughout the course of this
study, pH values were found to be within acceptable ranges as were turbidity values. The lack of
elevated pH and turbidity along with generally low chlorophyll-a levels indicate that algal
blooms were generally not a problem. In fact, no algal blooms were identified within any
sampling site during the course of this study.
A number of sites contained dissolved oxygen levels below the State standard during the course
of this 12-month study, although no samples collected within Barnards Creek, Lords Creek, or
Motts Creek dropped below this level. The majority (71%) of the samples that fell below the
State standard were collected during June, July, and August when water temperatures were the
highest. The lowest dissolved oxygen, on average, was observed at PG-NC where the standard
was breached six (6) of twelve (12) sampling events. This portion of the creek is characterized
by a broad shallow bank in a swamp-like setting. It is typical of swamps to contain low levels of
dissolved oxygen and higher levels of pH, as observed. Therefore, the low dissolved oxygen
observed in Prince Georges Creek, particularly at PG-NC, could be regarded as a natural
phenomenon. Along with Prince Georges Creek, Pages Creek experienced relatively low
dissolved oxygen within the two sampling sites located in the Bayshore neighborhood. PC-
BDDS and PC-BDUS both exceeded the standard four (4) of the twelve (12) sampling events
over this past monitoring year.
High levels of Enterococci bacteria persisted within five (5) of the seven (7) watersheds
throughout the study period. Samples collected from Futch Creek did not contain any samples
with levels of Enterococci above the State standard while Lords Creek contained two (2)
exceedences. Enterococci levels exceeded the State standard in individual sampling sites within
Barnards Creek, Pages Creek, Smith Creek, Prince Georges Creek, and Motts Creek 33%, 42%,
52%, 56%, and 77% of the time, respectively. The sites with the most frequent high
concentrations of Enterococci bacteria were located within Motts Creek at Normandy Drive and
Smith Creek at Candlewood Drive where ten (10) of the twelve (12) samples obtained at each
sample exceeded the State standard. Samples collected at SC-GR and PC-BDUS also contained
high levels of Enterococci on a consistent basis as nine (9) of the twelve (12) sampling events
exceeded the standard.
Along with Enterococci, fecal coliform bacteria were tested within Pages Creek and Futch
Creek. A very high percentage of samples exceeded the single-sample NCDENR Shellfish
Sanitation standard of 14 CFU/100ml within these creeks. In fact, 40% of all samples collected
within Futch Creek exceeded this standard. Seventy-two percent (72%) of all samples collected
within Pages Creek also exceeded this standard.
One potential source of the degraded water quality observed within several of the creeks
monitored during this study could originate from failing sewage and septic systems. A source
tracking study found bacteria originating from humans, ruminants, and canines within six (6)
tidal creeks in New Hanover County (Spivey, 2008). In the New Hanover County Water Quality
Monitoring Report 2008-2009, it was reported that human borne fecal bacteria was also present
within two (2) sites within Pages Creek. The source of this human-borne bacteria may have been
be indicative of either sewer-line problems, septic system failures, or a general persistence in the
bacteria itself (Spivey, 2008).
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As mentioned above, persistent high levels of Enterococci bacteria have also been identified
within the headwaters of Smith Creek and within Motts Creek. In order to address the chronic
problems within Pages Creek, Smith Creek, and Motts Creek and to serve as a more in-depth
study following the 2008 source tracking effort, a modified source tracking study was
implemented by UNC-Chapel Hill’s Dr. Rachel Noble during this monitoring year. The results
of this study, as detailed above and in Appendix C, suggest that human fecal contamination has
been present within all four sampling sites.
Following the initial source tracking study in 2008, New Hanover County and the Cape Fear
Public Utility Authority (CFPUA) have investigated the presence of abandoned septic tanks and
malfunctioning sewage lift stations in proximity to Pages Creek. These efforts were inconclusive
and high levels of Enterococci bacteria and fecal coliform continue to persist within these sites.
Signage has been posted at the boat ramp on Bayshore Drive warning the public of a potential
human health risk associated with swimming or wading in the creek.
The homes in the Marquis Hills area, which is within the Motts Creek watershed, have
historically had the highest rate of septic tank failure of any area in the County. Over 342 septic
tanks have failed with costly repairs to citizens and environmental impacts to surface waters.
Most likely, these failing septic tanks have been the cause of the human fecal contamination
within the creek. In early May 2013, New Hanover County, in partnership with the Cape Fear
Public Utility Authority (CFPUA), accepted a loan to install sewer within the Marquis Hills
subdivision which will permanently remove the need for septic systems.
It has been recommended that future source tracking work should include sampling each site
multiple times over the duration of storm events rather than collecting a single grab sample. This
method would be used to determine if the source of the human fecal contamination is originating
from runoff or from failing septic tanks or sewer infrastructure leading to the contamination of
groundwater.
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5.0 LITERATURE CITED
Ahmed, W., A. Goonetilleke, D. Powell and T. Gardner. 2009. Evaluation of multiple sewage-
associated Bacteroides PCR markers for sewage pollution tracking. Water Research 43(19):4872-
4877.
Bernhard, A.E. and K. G. Field. 2000. A PCR assay to discriminate human and ruminant feces on
the basis of host differences in Bacteroides-Prevotella genes encoding 16S rRNA. Applied and
environmental microbiology. 66(10):4571-4574.
Converse, R.R., J.F. Griffith, and R.T. Noble (2009) Rapid QPCR-based assays for fecal
Bacteroides and Enterococcus speciation as tools for assessing fecal contamination in
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Grizzard, T.J., Randall, C.W., Helsel, D.R., and Hartigan, J.P. 1980. Analysis of non-point
pollution export from small catchments. Journal of Water Pollution Control Federation, 52:
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Howarth, R.W. and Marino, R. 2006. Nitrogen as the limiting nutrient for eutrophication in
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Hume, A. 2008. Determination of Impervious Surface in New Hanover County, North Carolina.
Report submitted to New Hanover County. Wilmington, North Carolina.
Jeng, J.G., Bradford, H, and Englande, A.J. 2004. "Comparison of E. coli, enterococci, and fecal
coliform as indicators for brackish water quality assessment". Water Environmental Research.
76: 245–55.
Kelsey, H., Porter, D.E, Scott, G., Neet, M., and White, D. 2004. Using geographic information
systems and regression analysis to evaluate relationships between land use and fecal coliform
bacterial pollution. Journal of Experimental Marine Biology and Ecology. 298:197-209.
Kildare, B.J., C.M. Leutenegger, B.S. McSwain, D.G. Bambic, V.B. Rajal and S. Wuertz. 2007.
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using multiple stable isotopes. Oecologia 110: 262–277.
Mallin, M.A.; Williams, K.E.; Esham, C.E.; and Lowe, P.R., 2000. Effect of human
development on bacteriological water quality in coastal watersheds. Ecological Applications
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Mallin, M.A., Ensign, S.H., McIver, M.R., Shank, G.C., and Fowler, P.K. 2001. Demographic,
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Mallin, M.A., 2010. University of North Carolina at Wilmington, Aquatic Ecologist. Personal
communication regarding findings of water samples obtained within PG-NC.
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Freshwater Marshes of the United States East Coast: A Community Profile. U.S. Fish and
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Ricks, C., 2011. Cape Fear Public Utility Authority. Personal communication regarding sewage
spills in New Hanover County.
Schueler, T., 1994. The importance of imperviousness. Water Protection Technology. 1: 100-
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Spivey, 2008. The use of PCR and T-RFLP as a means of identifying sources of fecal bacteria
pollution in the tidal creeks of New Hanover County, North Carolina. Masters Thesis.
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Wade, T. J., Sams, E., Brenner, K. P., Haugland, R., Chern, E. Beach, M., Wymer, L., Rankin,
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recreational water quality and swimming-associated illness at marine beaches. Journal of
Environmental Health Perspectives. 9:66-80.
APPENDIX A
Photographs of Sampling Sites
Barnards Creek at Carolina Beach Road (BC-CBR)
Futch Creek 4 (FC-4)
Futch Creek 6 (FC-6)
Futch Creek 13 (FC-13)
Futch Creek at Foy Branch (FC-FOY)
Lords Creek at River Road (LC-RR)
Motts Creek at Carolina Beach Road (MOTT-CBR)
Motts Creek at Normandy Drive (MOT-ND)
Pages Creek at Bayshore Drive Upstream (PC-BDUS)
Pages Creek at Bayshore Drive (PC-BDDS)
Pages Creek Mouth (PC-M)
Prince Georges Creek at Castle Hayne Road (PG-CH)
Prince Georges Creek at Marathon Landing (PG-ML)
Prince Georges Creek at North College Road (PG-NC)
Smith Creek at Candlewood Drive (SC-CD)
Smith Creek at Castle Hayne Road (SC-CH)
Smith Creek at 23rd Street (SC-23)
Smith Creek at North Kerr Ave. (SC-NK)
Smith Creek at Gordon Road (SC-GR)
APPENDIX B
Raw Data
APPENDIX B
Raw Data
Depth Temp. Cond. Salinity
DO
mg/L DO% pH Turb.Entero. FC Chl-a
0.1 25.1 235 0.1 5.1 63% 7.5 1 410 N/A 6
1.2 25.0 218 0.1 5.0 62% 7.3 24 N/A N/A N/A
0.1 25.0 211 0.1 5.5 67% 7.2 2 512 N/A 2
1.3 25.0 211 0.1 5.4 66% 7.1 30 N/A N/A N/A
0.1 22.6 288 0.1 6.5 75% 7.8 0 1120 N/A 2
1.1 22.4 250 0.1 6.4 74% 7.7 10 N/A N/A N/A
0.1 17.9 285 0.2 6.7 70% 8.0 1 173 N/A 1
1.1 17.7 213 0.1 6.6 69% 8.0 24 N/A N/A N/A
0.1 15.9 313 0.2 7.2 73% 8.4 0 134 N/A 1
1.3 15.7 213 0.1 6.7 68% 7.2 7 N/A N/A N/A
0.1 13.5 201 0.1 9.3 89% 7.9 14 41 N/A 2
0.1 15.6 197 0.1 9.2 93% 7.6 3 305 N/A 4
1.6 15.0 195 0.1 9.1 91% 7.4 8 N/A N/A N/A
0.1 13.3 179 0.1 9.4 90% 7.7 2 146 N/A 6
1.5 13.1 178 0.1 9.3 89% 7.6 32 N/A N/A N/A
0.1 12.3 374 0.2 10.0 94% 7.5 2 109 N/A 1
1.3 11.8 195 0.1 9.7 89% 7.4 20 N/A N/A N/A
0.1 15.2 223 0.1 7.8 78% 7.4 1 355 N/A 2
1.7 15.2 170 0.1 7.7 77% 7.4 28 N/A N/A N/A
0.1 18.3 255 0.1 7.2 77% 7.5 3 677 N/A 1
1.6 18.2 198 0.1 7.0 75% 7.4 3 N/A N/A N/A
0.1 24.6 171 0.1 6.4 77% 7.1 0 1467 N/A 2
1.8 24.4 169 0.1 6.3 75% 7.0 7 N/A N/A N/A
1.2 13.0 195 0.1 9.0 86% 7.7 8 N/A N/A N/A
0.1 28.2 54862 33.9 3.1 48% 7.7 6 120 1000 5
1.0 28.3 54922 33.9 3.1 49% 7.7 28 N/A N/A N/A
0.1 27.8 57603 36.1 5.2 81% 7.7 7 82 10 4
1.0 27.8 57714 36.2 5.2 88% 7.7 7 N/A N/A N/A
0.1 24.9 48721 33.1 5.3 83% 7.5 6 10 10 2
1.0 24.9 48588 33.0 5.2 82% 7.4 3 N/A N/A N/A
0.1 20.3 49712 36.2 6.5 89% 7.8 3 5 5 2
1.2 20.2 49565 36.2 6.5 89% 7.8 5 N/A N/A N/A
0.1 13.7 43382 34.3 7.2 86% 7.7 2 156 46 2
1.0 13.9 49222 34.9 7.2 85% 7.8 2 N/A N/A N/A
0.1 15.5 39147 31.2 7.9 96% 7.7 4 10 46 1
0.9 15.5 39397 31.5 7.9 96% 7.7 7 N/A N/A N/A
0.1 14.8 38210 30.8 10.0 118% 7.5 2 31 5 4
0.9 14.7 38215 30.8 10.0 118% 7.6 3 N/A N/A N/A
0.1 11.8 33333 28.7 9.0 100% 6.8 1 350 199 1
0.7 11.8 34772 30.1 9.2 102% 6.9 1 N/A N/A N/A
0.1 12.4 37488 31.9 6.6 77% 7.6 0 5 10 1
1.0 12.4 37235 31.8 6.6 77% 7.6 0 N/A N/A N/A
0.1 18.0 41043 30.9 6.3 80% 7.9 1 160 1460 1
1.1 18.0 42142 32.0 6.3 81% 8.0 5 N/A N/A N/A
0.1 20.2 40731 29.1 5.2 68% 7.8 3 249 3800 2
1.0 20.2 41465 29.6 5.3 69% 7.8 11 N/A N/A N/A
0.1 27.5 41310 25.0 5.5 80% 7.9 15 474 1000 26
0.9 27.4 41748 25.4 5.1 74% 7.9 17 N/A N/A N/A
0.1 28.0 56362 35.1 4.3 67% 7.8 4 100 5 4
1.7 27.9 56382 35.1 4.3 67% 7.8 19 N/A N/A N/A
0.1 27.5 57660 36.4 5.5 85% 7.8 3 10 19 3
2.1 27.2 57304 36.4 5.5 86% 7.8 4 N/A N/A N/A
0.1 23.6 51803 35.1 6.0 87% 7.4 5 10 10 2
1.2 23.5 51981 35.2 6.0 87% 7.4 5 N/A N/A N/A
0.1 21.6 51212 36.3 7.2 100% 7.9 3 50 5 3
1.8 21.5 50983 36.3 7.2 101% 7.9 3 N/A N/A N/A
0.1 14.3 44363 35.3 7.4 88% 7.8 2 156 10 3
1.6 14.3 44685 35.3 7.5 88% 7.8 4 N/A N/A N/A
0.1 17.5 27565 20.1 7.6 89% 7.9 6 5 5 1
1.3 15.1 41963 34.0 8.5 104% 7.9 0 N/A N/A N/A
0.1 15.2 40101 32.3 10.0 117% 7.7 0 20 19 4
1.7 15.1 40115 32.3 10.0 117% 7.7 1 N/A N/A N/A
0.1 11.4 36090 31.7 11.3 126% 7.3 0 41 19 1
1.3 11.3 36240 31.9 11.3 126% 7.3 0 N/A N/A N/A
0.1 12.8 38448 32.3 6.7 78% 7.8 0 5 5 1
1.6 12.8 38521 32.3 6.7 78% 7.8 0 N/A N/A N/A
0.1 17.4 42360 32.4 7.3 93% 8.0 0 74 637 1
1.4 17.0 42222 33.0 7.5 94% 8.1 2 N/A N/A N/A
0.1 19.9 44280 32.1 6.4 85% 8.0 5 20 73 2
1.7 20.0 44308 32.3 6.6 86% 8.0 5 N/A N/A N/A
0.1 27.3 51799 32.5 6.5 98% 8.1 5 5 10 6
2.0 26.9 51594 32.5 6.4 96% 8.1 11 N/A N/A N/A
0.1 14.9 39878 31.3 9.9 112% 7.7 1 31 5 4
0.1 28.0 56340 35.1 3.8 60% 7.8 4 5 5 5
1.2 28.0 56378 35.1 3.9 61% 7.8 3 N/A N/A N/A
0.1 27.7 57892 36.4 5.3 82% 7.7 3 150 5 3
1.3 27.7 57906 36.4 5.2 81% 7.7 4 N/A N/A N/A
0.1 24.2 51001 35.0 6.0 87% 7.4 7 5 5 2
1.7 24.0 51058 35.0 6.1 88% 7.5 7 N/A N/A N/A
0.1 21.3 50871 36.3 7.1 99% 7.8 2 5 5 2
1.7 21.3 50987 36.3 7.1 99% 7.8 2 N/A N/A N/A
0.1 14.3 44480 35.1 7.6 87% 7.9 0 20 10 2
1.5 14.2 44550 35.2 7.4 87% 7.9 0 N/A N/A N/A
0.1 15.4 41947 33.8 8.2 101% 7.8 0 5 5 1
1.0 15.4 41967 33.8 8.3 102% 7.8 0 N/A N/A N/A
1.1 14.6 39900 31.3 9.9 112% 7.7 1 N/A N/A N/A
0.1 11.7 35770 31.2 10.7 120% 7.2 0 31 64 1
1.1 11.7 35865 31.3 10.8 122% 7.2 0 N/A N/A N/A
0.1 12.6 38210 32.2 6.6 77% 7.8 0 10 5 1
1.4 12.6 38114 32.2 6.6 77% 7.8 0 N/A N/A N/A
0.1 17.5 42521 32.5 7.2 91% 8.1 1 5 154 1
1.1 17.5 42520 32.5 7.1 90% 8.1 1 N/A N/A N/A
0.1 20.0 44029 31.8 6.2 82% 7.9 3 31 154 1
1.2 20.0 44136 40.0 6.2 82% 8.0 4 N/A N/A N/A
0.1 27.4 51557 32.2 6.3 96% 8.1 6 41 37 6
1.5 27.4 51738 32.4 6.3 95% 8.1 7 N/A N/A N/A
0.1 28.4 54711 33.7 3.3 50% 7.7 5 20 8 6
0.7 28.2 55390 34.3 3.3 50% 7.7 16 N/A N/A N/A
0.1 27.8 57335 35.9 4.5 70% 7.7 7 150 10 3
0.7 27.8 57735 36.2 4.5 71% 7.7 12 N/A N/A N/A
0.1 24.7 47721 32.9 5.2 82% 7.4 4 5 10 2
1.3 24.9 47658 32.9 5.1 81% 7.4 3 N/A N/A N/A
0.1 20.7 50105 36.3 6.8 94% 7.8 3 323 5 2
1.2 20.7 50104 36.3 6.8 93% 7.8 10 N/A N/A N/A
0.1 13.9 44021 34.8 7.1 85% 7.8 3 41 46 2
1.0 13.8 44436 35.1 7.2 85% 7.8 1 N/A N/A N/A
0.1 15.6 40256 32.1 8.0 98% 7.7 3 5 5 1
0.9 15.5 40861 32.7 8.1 99% 7.8 8 N/A N/A N/A
0.1 14.6 38423 30.8 9.8 111% 7.6 1 5 28 3
0.8 14.6 38420 30.8 9.8 111% 7.6 1 N/A N/A N/A
0.1 11.8 34410 29.8 9.7 107% 7.1 0 119 64 1
0.9 11.8 35045 30.4 9.5 106% 7.1 4 N/A N/A N/A
0.1 12.4 37189 31.8 6.7 78% 7.6 0 10 37 1
1.0 12.3 37222 31.8 6.7 78% 7.6 0 N/A N/A N/A
0.1 18.3 39910 29.8 6.4 82% 7.9 2 20 370 2
0.7 18.3 38104 29.2 6.4 82% 7.9 3 N/A N/A N/A
0.1 20.1 41599 29.8 5.5 72% 7.9 3 134 590 2
1.0 20.0 42712 30.7 5.6 74% 7.9 4 N/A N/A N/A
0.1 27.3 42145 25.8 5.8 84% 8.0 12 226 290 6
0.9 27.4 45250 27.8 5.7 84% 8.0 22 N/A N/A N/A
0.1 28.7 31192 17.9 4.5 64% 6.0 15 50 N/A 41
1.3 28.6 31187 17.9 3.0 43% 6.2 21 N/A N/A N/A
0.1 25.5 6078 3.4 4.6 58% 6.5 7 350 N/A 5
1.2 27.4 14588 8.1 4.4 58% 6.2 10 N/A N/A N/A
0.1 26.0 31964 19.5 6.5 90% 6.8 5 2420 N/A 9
1.6 31.5 32107 19.6 6.6 90% 6.9 5 N/A N/A N/A
0.1 21.4 33718 22.9 6.4 83% 7.1 5 1300 N/A 5
1.3 21.4 33717 22.9 6.4 83% 7.1 5 N/A N/A N/A
0.1 15.3 32127 25.2 91.1 78% 6.7 3 96 N/A 4
1.9 15.3 32150 25.2 7.7 90% 6.7 6 N/A N/A N/A
0.1 12.4 23932 19.6 9.1 97% 6.0 5 86 N/A 5
1.3 12.4 23951 19.6 9.0 95% 6.0 5 N/A N/A N/A
0.1 12.6 19527 15.6 9.8 100% 6.1 2 134 N/A 3
2.0 12.4 20444 16.5 9.8 100% 6.1 2 N/A N/A N/A
0.1 11.3 19410 16.1 10.1 100% 6.0 3 10 N/A 5
1.3 11.3 19395 16.1 10.1 100% 6.0 3 N/A N/A N/A
0.1 10.8 153308 1206.0 10.8 106% 6.0 4 119 N/A 9
1.5 10.8 15246 12.5 10.7 105% 6.0 5 N/A N/A N/A
0.1 14.9 13252 9.7 7.2 75% 6.7 15 336 N/A 13
2.0 14.9 13529 9.9 7.0 73% 6.8 16 N/A N/A N/A
0.1 18.6 17941 12.3 6.8 78% 7.3 9 189 N/A 7
1.8 18.6 17943 12.3 6.8 78% 7.3 9 N/A N/A N/A
0.1 26.4 9265 5.0 7.3 93% 7.1 17 161 N/A 21
1.9 26.4 9258 5.0 7.3 93% 7.1 17 N/A N/A N/A
0.1 26.2 303 0.1 4.7 54% 7.0 3 570 N/A 19
0.1 25.7 328 0.2 6.3 77% 6.8 5 538 N/A 8
0.1 23.6 382 0.2 7.2 85% 7.2 4 771 N/A 4
0.1 19.4 363 0.2 5.5 60% 7.3 5 2420 N/A 2
0.1 17.2 282 0.2 7.7 80% 7.6 6 2420 N/A 4
0.1 14.3 338 0.2 8.4 82% 7.0 9 158 N/A 2
0.1 15.6 296 0.2 7.4 74% 6.8 12 536 N/A 1
0.1 13.0 237 0.2 9.7 82% 6.9 9 109 N/A 3
0.1 12.6 323 0.2 7.8 74% 6.8 8 35 N/A 1
0.1 14.9 225 0.1 7.4 74% 6.9 8 102 N/A 3
0.1 18.2 261 0.1 6.2 66% 6.8 10 276 N/A 3
0.1 25.7 215 0.1 5.3 65% 7.0 1 2420 N/A 8
0.1 25.7 277 0.1 6.4 73% 7.0 3 1400 N/A 4
0.1 25.3 325 0.2 4.9 59% 6.9 7 959 N/A 3
0.1 22.8 377 0.2 7.5 87% 7.2 7 1733 N/A 3
0.1 17.5 347 0.2 5.7 60% 7.2 4 727 N/A 2
0.1 15.7 320 0.2 6.7 67% 7.3 5 1300 N/A 1
0.1 13.7 302 0.2 8.7 84% 6.9 8 218 N/A 16
0.1 15.7 301 0.2 7.5 75% 6.7 9 670 N/A 2
0.1 12.5 234 0.2 9.4 88% 6.7 8 77 N/A 3
0.1 11.2 291 0.2 8.1 75% 6.7 9 727 N/A 4
0.1 14.5 220 0.1 7.4 73% 7.0 7 687 N/A 2
0.1 17.8 297 0.1 6.2 65% 7.0 10 1120 N/A 2
0.1 25.0 212 0.1 6.0 73% 6.9 3 2420 N/A 4
0.1 29.0 56592 34.5 2.2 34% 7.6 6 30 46 7
0.5 29.0 56628 34.6 2.0 30% 7.6 21 N/A N/A N/A
0.1 28.4 57155 35.4 4.0 63% 7.6 2 10 10 12
0.6 28.3 57120 35.4 2.7 43% 7.6 2 N/A N/A N/A
0.1 23.1 49040 33.5 4.6 65% 7.5 5 134 154 10
0.7 23.3 50594 34.5 4.5 64% 7.5 7 N/A N/A N/A
0.1 19.0 47251 35.3 6.6 86% 7.6 5 41 82 7
1.3 20.8 50280 36.3 6.7 93% 7.7 15 N/A N/A N/A
0.1 12.8 38790 33.1 8.3 97% 6.8 3 226 100 1
0.1 14.8 39731 32.3 7.5 89% 7.7 11 369 127 1
0.1 16.0 37680 24.6 7.8 94% 7.3 5 2282 1730 2
0.1 12.3 34706 29.7 12.4 140% 7.4 0 14136 17000 1
0.1 12.4 37267 31.5 6.0 70% 7.7 0 771 370 2
0.1 18.4 41052 30.6 6.3 81% 7.9 5 2481 273 10
0.1 20.7 40588 28.7 5.3 71% 7.7 5 9804 400 7
0.1 27.6 46873 28.8 4.4 65% 7.7 7 6488 4800 5
0.1 28.7 53398 32.5 2.9 44% 7.6 8 10000 819 12
0.1 28.4 54843 33.8 5.0 77% 7.7 10 10 2100 14
0.1 25.3 45701 29.4 5.3 74% 7.6 11 134 1455 9
0.1 19.6 39968 28.8 5.1 66% 7.7 8 17329 819 4
0.1 12.7 34982 29.6 7.7 88% 6.6 5 259 200 1
0.1 17.5 27565 20.1 7.6 89% 7.9 6 187 163 2
0.1 19.5 26710 18.5 7.2 86% 7.4 3 24196 35000 2
0.1 12.8 26002 21.3 12.0 140% 7.5 12 6131 2200 2
0.1 12.1 34120 28.8 5.4 65% 7.4 6 336 340 3
0.1 19.2 28900 20.3 4.8 57% 7.3 4 2755 7000 37
0.1 21.0 35102 24.2 3.8 50% 7.3 9 2755 33000 6
0.1 28.1 41063 24.6 4.7 69% 7.7 21 960 1640 4
0.1 28.5 56798 35.1 4.3 68% 7.7 3 5 10 6
1.4 28.5 56799 35.1 4.1 63% 7.7 8 N/A N/A N/A
0.1 27.5 57201 36.1 4.8 75% 7.7 5 10 10 5
1.4 27.5 57226 36.1 4.8 75% 7.7 13 N/A N/A N/A
0.1 25.6 53671 35.8 5.5 80% 7.7 5 5 5 5
1.4 24.4 53310 35.6 5.2 76% 7.7 8 N/A N/A N/A
0.1 20.8 50286 36.3 6.8 94% 7.7 3 5 154 3
1.7 20.7 50291 36.3 6.8 94% 7.7 5 N/A N/A N/A
0.1 13.8 41151 34.5 7.9 95% 7.2 3 20 10 3
1.8 13.8 4185 34.5 8.0 95% 7.2 14 N/A N/A N/A
0.1 14.9 41800 34.1 7.4 90% 7.7 0 10 5 2
1.3 14.7 41612 34.1 7.6 92% 7.7 1 N/A N/A N/A
0.1 20.4 39429 27.9 8.0 104% 7.4 0 10 10 1
1.0 20.2 39252 27.9 8.2 106% 7.4 0 N/A N/A N/A
0.1 11.3 36473 32.2 12.4 138% 7.4 0 52 5 1
1.2 11.3 36464 32.2 12.3 137% 7.5 0 N/A N/A N/A
0.1 12.3 39524 32.5 6.9 79% 7.8 0 5 5 1
1.7 12.3 39777 32.5 6.8 79% 7.8 0 N/A N/A N/A
0.1 16.1 41128 32.5 7.7 95% 8.1 1 51 560 3
1.7 15.9 41112 32.5 7.7 95% 8.1 4 N/A N/A N/A
0.1 19.0 43950 32.5 7.4 97% 8.0 6 5 37 2
1.7 18.9 43880 32.5 7.1 93% 8.0 11 N/A N/A N/A
0.1 27.8 52913 33.5 6.0 88% 8.0 5 10 10 7
1.1 26.0 51956 33.6 6.1 89% 8.2 20 N/A N/A N/A
0.1 25.0 516 0.3 2.2 27% 7.1 3 7000 N/A 3
1.3 24.8 516 0.3 2.1 25% 7.1 9 N/A N/A N/A
0.1 25.2 393 0.2 3.0 37% 7.2 8 173 N/A 6
1.7 25.0 393 0.2 2.4 28% 7.1 12 N/A N/A N/A
0.1 22.5 374 0.2 4.6 53% 7.2 10 1554 N/A 20
1.3 22.1 374 0.2 4.4 50% 7.2 13 N/A N/A N/A
0.1 17.1 359 0.2 3.4 35% 7.3 8 2420 N/A 2
1.1 17.1 362 0.1 3.1 32% 7.3 11 N/A N/A N/A
0.1 12.4 298 0.2 4.8 45% 7.7 2 1120 N/A 1
1.7 12.3 299 0.2 4.8 45% 7.3 15 N/A N/A N/A
0.1 11.8 224 0.1 8.0 75% 7.8 2 215 N/A 2
1.4 11.6 221 0.1 7.8 71% 7.7 3 N/A N/A N/A
0.1 15.5 217 0.1 7.0 70% 7.4 2 150 N/A 2
1.5 15.5 217 0.1 6.8 68% 7.3 5 N/A N/A N/A
0.1 12.2 155 0.1 8.3 77% 6.8 5 225 N/A 2
1.2 12.2 155 0.1 8.3 77% 6.8 6 N/A N/A N/A
0.1 13.7 218 0.1 8.0 77% 7.2 3 205 N/A 3
1.5 13.3 219 0.1 7.8 75% 7.1 20 N/A N/A N/A
0.1 13.7 143 0.1 6.6 64% 6.6 2 154 N/A 2
1.6 13.7 144 0.1 5.8 54% 6.6 6 N/A N/A N/A
0.1 16.5 171 0.1 5.3 54% 6.7 8 867 N/A 2
1.4 16.4 171 0.1 4.8 49% 6.6 6 N/A N/A N/A
0.1 23.7 146 0.1 4.1 48% 6.5 1 1414 N/A 1
1.7 23.6 146 0.1 4.0 47% 6.4 3 N/A N/A N/A
0.1 27.1 378 0.2 3.3 42.00% 7.2 0 33000 N/A 13
0.1 27.0 314 0.1 3.2 40% 7.4 1 1483 N/A 13
0.1 23.9 244 0.1 5.1 61% 7.4 1 326 N/A 1
0.1 17.9 251 0.1 3.7 39% 7.7 1 1733 N/A 2
0.1 12.5 278 0.2 5.9 55% 8.2 0 817 N/A 1
0.1 11.6 199 0.1 8.0 73% 8.1 1 345 N/A 0
0.1 14.6 215 0.1 6.8 67% 7.7 3 345 N/A 1
0.1 11.8 161 0.1 8.6 80% 6.9 3 1733 N/A 3
0.1 13.1 174 0.1 8.8 84% 7.4 1 727 N/A 2
0.1 15.5 164 0.1 5.8 58% 7.0 2 308 N/A 3
0.1 18.0 173 0.1 4.4 46% 6.9 3 436 N/A 3
0.1 24.7 101 0.1 4.5 54% 6.7 5 2420 N/A 4
0.1 24.5 207 0.1 2.0 24% 6.5 39 600 N/A 8
2.9 18.0 561 0.3 0.6 7% 6.4 2 N/A N/A N/A
0.1 24.9 185 0.1 2.2 27% 6.9 7 384 N/A 14
3.0 18.2 606 0.3 0.8 9% 6.6 2 N/A N/A N/A
0.1 22.4 172 0.1 3.5 39% 7.0 16 308 N/A 2
3.1 19.5 411 0.2 2.8 29% 6.8 7 N/A N/A N/A
0.1 15.7 171 0.1 3.9 39% 7.1 29 180 N/A 2
2.9 15.0 249 0.2 0.6 6% 6.9 30 N/A N/A N/A
0.1 10.5 147 0.1 5.0 45% 7.5 2 138 N/A 1
3.4 9.3 256 0.2 3.1 26% 7.2 17 N/A N/A N/A
0.1 10.3 149 0.1 6.4 57% 7.5 5 37 N/A 1
3.4 8.1 255 0.2 5.0 42% 7.3 7 N/A N/A N/A
0.1 15.7 180 0.1 5.0 50% 7.1 6 96 N/A 4
3.3 11.3 409 0.3 3.0 27% 6.9 2 N/A N/A N/A
0.1 12.2 140 0.1 7.5 70% 6.6 7 1733 N/A 2
2.9 12.0 135 0.1 7.5 70% 6.6 6 N/A N/A N/A
0.1 13.0 157 0.1 9.8 93% 7.0 6 215 N/A 3
3.3 9.6 261 0.2 5.8 51% 6.8 9 N/A N/A N/A
0.1 14.1 119 0.1 5.6 55% 6.1 7 59 N/A 3
3.6 14.0 128 0.1 3.6 35% 6.2 11 N/A N/A N/A
0.1 16.6 147 0.1 3.7 38% 6.2 6 76 N/A 2
3.5 15.6 202 0.1 1.4 14% 6.4 8 N/A N/A N/A
0.1 23.7 125 0.1 2.3 27% 6.1 2 345 N/A 3
3.5 23.6 132 0.1 2.5 30% 6.1 7 N/A N/A N/A
0.1 30.0 9051 4.5 4.5 61% 7.0 4 580 N/A 23
2.0 30.0 9171 4.6 4.4 59% 7.0 4 N/A N/A N/A
0.1 29.0 2024 1.0 4.8 63% 7.5 6 52 N/A 22
1.6 29.0 2008 0.9 4.7 62.00% 7.4 7 N/A N/A N/A
0.1 25.9 6804 3.9 5.6 70% 7.3 26 249 N/A 5
1.6 25.9 6820 3.9 5.7 71% 7.2 24 N/A N/A N/A
0.1 20.4 6978 4.2 6.5 74% 7.3 18 817 N/A 9
1.8 20.4 71128 4.3 5.6 64% 7.2 20 N/A N/A N/A
0.1 13.7 10445 7.7 8.5 87% 7.4 14 313 N/A 3
1.9 13.7 10500 7.7 8.5 87% 7.3 18 N/A N/A N/A
0.1 12.1 3666 2.6 10.3 97% 7.6 5 41 N/A 2
1.8 12.0 3879 2.8 10.0 94% 7.5 5 N/A N/A N/A
0.1 13.5 522 0.3 10.0 97% 7.6 11 85 N/A 3
2.3 13.5 915 0.6 10.0 96% 7.5 11 N/A N/A N/A
0.1 12.1 465 0.3 9.8 83% 7.2 13 341 N/A 4
1.7 12.1 460 0.3 9.7 91% 7.1 13 N/A N/A N/A
0.1 12.0 1189 0.8 10.4 97% 7.1 15 63 N/A 4
1.9 12.0 1217 0.8 10.2 96% 7.0 16 N/A N/A N/A
0.1 18.0 1201 0.7 6.4 68% 7.3 12 109 N/A 15
2.0 18.0 1320 0.8 6.3 67% 7.2 14 N/A N/A N/A
0.1 19.5 2092 1.2 6.5 72% 7.3 5 98 N/A 6
1.9 19.5 2211 1.3 6.4 70% 7.2 7 N/A N/A N/A
0.1 26.7 319 0.2 4.3 54% 7.1 8 1333 N/A 13
2.0 26.7 324 0.2 4.1 52% 7.0 9 N/A N/A N/A
0.1 26.1 216 0.1 6.6 81% 7.1 1 60000 N/A 12
0.1 24.8 230 0.1 6.9 83% 7.2 0 1918 N/A 1
0.1 23.5 242 0.1 7.5 88% 7.1 6 2420 N/A 1
0.1 17.3 502 0.1 7.8 82% 7.1 0 2420 N/A 0
0.1 13.2 175 0.1 8.6 82% 7.3 0 867 N/A 1
0.1 15.1 192 0.1 9.1 90% 7.3 1 722 N/A 1
0.1 17.5 182 0.1 10.0 104% 7.1 2 518 N/A 1
0.1 14.0 132 0.1 10.4 101% 6.6 4 345 N/A 2
0.1 14.8 123 0.1 10.0 99% 6.9 29 2420 N/A 6
0.1 15.5 135 0.1 8.8 88% 6.8 4 143 N/A 2
0.1 17.5 153 0.1 8.3 87% 6.9 4 1204 N/A 1
0.1 23.6 162 0.1 7.2 85% 6.7 2 1300 N/A 1
0.1 29.4 5864 2.9 4.1 54% 7.1 3 22000 N/A 13
1.8 29.2 5844 2.9 3.6 48% 7.0 12 N/A N/A N/A
0.1 28.3 5156 2.6 4.9 64% 7.5 6 1081 N/A 3
2.1 28.3 5423 2.7 4.2 55% 7.4 18 N/A N/A N/A
0.1 26.1 13647 7.7 6.3 81% 7.3 24 687 N/A 4
2.5 26.1 13635 7.7 6.2 80% 7.2 32 N/A N/A N/A
0.1 21.2 14234 9.0 5.5 65% 7.1 27 1414 N/A 3
1.9 21.7 14413 9.1 5.5 65% 7.1 40 N/A N/A N/A
0.1 14.2 18090 13.8 8.8 94% 7.1 23 74 N/A 4
2.8 14.2 19075 14.6 8.6 91% 7.1 66 N/A N/A N/A
0.1 12.2 10323 7.9 11.0 108% 7.3 5 41 N/A 2
2.1 12.1 10921 8.4 10.5 103% 7.3 11 N/A N/A N/A
0.1 11.8 2757 2.0 10.4 97% 7.4 11 85 N/A 1
2.6 11.7 3021 2.2 10.1 94% 7.3 28 N/A N/A N/A
0.1 10.9 212 0.1 10.5 96% 7.7 12 84 N/A 2
2.2 10.9 212 0.1 10.5 96% 7.7 16 N/A N/A N/A
0.1 11.2 3092 2.2 11.4 106% 6.6 21 95 N/A 4
2.2 11.2 3113 2.3 11.4 105% 6.6 41 N/A N/A N/A
0.1 18.2 13174 8.9 7.0 78% 7.4 8 85 N/A 9
2.8 18.1 13910 9.4 6.7 75% 7.4 38 N/A N/A N/A
0.1 19.1 7899 5.0 9.0 100% 7.3 7 146 N/A 3
2.4 19.0 8071 5.1 7.0 78% 7.2 12 N/A N/A N/A
0.1 26.0 198 0.1 4.8 59% 7.0 6 218 N/A 3
2.4 26.0 198 0.1 4.8 58% 6.9 15 N/A N/A N/A
0.1 23.4 190 0.1 7.3 87% 7.5 0 2100 N/A 1
0.1 23.2 211 0.1 6.8 79% 7.3 7 2187 N/A 1
0.1 22.6 284 0.1 6.5 76% 7.1 32 2420 N/A 13
0.1 17.3 159 0.1 7.8 81% 7.4 1 867 N/A 1
0.1 13.5 140 0.1 8.6 83% 7.5 0 1300 N/A 1
0.1 12.6 173 0.1 8.2 77% 7.4 4 416 N/A 1
0.1 16.2 170 0.1 9.1 92% 7.2 13 462 N/A 1
0.1 13.7 117 0.1 9.8 96% 6.8 3 2420 N/A 1
0.1 14.4 129 0.1 9.8 97% 7.1 37 1733 N/A 6
0.1 15.4 218 0.1 8.0 80% 6.9 4 179 N/A 1
0.1 17.3 135 0.1 8.4 87% 6.9 10 2420 N/A 4
0.1 22.9 134 0.1 7.3 85% 6.7 2 2420 N/A 2
0.1 27.3 1995 1.0 3.9 50% 6.9 2 31000 N/A 26
1.5 27.3 2003 1.0 3.9 50% 6.8 2 N/A N/A N/A
0.1 27.6 743 0.3 4.4 56% 7.0 3 327 N/A 43
2.8 27.5 738 0.3 4.2 57% 7.0 4 N/A N/A N/A
0.1 247.0 807 0.4 5.6 67% 7.0 5 518 N/A 2
2.1 24.7 811 0.4 5.6 67% 7.0 6 N/A N/A N/A
0.1 18.6 837 0.5 5.5 57% 7.0 8 172 N/A 8
1.5 18.6 837 0.5 5.4 58% 7.0 8 N/A N/A N/A
0.1 13.8 1469 1.0 7.3 70% 6.8 6 468 N/A 3
1.5 13.2 1467 1.0 7.3 70% 6.8 6 N/A N/A N/A
0.1 12.5 307 0.2 8.6 81% 7.2 1 136 N/A 2
2.5 12.5 307 0.2 8.4 78% 7.2 4 N/A N/A N/A
0.1 16.0 283 0.2 8.7 88% 7.0 2 215 N/A 5
2.6 16.0 283 0.2 8.8 89% 7.0 3 N/A N/A N/A
0.1 12.8 170 0.1 9.4 88% 6.6 4 1733 N/A 6
2.0 12.8 170 0.1 9.4 88% 6.6 4 N/A N/A N/A
0.1 13.3 243 0.2 11.1 106% 6.8 4 249 N/A 21
2.0 13.3 243 0.2 11.0 105% 6.8 4 N/A N/A N/A
0.1 15.7 164 0.1 6.4 65% 6.9 5 186 N/A 4
2.8 15.7 164 0.1 6.2 62% 6.9 5 N/A N/A N/A
0.1 18.8 253 0.1 5.6 60% 7.0 4 817 N/A 10
2.1 18.8 254 0.1 5.6 60% 7.0 4 N/A N/A N/A
0.1 24.2 158 0.1 4.4 53% 6.7 3 1987 N/A 17
3.0 24.2 158 0.1 4.3 52% 6.7 6 N/A N/A N/A
APPENDIX C
Source Tracking Study
1
Final Report: Specific Quantitative Microbial Source Tracking Investigation
in Wilmington, NC
Dr. Rachel T. Noble, University of North Carolina Chapel Hill
Contact Information:
UNC Chapel Hill – Dr. Rachel Noble, Professor
3431 Arendell Street, Morehead City, NC 28557
July 3, 2013
2
Introduction
The concept for this small-scale fecal contamination study was to use a trio of Bacteroidales
based quantitative markers to confirm the presence of human fecal contamination and to quantify
that contamination in a framework of other available environmental parameter and fecal
indicator bacteria (FIB) data. This information is being interpreted in the context of available
local knowledge to deduce possible mechanisms of fecal contamination delivery and transport
dynamics. Bacteroides species are non-sporing, obligate anaerobes that are the numerically
dominant bacteria in the human large intestine with up to 1011cells per gram of human feces.
Previous research conducted by PI Noble has demonstrated a strong correlation between
Bacteroides thetaiotamicron concentrations to respective human sewage influent amounts
(Converse et al. 2009). We used three different Bacteroides based assays in order to determine
the presence of human fecal or other contamination in the samples. For more methodological
details see Converse et al. 2009, Kildare et al. 2007, and Layton et al. 2013).
Study Areas
Four sampling locations were identified by the Shaw Group as chronically contaminated during
stormwater events, and as such were areas of concern. These four sites are: Motts Creek, Smith
Creek, and an upstream and downstream location each in Pages Creek (Table 1).
Table 1. List of Sampling Sites
Creek Name Site Name Site Code Latitude Longitude
Motts Creek Normandy Drive MOT-ND 34° 08.373 77° 54.580
Smith Creek Candlewood Drive SC-CD 34° 17.438 77° 51.332
Pages Creek Bayshore Drive Down Stream PC-BDDS 34° 16.685 77° 47.673
Pages Creek Bayshore Drive Up Stream PC-BDUS 34° 16.623 77° 48.104
Motts Creek
Motts Creek watershed encompasses approximately 2,389 acres and is located in the
southwestern portion of the County, just below Sanders Road (Figure 1). The Creek drains
portions of Carolina Beach Road at its headwaters and then drains toward River Road before
entering into the Cape Fear River. Zoning in the watershed is predominately residential with
commercial business districts along Carolina Beach Road. Land in the watershed is classified as
transition, conservation or wetland resource protection according to the CAMA land use plan.
This watershed contains approximately 12.6% impervious surface coverage (Hume, 2009, Figure
2). Sampling was conducted at MOT-ND within the Motts Creek watershed between the months
of August 2012 and April 2013.
3
Figure 1. Water Quality Sites within the Motts Creek Watershed
Pages Creek
Located in northeastern New Hanover County and encompassing 2,044 acres, Pages Creek
watershed drains into the Intracoastal Waterway, north of Middle Sound Loop Road. Zoning
within the Pages Creek watershed is predominately residential, with commercial zoning along
Highway 17. The land within the Pages Creek watershed is predominately classified as
watershed resource protection and conservation, with a small portion classified as transitional
according to the CAMA land use plan. This watershed contains approximately 23.2%
impervious surface coverage (Hume, 2009). Sampling was conducted at two sites (PC-BDDS,
PC-BDUS) within the Pages Creek watershed (Figure 2).
4
Figure 2. Water Quality Sites within the Pages Creek Watershed
Smith Creek
Located in north-central New Hanover County and containing approximately 14,665 acres, the
Smith Creek watershed drains into the lower northeast Cape Fear River, just north of the Isabelle
Holmes Bridge. The watershed drains land within the City limits and the unincorporated
County, including the Wilmington International Airport. Zoning within the Smith Creek
watershed is a mix of industrial, residential, and commercial. The land within the watershed is
predominately classified as urban and transition, with a small portion classified as conservation.
This watershed contains approximately 21.9% impervious surface coverage (Hume, 2009).
Along with increased development and impervious surfaces, water quality in Smith Creek has
declined in recent years. High bacteria levels have been reported, as well as low dissolved
oxygen levels. As a result, Smith Creek has been listed on the 303(d) list for impaired waters
due to impaired biological integrity. One sampling location, SC-CD, was sampled over the
duration of the project (Figure 3).
5
Figure 3. Water Quality Sites within the Smith Creek Watershed
Sampling and Storm Event Analysis Approach:
Sampling was conducted by Coastal Planning & Engineering over the course of six storm events
at the four sites selected. Environmental data collected and rainfall data available electronically
is presented in Table 2. Water samples were collected for enumeration via Enterolert™, and
additional samples were collected and filtered and processed aseptically (as guided by the Noble
laboratory) by the Coastal Planning & Engineering for later batch analysis using well described
molecular methods (see below). 100 ml sample volumes were filtered in triplicate through 0.45
µm polycarbonate filters and frozen at -20 C and delivered to UNC Chapel Hill IMS within two
weeks of sample collection.
The filters were subjected to the following molecular analyses:
1. Fecal Bacteroides qPCR (Converse et al. 2009)
2. BacHum analyses (Kildare et al. 2007)
3. Human specific marker for Bacteroides (HF183, Layton et al. 2013)
Methodology: Bacteroides spp. comprise approximately one-third of the human fecal microflora,
considerably outnumbering Enterococcus and E. coli. The Bacteroides group belongs to a group
of non-spore-forming, gram-negative, obligate anaerobes, so there is little concern over regrowth
6
in the environment. Quantitative polymerase chain reaction (qPCR) methods are used to conduct
the Bacteroides assays:
Fecal Bacteroides qPCR assay (Converse et al. 2009) relies on Taqman chemistry and all
the reagents are in a liquid formulation, except the OmniMix. The assay quantifies a
cohort of bacteria found in high concentrations in the human gut, including Bacteroides
thetaiotaomicron, Bacteroides distastonis, and Bacteroides fragilis. However, the method
is not human specific. The assay has been tested against a range of different fecal
samples types, and has been shown to be capable of quantifying over a wide range of
concentrations, and to be sensitive at concentrations relevant to water quality source
tracking studies. When using the qPCR approach for fecal Bacteroides, strong
relationships have been observed with a wide array of human sewage collected from
areas on both east and west US coastlines. The assay is highly sensitive and the target
bacteria that are enumerated have been shown to be a predictor of human health in both
sand and recreational waters (Wade et. al. 2010, Heaney et al. 2012) during large-scale
EPA-run epidemiology studies. This is a fully quantitative qPCR-based assay that is
being used in an array of studies in stormwater contaminated areas and that, with the use
of other additional confirmatory methods, can be used to both identify potential hot spots
of human fecal contamination (Converse et al, 2009).
BacHum Human Marker: A separate qPCR assay was utilized to quantify the BacHum
molecular markers reported by Kildare et al., 2007. The assay has been widely tested for
specificity against a range of fecal sample types and has shown high capacity for
discrimination against human and animal fecal types (Ahmed et al., 2009).
HF (human fecal) 183: Human specific marker by qPCR has been conducted previously
by Bernhard and Field (2000) and updated by Seurinck et al., 2006. This assay is specific
to a region of ribosomal rDNA within the Bacteroides spp. that is found almost
exclusively in human feces. The assay has been tested repeatedly in a range of different
environments for cross reactivity with other types of fecal material, and various
researchers have found either a 90- to 100-percent ability to discriminate between human
and animal feces when using this assay. The assay, however, can be problematic when
used alone, because the target copy concentration in fecal material contributed to
receiving water environments can be quite low due to dilution and the assay has a
relatively low sensitivity.
Results:
The data generated over the course of this project is presented in Table 2. Very high
concentrations of Enterococcus spp. occurred over the period of time sampled and the array of
storm events captured, indicating a continued level of elevated concern about the microbial water
quality of the waters in question. Enterococcus concentrations ranged from 66.8 to >24196
MPN/100 ml, with 96% of the samples exhibiting Enterococcus concentrations that exceeded
EPA single sample standards for recreational waters (Table 2 and Figure 4). Enterococcus sp.
concentrations are not available for samples collected on April 29, 2013. Rainfall amounts for
the storms sampled ranged from 1.25 to 2.00 inches over the course of the study. These are
rainfall amounts that are typical of storms in the Wilmington, NC area, and would not be
expected to be categorized as an extreme event.
7
Table 2. Summary of site, date, environmental parameters, and molecular marker data for
four sites of concern for fecal contamination
Site Date
Rain
(inches)Time
Temp
oC
Cond
mS
Salinity
psu
DO
mg/L DO%pH
Turbidity
NTU
Entero.
(MPN/10
0 ml)
Fecal
Bacteroides
spp.
(CE/100 ml)
BacHum (gene
copies/100 ml)
HF183 (gene
copies/100 ml)
MOT-ND 8/29/2012 1.25 12:31 25.0 218.0 0.1 5.8 71 8 7 533.5 219,807 26,897 0
PC-BDDS 8/29/2012 1.25 13:44 25.0 1769.0 0.9 7.6 92 7.6 27 24196 133,887 49,889 0
PC-BDUS 8/29/2012 1.25 13:50 25.3 2171.0 1.1 7.2 88 7.7 20 24196 161,214 22,577 0
SC-CD 8/29/2012 1.25 13:31 24.6 113.0 0.1 6.8 82 7.5 17 24196 47,361 35,847 0
MOT-ND 10/3/2012 2.00 9:35 23.5 282 0.1 6.2 73 7.8 4 66.8 25,962 7,913 0
PC-BDDS 10/3/2012 2.00 10:30 24.8 48687 31.9 4 58 7.2 16 770 2,654 1,252 0
PC-BDUS 10/3/2012 2.00 10:25 24.3 41190 26.8 4.4 62 6.9 15 866.7 6,059 1,491 0
SC-CD 10/3/2012 2.00 10:07 23.1 228 0.1 6.4 75 7.5 0 1732.9 9,137 4,791 2,261
MOT-ND 11/15/2012 1.50 9:35 11.9 245 0.2 7.5 69 7.4 2 504 15,294 13 0
PC-BDDS 11/15/2012 1.50 10:24 12.8 38790 33.1 8.3 97 6.8 3 2481 1,936 1,211 0
PC-BDUS 11/15/2012 1.50 10:20 12.7 34982 29.6 7.7 88 6.6 5 1274 2,818 823 0
SC-CD 11/15/2012 1.50 10:03 12.4 178 0.1 9.1 85 7.3 0 384 308 5,607 0
MOT-ND 2/13/2013 1.75 12:06 12.5 234 0.2 9.4 88 6.1 8 8664 14,206 81,564 0
PC-BDDS 2/13/2013 1.75 10:52 12.8 34706 29.7 12.4 140 7.4 0 24196 29,434 8,461 1,010
PC-BDUS 2/13/2013 1.75 10:45 12.8 26002 21.3 12 140 7.5 12 24196 14,079 16,470 0
SC-CD 2/13/2013 1.75 9:42 14 132 0.1 10.4 101 6.6 4 6488 30,788 33,498 0
MOT-ND 3/12/2013 1.50 10:31 14.2 230 0.1 9.5 93 7.8 27 3998 1 508 97
PC-BDDS 3/12/2013 1.50 12:34 15 33327 26.5 8.3 84 6.1 12 24196 15907 53 POSITIVE BUT INHIBITED
PC-BDUS 3/12/2013 1.50 12:31 13.7 36230 30 8.3 84 6.3 0 24196 4685 18730 0
SC-CD 3/12/2013 1.50 11:53 14.8 123 0.1 10 99 6.9 28 24196 1596 0 POSITIVE BUT INHIBITED
MOT-ND 4/29/2013 1.5 11:18 17.8 161 0.1 7.2 74 7.4 38 NA 1930 102881 0
PC-BDDS 4/29/2013 1.5 11:38 18 88 0.1 8.4 86 7 42 NA 4122 41112 0
PC-BDUS 4/29/2013 1.5 11:53 18.1 40087 28.1 7.1 73 7.4 29 NA 15766 81640 0
SC-CD 4/29/2013 1.5 12:00 18.8 41338 30.6 7 79 7.8 9 NA 1594 72348 0
Figure 4. Enterococcus sp. concentrations as measured via Defined Substrate Technology
(Enterolert™) reported in Most Probable Number/100 ml for all four sampling locations.
Note, samples were not analyzed using Enterolert™ for samples collected on 4/29/2013.
8
A trio of Bacteroides-based molecular markers were quantified in order to assess the potential for
the presence of human fecal contamination at the four sites studied. To interpret molecular
microbial source tracking data, it is useful to cover a few terms used in the field as related to
sensitivity and specificity. These Bacteroides-based markers have been selected based upon
previous successfully conducted blind studies of human and animal fecal contamination
quantification and discrimination, and for their coverage of a range of specificities and
sensitivities. The Bacteroides-based methods chosen for this project have been recently
included in a range of publications (Layton et al. 2013, Boehm et al. 2013, Stewart et al. 2013,
Converse et al. 2009, Kildare et al. 2007, to name a few). These methods are well represented in
the peer reviewed literature. The three assays cover a range of specificities for human fecal
contamination. One way to look at specificity is to use a percentage attribution. That is, if 100
water sample containing human or animal fecal contamination were tested using each of the
three assay, what is the number of samples upon which the correct discrimination between the
two types of samples would have been made. For the Fecal Bacteroides spp., BacHum, and
HF183 assays, the specificities increase across the trio from 85%, 92% and 96% respectively.
Conversely, sensitivity is the chance that in a water sample containing human fecal
contamination that the marker will be detectable or present. Sensitivity is the lowest for the
HF183 assay, and increases strongly from the BacHum to the Fecal Bacteroides spp. assay. This
means that while HF183 is the most specific to human fecal contamination, that there is danger
in using it alone as a source tracking marker, because in some human fecal contamination, it will
occur at such low concentrations that false negatives may occur. Alternatively, it would not be
useful to base an entire source tracking study upon Fecal Bacteroides spp. quantification,
because while it occurs in the highest concentrations in human fecal contamination of the three
markers, it is the least specific.
The importance of specificity and sensitivity cannot be understated because of implications of
false negatives during real-world fecal contamination studies such as the one conducted here.
False negatives are essentially a non-detect result or low concentration result that occurs on a
sample due to methodological limitations. In a human fecal contamination source tracking study,
a non-detect, or negative result can lead someone to believe that human fecal contamination was
not present in water tested, when it the outcome could be a result of heterogeneity of the original
water sample, an inappropriate sampling and concentration approach, or poor methodological
constraints. Every effort has been made with this work to generate quantitative results on water
samples collected, even those that pose methodological limitations such as qPCR. While a full
discussion of false negatives and their implications is beyond the scope of this document, the
reader can refer to a series of well written articles resulting from the Source Identification Pilot
Project (SIPP) in the Journal of Water Research in the coming months in which PI Noble was a
major participant (Layton et al. 2013, Stewart et al. 2013, Boehm et al. 2013).
In previous studies conducted blindly on human and animal fecal contamination (HRSD AH
Environmental Report 2012), all three markers measured in this study were positive and
correctly identified human fecal contamination 100% of the time when applied in a similar
manner. Based upon these results, and other results of blind studies conducted in the past five
years, samples for which all three assays yield positive results are confirmed to contain at least
some level of human fecal contamination. If two of the assays are positive, it is likely that there
is the potential for human fecal contamination to have existed in the water sample. Finally, the
9
concentrations of the markers can be used to examine the levels of human fecal contamination in
the water tested and to prioritize remediation strategies.
In this study, 88% (21 of 24) of the site/storm dates yielded strongly positive results for at least 2
of the three human fecal contamination markers indicating that there is a strong likelihood for the
presence of human fecal contamination. Methodological limitations prevented accurate
quantification of the HF183 in a few instances, because the water sample collected and purified
had to be diluted in order to gain a proper qPCR signal from the sample. This is called “qPCR
inhibition”. Inhibition is typically caused by large high molecular weight molecules such as
humic and fulvic acids, which are present in high quantities in the Creeks studied here. Even
though there was inhibition of the samples, 13% of the site/storm dates studied yielded positive
results for all three of the human markers tested. Motts and Pages Creek (Figures 5, 6, and 7)
were the locations (both upstream and downstream) that dominated the Fecal Bacteroides spp.
concentrations with concentrations reported at both sites in excess of 100,000 CE/100 ml.
Smith Creek was the only location for which the HF183 marker concentration exceeded 1000
gene copies/100 ml (Figure 8). Two locations very weakly positive HF183 concentrations
(denoted as “positive but inhibited” in Table 2), Smith Creek and the Upstream site at Page’s
Creek (Figure 2B, C, and D). Even when the HF183 marker was measured, it was measured at
very low concentrations throughout this small study (Table 2). For the BacHum based marker
(see Kildare et al. 2007 for details), 96% of the samples were positive, ranging in concentrations
from 53 to 102,881 gene copies/100 ml. Motts Creek exhibited some of the highest BacHum
marker concentrations, along with the highest concentrations of this marker being observed
during the April 29, 2013 storm event for all three sites. There was no statistical relationship
between Bacteroides-based molecular markers and the Enterococcus concentrations or total
rainfall, but this study includes a small sample size, upon which it is often difficult to conduct
statistical analyses appropriately (p > 0.05, correlation analysis). This is a small study, and the
sites were selected based upon previous historical data showing contamination. All of the sites
indicate that human fecal contamination has the potential to pose a serious problem to these
receiving waters. The storm on 3/12/2013 posed a methodological problem because the storm
was so strong that the landscape was scoured resulting in high amount of inhibition in the water
samples collected. This can be viewed as inhibition of the qPCR reaction conducted. To remedy
this situation, the samples require either further purification or dilution to conduct full
quantification. With dilution of the sample comes not only dilution of the inhibitory
compounds, but also of course, dilution of the intended target, making it likely that false
negatives can be reported when the samples could have contained some of the marker. Indeed,
even with dilution of the sample to 1/125 of its original strength, inhibition was still being
observed in the qPCR reaction. Based upon the data generated, and especially the concentrations
of Fecal Bacteroides spp. and BacHum marker present during smaller rainfall events, it appears
that all three Creeks exhibit the propensity to be conduits of human fecal contamination but
delivery mechanisms for each of the creeks have not been elucidated. The patterns observed
indicate a risk to public health. Five priorities for future efforts to characterize and quantify
human fecal contamination at these three locations would be 1) assessment of the prevalence of
the HF183 marker in septic tanks/distribution boxes within each watershed. It has been
previously demonstrated that HF183 is a marker that is not always found in measurable
concentrations in septage (Converse et al. 2009) in which case moving to a marker more useful
for tracking septage based human fecal contamination would be useful, 2) further extraction and
10
purification of samples to remove inhibitory compounds, thereby improving sensitivity, 3) work
to further assess the signal of fecal contamination over the duration of storms, instead of a single
grab sample used to extrapolate to the entire storm, 4) focus on a single area, thereby permitting
greater spatial coverage of sampling, and 5) some simple assessment of the role of groundwater
and overland contamination delivery over a range of storm sizes will be useful.
Figure 5: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Motts Creek at Normandy Drive. Note axis is
on logarithmic scale.
Figure 6: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Pages Creek at Bayshore Drive Up Stream.
Note axis is on logarithmic scale.
11
Figure 7: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Pages Creek at Bayshore Drive Down Stream.
Note axis is on logarithmic scale.
Figure 8: Concentrations of molecular microbial source tracking markers Fecal
Bacteroides spp., BacHum, and HF183 reported in either cell equivalents (CE)/100 ml or
gene copies/100 ml from five storm events in Smith Creek at Candlewood Drive. Note axis
is on logarithmic scale.
12
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