2018-2019 Final ReportAPTIM
NEW HANOVER COUNTY WATER QUALITY MONITORING PROGRAM
2018-2019
FINAL REPORT
Prepared by:
Aptim Environmental & Infrastructure, Inc.
Marine Scientist: Brad Rosov, M.Sc.
Prepared For:
New Hanover County, North Carolina
Recommended Citation: Rosov, B., 2019. New Hanover County Water Quality Monitoring
Program: 2018-2019 Final Report. New Hanover County, North Carolina: Aptim Environmental and Infrastructure, Inc. 52p.
August 2019
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EXECUTIVE SUMMARY
This report represents the results of the New Hanover County Water Quality Monitoring Program between July 2018 and June 2019. Nineteen (19) monitoring stations within seven (7) tidal 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, and Enterococci 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 table 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 Mott Barnards Creek and Mott Creek while Futch Creek, Lords Creek, Prince George Creek, and Smith
Creek were deemed to be “Fair”. Only Pages Creek was “Poor” for dissolved oxygen during the
study period. Enterococci was “Good” within three of these watersheds- Futch Creek, Smith Creek, and Prince George Creek while Barnards Creek, Mott Creek, Pages Creek, and Lords Creek were deemed “Fair” for Enterococci. No creeks demonstrated “Poor” water quality for bacteria during the 2018-2019 sampling effort.
Ratings by Watershed
Parameter Barnards
Creek
Futch
Creek
Lords
Creek
Mott
Creek
Pages
Creek
Prince
George
Creek
Smith
Creek
Turbidity GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD FAIR FAIR GOOD POOR FAIR FAIR
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Enterococci FAIR GOOD FAIR FAIR FAIR GOOD GOOD
In general, the ratings for Entertococci bacteria improved between the 2017-2018 and the 2018-2019 reporting periods. One possible reason for this improvement could have been a result of a “flushing” of the watersheds following the passing of Hurricane Florence and its associated heavy rains and flooding.
On September 14, 2018, Hurricane Florence made landfall at Wrightsville Beach. This Category 1 storm brought winds over 100mph and over 20 inches of rain throughout New Hanover County. Post-storm water quality monitoring revealed low dissolved oxygen within sixteen (16) of the nineteen (19) sampling sites, however, bacterial levels were relatively low following the storm. It
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is hypothesized that the floodwaters delivered low oxygenated waters into the tidal creeks while
flushing the system of bacterial contamination.
Enterococci Ratings for each watershed during the 2017-2018 and the 2018-2019 reporting
periods. Barnards
Creek
Futch
Creek
Lords
Creek
Mott
Creek
Pages
Creek
Prince
George
Creek
Smith
Creek
Enterococci
2017-2018 FAIR FAIR POOR FAIR POOR POOR POOR
Enterococci
2018-2019 FAIR GOOD FAIR FAIR FAIR GOOD GOOD
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 water temperatures increase. However, during the cooler months, when the water temperature drops, these parameters improve. Generally speaking, the dissolved oxygen levels within each creek have not changed drastically from year to year. Turbidity and chlorophyll-a were not problematic in any creeks. Enterococci bacteria, however, has been a chronic problem within several of the creeks
monitored in this study. Mott Creek, Pages Creek, Barnards Creek, Smith Creek, and Prince George Creek have all maintained a relatively high level of bacteria over time. Lords Creek and Futch Creek, on average, have contained relatively lower bacteria levels compared to the other creeks included within this study. Since June 2008, samples collected within Mott Creek exceeded the State standard for Enterococci 46% of the time while Pages Creek, Barnards Creek, Smith
Creek, and Prince George Creek exceeded standard 39%, 31%, 30%, and 26% of the time, respectively. Lords Creek and Futch Creek contained the least amount of bacteria, exceeding standards only 12% and 5% of the time, respectively.
Airlie Gardens Three sampling sites within the lake at Airlie Gardens were included in the 2018-2019 monitoring effort. The results of the monitoring efforts within these locations suggested that dissolved oxygen varied significantly over the 12-month study within the lake. Similar to previous year’s results, the levels of the nutrient orthophosphate were relatively higher at the sampling location closest to the main storm water runoff input in proximity to the entrance of the gardens at Airlie Road. These
levels were generally lower at the two other sites indicating that the aquatic vegetation in the lake was utilizing the available orthophosphate in the water column to facilitate growth. This was indicated by the presence of algal blooms throughout much of the lake during the summer months, as nutrient-rich stormwater runoff contributes to eutrophication and resulting algal blooms. To help combat problems associated with this eutrophication, Airlie Gardens has installed several
aerators in the lake in an attempt to increase the dissolved oxygen levels, and the tributary upstream from one sampling location has recently undergone restoration efforts with the installation of a wetland BMP. Once established, this constructed wetland may help reduce the amount of nutrients entering the lake and the frequency and magnitude of algal blooms.
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Recommendations
The long-term water quality monitoring results suggest that the seven (7) creeks have experienced fairly good water quality in terms of turbidity and chlorophyll-a levels over the course of the twelve (12) year study thus far. The one parameter, however, that has been problematic has been
Enterococci bacteria. Of the 2,511 samples collected and analyzed since 2008, 679 (27%) of all samples have exceeded the standard for this bacteria. While several creeks have exhibited
relatively low levels of bacteria throughout the study (namely Futch Creek and Lords Creek), other creeks have proven to contain chronically high levels of Enterococci. Mott Creek has exceeded the standard 46% of the time and PC-BDDS and PC-BDUS within Pages Creek have exceeded the standard 47% and 62% of the time, respectively.
County-funded source tracking studies conducted in 2009 and 2013 suggested that human sewage was a contributing factor to the bacteria loading in Pages Creek. Although the bacteria levels dropped considerably following the passage of Hurricane Florence, the trend of relatively high
Enterococci bacteria resumed during the remainder of the 2018-2019 study period suggesting that the problem persists to this day. The resurgence of the bacteria indicates there is a possible source
driving the Enterococci levels to where further investigation is needed. While the CFPUA performed inspections of the lift stations adjacent to the two sampling sites and a public health warning sign has been posted at the private boat ramp at PC-BDUS, no further actions have been taken to resolve the issue.
Additional methods to identify the source of the contamination are currently being investigated. One possible method would employ the use of a fixed-wing unmanned aerial vehicle (UAV, aka drone) equipped with a thermal infrared sensor. The sensor may be used to identify areas of previously unidentified locations of point-source contamination within the watershed by discerning temperature differentials between the surface waters of the creek and its surrounding
environs. Once potential point source targets are located, ground truthing efforts may be employed to investigate further. Researchers at UNCW possess the required equipment and experience to conduct this sort of study should funding become available.
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TABLE OF CONTENTS
1.0 Introduction ...................................................................................................................... 1
Parameters ........................................................................................................................ 5
Standards .......................................................................................................................... 8
2.0 METHODS..................................................................................................................... 10
Physical Parameters........................................................................................................ 10
Chemical and Biological Parameters ............................................................................. 10
3.0 RESULTS....................................................................................................................... 11
Rating System ................................................................................................................ 11
Barnards Creek ............................................................................................................... 11
Futch Creek .................................................................................................................... 14
Lords Creek .................................................................................................................... 19
Mott Creek...................................................................................................................... 22
Pages Creek .................................................................................................................... 25
Prince George ................................................................................................................. 29
Smith Creek .................................................................................................................... 33
Comprehensive Rating by Watershed ............................................................................ 39
Long-Term Trends ...................................................................................................... 39
3.10.1 Dissolved Oxygen ................................................................................................... 39
3.10.2 Turbidity ................................................................................................................. 40
3.10.3 Chlorophyll-a .......................................................................................................... 42
3.10.4 Enterococci ............................................................................................................. 43
Airlie Gardens............................................................................................................. 44
4.0 DISCUSSION AND RECOMMENDATIONS ............................................................. 46
5.0 LITERATURE CITED .................................................................................................. 52
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LIST OF FIGURES
Figure 1. Map of New Hanover County and watersheds included in this study ......................... 3
Figure 2. Airlie Gardens Sampling Sites ..................................................................................... 4
Figure 3. Water Quality Sites within the Barnards Creek Watershed ....................................... 12
Figure 4. Dissolved Oxygen at BC-CBR ................................................................................... 13
Figure 5. Enterococci at BC-CBR ............................................................................................. 13
Figure 6. Water Quality Sites within the Futch Creek Watershed ............................................. 15
Figure 7. Dissolved Oxygen at FC-4 ......................................................................................... 16
Figure 8. Dissolved Oxygen at FC-6 ......................................................................................... 16
Figure 9. Dissolved Oxygen at FC-13 ....................................................................................... 16
Figure 10. Dissolved Oxygen at FC-FOY ................................................................................... 17
Figure 11. Enterococci at FC-4 .................................................................................................... 17
Figure 12. Enterococci at FC-6 .................................................................................................... 17
Figure 13. Enterococci at FC-13 .................................................................................................. 18
Figure 14. Enterococci at FC-FOY .............................................................................................. 18
Figure 15. Water Quality Site within the Lords Creek Watershed .............................................. 20
Figure 16. Dissolved Oxygen at LC-RR ...................................................................................... 21
Figure 17. Enterococci Levels at LC-RR .................................................................................... 21
Figure 18. Water Quality Sites within the Mott Creek Watershed .............................................. 23
Figure 19. Dissolved Oxygen at MOT-CBR ............................................................................... 24
Figure 20. Dissolved Oxygen at MOT-ND.................................................................................. 24
Figure 21. Enterococci at MOT-CBR .......................................................................................... 24
Figure 22. Enterococci at MOT-ND ............................................................................................ 25
Figure 23. Water Quality Sites within the Pages Creek Watershed ............................................ 26
Figure 24. Dissolved Oxygen at PC-BDDS ................................................................................. 27
Figure 25. Dissolved Oxygen at PC-BDUS ................................................................................. 27
Figure 26. Dissolved Oxygen at PC-M ........................................................................................ 28
Figure 27. Enterococci at PC-BDDS ........................................................................................... 28
Figure 28. Enterococci at PC-BDUS ........................................................................................... 28
Figure 29. Enterococci at PC-M .................................................................................................. 29
Figure 30. Water Quality Sites within the Prince George Creek Watershed ............................... 30
Figure 31. Dissolved Oxygen at PG-CH...................................................................................... 31
Figure 32. Dissolved Oxygen at PG-ML ..................................................................................... 31
Figure 33. Dissolved Oxygen at PG-NC...................................................................................... 32
Figure 34. Enterococci at PG-CH ................................................................................................ 32
Figure 35. Enterococci at PG-ML ............................................................................................... 32
Figure 36. Enterococci at PG-NC ................................................................................................ 33
Figure 37. Water Quality Sites within the Smith Creek Watershed ............................................ 34
Figure 38. Dissolved Oxygen at SC-23 ....................................................................................... 35
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Figure 39. Dissolved Oxygen at SC-CD ...................................................................................... 35
Figure 40. Dissolved Oxygen at SC-CH ...................................................................................... 36
Figure 41. Dissolved Oxygen at SC-GR ...................................................................................... 36
Figure 42. Dissolved Oxygen at SC-NK...................................................................................... 37
Figure 43. Enterococci at SC-23 .................................................................................................. 37
Figure 44. Enterococci at SC-CD ................................................................................................ 37
Figure 45. Enterococci at SC-CH ................................................................................................ 38
Figure 46. Enterococci at SC-GR ................................................................................................ 38
Figure 47. Enterococci at SC-NK ................................................................................................ 38
Figure 48. Long-term Surface Dissolved Oxygen data Within Tidal Creeks .............................. 42
Figure 49. Long-term Surface Dissolved Oxygen data Within Tidal Creeks .............................. 42
Figure 50. Long-term Surface Turbidity data Within Tidal Creeks ............................................ 40
Figure 51. Long-term Surface Turbidity data Within Tidal Creeks ............................................ 42
Figure 52. Long-term Chlorophyll-a data Within Tidal Creeks .................................................. 42
Figure 53. Long-term Chlorophyll-a data Within Tidal Creeks .................................................. 42
Figure 54. Long-term Enterococci data Within Tidal Creeks ..................................................... 42
Figure 55. Long-term Enterococci data Within Tidal Creeks ..................................................... 42
Figure 56. Dissolved Oxygen at AG-IN ...................................................................................... 45
Figure 57. Dissolved Oxygen at AG-FD ..................................................................................... 45
Figure 58. Dissolved Oxygen at AG-OUT .................................................................................. 45
Figure 59. Newly constructed wetland BMP at AG-IN………………………….……………...51
LIST OF TABLES
Table 1. List of Tidal Creek Sampling Sites ................................................................................ 2
Table 2. List of Airlie Gardens Sampling Sites ........................................................................... 2
Table 3. North Carolina Water Quality Standards ....................................................................... 8
Table 4. Single sample standards for Enterococci as determined by the US EPA ...................... 9
Table 5. Single sample standards for Enterococci as determined by the NC DEQ Recreational
Water Quality Program ................................................................................................................... 9
Table 6. Tier Classification for New Hanover County Water Quality Monitoring Sites ............ 9
Table 7. Mean values of select parameters from Barnards Creek. Range in parentheses. ....... 12
Table 8. Ratings of parameters within sampling stations within Barnards Creek ..................... 13
Table 9. Mean values of select parameters from Futch Creek. Range in parentheses. ............. 15
Table 10. Ratings of parameters within sampling stations within Futch Creek .......................... 18
Table 11. Mean values of select parameters from Lords Creek. Range in parentheses. ............ 20
Table 12. Ratings of parameters within sampling stations within Lords Creek .......................... 21
Table 13. Mean values of select parameters from Mott Creek. Range in parentheses. .............. 23
Table 14. Ratings of parameters within sampling stations within Mott Creek ............................ 25
Table 15. Mean values of select parameters from Pages Creek. Range in parentheses. ............ 27
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Table 16. Ratings of parameters within sampling stations within Pages Creek .......................... 29
Table 17. Mean values of select parameters from Prince George Creek. . ................................. 31
Table 18. Ratings of parameters within sampling stations within Prince George Creek ............ 33
Table 19. Mean values of select parameters from Smith Creek. Range in parentheses. ............ 35
Table 20. Ratings of parameters within sampling stations within Smith Creek .......................... 38
Table 21. Ratings of parameters within each watershed.............................................................. 39
Table 22. Enterococci ratings for each watershed during all reporting periods…………….......43
Table 23. Mean values of select parameters from Airlie Gardens. Range provided in
parentheses. ................................................................................................................................... 46
LIST OF APPENDICES
Appendix No.
A Photographs of Sampling Sites B Raw Data C Airlie Gardens Data
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1.0 INTRODUCTION
New Hanover County is the second smallest county and the second most densely populated county
in N.C. The county is an urban, coastal county containing many watersheds. 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. The population within the County
continues to grow, with an increase of approximately 25,000 people since the 2010 US Census. The census estimates the County contains a population of 227,198 as of July 2018 (US Census Bureau, 2018). To address these issues associated with growth that impact water quality, the County has administered a long-standing water quality monitoring program designed to assess the
water quality within the creeks located within the County since 1993.
Aptim Environmental and Infrastructure, Inc. (APTIM) began monitoring seven (7) tidal creeks within New Hanover County on a monthly basis in November 2007. The information presented in this report focuses on the results of this monitoring between the months of July 2018 and June
2019. The creeks included in this study are Pages and Futch Creek, which drain into the Atlantic
Intracoastal Waterway (ICW) and Lords, Mott, Barnards, Smith, and Prince George Creek, which drain into the Cape Fear River (Figure 1, Table 1). Along with examining the data collected from the past 12 months, long term trends have been assessed using data obtained by APTIM since 2007.
In addition to the continued sampling from the seven tidal creeks, three sampling sites from within Airlie Gardens were added to the program during the 2015-2016 sampling efforts. Airlie Gardens is a 67-acre public garden owned and operated by New Hanover County since 1999. The property, located within the Bradley Creek watershed, includes a 10-acre freshwater lake. The lake receives
input from several stormwater culverts which serves to manage runoff from nearby development.
Water quality monitoring was conducted at three locations within the lake. These locations include AG-IN which is located on the northern portion of the lake where stormwater enters the lake. AG-FD is located in a central portion of the lake. AG-OUT is located at the southern portion in proximity to the drainage outfall (Figure 2, Table 2).
Photographs of each sampling site are found in Appendix A. Raw data from the tidal creeks sampling sites and the Airlie Garden sampling sites are found in Appendix B and Appendix C, respectively.
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Table 1. List of Tidal Creek Sampling Sites
Creek Name Site Name Site Code Latitude Longitude
Mott Creek Carolina Beach Road MOT-CBR 34° 08.610 77° 53.830
Mott 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 George Creek Marathon Landing PG-ML 34° 21.088 77° 55.349
Prince George Creek Castle Hayne Road PG-CH 34° 20.675 77° 54.217
Prince George 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
Table 2. List of Airlie Gardens Sampling Sites
Site Name Site Code Latitude Longitude
Airlie Gardens In AG-IN 34° 21749 77° 82873
Airlie Gardens Floating Dock AG-FD 34° 21549 77° 82796
Airlie Gardens Out AG-OUT 34° 21336 77° 82713
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Figure 1. Map of New Hanover County and watersheds included in this study
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Figure 2. Airlie Gardens Sampling Sites
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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:
C: Waters protected for uses such as secondary recreation, fishing, wildlife, fish
consumption, aquatic life including propagation, survival and maintenance of biological
integrity, and agriculture. Secondary recreation includes wading, boating, and other uses involving human body contact with water where such activities take place in an infrequent, unorganized, or incidental manner. This includes the lake within Airlie Gardens
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, Mott Creek, Barnards Creek, Smith Creek, and Prince George 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.
PARAMETERS
Physical, chemical, and biological water quality monitoring data have been collected at each of
the tidal creek sampling locations. 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 Enterococci, a fecal indicator bacteria. At the Airlie Gardens sampling locations, the same physical parameters were collected. Due to funding limitations and the determination that bacterial contamination was
not determined to be a potential threat, Enterococci samples were not collected. Rather, due to the
fact that the lake has historically undergone periods if high macroalgae growth, two indicators of nutrients were collected; orthophosphate and nitrate/nitrite,
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
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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.
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.
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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.
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.
Orthophosphate:
Phosphorus is a nutrient required by all organisms for the basic processes of life. Phosphorus is a
natural element found in rocks, soils and organic material. Phosphorus clings tightly to soil particles and is used by plants, so its concentration in clean waters is generally very low. However, phosphorus is used extensively in fertilizer and other chemicals, so it can be found in higher concentrations in areas of human activity. High levels in the water column can be detrimental to
water quality as phosphates can cause algal blooms resulting in decreased dissolved oxygen levels.
Orthophosphate is sometimes referred to as "reactive phosphorus." Orthophosphate is the most stable kind of phosphate, and is the form used by plants. Orthophosphate is produced by natural processes and is found in sewage.
Nitrate/Nitrite: Nitrate is highly soluble (dissolves easily) in water and is stable over a wide range of environmental conditions. It is easily transported in streams and groundwater. Nitrates feed plankton (microscopic plants and animals that live in water), aquatic plants, and algae, which are then eaten by fish. Nitrite
is relatively short-lived in water because it is quickly converted to nitrate by bacteria.
Excessive concentrations of nitrate and/or nitrite can be harmful to humans and wildlife. If excessive amounts of nitrates are added to the water, algae and aquatic plants can be produced in large quantities. When these algae die, bacteria decompose them, and use up oxygen.
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STANDARDS
Water quality standards have been established legislatively for a number of these parameters
(Table 3). 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 4). 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 5). 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 and the lake in Airlie Gardens 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 6). Based on this analysis, of the nineteen (19) tidal creek sampling sites, two (2) could be considered Tier II and seventeen (17) could be considered Tier III. All three (3) of the Airlie Garden sites are considered Tier III
Table 3. North Carolina Water Quality Standards
Parameter Standard for C Waters Standard for C Sw Waters Standard for SA Waters Dissolved
Oxygen
4.0 mg/la 4.0 mg/la 5.0 mg/l
Turbidity 50 NTU 50 NTU 25 NTU
pH 6.0-9.0b 6.0-9.0b 6.8-8.5
Chlorophyll-a 40.0 ug/l 40.0 ug/l 40.0 ug/l
Fecal Coliform Geometric Mean (5 samples within 30 days) <200 CFU/100ml; or single sample <400 CFU/100ml
Geometric Mean (5 samples within 30 days) <200 CFU/100ml; or single sample <400 CFU/100ml
Geometric Mean (5 samples within 30 days) <14 CFU/100ml; or 10% of samples <43 CFU/100ml
Enterococci c Geometric Mean (5 samples
within 30 days) <35 CFU/100ml
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 DEQ Recreational Water Quality Program
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Table 4. 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 5. Single sample standards for Enterococci as determined by the NC DEQ Recreational Water Quality
Program
Description 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 6. 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
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
AG-IN Tier III No Northern portion of Airlie Gardens Lake
AG-FD Tier III No Central portion of Airlie Gardens Lake
AG-OUT Tier III No Southern portion of Airlie Gardens Lake
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2.0 METHODS
These seven tidal creeks included within this study and the lake in Airlie Gardens 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 tidal creek 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/). The sites sampled within Airlie Gardens are not influenced by the tide and therefore no efforts were made to associate the timing of sampling with the tidal stage in the surrounding waters.
Due to time constraints, monthly sampling events were conducted on three subsequent days each
month. Sites within Airlie Gardens, Lords Creek, Mott Creek, and Barnards Creek were visited on the first sampling day while Smith Creek and Prince George 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).
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.
CHEMICAL AND BIOLOGICAL PARAMETERS
Water samples were obtained for the laboratory analysis of chemical (nitrate/nitrite and orthophosphate) and biological (Enterococci 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 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:
Orthophosphate: SM 4500E Nitrate/Nitrite: EPA 353.2 Chlorophyll-a: SM 10200H
Enterococci: EnterolertE
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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 2018 and June 2019. These results are primarily organized by watershed with the results of the 7 tidal creeks presented first followed by the results from Airlie Gardens. All raw data, including parameters not summarized in this section, are included in Appendix B.
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.
BARNARDS CREEK
The Barnards Creek watershed covers 4,176 acres and is among the most urban of watersheds located within Unincorporated New Hanover County. While most of the Barnards Creek watershed lies within the City of Wilmington’s jurisdiction, roughly eighteen percent of the watershed is within the unincorporated County. The watershed is home to a large amount of development with
a wide range of different zoning classifications and different uses including B-1, B-2, O&I, I-2, R-7, R-10, and R-15 in the unincorporated portion of New Hanover County. Barnards Creek flows in a generally westerly direction from its headwaters near the intersection of S. College Road and 17th Street to the Cape Fear River between the intersection of River Road and Independence Blvd, and the Riverlights development. Sampling was conducted at one site (BC-CBR) within the
Barnards Creek watershed (Figure 3). Dissolved oxygen within BC-CBR ranged between 1.9 mg/l and 11.1 mg/l with a mean value of 6.7 mg/l (Table 7). One (1) sample contained dissolved oxygen levels below the State standard of 4.0 mg/l for C Sw waters at the surface. Two (2) samples broached this limit near the bottom of
the water column (Figure 4). Chlorophyll-a ranged between 0.0 ug/l and 4.0 ug/l with a mean value of 2.0 ug/l at BC-CBR (Table 7). These values did not approach the 40ug/l standard.
Enterococci ranged between 10 CFU/100ml and 867 CFU/100ml with a geometric mean value of 70 CFU/100ml, which is below the NCDEQ standard of 500 CFU/100ml for Tier III waters (Figure 5, Table 7). Two (2) of the twelve (12) samples collected during this period exceeded this standard.
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Turbidity values were generally good ranging between 3 and 58 NTU with a mean value of 12 NTU (Table 7). One (one) sample exceeded the State standard of 50 NTU for C SW waters.
Table 8 depicts the ratings for these parameters for the watershed.
Figure 3. Water Quality Sites within the Barnards Creek Watershed
Table 7. Mean values of select parameters from Barnards Creek. Range in parentheses.
Parameter BC-CBR
Turbidity (NTU) 12 (3-58)
Dissolved Oxygen (mg/l) 6.7 (1.9-11.1)
Chlorophyll-a (ug/l) 2.0 (0.0-4.0)
Enterococci (#CFU/100ml) 70 (10-867)1
(1)Enterococci values expressed as geometric mean
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Figure 4. Dissolved Oxygen at BC-CBR at surface (DO-S) and bottom (DO-B)
Figure 5. Enterococci at BC-CBR
Table 8. Ratings of parameters within sampling stations within Barnards Creek
Parameter BC-CBR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci FAIR
0.0
2.0
4.0
6.0
8.0
10.0
12.0
DO
m
g
/
L
BC-CBR Dissolved Oxygen
DO-S
DO-B
1
10
100
1000
En
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#
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Enterococci Levels at BC-CBR
Entero.
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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 3,813 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 (R-15 and R-20) with a small business district (B-1 and O&I) along Highway 17. Sampling was conducted at four (4) sites (FC-4, FC-6, FC-13, and FC-FOY) within the Futch Creek watershed (Figure 6) on eleven
(11) occasions over the twelve (12) month study.
Dissolved oxygen within Futch Creek ranged between 3.1 mg/l and 9.6 mg/l with a mean value of 6.7 mg/l (Figure 7 - Figure 10, Table 9). One sample collected each from FC-4 and FC-13 contained dissolved oxygen levels below the State standard of 5.0 mg/l for SA while two samples
from both FC-6 and FC-FOY exceeded the standard. The rest of the samples were compliant.
Chlorophyll-a ranged between 0.0 ug/l and 25.0 ug/l with a mean value of 4.0 ug/l (Table 8). None of these values approached the 40ug/l Chlorophyll-a standard.
Enterococci ranged between 5 CFU/100ml and 1,550 CFU/100ml with a geometric mean value of
14 CFU/100ml. One (1) sample collected within Futch Creek during exceeded the NCDEQ
Enterococci standard of 500 CFU/100ml for Tier III waters (Figure 11 - Figure 14, Table 8). Turbidity values were generally low ranging between 1 and 27 NTU with a mean value of 6 NTU
(Table 10). One (1) sample collected near the bottom of the water column at FC-FOY exceeded
the State standard of 25 NTU for SA waters, however no surface samples broached this standard. Table 10 depicts the ratings for these parameters for the watershed.
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Figure 6. Water Quality Sites within the Futch Creek Watershed
Table 9. Mean values of select parameters from Futch Creek. Range in parentheses.
Parameter FC-4 FC-6 FC-13 FC-FOY
Turbidity
(NTU) 6 (1-17) 5 (2-14) 6 (1-18) 7 (2-27)
Dissolved
Oxygen (mg/l) 6.8 (4.6-9.6) 6.8 (4.2-9.6) 6.7 (3.1-9.1) 6.7 (4.0-9.4)
Chlorophyll-a (ug/l) 3.0 (0.0-6.0) 4.0 (0.0-18.0) 6.0 (1.0-25.0) 3.0 (1.0-11.0)
Enterococci (#CFU/100ml) 17 (5-201)1 11 (5-107)1 21 (5-1550)1 11 (5-129)1
(1)Enterococci values expressed as geometric mean
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Figure 7. Dissolved Oxygen at FC-4 at surface (DO-S) and bottom (DO-B)
Figure 8. Dissolved Oxygen at FC-6 at surface (DO-S) and bottom (DO-B)
Figure 9. Dissolved Oxygen at FC-13 at surface (DO-S) and bottom (DO-B)
0.0
2.0
4.0
6.0
8.0
10.0
12.0
DO
m
g
/
L
FC-4 Dissolved Oxygen
DO-S
DO-B
0.0
2.0
4.0
6.0
8.0
10.0
12.0
DO
m
g
/
L
FC-6 Dissolved Oxygen
DO-S
DO-B
0.0
2.0
4.0
6.0
8.0
10.0
DO
m
g
/
L
FC-13 Dissolved Oxygen
DO-S
DO-B
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Figure 10. Dissolved Oxygen at FC-FOY at surface (DO-S) and bottom (DO-B)
Figure 11. Enterococci at FC-4
Figure 12. Enterococci at FC-6
0.0
2.0
4.0
6.0
8.0
10.0
DO
m
g
/
L
FOY Dissolved Oxygen
DO-S
DO-B
0
50
100
150
200
250
En
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m
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)
Enterococci Levels at FC-4
Entero.
0
20
40
60
80
100
120
En
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m
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)
Enterococci Levels at FC-6
Entero.
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Figure 13. Enterococci at FC-13
Figure 14. Enterococci at FC-FOY
Table 10. 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 FAIR GOOD FAIR
Chlorophyll-a GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD
1
10
100
1000
10000
En
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)
Enterococci Levels at FC-13
Entero.
0
20
40
60
80
100
120
140
En
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Enterococci Levels at FC-FOY
Entero.
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LORDS CREEK
The Lords Creek Watershed is located in the southwestern portion of the County and encompasses
approximately 1,058acres. Zoning within the watershed vastly residential (R-15) but also contains
and industrial parcel (I-2) and an office and institutional parcel (O&I). Sampling was conducted at one (1) site (LC-RR) within the Lords Creek watershed (Figure 15). During the 2018-2019 study period, the sampling site was inaccessible during 6 of the 12 sampling events due to the closure of the bridge crossing Lords Creek on River Road.
Dissolved oxygen LC-RR ranged between 2.1 mg/l and 10.3 mg/l with a mean value of 7.4 mg/l (Table 11). Two (2) samples were below the acceptable level above the State standard of 4.0 mg/l for C Sw waters during the sampling period (Figure 16).
Chlorophyll-a ranged between 2.0 ug/l and 28.0 ug/l with a mean value of 9.0 ug/l (Table 10). No
samples exceeded the State standard of 40ug/l for Chlorophyll-a.
Enterococci ranged between 5 CFU/100ml and 2,420 CFU/100ml with a geometric mean value of 61 CFU/100ml (Table 11). Two (2) of the twelve (12) samples collected over this reporting period
contained high levels of Enterococci beyond the NCDEQ standard of 500 CFU/100ml for Tier III
waters. Turbidity values were generally moderate ranging between 7 and 27 NTU with a mean value of 17 NTU (Table 11). No samples exceeded the State standard of 50 NTU for C Sw waters in Lords
Creek during the reporting period.
Table 12 depicts the ratings for these parameters for the watershed.
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Figure 15. Water Quality Site within the Lords Creek Watershed
Table 11. Mean values of select parameters from Lords Creek. Range in parentheses.
Parameter LC-RR
Turbidity (NTU) 17 (7-27)
Dissolved Oxygen (mg/l) 7.4 (2.1-10.3)
Chlorophyll-a (ug/l) 9 (2.0-28.0)
Enterococci (#CFU/100ml) 61 (5-2420)1
(1)Enterococci values expressed as geometric mean
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Figure 16. Dissolved Oxygen at LC-RR at surface (DO-S) and bottom (DO-B)
Figure 17. Enterococci Levels at LC-RR
Table 12. Ratings of parameters within sampling stations within Lords Creek
Parameter LC-RR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci FAIR
0.0
2.0
4.0
6.0
8.0
10.0
12.0
DO
m
g
/
L
LC-RR Dissolved Oxygen
DO-S
DO-B
1
10
100
1000
10000
En
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Enterococci Levels at LC-RR
Entero.
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MOTT CREEK
Mott Creek is located in the southern portion of New Hanover County and drains an area of 3,342
acres in size where a small portion of the watershed crosses into the City of Wilmington. Three
quarters of the total area of the watershed is residential. At the same time, the watershed is also home to Monkey Junction, the intersection of Carolina Beach and S. College Roads and the most intensely developed area in the southern portion of unincorporated New Hanover County. The creek itself flows from its headwaters through the center of the immediate Monkey Junction area,
then in a generally southwesterly direction until it meets the Cape Fear River near the intersection
of River and Sanders Roads. Zoning districts of the unincorporated area of the Mott Creek watershed include B-1, B-2, O&I, PD, R-10, and R-15. Sampling was conducted at two (2) sites (MOT-CBR, MOT-ND) within the Mott Creek watershed (Figure 18).
Dissolved oxygen within Mott Creek ranged between 4.2 mg/l and 10.8 mg/l with a mean value
of 7.4 mg/l (Figure 19 and Figure 20, Table 13). No samples collected during the reporting period contained dissolved oxygen levels below the standard (Figure 19 and Figure 20). Chlorophyll-a ranged between 1.0 ug/l and 83.0 ug/l with a mean value of 8.0 ug/l (Table 13).
One sample exceeded the 40ug/l standard.
Enterococci ranged between 10 CFU/100ml and 7220 CFU/100ml with a geometric mean value of 179 CFU/100ml (Table 12). Samples exceeded the NCDEQ standard of 500 CFU/100ml for Tier III waters during six (6) sampling events during the reporting period (Figure 20 and Figure
21).
Turbidity values were generally good ranging between 6 and 21 NTU with a mean value of 11 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 18. Water Quality Sites within the Mott Creek Watershed
Table 13. Mean values of select parameters from Mott Creek. Range in parentheses.
Parameter MOT-CBR MOT-ND
Turbidity (NTU) 9 (6-20) 12 (7-21)
Dissolved Oxygen (mg/l) 7.2 (4.3-10.8) 7.6 (4.2-10.7)
Chlorophyll-a (ug/l) 10.0 (1.0-83.0) 6.0 (2.0-20.0)
Enterococci (#CFU/100ml) 117 (10-2420)1 275 (31-7220)1
(1)Enterococci values expressed as geometric mean
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Figure 19. Dissolved Oxygen at MOT-CBR at surface (DO-S)
Figure 20. Dissolved Oxygen at MOT-ND at surface (DO-S)
Figure 21. Enterococci at MOT-CBR
0.0
2.0
4.0
6.0
8.0
10.0
12.0
DO
m
g
/
L
MOT-CBR Dissolved Oxygen
DO-S
0.0
2.0
4.0
6.0
8.0
10.0
12.0
DO
m
g
/
L
MOT-ND Dissolved Oxygen
DO-S
1
10
100
1000
10000
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)
Enterococci Levels at MOT-CBR
Entero.
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Figure 22. Enterococci at MOT-ND
Table 14. Ratings of parameters within sampling stations within Mott Creek
Parameter MOT-CBR MOT-ND
Turbidity GOOD GOOD
Dissolved Oxygen GOOD GOOD
Chlorophyll-a GOOD GOOD
Enterococci FAIR POOR
PAGES CREEK
Located in northeastern New Hanover County and encompassing 5,025 acres, Pages Creek
watershed drains into the Intracoastal Waterway, north of Middle Sound Loop Road. Zoning within the Pages Creek watershed is predominately residential (R-15 and R-20), with commercial (B-1 and B-2) zoning along Highway 17. Sampling was conducted at three (3) sites (PC-BDDS, PC-BDUS, and PC-M) within the Pages Creek watershed (Figure 23).
Dissolved oxygen within Pages Creek ranged between 3.0 mg/l and 9.6 mg/l with a mean value of 6.3 mg/ (Table 15) (Figure 24 through Figure 26). Of the three (3) sites monitored over the twelve (12) month study, the dissolved oxygen levels exceeded the standard twelve (12) times- six (6) of these exceedances were observed within PC-BDDS (Figure 24 and Figure 25).
Chlorophyll-a ranged between 0.0 ug/l and 350.0 ug/l with a mean value of 15.0 ug/l (Table 15). Two samples exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 5 CFU/100ml and 2,610 CFU/100ml with a geometric mean value of 79 CFU/100ml (Figure 27 through Figure 29, Table 15). One (1) sample from PC-M contain high
levels of Enterococci while three (3) and five (5) samples from PC-BDDS and PC-BDUS, respectively, contained levels higher than the NCDEQ standard.
1
10
100
1000
10000
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Enterococci Levels at MOT-ND
Entero.
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Turbidity values were generally good ranging between 2and 32NTU with a mean value of 9 NTU (Table 14). One (1) of the observed turbidity values exceeded the State standard of 25 NTU for
class SA waters.
Table 16 depicts the ratings for these parameters for the watershed.
Figure 23. Water Quality Sites within the Pages Creek Watershed
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Table 15. Mean values of select parameters from Pages Creek. Range in parentheses.
Parameter PC-BDUS PC-BDDS PC-M
Turbidity (NTU) 9 (3-32) 9 (2-32) 8 (2-22)
Dissolved Oxygen (mg/l) 6.3 (3.7-8.4) 5.9 (3.4-9.4) 6.7 (3.0-9.6)
Chlorophyll-a (ug/l) 34.0 (1.0-350.0) 4.0(1.0-14.0) 8.0 (0.0-63.0)
Enterococci (#CFU/100ml) 203 (41-1610)1 164 (5-2610)1 15 (5-350)1
(1)Enterococci values expressed as geometric mean
Figure 24. Dissolved Oxygen at PC-BDDS at surface (DO-S)
Figure 25. Dissolved Oxygen at PC-BDUS at surface (DO-S)
0.0
2.0
4.0
6.0
8.0
10.0
DO
m
g
/
L
PC-BDDS Dissolved Oxygen
DO-S
0.0
2.0
4.0
6.0
8.0
10.0
DO
m
g
/
L
PC-BDUS Dissolved Oxygen
DO-S
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Figure 26. Dissolved Oxygen at PC-M at surface (DO-S) and bottom (DO-B)
Figure 27. Enterococci at PC-BDDS
Figure 28. Enterococci at PC-BDUS
0.0
2.0
4.0
6.0
8.0
10.0
DO
m
g
/
L
PC-M Dissolved Oxygen
DO-S
DO-B
1
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10000
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Enterococci Levels at PC-BDDS
Entero.
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Enterococci Levels at PC-BDUS
Entero.
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Figure 29. Enterococci at PC-M
Table 16. Ratings of parameters within sampling stations within Pages Creek
Parameter PC-BDDS PC-BDUS PC-M
Turbidity GOOD GOOD GOOD
Dissolved Oxygen POOR FAIR FAIR
Chlorophyll-a GOOD GOOD GOOD
Enterococci FAIR POOR GOOD
PRINCE GEORGE
Prince George Creek drains into the Cape Fear River. The Prince George Creek watershed is approximately 13,475 acres and drains most of Castle Hayne, extending eastward across I-40 into the Blue Clay Road area. Zoning within the Prince George Creek watershed is predominately residential (RA, R-15, and R-20) with some business (B-1 and B-2) and industrial parcels (I-1 and O&I) within Castle Hayne. Sampling was conducted at three (3) sites (PG-CH, PG-ML, and PG-
NC) within the Prince George Creek watershed (Figure 30). Dissolved oxygen within Prince George Creek ranged between 0.2 mg/l and 11.4 mg/l with a mean value of 6.1 mg/l (Table 16). Surface dissolved oxygen values were below the State standard of 4.0 mg/l for C Sw on nine (9) occasions during the reporting period at PG-NC, five (5) times at
PG-NC, and three (3) times at PG-ML (Figure 31 through Figure 33). Chlorophyll-a ranged between 1.0 ug/l and 108.0 ug/l with a mean value of 7.0 ug/l (Table 17). Two samples from Prince George Creek exceeded the 40ug/l standard.
Enterococci ranged between 5 CFU/100ml and 609 CFU/100ml with a geometric mean value of 36 CFU/100ml (Table 17). During this study, one (1) sample collected from within PG-CH contained Enterococci levels above the NCDEQ standard of 500 CFU/100ml for Tier III waters (Figure 34 through Figure 36).
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Turbidity values were generally good ranging between 2 and 14 NTU with a mean value of 6 NTU (Table 17). No samples exceeded the State standard of 50 NTU for C Sw waters.
Table 18 depicts the ratings for these parameters for the watershed.
Figure 30. Water Quality Sites within the Prince George Creek Watershed
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Table 17. Mean values of select parameters from Prince George Creek. Range in parentheses.
Parameter PG-CH PG-ML PG-NC
Turbidity (NTU) 6 (3-10) 6 (2-14) 6 (3-9)
Dissolved Oxygen (mg/l) 7.6 (6.1-8.8) 6.4 (0.2-11.4) 4.3 (0.2-10.1)
Chlorophyll-a (ug/l) 7.0 (1.0-57.0) 3.0 (1.0-18.0) 11.0 (1.0-108.0)
Enterococci (#CFU/100ml) 41 (5-169)1 63 (5-609)1 18 (5-97)1
(1)Enterococci values expressed as geometric mean
Figure 31. Dissolved Oxygen at PG-CH at surface (DO-S) and bottom (DO-B)
Figure 32. Dissolved Oxygen at PG-ML at surface (DO-S)
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Figure 33. Dissolved Oxygen at PG-NC at surface (DO-S) and bottom (DO-B)
Figure 34. Enterococci at PG-CH
Figure 35. Enterococci at PG-ML
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Figure 36. Enterococci at PG-NC
Table 18. Ratings of parameters within sampling stations within Prince George Creek
Parameter PG-CH PG-ML PG-NC
Turbidity GOOD GOOD GOOD
Dissolved Oxygen GOOD FAIR POOR
Chlorophyll-a GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD
SMITH CREEK
Smith Creek is located in the north-central portion of New Hanover County and drains an area
covering more than 26 square miles (16,650 acres). It is in both the City of Wilmington and the unincorporated portion of the County, where a majority of the watershed in within the unincorporated area. The Smith Creek watershed is the largest creek watershed in New Hanover County beginning near Murrayville and flowing in a generally west-southwesterly direction, passing Wilmington International Airport and under Martin Luther King, Jr. Parkway multiple
times before reaching its confluence with the Northeast Cape Fear River north of downtown Wilmington. Zoning districts in the unincorporated county in this watershed include A-I, A-R, B-1, B-2, I-1, I-2, O&I, PD, R-10, R-15 and R-20. Sampling was conducted at five (5) sites (SC-CH, SC-23, SC-NK, SC-GR, SC-CD) within the Smith Creek watershed (Figure 37).
Dissolved oxygen within the creek ranged between 0.2 mg/l and 9.9 mg/l with a mean value of 6.8
mg/l (Table 19; Figure 38 through Figure 40).
Chlorophyll-a ranged between 1.0 ug/l and 1.0 ug/l with a mean value of 5.0 ug/l (Table 19). No
samples exceeded the State Standard for Chlorophyll-a from within Smith Creek.
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Enterococci ranged between 5 CFU/100ml and 5,170 CFU/100ml with a geometric mean value of
57 CFU/100ml (Table 19). Five (5) samples exceeded the NCDEQ standard of 500 CFU/100ml
for Tier III waters (Figure 43 through Figure 47).
Turbidity values were generally good ranging between 2 and 29 NTU with a mean value of 9 NTU
(Table 19).
No observations exceeded the State standard of 50 NTU for SW class C waters.
Table 20 depicts the ratings for these parameters for the watershed.
Figure 37. Water Quality Sites within the Smith Creek Watershed
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Table 19. Mean values of select parameters from Smith Creek. Range in parentheses.
Parameter SC-23 SC-CD SC-CH SC-GR SC-NK
Turbidity (NTU) 11 (4-21) 8 (3-16) 12 (2-29) 8 (2-17) 8 (3-22)
Dissolved Oxygen (mg/l) 6.2 (0.2-9.6) 7.6 (3.5-9.7) 6.3 (0.5-9.9) 7.2 (3.7-9.6) 6.7 (0.4-9.2)
Chlorophyll-a (ug/l) 6.0 (1.0-14.0) 2.0 (1.0-5.0) 5.0 (1.0-31.0) 2.0 (1.0-4.0) 8.0 (1.0-26.0)
Enterococci (#CFU/100ml) 37 (5-1470)1 209 (41-5170)1 16 (5-156)1 53 (10-156)1 89 (20-1160)1
(1)Enterococci values expressed as geometric mean
Figure 38. Dissolved Oxygen at SC-23 at surface (DO-S) and bottom (DO-B)
Figure 39. Dissolved Oxygen at SC-CD at surface (DO-S)
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Figure 40. Dissolved Oxygen at SC-CH at surface (DO-S) and bottom (DO-B)
Figure 41. Dissolved Oxygen at SC-GR at surface (DO-S)
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Figure 42. Dissolved Oxygen at SC-NK at surface (DO-S) and bottom (DO-B)
Figure 43. Enterococci at SC-23
Figure 44. Enterococci at SC-CD
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Figure 45. Enterococci at SC-CH
Figure 46. Enterococci at SC-GR
Figure 47. Enterococci at SC-NK
Table 20. 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 FAIR GOOD FAIR
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD
Enterococci GOOD FAIR GOOD GOOD FAIR
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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 21). As displayed in the table 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 Barnards Creek and Mott Creek while Lords Creek, Futch Creek, Smith Creek, and Prince George were all deemed to be “fair”. Pages Creek was the only creek to demonstrate “poor” levels of dissolved oxygen during the study
period. Enterococci was determined to be “good” in Futch Creek, Prince George Creek and Smith
Creek. The rest of the creeks all proved to be “fair” for Enterococci bacteria. It should be noted that no creeks demonstrated “poor” levels of bacteria during the 2018-2019 study period.
Table 21. Ratings of parameters within each watershed Parameter Barnards
Creek
Futch
Creek
Lords
Creek
Mott
Creek
Pages
Creek
Prince
George
Creek
Smith
Creek
Turbidity GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD FAIR FAIR GOOD POOR FAIR FAIR
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Enterococci FAIR GOOD FAIR FAIR FAIR GOOD GOOD
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 data collected within the seven (7) tidal creeks under current investigation. The long-term trends from these creeks have been derived from data obtained between July 2008 and June 2019.
3.10.1 Dissolved Oxygen
Figure 48 and 49 depict the long-term trends in dissolved oxygen within the seven (7) creeks examined within this study. The data shows 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. Since 2008, dissolved oxygen levels exceeded the State standard
within surface samples 35%, 22%, 17%, and 9% of the time within Prince George Creek, Pages Creek, Futch Creek, and Mott Creek, respectively. Dissolved oxygen exceeded the standard in Barnards Creek 9% as well while Smith Creek and Lords Creek exceeded the dissolved oxygen standard 7%, and 6% of the time, respectively.
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Figure 48. Long-term surface dissolved oxygen data within tidal creeks
Figure 49. Long-term surface dissolved oxygen data within tidal creeks
3.10.2 Turbidity
Figure 50 through 51 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 several creeks have experienced insignificant increases over time and seasonal patterns have emerged. This includes higher turbidity observations during
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Dissolved Oxygen Levels in Creeks Over Time
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
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2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
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the warmer months and lower turbidity during the cooler months. Since 2008, the turbidity standard was only breached sixteen (16) times in total; seven (7) from within Pages Creek, five (5)
from Smith Creek, two (2) from Prince George Creek, and once from within both Lords Creek and
Mott Creek.
Figure 50. Long-term surface turbidity data within tidal creeks
Figure 51. Long-term surface turbidity data within tidal creeks
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3.10.3 Chlorophyll-a
Figure and 53 depicts the long-term trends in chlorophyll-a within the seven (7) creeks examined within this study. In general, the long term trend of chlorophyll-a has remained fairly constant
within each creek. Contrary 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 30 exceedances of the chlorophyll-a standard were observed of the 2,512 samples collected since July 2008.
Figure 52. Long-term chlorophyll-a data within tidal creeks
Figure 53. Long-term chlorophyll-a data within tidal creeks
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3.10.4 Enterococci
Figure 54, Figure 55 and Table 22 depict the long-term trends in Enterococci within the seven (7) creeks examined within this study. Of these creeks, Mott Creek, Pages Creek, Smith Creek, and
Prince George Creek have maintained relatively higher levels of bacteria over time compared to Lords Creek and Futch Creek. Two sites within the Bayshore community (PC-BDDS and PC-BDUS) in the Pages Creek watershed have demonstrated relatively high levels of Enterococci bacteria over time as well. The levels of bacteria in Barnards, Smith, and Mott Creek have moderated over recent years (Table 22).
Since June 2008, samples collected within Mott Creek exceeded the State standard for Enterococci 46% of the time while Pages Creek, Barnards Creek, Smith Creek, and Prince George Creek exceeded standard 39%, 31%, 30%, and 26% of the time, respectively. Lords Creek and Futch
Creek contained the least amount of bacteria with exceedances only 12% and 5% of the time,
respectively.
Figure 54. Long-term Enterococci data within tidal creeks
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Figure 55. Long-term Enterococci data within tidal creeks
Table 22. Enterococci ratings for each watershed during all reporting periods.
Barnards
Creek
Futch
Creek
Lords
Creek
Mott
Creek
Pages
Creek
Prince
George
Creek
Smith
Creek
2008-2009 POOR GOOD FAIR POOR POOR FAIR POOR
2009-2010 POOR GOOD POOR POOR POOR POOR POOR
2010-2011 POOR GOOD GOOD POOR FAIR POOR POOR
2011-2012 POOR GOOD GOOD POOR POOR POOR POOR
2012-2013 POOR GOOD FAIR POOR POOR POOR POOR
2013-2014 GOOD GOOD GOOD POOR POOR POOR FAIR
2014-2015 GOOD GOOD GOOD POOR POOR POOR FAIR
2015-2016 POOR FAIR FAIR POOR POOR POOR FAIR
2016-2017 GOOD GOOD GOOD FAIR POOR GOOD FAIR
2017-2018 FAIR FAIR POOR FAIR POOR POOR POOR
2018-2019 FAIR GOOD FAIR FAIR FAIR GOOD GOOD
AIRLIE GARDENS
Located east-centrally within New Hanover County and encompassing approximately 10 acres, the lake in Airlie Gardens is situated within the 4,583 acre Bradley Creek watershed. The lake drains directly into Bradley Creek only several hundred yards from the Intracoastal Waterway. The Bradley Creek watershed is characterized as highly developed with 27.8% of its land is
covered by impervious surface (Mallin et al., 2014). As stated above, during the study period, monitoring was conducted at three locations within the lake: AG-IN, which is located on the northern portion of the lake where stormwater enters the lake, AG-FD located in a central portion
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of the lake, and AG-OUT located at the southern portion in proximity to the drainage outfall (Figure 2).
Dissolved oxygen within the lake ranged between 1.7 mg/l and 10.5 mg/l with a mean value of 6.9 mg/l (Table 23); Figure 56 through Figure 58). Turbidity values were generally good ranging between 1 and 58 NTU with a mean value of 9.0
NTU (Table 23). One observation exceeded the State standard of 50 NTU for Class C waters.
Chlorophyll-a ranged from 0 mg/l to 147 mg/l with a mean value of 25 mg/l. The standard of 40 mg/l was exceeded six (6) times.
Figure 56. Dissolved Oxygen at AG-IN
Figure 57. Dissolved Oxygen at AG-FD
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Figure 58. Dissolved Oxygen at AG-OUT
Table 23. Mean values of select parameters from Airlie Gardens. Range provided in parentheses.
Parameter AG-IN AG-FD AG-OUT
Turbidity (NTU) 10 (1-58) 10 (3-25) 7 (1-15)
Dissolved Oxygen
(mg/l) 6.0 (2.6-10.3) 7.2 (1.7-10.3) 7.5 (1.7-10.5)
Chlorophyll-a (mg/l) 14 (0-55) 24 (2-41) 37 (1-147)
Orthophosphate 0.05 (0.02-0.25) 0.05 (0.01-0.17) 0.05 (0.01-0.12)
Nitrate/Nitrite 0.12 (0.01-0.29) 0.01 (0.01-0.16) 0.02 (0.01-0.10)
4.0 DISCUSSION AND RECOMMENDATIONS
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).
Furthermore, the County’s population as of July 2014 was 216,995 and was determined to be
227,198 as of July 2018 (US Census Bureau, 2018) which reflects a growth rate of 4.7% over that four year time period. Along with this population growth came increased stormwater runoff, aging wastewater infrastructure, and other issues that potentially impacted the water quality within the County’s creeks. Since this time of rapid growth, New Hanover County’s water quality within its
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tidal creeks has become altered. This has led to a strong community desire for greater protection and enhancement of surface and ground water resources. In 2017, the Cape Fear Public Utility
Authority (CFPUA) finalized its work to provide the Marquis Hills subdivision within the Mott
Creek watershed with sewer service. With this new wastewater infrastructure in place, aging septic tanks have been removed and homes have been connected to the Utility’s sewer system. The County, meanwhile, continues to work toward preventing further deterioration and loss of public uses in surface water through initiatives such as the implementation of best management practices
(BMPs) and promoting low impact development. 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. Over the past eleven years of water quality monitoring within these seven creeks, we have observed
some trends. Typically, water quality degrades as the water temperature increases and oxygen is
not as readily dissolved in the water column. This phenomenon has been observed while investigating the long term trends of water quality in this study. The dissolved oxygen along with chlorophyll-a and turbidity levels generally increased during the warmer summer months. The longer summer days allow for increased photosynthetic activity that, as a result, allows 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 pH and turbidity may indicate the presence of an algal bloom. Throughout the course of this study, pH values were generally found to be within acceptable ranges as were turbidity values. However, five (5) occurrences of high levels of
chlorophyll-a above the State standard were observed during the 2018-2019 study period. It is
possible that algal blooms were occurring within the creeks during those times. Of the 37 samples that fell below the standard for dissolved oxygen, more than a third (35%) were observed during June, July, and August when water temperatures were the highest. The lowest dissolved oxygen, on average, was observed at PC-BDDS, located within Pages Creek, where the standard was
breached six (6) of twelve (12) sampling events. Compared to the last reporting period (2017-
2018), the DO levels decreased from “Good” to “Fair” at Lords Creek, Smith Creek, Pages Creek, and Futch Creek. Mott Creek and Prince George Creek remained “Good” and “Poor”, respectively, over the past two reporting periods.
High levels of Enterococci bacteria persisted within a number of sites throughout the study period,
however, collectively, bacteria was less of a problem than in previous years. Enterococci levels exceeded the State standard in Futch Creek and Prince George Creek 2% and 3% of the time, respectively, while Smith Creek exceeded the standard only 8% of the time. Barnard Creek and Lords Creek both demonstrated high levels of Enterococci bacteria 17%. Mott Creek and Pages
Creek contained the highest levels of bacteria with exceedances occurring 25% of the time sampled
this past year. Two sampling sites in the Bayshore neighborhood within the Pages Creek watershed exceeded the standard 50% of the time, which was a stark improvement in water quality compared to last year when they exceeded the standard 83% of the time. Two years ago, however, these two sites exceed the standard 46% of the time. Meanwhile, PC-M, located near the mouth of the creek
in proximity of the Intracoastal Waterway, did not exceed the Enterococci throughout the 12-
month study period while last year 25% of the samples collected at PC-M exceeded the standard. Therefore, over the course of this study period, the bacteria levels in Pages Creek has improved considerably compared to last year however the contamination at the two Bayshore Drive sites
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persist. At Mott Creek, the bacteria levels remained similar to what was observed the past two years with six (6) exceedances of the Enterococci standard within the creek resulting in a “Fair”
rating. Prior to the 2016-2017 sampling effort, Mott Creek had consistently demonstrated “Poor”
water quality in terms of bacterial contamination. As mentioned above, the CFPUA installed a centralized sewer system in the Marquis Hills community (located within the Mott Creek watershed) several years ago and septic tanks have been removed. This improvement in wastewater infrastructure may be a cause for the improved water quality within the creek. It should
also be noted that this was the first time that the Smith Creek watershed exhibited “Good” water
quality for Enterococci since the first reporting period dating back to 2008-2009. Rain events can facilitate higher concentrations of bacteria concentration within the watersheds (through surface runoff and/or flushing of groundwater contaminants). However, rain does not
appear to be the driving cause for the reduction in Enterococci over the past year due to the fact
that sampling occurred during rain events 22% of the time during both the 2017-2018 and 2018-2019 study periods.
Hurricane Florence Hurricane Florence, a large and slow moving category one hurricane, made landfall during the
morning of September 14, 2018. After the eye crossed Wrightsville Beach, NC at 7:15 a.m., the storm spent the next two days producing record-breaking rainfall across eastern North Carolina and a portion of northeastern South Carolina. As of September 17, the National Weather Service had recorded 23.02 inches of rain at Wilmington International Airport (ILM), 26.58 inches of rain
at a location 7.3 miles northeast of ILM, and 20.11 inches 3.0 southeast of the airport.
Post-storm water quality monitoring was performed on September 20, September 24, October 8, and October 9. The dissolved oxygen levels were below the State Standard at sixteen (16) of the nineteen (19) sites. Enterococci and chlorophyll-a levels, however, exceeded the standard at only
three (3) and one (one) of the nineteen sites, respectively. The low dissolved oxygen levels may
have been created as a result of the delivery of low-oxygenated flood waters into the tidal creek system. The relatively low bacteria and chlorophyll-a levels could have been a result of tremendous flushing of the system following the massive amounts of rain.
Long Term Trends
An assessment of the past twelve (12) years of water quality monitoring has revealed long-term trends regarding the ratings for dissolved oxygen and Enterococci bacteria within each creek. In general, the dissolved oxygen within Barnards Creek, Lords Creek, Mott Creek, and Smith Creek has been rated “Good” over time, with few exceptions. Barnards Creek had declined in dissolved
oxygen in recent years, however it improved to “Good” again over the past two years. Recent
increases in residential development within the Barnards Creek watershed could have been a contributing factor to this temporary decline in water quality. Futch Creek has maintained a “Fair” rating for eight (9) of the eleven (12) years. Pages Creek has demonstrated varying dissolved oxygen levels over time ranging from “Poor” to “Good” over the years. Prince George Creek has
demonstrated the worst long term dissolved oxygen levels compared to the other creeks in the
study as it has been designated as “Poor” ten (10) of the twelve (12) years. It should be noted, however, that Prince George has improved over the past two reporting periods and has contained “Fair” dissolved oxygen levels.
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The long-term trends for Enterococci ratings over the past twelve (12) years have shown that a
number of creeks had maintained “Poor” ratings during much of the time. These include Mott
Creek, Pages Creek, and Prince George Creek. In recent years, however, these three creeks have demonstrated some improvements. Specifically, Mott Creek, which was deemed “Poor” between 2008 and 2016 has improved to “Fair” over the past three study periods. Barnards Creek and Lords Creek have demonstrated varying conditions since sampling was first initiated. Futch Creek,
meanwhile, has maintained a “Good” rating consistently with the exception of just twice when it
was deemed “Fair”.
Airlie Gardens Sampling from within the lake at Airlie Gardens has only been performed for four (4) years, and,
therefore, no significant long-term trends can be discerned at this time. However, the results from
monthly sampling over the past 48 months have provided some insight into the water quality within the lake. There are no state or federal standards for nutrients including the two monitored within Airlie Gardens (orthophosphate and nitrate/nitrite). That said, the levels of orthophosphate and nitrate/nitrite observed within the three sites in Airlie Gardens were generally low. However, the
nutrients within AG-IN have been relatively higher on average compared to the other two sites
further south and closer to the outfall. Over the past three (3) years of sampling, the orthophosphate level within AG-IN has have averaged 0.05 mg/l while both AG-FD and AG-OUT have averaged 0.03 mg/l. Nitrite/Nitrate levels has been 0.06 mg/l at AG-IN while AG-FD and AG-OUT both averaged 0.02 mg/l. This suggests that the nutrient-rich stormwater runoff
delivered to the lake at AG-IN are ultimately taken up by aquatic plants and macroaglae within the
lake. Excess nutrients often promotes the growth of the vegetation. This is called eutrophication and can lead to algae blooms. As the vegetation dies off and the plant matter decomposes, bacteria take up the oxygen in the water column which can be harmful to fish and other aquatic life. To help combat problems associated with this eutrophication, Airlie Gardens has installed several
aerators in the lake in an attempt to increase the dissolved oxygen levels. In addition, the tributary
that delivers stormwater runoff into the lake just upstream from the AG-IN sampling location has recently undergone restoration efforts with the installation of a wetland BMP (Figure 59). Once established, this constructed wetland may help reduce the amount of nutrients entering the lake and therefore reduce the frequency and magnitude of algal blooms.
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Figure 59. Newly constructed wetland BMP upstream from AG-IN
Recommendations
The long-term water quality monitoring results suggest that the seven (7) creeks have experienced
fairly good water quality in terms of turbidity and chlorophyll-a levels over the course of the twelve
(12) year study thus far. The one parameter, however, that has been problematic has been
Enterococci bacteria. Of the 2,511 samples collected and analyzed since 2008, 679, or 27% of all
samples have exceeded the standard for this bacteria.
While several creeks have exhibited relatively low levels of bacteria throughout the study (namely
Futch Creek and Lords Creek), other creeks have proven to contain chronically high levels of
Enterococci. Mott Creek has exceeded the standard 46% of the time and PC-BDDS and PC-BDUS
within Pages Creek have exceeded the standard 47% and 62% of the time, respectively. In an
attempt to determine the source of this contamination, the County funded two studies in 2008 and
2013. The results of these studies suggested that human sewage was a contributing factor to the
bacteria loading in Pages Creek. The CFPUA performed inspections of the lift stations adjacent
to the two sampling sites and a public health warning sign has been posted at the private boat ramp
at PC-BDUS, no further actions have been taken to resolve the issue. Although the bacteria levels
dropped considerably following the passage of Hurricane Florence as seen on Figure 27, Figure
28, and Table 16, the trend of relatively high Enterococci bacteria resumed during the remainder
of the 2018-2019 study period suggesting that the problem persists to this day.
The resurgence of the bacteria indicates there is a possible source driving the Enterococci levels
to where further investigation is needed. In 2018, the County attempted to receive grant funding
which would have been used to investigate the source of the human contamination entering the
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creek, however, this funding was not awarded and the funding source is no longer available.
Therefore, additional methods to identify the source of the contamination are being investigated.
One possible method would employ the use of a fixed-wing unmanned aerial vehicle (UAV, or
drone) equipped with a thermal infrared sensor. The sensor may be used to identify areas of
previously unidentified locations of point-source contamination within the watershed by
discerning temperature differentials between the surface waters of the creek and its surrounding
environs. Once potential point source targets are located, ground trothing efforts may be employed
to investigate further. Researchers at UNCW possess the required equipment and experience to
conduct this sort of study should funding become available.
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5.0 LITERATURE CITED
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: 780-790. Howarth, R.W. and Marino, R. 2006. Nitrogen as the limiting nutrient for eutrophication in
coastal marine ecosystems: Evolving views over three decades. Limnology and Oceanography,
51: 364-376. 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.
Kwak, T.J. and Zedler, J.B. 1997. Food web analysis of southern California coastal wetlands 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 10:1047-1056. Mallin, M.A., Ensign, S.H., McIver, M.R., Shank, G.C., and Fowler, P.K. 2001. Demographic, landscape, and meteorological factors controlling the microbial pollution of coastal waters.
Hydrobiologia. 460: 185-193.
Mallin, M.A., 2010. University of North Carolina at Wilmington, Aquatic Ecologist. Personal communication regarding findings of water samples obtained within PG-NC.
Michael A. Mallin, Matthew R. McIver, Anna R. Robuck and John D. Barker. 2014.
Environmental Quality of Wilmington And New Hanover County Watersheds. CMS Report 15-
01. Center for Marine Science University of North Carolina Wilmington. 92pp. NC Division of Commerce, Labor, Economic Data and Site Information. 2015. Thrive in North Carolina, County Demographics Report. http://accessnc.commerce.state.nc.us/docs/countyProfile/NC/37129.pdf. Last visited July 8,
2015. Odum, W.E., Smith, T.J., Hoover, J.K., and McIvor, C.C. 1984. The Ecology of Tidal Freshwater Marshes of the United States East Coast: A Community Profile. U.S. Fish and Wildlife Service FWS/OBS-83/17, 177 pp.
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-
111.
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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. University
of North Carolina at Wilmington. 54pp.
U.S. Census Bureau, 2018. Quick facts: New Hanover County, NC. https://www.census.gov/quickfacts/fact/table/newhanovercountynorthcarolina/PST045217
U.S. Environmental Protection Agency. 1984. Health effects criteria for fresh recreational waters.
EPA-600/1-84-004, U.S. Environmental Protection Agency, Washington, D.C. U.S. Environmental Protection Agency. 1986. Ambient Water Quality Criteria for Bacteria- 1986. EPA-440/5/84-002, U.S. Environmental Protection Agency, Washington, D.C.
Wade, T. J., Sams, E., Brenner, K. P., Haugland, R., Chern, E. Beach, M., Wymer, L., Rankin, C. C., Love, D., Li, Q., Noble, R., and A.P. Dufour. 2010. Rapidly measured indicators of recreational water quality and swimming-associated illness at marine beaches. Journal of Environmental Health Perspectives. 9:66-80.
APPENDIX A
Photographs of Sampling Sites
54
Barnards Creek at Carolina Beach Road (BC-CBR)
Futch Creek 4 (FC-4)
Futch Creek 6 (FC-6)
55
Futch Creek 13 (FC-13)
Futch Creek at Foy Branch (FC-FOY)
Lords Creek at River Road (LC-RR)
56
Motts Creek at Carolina Beach Road (MOTT-CBR)
Motts Creek at Normandy Drive (MOT-ND)
Pages Creek at Bayshore Drive Upstream (PC-BDUS)
57
Pages Creek at Bayshore Drive (PC-BDDS)
Pages Creek Mouth (PC-M)
Prince Georges Creek at Castle Hayne Road (PG-CH)
58
Prince Georges Creek at Marathon Landing (PG-ML)
Prince Georges Creek at North College Road (PG-NC)
Smith Creek at Candlewood Drive (SC-CD)
59
Smith Creek at Castle Hayne Road (SC-CH)
Smith Creek at 23rd Street (SC-23)
Smith Creek at North Kerr Ave. (SC-NK)
60
Smith Creek at Gordon Road (SC-GR)
61
Airlie Gardens Lake at Input (AG-IN)
Airlie Gardens Lake at Floating Dock (AG-FD)
Airlie Gardens Lake at Output (AG-OUT)
62
Date Site Depth Temp.Cond.Salinity DO mg/L DO%pH Turb Entero.Chl-A
7/24/2018 BC-CBR 0.1 25.1 277 0.1 7.0 85 7.2 6 867 1
7/24/2018 LC-RR 0.1 25.2 5543 2.9 8.8 108 6.9 20 1200 4
7/24/2018 MOT-CBR 0.1 25.3 287 0.1 7.3 89 6.9 12 1990 2
7/24/2018 MOT-NB 0.1 25.1 295 0.1 7.2 88 7.0 21 2420 2
7/26/2018 PG-CH 0.1 24.1 203 0.1 5.6 67 6.3 8 169 3
7/26/2018 PG-ML 0.1 24.5 211 0.1 6.1 74 7.0 10 156 2
7/26/2018 PG-NC 0.1 24.0 193 0.1 5.5 66 5.8 7 84 2
7/26/2018 SC-23 0.1 25.3 233 0.1 5.3 64 7.1 21 441 3
7/26/2018 SC-CD 0.1 24.3 222 0.1 7.0 84 6.0 16 134 3
7/26/2018 SC-CH 0.1 27.5 344 0.2 5.1 65 7.9 5 156 1
7/26/2018 SC-GR 0.1 24.1 212 0.1 7.1 85 5.9 14 156 2
7/26/2018 SC-NK 0.1 24.4 222 0.1 7.2 86 6.4 13 72 1
7/30/2018 FC-13 0.1 26.7 40640 25.0 6.6 97 7.8 10 1550 8
7/30/2018 FC-4 0.1 26.9 45917 28.5 6.2 92 8.0 17 74 4
7/30/2018 FC-6 0.1 25.0 44905 28.1 6.1 91 8.0 14 28 10
7/30/2018 FC-FOY 0.1 26.7 39517 24.3 6.0 89 7.9 9 31 6
7/30/2018 PC-BDDS 0.1 26.7 35355 21.5 4.5 53 7.5 32 121 7
7/30/2018 PC-BDUS 0.1 26.4 28208 16.5 5.3 72 7.6 10 173 3
7/30/2018 PC-M 0.1 27.3 47168 29.6 6.3 95 8.0 8 16 3
8/27/2018 LC-RR 0.1 27.7 1107 6.0 3.9 51 7.2 17 72 11
8/27/2018 BC-CBR 0.1 24.1 407 0.2 5.0 60 7.7 5 62 1
8/27/2018 MOT-CBR 0.1 25.6 573 0.3 4.3 53 7.3 9 41 2
8/27/2018 MOT-NB 0.1 25.9 567 0.3 6.8 72 7.5 12 63 2
8/28/2018 PG-ML 0.1 26.2 352 0.2 2.6 32 7.1 4 160 2
8/28/2018 PG-CH 0.1 24.3 622 0.3 3.2 38 7.1 6 63 1
8/28/2018 PG-NC 0.1 24.1 658 0.3 3.1 34 7.0 7 41 2
8/28/2018 SC-CH 0.1 27.9 346 0.2 3.5 44 7.8 10 10 2
8/28/2018 SC-23 0.1 28.2 457 0.2 4.1 53 7.2 7 10 9
8/28/2018 SC-CD 0.1 25.4 352 0.2 7.3 89 7.4 8 213 1
8/28/2018 SC-NK 0.1 26.5 386 0.2 6.5 81 7.4 5 31 10
8/28/2018 SC-GR 0.1 24.5 320 0.2 7.2 87 7.3 11 145 1
8/29/2018 FC-4 0.1 27.6 44844 33.2 5.1 57 8.1 1 5 5
8/29/2018 FC-6 0.1 28.1 44814 33.1 4.8 52 8.0 4 5 5
Appendix B: Raw Data
63
8/29/2018 FC-13 0.1 27.8 47632 34.2 5.2 63 7.8 3 5 14
8/29/2018 FC-FOY 0.1 27.1 45013 33.4 4.8 53 8.0 2 5 4
8/29/2018 PC-BDUS 0.1 28.3 43121 33.0 4.7 51 7.7 4 1610 7
8/29/2018 PC-BDDS 0.1 28.1 48556 34.1 3.7 48 7.7 5 2610 5
8/29/2018 PC-M 0.1 28.5 54122 35.3 4.8 77 8.0 6 5 3
9/10/2018 LC-RR 0.1 29.4 37884 31.9 5.1 77 7.8 7 72 20
9/10/2018 BC-CBR 0.1 24.7 426 0.2 5.9 71 8.4 4 62 1
9/10/2018 MOT-CBR 0.1 26.5 441 0.2 4.3 54 7.8 7 41 83
9/10/2018 MOT-NB 0.1 25.7 499 0.2 6.1 75 7.9 7 63 20
9/20/2018 PG-ML 0.1 N/A N/A N/A N/A N/A N/A N/A N/A N/A
9/20/2018 PG-CH 0.1 26.1 322 0.2 3.2 38 7.7 7 5 3
9/20/2018 PG-NC 0.1 25.9 245 0.1 1.1 13 8.7 6 5 1
9/20/2018 SC-CH 0.1 27.8 352 0.2 3.2 41 7.7 8 5 1
9/20/2018 SC-23 0.1 26.5 426 0.2 4.0 52 7.2 4 75 1
9/20/2018 SC-CD 0.1 24.9 265 0.1 3.5 43 6.3 7 41 1
9/20/2018 SC-NK 0.1 27.8 309 0.1 1.1 14 6.5 8 1160 2
9/20/2018 SC-GR 0.1 26.7 314 0.1 3.7 42 7.1 17 10 1
9/24/2018 FC-4 0.1 26.9 45192 28.0 4.6 68 7.9 6 31 6
9/24/2018 FC-6 0.1 26.7 414515 25.6 4.4 63 7.7 6 10 18
9/24/2018 FC-13 0.1 25.8 21387 12.5 3.2 43 7.8 7 10 25
9/24/2018 FC-FOY 0.1 25.8 28213 17.0 4.0 55 7.7 6 63 11
9/24/2018 PC-BDUS 0.1 25.2 12510 7.7 4.1 52 8.0 11 700 350
9/24/2018 PC-BDDS 0.1 26.8 34918 20.2 3.4 48 7.5 7 41 2
9/24/2018 PC-M 0.1 25.6 529 0.3 3.8 46 7.7 6 41 10
10/8/2018 LC-RR 0.1 26.5 5897 3.1 2.3 29 7.4 7 31 28
10/8/2018 BC-CBR 0.1 24.6 420 0.2 3.9 47 7.7 5 52 4
10/8/2018 MOT-CBR 0.1 25.9 505 0.2 5.0 62 7.3 8 121 4
10/8/2018 MOT-NB 0.1 25.4 488 0.2 4.2 50 7.4 8 7220 4
10/9/2018 PG-ML 0.1 25.0 345 0.2 0.9 10 7.1 14 195 18
10/9/2018 PG-CH 0.1 24.2 444 0.2 1.0 12 7.0 10 20 57
10/9/2018 PG-NC 0.1 24.1 329 0.2 0.9 11 6.7 9 52 108
10/9/2018 SC-CH 0.1 25.8 286 0.1 0.6 8 7.5 18 10 10
10/9/2018 SC-23 0.1 26.2 340 0.2 0.3 3 7.0 14 5 14
10/9/2018 SC-CD 0.1 24.9 346 0.2 5.4 95 6.9 8 189 5
64
10/9/2018 SC-NK 0.1 26.3 405 0.2 3.5 40 7.1 3 121 17
10/9/2018 SC-GR 0.1 24.3 306 0.2 4.7 56 6.9 5 109 4
10/10/2018 FC-4 0.1 26.7 53031 33.7 5.9 89 8.3 8 10 3
10/10/2018 FC-6 0.1 26.6 52687 33.6 6.6 99 8.2 8 5 4
10/10/2018 FC-13 0.1 26.1 50428 32.3 6.7 94 7.9 6 5 3
10/10/2018 FC-FOY 0.1 26.2 51342 32.8 6.1 92 8.0 6 5 2
10/10/2018 PC-BDUS 0.1 26.1 4532 2.4 6.2 77 8.6 7 41 6
10/10/2018 PC-BDDS 0.1 25.9 39057 24.3 6.1 86 7.9 5 462 14
10/10/2018 PC-M 0.1 26.7 53550 34.1 7.3 104 8.1 7 5 4
11/6/2018 LC-RR 0.1 19.6 6705 4.1 8.3 93 7.5 12 10 8
11/6/2018 BC-CBR 0.1 20.1 394 0.2 5.6 61 8.3 4 10 1
11/6/2018 MOT-CBR 0.1 21.1 461 0.2 6.4 72 7.8 7 10 9
11/6/2018 MOT-NB 0.1 20.0 448 0.2 6.5 73 7.7 7 97 6
11/7/2018 PG-ML 0.1 20.0 348 0.2 3.7 41 8.1 2 63 2
11/7/2018 PG-CH 0.1 19.8 399 0.2 3.6 39 7.8 5 20 10
11/7/2018 PG-NC 0.1 9.6 323 0.2 1.4 17 7.3 5 20 5
11/7/2018 SC-CH 0.1 18.3 1336 0.8 7.4 79 8.9 13 20 3
11/7/2018 SC-23 0.1 19.0 350 0.2 7.4 80 8.5 9 41 7
11/7/2018 SC-CD 0.1 20.8 377 0.2 7.8 87 7.4 8 663 1
11/7/2018 SC-NK 0.1 20.6 412 0.2 6.5 73 7.7 4 52 26
11/7/2018 SC-GR 0.1 20.9 342 0.2 6.6 75 7.6 6 135 1
11/8/2018 FC-4 0.1 20.6 48273 34.8 7.1 97 8.4 5 10 3
11/8/2018 FC-6 0.1 20.6 48446 34.9 6.3 86 8.3 5 10 2
11/8/2018 FC-13 0.1 20.4 45228 32.5 6.4 85 8.0 5 41 12
11/8/2018 FC-FOY 0.1 20.7 47121 33.8 7.0 95 8.2 6 5 2
11/8/2018 PC-BDUS 0.1 20.3 36414 25.5 7.7 99 8.3 9 95 3
11/8/2018 PC-BDDS 0.1 20.4 40633 28.8 7.6 97 8.2 5 1590 3
11/8/2018 PC-M 0.1 20.8 48728 35.0 8.3 10 8.3 7 5 3
12/7/2018 LC-RR 0.1 10.1 3531 2.7 10.1 93 7.6 20 20 4
12/7/2018 BC-CBR 0.1 11.0 330 0.2 11.1 103 8.9 4 10 0
12/7/2018 MOT-CBR 0.1 11.9 370 0.2 10.8 97 7.9 10 74 3
12/7/2018 MOT-NB 0.1 10.4 360 0.2 10.7 95 7.9 21 84 3
12/11/2018 PG-ML 0.1 8.3 217 0.1 11.4 97 8.5 6 609 1
12/11/2018 PG-CH 0.1 8.2 205 0.1 11.3 95 8.1 5 132 2
65
12/11/2018 PG-NC 0.1 8.0 193 0.1 7.7 81 7.9 5 97 2
12/11/2018 SC-CH 0.1 8.8 218 0.2 9.1 88 9.0 2 20 1
12/11/2018 SC-23 0.1 8.6 237 0.2 9.2 90 8.7 10 1470 9
12/11/2018 SC-CD 0.1 10.6 218 0.1 9.3 91 7.6 5 131 2
12/11/2018 SC-NK 0.1 9.1 211 0.1 9.0 89 7.7 10 676 2
12/11/2018 SC-GR 0.1 10.6 210 0.1 9.0 86 7.5 6 122 1
12/12/2018 FC-4 0.1 10.0 36859 33.8 6.2 63 8.4 6 31 1
12/14/2018 FC-6 0.1 9.4 35051 32.4 6.4 69 8.3 3 10 1
12/16/2018 FC-13 0.1 9.1 28317 25.8 7.6 78 8.0 3 30 1
12/18/2018 FC-FOY 0.1 9.0 30402 28.0 6.8 72 8.0 4 41 1
12/20/2018 PC-BDUS 0.1 9.6 18315 16.0 5.3 54 8.7 8 185 5
12/21/2018 PC-BDDS 0.1 8.8 31617 29.5 3.7 40 8.4 4 328 3
12/22/2018 PC-M 0.1 10.6 38014 34.3 6.3 66 8.5 5 5 1
1/7/2019 LC-RR 0.1 12.6 763 0.5 9.2 87 6.8 27 10 2
1/7/2019 BC-CBR 0.1 14.1 299 0.2 8.3 85 7.3 5 20 1
1/7/2019 MOT-CBR 0.1 14.0 352 0.2 8.4 82 6.8 6 31 1
1/7/2019 MOT-NB 0.1 13.7 342 0.2 8.5 83 6.9 7 31 2
1/8/2019 PG-ML 0.1 12.9 276 0.2 7.6 72 7.4 4 41 1
1/8/2019 PG-CH 0.1 2.2 253 0.2 7.4 68 7.3 4 52 2
1/8/2019 PG-NC 0.1 12.1 181 0.1 6.6 61 7.1 4 5 2
1/8/2019 SC-CH 0.1 14.1 215 0.1 7.7 75 7.9 6 10 1
1/8/2019 SC-23 0.1 14.3 290 0.2 7.7 75 7.5 7 30 2
1/8/2019 SC-CD 0.1 14.5 263 0.2 8.6 85 7.0 5 74 1
1/8/2019 SC-NK 0.1 13.6 267 0.2 8.6 85 7.1 5 20 2
1/8/2019 SC-GR 0.1 14.0 234 0.1 8.5 83 6.9 5 31 1
1/9/2019 FC-4 0.1 14.1 40341 33.9 8.3 99 7.7 3 5 2
1/9/2019 FC-6 0.1 14.1 40015 33.1 8.3 98 7.6 3 5 1
1/9/2019 FC-13 0.1 14.0 35730 39.2 8.0 92 7.3 4 30 2
1/9/2019 FC-FOY 0.1 14.0 36453 30.1 8.2 96 7.5 3 5 2
1/9/2019 PC-BDUS 0.1 16.1 19656 14.5 7.2 80 7.8 8 41 1
1/9/2019 PC-BDDS 0.1 14.2 37905 31.2 8.1 95 7.7 10 10 3
1/9/2019 PC-M 0.1 14.1 41032 34.0 8.4 100 7.8 4 245 1
2/5/2019 LC-RR 0.1 10.1 7299 5.8 10.3 95 6.8 14 51 4
2/5/2019 BC-CBR 0.1 12.2 299 0.2 8.6 80 7.7 5 42 2
66
2/5/2019 MOT-CBR 0.1 12.6 347 0.2 9.1 86 7.3 20 26 3
2/5/2019 MOT-NB 0.1 12.3 357 0.2 9.0 84 7.3 16 125 3
2/6/2019 PG-ML 0.1 12.7 289 0.2 8.6 81 7.8 3 5 2
2/6/2019 PG-CH 0.1 12.4 304 0.2 7.7 73 7.5 4 31 1
2/6/2019 PG-NC 0.1 12.3 252 0.2 6.7 82 7.4 5 5 3
2/6/2019 SC-CH 0.1 10.0 448 0.3 9.9 88 8.1 10 20 2
2/6/2019 SC-23 0.1 11.4 310 0.2 9.6 88 7.9 10 10 5
2/6/2019 SC-CD 0.1 14.5 273 0.3 9.0 88 7.3 5 246 1
2/6/2019 SC-NK 0.1 13.0 295 0.2 9.1 88 7.3 5 20 5
2/6/2019 SC-GR 0.1 13.8 257 0.2 8.6 83 7.2 11 146 2
2/7/2019 FC-4 0.1 13.5 39903 33.6 8.8 103 7.9 2 96 1
2/7/2019 FC-6 0.1 13.9 39836 33.2 8.7 103 7.8 2 107 1
2/7/2019 FC-13 0.1 14.3 37976 31.1 8.5 101 7.4 2 110 1
2/7/2019 FC-FOY 0.1 14.3 37440 30.5 8.7 103 7.7 2 129 1
2/7/2019 PC-BDUS 0.1 17.1 33375 25.1 8.0 96 7.9 6 326 2
2/7/2019 PC-BDDS 0.1 14.5 39401 32.3 8.3 99 7.8 10 1120 1
2/7/2019 PC-M 0.1 13.6 40304 33.9 7.6 90 7.9 2 7 1
3/5/2019 LC-RR 0.1 11.6 3493 2.5 8.7 81 6.9 17 134 4
3/5/2019 BC-CBR 0.1 12.0 259 0.2 8.7 82 7.6 58 817 2
3/5/2019 MOT-CBR 0.1 12.0 278 0.2 9.0 87 7.2 8 309 4
3/5/2019 MOT-NB 0.1 11.1 273 0.2 9.0 86 7.2 12 933 6
3/6/2019 PG-ML 0.1 10.5 235.0 0.1 10.1 90.0 7.6 9 63 3
3/6/2019 PG-CH 0.1 8.2 216 0.2 10.4 88 7.4 8 31 1
3/6/2019 PG-NC 0.1 7.9 203 0.1 10.1 85 7.2 8 10 2
3/6/2019 SC-CH 0.1 12.6 249 0.2 9.2 87 8.1 5 74 2
3/6/2019 SC-23 0.1 13.1 342 0.2 8.7 83 7.7 8 97 7
3/6/2019 SC-CD 0.1 10.8 234 0.2 9.7 88 7.1 9 265 3
3/6/2019 SC-NK 0.1 10.4 235 0.2 9.2 82 7.2 9 160 5
3/6/2019 SC-GR 0.1 10.7 219 0.2 9.6 86 7.0 9 146 3
3/7/2019 FC-4 0.1 10.4 35601 32.1 9.6 105 7.8 2 201 0
3/7/2019 FC-6 0.1 10.3 34872 31.4 9.6 104 7.7 2 20 1
3/7/2019 FC-13 0.1 9.9 31150 28.0 9.1 96 7.3 2 10 1
3/7/2019 FC-FOY 0.1 10.1 33240 30.1 9.4 700 7.6 2 5 1
3/7/2019 PC-BDUS 0.1 11.6 24451 20.4 8.4 93 7.9 11 404 2
67
3/7/2019 PC-BDDS 0.1 10.3 32355 29.1 9.4 101 7.8 2 119 1
3/7/2019 PC-M 0.1 11.3 37059 32.7 9.6 107 7.9 2 5 1
4/3/2019 LC-RR 0.1 11.1 9327 7.3 10.2 97 7.2 19 5 6
4/3/2019 BC-CBR 0.1 11.3 280 0.2 9.0 83 8.4 11 61 1
4/3/2019 MOT-CBR 0.1 12.7 314 0.2 9.6 91 8.0 9 175 4
4/3/2019 MOT-NB 0.1 11.9 328 0.2 9.8 90 7.9 8 171 2
4/4/2019 PG-ML 0.1 12.9 289 0.2 8.9 85 8.5 6 41 2
4/4/2019 PG-CH 0.1 12.5 262 0.2 8.3 78 8.4 4 86 2
4/4/2019 PG-NC 0.1 12.9 248 0.2 7.5 71 8.2 3 30 1
4/4/2019 SC-CH 0.1 14.7 1456 0.9 8.9 88 8.8 11 5 31
4/4/2019 SC-23 0.1 14.3 432 0.2 9.3 91 8.8 11 52 5
4/4/2019 SC-CD 0.1 14.2 272 0.2 8.9 87 7.9 3 169 2
4/4/2019 SC-NK 0.1 13.5 257 0.2 8.7 84 7.9 4 63 4
4/4/2019 SC-GR 0.1 14.0 247 0.2 9.0 88 7.8 2 20 3
4/5/2019 FC-4 0.1 14.9 41953 34.2 9.0 110 8.2 1 5 1
4/5/2019 FC-6 0.1 15.4 41908 33.8 8.9 108 8.1 2 5 1
4/5/2019 FC-13 0.1 15.9 40321 32.0 8.9 102 7.8 3 10 1
4/5/2019 FC-FOY 0.1 15.7 40676 32.4 8.5 104 7.9 2 5 1
4/5/2019 PC-BDUS 0.1 17.3 30822 23.0 7.7 93 8.2 3 697 16
4/5/2019 PC-BDDS 0.1 16.1 40588 32.0 8.2 101 8.1 8 189 6
4/5/2019 PC-M 0.1 15.2 41860 33.9 8.4 102 8.2 3 10 0
5/6/2019 LC-RR 0.1 24.0 12840 7.5 7.4 91 8.0 17 85 6
5/6/2019 BC-CBR 0.1 22.3 338 0.2 4.7 54 9.1 5 48 1
5/6/2019 MOT-CBR 0.1 22.3 358 0.2 6.3 72 8.2 8 207 1
5/6/2019 MOT-NB 0.1 23.0 415 0.2 7.6 89 8.2 12 225 7
5/7/2019 PG-ML 0.1 23.7 246 0.1 5.4 64 8.7 3 20 2
5/7/2019 PG-CH 0.1 21.7 369 0.2 3.7 43 7.9 4 20 4
5/7/2019 PG-NC 0.1 20.9 212 0.1 8.1 91 7.9 4 10 3
5/7/2019 SC-CH 0.1 23.7 2662 1.4 6.2 74 8.9 18 10 3
5/7/2019 SC-23 0.1 25.2 1197 0.6 4.5 55 8.7 11 10 4
5/7/2019 SC-CD 0.1 22.9 251 0.1 7.4 87 8.1 7 5170 4
5/7/2019 SC-NK 0.1 24.8 325 0.2 4.8 57 8.2 4 189 3
5/7/2019 SC-GR 0.1 23.0 232 0.1 5.7 67 7.8 10 10 4
5/9/2019 FC-4 0.1 24.4 56760 38.3 6.5 96 8.6 5 5 2
68
5/9/2019 FC-6 0.1 24.7 56631 37.9 6.3 94 8.5 5 5 2
5/9/2019 FC-13 0.1 25.1 52703 34.7 5.7 85 8.5 9 5 5
5/9/2019 FC-FOY 0.1 25.0 54528 36.1 5.9 88 8.4 8 5 3
5/9/2019 PC-BDUS 0.1 25.5 35002 21.7 6.9 95 8.5 11 109 6
5/9/2019 PC-BDDS 0.1 25.3 53181 35.6 3.8 58 8.4 8 5 2
5/9/2019 PC-M 0.1 24.8 57085 38.1 4.9 68 8.5 4 350 63
6/3/2019 LC-RR 0.1 27.4 33498 19.9 5.4 76 7.3 20 2420 16
6/3/2019 BC-CBR 0.1 23.6 229 0.1 4.9 58 9.3 4 407 4
6/3/2019 MOT-CBR 0.1 25.6 241 0.1 5.4 67 8.7 8 2420 5
6/3/2019 MOT-NB 0.1 24.6 296 0.1 5.8 70 8.3 16 2420 9
6/4/2019 PG-ML 0.1 25.4 450 0.2 4.6 55 9.3 3 30 1
6/4/2019 PG-CH 0.1 23.8 526 0.3 4.6 54 8.8 3 97 2
6/4/2019 PG-NC 0.1 23.0 224 0.1 2.0 22 8.6 7 10 2
6/4/2019 SC-CH 0.1 27.6 24164 13.9 4.5 61 8.1 18 10 8
6/4/2019 SC-23 0.1 27.6 11871 6.4 5.1 66 8.3 12 5 10
6/4/2019 SC-CD 0.1 24.7 252 0.1 7.6 92 8.4 9 85 3
6/4/2019 SC-NK 0.1 25.9 3084 1.6 6.9 85 7.7 7 30 21
6/4/2019 SC-GR 0.1 24.2 232 0.1 6.7 80 8.6 4 10 3
6/6/2019 FC-4 0.1 26.4 56672 36.4 5.7 87 8.6 5 5 2
6/6/2019 FC-6 0.1 26.8 56717 36.3 5.9 90 8.5 6 10 0
6/6/2019 FC-13 0.1 27.0 54923 34.8 5.3 80 8.5 10 10 4
6/6/2019 FC-FOY 0.1 27.0 55177 35.0 5.2 80 8.5 7 5 2
6/6/2019 PC-BDUS 0.1 27.4 52732 32.9 3.7 56 8.4 22 85 5
6/6/2019 PC-BDDS 0.1 26.6 55352 35.4 3.6 53 8.3 7 98 5
6/6/2019 PC-M 0.1 26.8 56729 36.3 5.2 80 8.5 7 10 2
69
Appendix C
2017-2018 Airlie Gardens Lake Raw Data
Site Date Rain Temp. Cond. Salinity
DO
mg/L DO% pH Turb. Ortho.
Nitrate
+
Nitrite Chl-a
AG-IN 7/21/17 0.0 27.6 442 0.2 6.8 89 7.6 12 0.03 0.01 11
AG-IN 8/8/17 0.5 25.0 140 0.1 6.6 80 7.8 11 0.05 0.01 6
AG-IN 9/6/17 0.0 24.7 242 0.1 6.3 77 7.9 3 0.08 0.04 40
AG-IN 10/4/17 0.0 20.2 499 0.3 4.4 49 8 20 0.02 0.01 1
AG-IN 11/6/17 0.0 19.7 400 0.2 5.6 62 7.2 4 0.03 0.01 8
AG-IN 12/19/17 0.0 11.7 466 0.3 5.7 53 8.3 3 0.02 0.01 4
AG-IN 1/17/18 0.0 7.5 466 0.3 8.2 68 8.2 3 0.03 0.01 0
AG-IN 2/20/18 0.0 20.2 424 0.2 10.3 113 7.6 10 0.04 0.01 11
AG-IN 3/19/18 0.0 13.1 349 0.3 8.2 84 8.1 8 0.02 0.04 6
AG-IN 4/17/18 0.0 13.4 355 0.2 6.8 65 7.3 8 0.03 0.13 3
AG-IN 5/15/18 0.0 27.4 509 0.2 3.6 45 7.5 6 0.07 0.01 161
AG-IN 6/13/18 0.3 23.0 540 0.3 3.6 43 7.2 14 0.11 0.01 16
AG-FD 7/21/17 0.0 32.7 386 0.2 10.8 121 9.3 0 0.01 0.01 4
AG-FD 8/8/17 0.5 28.0 296 0.1 3.8 49.0 7.6 11 0.02 0.01 7
AG-FD 9/6/17 0.0 26.6 327 0.1 6.0 75.0 7.7 6 0.05 0.01 43
AG-FD 10/4/17 0.0 20.9 321 0.2 6.6 74.0 8.4 15 0.02 0.01 19
AG-FD 11/6/17 0.0 19.8 308 0.2 6.4 69 7.6 1 0.03 0.01 6
AG-FD 12/19/17 0.0 10.9 316 0.2 12.9 116 8.2 1 0.01 0.01 55
AG-FD 1/17/18 0.0 7.8 500 0.4 10.3 87 8.2 2 0.02 0.01 5
AG-FD 2/20/18 0.0 19.1 433 0.2 9.5 102 7.9 1 0.03 0.01 23
AG-FD 3/19/18 0.0 14.0 454 0.3 9.7 94 9.4 3 0.03 0.01 3
AG-FD 4/17/18 0.0 18.2 349 0.2 7.4 78 7.8 2 0.02 0.01 44
AG-FD 5/15/18 0.0 27.7 474 0.2 2.4 30 7.4 2 0.07 0.01 15
70
AG-FD 6/13/18 0.0 26.8 480 0.2 1.5 19 7.1 3 0.13 0.01 8
AG-OUT 7/21/17 0.0 29.8 245 0.1 6.7 88 8.7 0 0.01 0.01 2
AG-OUT 8/8/17 0.5 27.4 253 0.1 2.9 37.0 7.7 127 0.02 0.01 3
AG-OUT 9/6/17 0.0 25.7 271 0.1 1.3 15.0 7.7 0 0.01 0.01 4
AG-OUT 10/4/17 0.0 21.6 265 0.1 5.1 58.0 8.3 5 0.02 0.01 21
AG-OUT 11/6/17 0.0 19.7 270 0.1 8.9 97 7.4 3 0.03 0.01 9
AG-OUT 12/19/17 0.0 9.6 265 0.2 13.3 118 8.2 0 0.02 0.1 9
AG-OUT 1/17/18 0.0 7.0 284 0.2 11.7 87 8 1 0.03 0.01 8
AG-OUT 2/20/18 0.0 16.8 357 0.2 10.1 104 8.2 1 0.03 0.01 11
AG-OUT 3/19/18 0.0 14.4 309 0.2 11.6 114 9.5 1 0.04 0.01 3
AG-OUT 4/17/18 0.0 17.0 316 0.2 8.3 86 7.9 2 0.02 0.01 16
AG-OUT 5/15/18 0.0 25.3 513 0.2 5.0 60 7.5 7 0.06 0.01 7
AG-OUT 6/13/18 0.3 27.3 448 0.2 1.9 23 7.2 2 0.09 0.01 7
71