2021- 2022 Final ReportCPE-NC
NEW HANOVER COUNTY WATER QUALITY MONITORING PROGRAM
2021-2022
FINAL REPORT
Prepared by:
Coastal Protection Engineering of North Carolina, Inc.
Marine Scientist: Brad Rosov, M.Sc.
Prepared For:
New Hanover County, North Carolina
Recommended Citation: Rosov, B., 2022. New Hanover County Water Quality Monitoring Program: 2021-
2022 Final Report. New Hanover County, North Carolina: Coastal Protection Engineering of North
Carolina, Inc.
September 2022
CPE-NC
i
EXECUTIVE SUMMARY
This report represents the findings of the New Hanover County Water Quality Monitoring Program for the
period July 2021 to June 2022. The results and long-term trends presented in this report are described
from a watershed perspective. Since 2007 the county has partnered with Coastal Protection Engineering
of North Carolina to test water quality at nineteen (20) monitoring stations within eight (8) tidal creeks in
New Hanover County. These monitored include Barnards, Futch, Lords, Mott, Pages, Prince George,
Smith, and Island. This monitoring period (2021-2022) included the addition of one (1) station at Island
Creek to capture baseline data since future development is expected within the watershed. Each creek is
monitored monthly for physical, chemical, and biological parameters that indicate overall water quality.
The objective is to evaluate the current parameters at each creek to determine the impact (if any) of the
built environment on water quality. In addition to the raw sampling results, a general assessment of the
water quality is provided for each watershed. The general assessment gives each parameter the rating of
either “Good”, “Fair”, or “Poor” depending on the percentage of samples that went above the State
standard for turbidity, chlorophyll-a, and Enterococci, or below the State standard for dissolved oxygen.
If the recorded value of a parameter went outside the acceptable range of the State standard less than
10% of the times sampled the watershed will receive a “Good” rating, a “Fair” rating 11%-25% of the times
sampled, or a “Poor” rating for greater than 25% of the sampling times.
Ratings by watershed during the 2021-2022 reporting period
Parameter
Barnards
Creek
Futch
Creek
Island
Creek
Lords
Creek
Mott
Creek
Pages
Creek
Prince
George
Creek
Smith
Creek
Turbidity GOOD GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Dissolved
Oxygen FAIR GOOD FAIR GOOD GOOD FAIR POOR GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD GOOD POOR FAIR GOOD
Long Term Trends
Dissolved oxygen, turbidity, and chlorophyll-a levels fluctuate on a seasonal basis where, typically, levels
decrease in the winter and increase in the summer. In general, turbidity and chlorophyll-a levels over
time have not been of concern. Likewise, dissolved oxygen levels have not changed drastically from year
to year and there have been minimal issues with low dissolved oxygen levels except for Prince George
Creek where levels in the creek have been consistently low over time. This is due to its naturally slow
water flow, which is more characteristic of swamp-like waters. Slower moving waters typically have lower
dissolved oxygen levels.
Overall, Enterococci bacteria levels during the 2021-2022 sampling for the majority of the watersheds
remained the same with the exception Mott Creek which saw an improvement. There is a history of
elevated levels of Enterococci bacteria that have been of carefully monitored over the years within Mott,
Pages, Barnards, Smith, and Prince George creeks. Lords Creek and Futch Creek, on average, have
contained relatively lower bacteria levels compared to the other creeks.
CPE-NC
ii
It should be noted that monitoring at Island Creek began this year, hence, long-term trends are not
available and have not been included in this report.
In addition to monitoring the tidal creeks, in 2015 New Hanover County began monthly testing at the lake
at Airlie Gardens due to concerns of water quality and noticeable algal blooms that had occurred over the
years. The lake drains directly into Bradley Creek close to the Intracoastal Waterway. There are three
sampling sites, one where contributing water enters the lake (intake), one in the middle of the lake, and
one at the outfall before the water enters Bradley Creek.
Since 2015 water quality monitoring has shown that dissolved oxygen varies significantly over an annual
basis, increasing during the warmer summer months and decreasing during the colder winter months.
Overall, there are no current concerns with the dissolved oxygen levels.
Over past 7 years, the levels of the nutrient Nitrite/Nitrate have generally been higher at the intake
compared to the sampling sites located at the middle and at the outfall of the lake. This trend with
orthophosphate was observed during the first three years of monitoring, however the trend reversed over
the past two years. High concentrations of orthophosphate and Nitrite/Nitrate have been linked to algae
growth leading to algal blooms which can cause low dissolved oxygen and a decline in overall water
quality. Since monitoring began, it has been observed that levels of orthophosphate have incrementally
increased each year. Nitrate/Nitrite levels have also increased over time, however not in the same linear
fashion as orthophosphate.
Chlorophyll-a levels are also indicative of the presence of algal blooms. In recent years levels have
increased at the middle and outfall of the lake compared to the sampling location in proximity to the
intake into the lake. In general, Chlorophyll-a levels have steadily increased within the lake over time
since sampling began in 2015.
Improvement Efforts
While urbanization and development are often factors that can impact water quality and while there is
continued growth in New Hanover County, the ratings for many water quality parameters as depicted in
this report have improved or remained steady over the past several years. This suggests that even though
the unincorporated portions of New Hanover County continue to build out, there are factors minimizing
the impact to water quality. While these factors facilitating this trend have not been identified, several
notable efforts maybe contributing to these improvements.
In addition to continued monitoring, New Hanover County has made efforts over the years to improve
water quality including property acquisition using grant and trust fund sources, working with the Cape
Fear Public Utility Authority to test sewer infrastructure, the installation of stormwater Best Management
Practices (BMPs) such as raingardens, infiltration basins, and impervious surface retrofits, and bacteria
source tracking. In 2008 New Hanover County partnered with University of North Carolina Wilmington’s
Center for Marine Science and Coastal Protection Engineering of North Carolina, Inc. to conduct DNA
source tracking which led to the identification of a human source for the bacteria in Pages Creek. This
suggested that the source of the bacteria in the creek was from nearby wastewater infrastructure such as
septic tanks systems and/or the municipal sewer system. Following the report, NHC Planning & Land Use
partnered with the Cape Fear Public Utility Authority and the NHC Health Department to search for leaking
septic or sewer, however, that investigation did not find the source of contamination. In 2013 the County
partnered with UNC-Chapel Hill to expand the source tracking and conducted a study on the enterococci
CPE-NC
iii
bacteria in Mott and Smith Creek and again at Pages Creek. That study found the presence of a human
signature in the bacteria for all three creeks.
In an attempt to identify any possible sources of bacteria entering Pages Creek, in 2019 New Hanover
County partnered with the University of North Carolina Wilmington’s (UNCW) Socio-Environmental
Analysis Laboratory and Coastal Protection Engineering (CPE) of North Carolina to conduct a thermal
imagery scan of two portions of the creek adjacent to monitoring sites that have consistently detected
elevated levels of Enterococci bacteria. Following the flight, UNCW and CPE analyzed the imagery and two
areas that showed uncommon differences in temperature variation were identified.
Ground truthing these areas revealed several subterranean groundwater seeps entering the creek from
the streambank in the vicinity of sewer lift stations. In June and July of 2022 planning staff, CPE, and the
Cape Fear Public Utility Authority coordinated to perform additional testing of the seep water coming
from the creek bank in these two locations. Laboratory analysis of those samples detected human fecal
pollution from both samples collected at one of the sampling locations while no human fecal pollution
was detected at the other. The results from the additional testing and indicator analysis can be found in
Appendix D of this report.
At Airlie Gardens, to help combat problems associated with eutrophication and overall water quality the
Park and Gardens department has implemented initiatives identified in their stormwater master plan.
These initiatives include installing several aerators in the lake to increase the dissolved oxygen levels,
restore a wetland area near the entry point where water enters the lake and the completion of a dredging
operation effectively removing approximately 4,000 cubic yards of bottom sediment and material. The
county continues to monitor the lake as it may take several years for a data trend to emerge. Data from
this past year has not shown a reduction in nutrient loading into the lake.
CPE-NC
TABLE OF CONTENTS
EXECUTIVE SUMMARY ....................................................................................................................... I
LONG TERM TRENDS.............................................................................................................................I
IMPROVEMENT EFFORTS ....................................................................................................................... II
INTRODUCTION..................................................................................................................................1
CREEK SUMMARIES ............................................................................................................................1
BARNARDS CREEK ...............................................................................................................................1
FUTCH CREEK.....................................................................................................................................4
ISLAND CREEK ....................................................................................................................................5
LORDS CREEK.....................................................................................................................................6
MOTT CREEK .....................................................................................................................................7
PAGES CREEK .....................................................................................................................................8
PRINCE GEORGE CREEK ........................................................................................................................9
SMITH CREEK .....................................................................................................................................9
AIRLIE GARDENS .................................................................................................................................4
DISCUSSION ..................................................................................................................................... 12
PARAMETERS ................................................................................................................................... 13
AIRLIE GARDENS DISCUSSION ............................................................................................................... 16
APPENDIX A: ADDITIONAL CREEK DATA ............................................................................................ 17
BARNARDS CREEK ............................................................................................................................. 17
FUTCH CREEK................................................................................................................................... 20
ISLAND CREEK .................................................................................................................................. 25
LORDS CREEK................................................................................................................................... 27
MOTT CREEK ................................................................................................................................... 29
PAGES CREEK ................................................................................................................................... 32
PRINCE GEORGE ............................................................................................................................... 36
SMITH CREEK ................................................................................................................................... 40
AIRLIE GARDENS ............................................................................................................................... 45
APPENDIX B: LONG TERM TRENDS .................................................................................................... 50
DISSOLVED OXYGEN .......................................................................................................................... 50
TURBIDITY....................................................................................................................................... 51
CHLOROPHYLL-A ............................................................................................................................... 51
ENTEROCOCCI .................................................................................................................................. 52
APPENDIX C ..................................................................................................................................... 54
WATER CLASSIFICATIONS .................................................................................................................... 54
PARAMETERS ................................................................................................................................... 54
STANDARDS..................................................................................................................................... 57
METHODS....................................................................................................................................... 60
APPENDIX D: PAGES CREEK PCR ANALYSIS ........................................................................................ 61
LITERATURE CITED ........................................................................................................................... 62
CPE-NC
INTRODUCTION
New Hanover County’s (NHC) location is unique since with the exception of the northeastern boundary,
it is surrounded by water on three sides; on the north and south by the Northeast Cape Fear River, on the
west by the Cape Fear River, and on the east by the Atlantic Ocean. It is primarily a coastal county
containing many creeks, streams, and water bodies that provide the opportunities for a wide range of
recreational activities for thousands of local citizens and visiting tourists yearly. Due to its proximity to
the Atlantic Ocean and the Intracoastal Waterway, NHC’s tidal creeks are not only used for recreation but
are an important resource for the natural environment as they provide habitats for various plant and
animal species. 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). Therefore, protection of the water
quality within these creeks is a high priority for the County.
Water quality has been monitored in New Hanover County since the early 1970s by the State in efforts to
study the impacts of adjacent septic systems on water quality in tidal creeks. An increase in the closure of
tidal creeks for shellfishing became an early concern for the citizens of New Hanover County and was a
topic included in early land use plans. The ongoing water quality conversation within the community led
to several watershed plans and in 1993, New Hanover County and the City of Wilmington partnered with
the University of North Carolina Wilmington to conduct a long-standing water quality monitoring
program.
However, in November 2007, Coastal Protection Engineering of North Carolina, Inc. (CPE) began a
separate, monthly water quality monitoring program on behalf of New Hanover County for the tidal creeks
within the unincorporated parts of the County.
The information presented in this report focuses on the results of this monitoring from July 2021 to June
2022. The creeks included in this study are Pages and Futch, which drain into the Atlantic Intracoastal
Waterway (ICW), Island Creek, which drains into the Northeast Cape Fear River and Lords, Mott, Barnards,
Smith, and Prince George, which drain into the Cape Fear River (Figure 1). 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.
The results described in this report represent the physical, biological, and chemical data collected monthly
from all sampling sites from July 2021 through June 2022. These results are organized by watershed
alphabetically, with the results of the eight (8) tidal creeks presented first, followed by the results from
Airlie Gardens. Additional creek data, including parameters not summarized in this section, from the tidal
creeks sampling sites and the Airlie Garden sampling sites are found in Appendix A.
Based on the raw data, a quantitative system assigns a rating of “Good”, “Fair”, or “Poor” to a sampling
station depending on the percentage of samples that went above the State standard for turbidity,
chlorophyll-a, Enterococci, or below the State standard for dissolved oxygen. If the recorded value of a
parameter went outside the acceptable range of the State standard less than 10% of the times sampled
the station will receive a “Good” rating, a “Fair” rating 11%-25% of the times sampled, or a “Poor” rating
for greater than 25% of the sampling times. This general description is useful when looking at trends from
year to year and across the entire time frame of the program. Ratings for all parameters can be found in
the Discussion section below.
CPE-NC
2
Figure 1: Watersheds Monitored
CPE-NC
3
CREEK SUMMARIES
Barnards Creek
• Location: South central New Hanover County
and a portion in the City of Wilmington. (Monkey
Junction, Echo Farms, Carriage Hills).
• 1 Sampling Location: BC-CBR
• Size: 4,234 Acres
• Drains To: Cape Fear River
• Land Use: Low and medium density residential,
commercial, and retail uses along Carolina Beach
Road, S. 17th Street, and S. College Road
Year at a Glance
• 2 (two) occurrences of dissolved oxygen below
State standard
• 0 (zero) occurrences above State standard for
chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
• 0 (zero) occurrences above State standards for
Enterococci
Overall Assessment
Overall, there were no issues with Barnards Creek for the
year. However, dissolved oxygen did drop below the State
standard twice.
Parameter BC-CBR
Turbidity (NTU) Good
Dissolved Oxygen Fair
Chlorophyll-a Good
Enterococci Good
CPE-NC
11
Futch Creek
• Location: Northeast New Hanover County and
a portion of Pender County (Porters Neck,
Scotts Hill).
• 4 Sampling Locations: FC-4, FC-6, FC-13,
FC-FOY
• Size: 3,429 Acres
• Drains To: Intracoastal Waterway
• Land Use: Low density residential and some
commercial/retail uses along U.S. 17.
Year at a Glance
• 2 (two) occurrences of dissolved oxygen below
State standard
• 0 (zero) occurrences above State standard for
chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
• 0 (zero) occurrences above State standards for
Enterococci
Overall Assessment
Overall, there were no issues with Futch Creek for the
year. Low dissolved oxygen was observed within the
upper reaches of the creek at FC-13 on two occasions.
Parameter FC-4, FC-6, FC-13, FC-FOY
Turbidity (NTU) Good
Dissolved Oxygen Good, Good, Fair, Good
Chlorophyll-a Good
Enterococci Good
CPE-NC
5
Island Creek
• Location: Northeast New Hanover County and
portions of Pender County (Sidbury Road & Holly
Shelter Road).
• 1 Sampling Location: IC-HS
• Size: 12,919 Acres
• Drains To: NE Cape Fear River
• Land Use: Undeveloped, low density residential.
Year at a Glance
• 3 (three) occurrences of dissolved oxygen below
State standard
• 0 (zero) occurrences above State standard for
chlorophyll-a
• 0 (zero occurrences above State standard for
turbidity
• 0 (zero) occurrences above State standards for
Enterococci
Overall Assessment
During the first year of water quality monitoring within
Island Creek, dissolved oxygen was determined to be fair
while all other parameters were good.
Parameter IC-HS
Turbidity (NTU) Good
Dissolved Oxygen Fair
Chlorophyll-a Good
Enterococci Good
CPE-NC
6
Lords Creek
• Location: Southwest New Hanover County
(Veterans Park, River Road).
• 1 Sampling Location: LC-RR
• Size: 1,076 Acres
• Drains To: Cape Fear River
• Land Use: Low density residential and
commercial/retail uses along Carolina Beach
Road.
Year at a Glance
• 0 (zero) occurrences of dissolved oxygen below
State standard
• 0 (zero) occurrences above State standard for
chlorophyll-a
• 0 (zero occurrences above State standard for
turbidity
• 0 (zero) occurrences above State standards for
Enterococci
Overall Assessment
Overall, there were no issues with Lords Creek for the
year as no parameters exceeded their respective
standards.
Parameter LC-RR
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good
CPE-NC
7
3
Mott Creek
• Location: South central New Hanover County
(Monkey Junction, Silver Lake, Piner Road).
• 2 Sampling Locations: MOT-ND, MOT-CBR
• Size: 2,906 Acres
• Drains To: Cape Fear River
• Land Use: Low to Moderate density residential
with commercial and retail along Carolina Beach
Road and S. College Road.
Year at a Glance
• 1 (one) occurrence of dissolved oxygen below
State standard
• 1 (one) occurrence above State standard for
chlorophyll-a
• 0 (zero) occurrence above State standard for
turbidity
• 2 (two) occurrences above State standards for
Enterococci
Overall Assessment
Overall, the water quality within Mott Creek for the year
was good. While Enterococci levels have decreased over the
years, there were two exceedances at the Normandy Drive
site (MOT-ND) this year.
Parameter MOT-CBR, MOT-ND
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good, Fair
CPE-NC
8
Pages Creek
• Location: Northeastern New Hanover County.
(Middle Sound, Ogden, Porters Neck).
• 3 Sampling Locations:
PC-BDUS, PC-BDDS, PC-M
• Size: 4,124 Acres
• Drains To: Intracoastal Waterway
• Land Use: Low density residential and some
commercial/retail uses along U.S. 17.
Year at a Glance
• 4 (four) occurrences of dissolved oxygen below
State standard.
• 1 (one) occurrence above State standard for
chlorophyll-a
• 0 (zero occurrences above State standard for
turbidity
• 11 (eleven) occurrences above State standards for
Enterococci
Overall Assessment
Dissolved Oxygen levels were below state standards a few
times throughout the year at all sites while Enterococci
levels remained elevated at the upstream and downstream
sites.
Parameter PC-BDDS, PC-BDUS, PC-M
Turbidity (NTU) Good
Dissolved Oxygen Poor, Good, Good
Chlorophyll-a Good
Enterococci Poor, Poor, Good
CPE-NC
9
Prince George Creek
• Location: North New Hanover County (Castle
Hayne).
• 4 Sampling Locations: PG-CH, PG-ML, PG-NC
• Size: 10,875 Acres
• Drains To: Northeast Cape Fear River
• Land Use: Low density residential, agricultural,
and some commercial/retail uses Castle Hayne
Road and N. College Road.
Year at a Glance
• 14 (fourteen) occurrences of dissolved oxygen
below State standard
• 0 (zero) occurrences above State standard for
chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
• 4 (four) occurrences above State standards for
Enterococci
Overall Assessment
Dissolved Oxygen at PG-NC was below state standards
throughout the year with the other sites also experiencing
issues with DO. There were 4 exceedances of state
standards for Enterococci, 3 of which occurred in
September.
Parameter PG-CH, PG-ML, PG-NC
Turbidity (NTU) Good
Dissolved Oxygen Fair, Fair, Poor
Chlorophyll-a Good
Enterococci Fair, Good, Good
CPE-NC
10
Smith Creek
• Location: Central New Hanover County including
portions of City of Wilmington (Wrightsboro, ILM,
Kings Grant, Coastal Carolina).
• 5 Sampling Locations: SC-CH, SC-23, SC-NK,
SC-GR, SC-CD
• Size: 17,535 Acres
• Drains To: Cape Fear River
• Land Use: Moderate density residential within the
city, light industrial around the airport, some
agricultural along Kerr Avenue, and some
commercial/retail uses along U.S. 17.
Year at a Glance
• 2 (two) occurrences of dissolved oxygen below
State standard
• 1 (one) occurrence above State standard for
chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
• 3 (three) occurrences above State standards for
Enterococci
Overall Assessment
Overall, there were no concerns with Smith Creek for the
year. However, Enterococci bacteria did exceed state
standards three (3) times across 5 sites.
Parameter SC-CH, SC-23, SC-NK, SC-GR, SC-CD
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good, Good, Good, Fair, Good
CPE-NC
11
Airlie Gardens
• Location: City of Wilmington.
• 4 Sampling Locations: AC-IN, AC-AD, AC-
OUT
• Size: 10 Acre Freshwater Lake
• Drains To: Bradley Creek
• Land Use: On a conservation site surrounded
by low density residential.
Year at a Glance
• 0 (zero) occurrences of dissolved oxygen below
State standard
• 13 (thirteen) occurrences above State standard
for chlorophyll-a
• 1 (one) occurrence above State standard for
turbidity
*Enterococci is not measured at Airlie Gardens
Overall Assessment
There are no issues with dissolved oxygen or turbidity.
However, Chlorophyll-a, Nitrate/Nitrite, and
Orthophosphate levels have increased over the years. It
may take several years for a trend to emerge after the
completion of recent water quality improvement projects,
and it is recommended to continue monitoring.
CPE-NC
12
DISCUSSION
Water quality is an important issue in the region since there are many economic and recreational
opportunities that are supported by the aquatic resources in and around these waterways. In New
Hanover County, different factors can affect water quality with a major one being land use. In more rural
parts of the county, agriculture and farming can introduce increased amounts of chemicals like those
found in fertilizer, as well and bacteria from animal waste. Additionally, failing or poorly maintained septic
systems can increase bacteria in a watershed. In more urbanized areas, experts have identified
stormwater runoff created by increased impervious surface coverage (Mallin et al., 2000) as a reason for
increases in chemicals like those found in fertilizer for landscaped lawns, as well as bacteria from pet
waste. Like rural areas, urban areas can also see human bacteria introduced into nearby waterways if
there are deficiencies or leaks in the sanitary sewer system. Due to many of the contaminants found in
stormwater runoff and its ability to concentrate especially after rain events, 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 estimated to be
216,995 and has grown by 4% to 225,702 based on the 2020 census. While long term monitoring suggests
that development and continued growth in New Hanover County may be altering water quality within its
tidal creeks, a more recent assessment of the ratings for many water quality parameters as depicted in
this report have improved or remained steady over the past several years. This suggests that even though
the unincorporated portions of New Hanover County continue to build out, there are factors minimizing
the impact to water quality. One rational may be the inclusion of state stormwater controls required for
all new development which aims to mitigate stormwater on site. Additionally, the county has created a
new stormwater services program to help maintain and improve drainage, primarily in areas developed
prior state stormwater regulations. However, these and other factors have not been clearly identified as
factors that may be facilitating this trend at this point but there have been several notable efforts made
that maybe contributing to the improved water quality.
From a bacteria perspective, in 2017, the Cape Fear Public Utility Authority (CFPUA) completed work to
provide the Marquis Hills subdivision within the Mott Creek watershed with sewer service providing a
more reliable way to treat sewage. Additionally, the CFPUA through their capital improvement plan,
identifies and prioritizes projects to upgrade aging infrastructure like pumpstations, and programs like
“Find it and Fix it” to maintain the integrity of the sewer system. For overall water quality, the county,
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. In addition, the New Hanover County Stormwater Services Program continues to
work on and has completed numerous drainage improvement projects. With this in mind, it is important
to continue to monitor the water quality and assess the potential impacts to both human health and
ecosystem function as conditions change.
The long-term water quality monitoring results suggest that the seven (7) creeks that have experienced
good water quality in terms of turbidity and chlorophyll-a levels over the course of the fourteen (14) year
study thus far. The one parameter, however, that has been problematic has been Enterococci bacteria.
Of the 3,189 samples collected and analyzed since June 2008, 722 samples (23% of all samples) have
CPE-NC
13
exceeded the State standard for this bacterium. This analysis does not include data from Island Creek
which was added to the monitoring program this past year and therefore was not included in the long-
term data set.
Parameters
Physical 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 for bacteria.
At the Airlie Gardens sampling locations, the same physical parameters were collected in addition to
chemical parameters including orthophosphate and nitrate/nitrite. It was determined at that time that
bacterial contamination was non problematic, Enterococci samples are not collected at Airlie Gardens.
Physical Parameter Discussion
Over the past fourteen (14) years of water quality monitoring, some trends have emerged. 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 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 and turbidity measurements were
generally found to be within acceptable ranges while only three (3) chlorophyll-a samples exceeded the
State standard during the 2021-2022 study period.
Overall Watershed Rating
In general, the dissolved oxygen within Barnards Creek, Lords Creek, Mott Creek, and Smith Creek has
been rated “Good” through the course of this long-term study with few exceptions. Barnards Creek had
declined in term of dissolved oxygen in recent years, however it had improved to “Good” again over the
four (4) of the past five (5) years with it reverting back to “Fair” during the most recent study period (2021-
2022). Futch Creek has maintained a “Fair” rating for nine (9) of the fourteen (14) years, however
improved to "Good" during the past two (2) study periods. Pages Creek has demonstrated varying
dissolved oxygen levels over time ranging from “Poor” to “Good” over the years and has been deemed
“Fair” during five (5) of the past six (6) study periods. 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” twelve (12) of the fourteen (14) years. It should be noted that the slow-moving water and swamp-
like features within portions of Prince George Creek may help naturally facilitate these low dissolved
oxygen levels.
Biological Parameter Discussion
While several creeks have exhibited relatively low levels of bacteria throughout the lifetime of the
program (namely Futch Creek and Lords Creek), other creeks have proven to show elevated levels of
Enterococci. Of the 3,189 samples collected and analyzed from all of the monitoring sites since June 2008,
722 samples (23% of all samples) have exceeded the State standard for this bacterium. Specifically, Mott
CPE-NC
14
Creek has exceeded the standard 39% of the time and PC-BDDS and PC-BDUS within Pages Creek have
exceeded the standard 41% and 62% of the time, respectively.
During this year's study period (2021-2022), the collective bacteria levels within the creeks were observed
to be similar to the previous year’s effort with the exception of Mott Creek which saw an improvement in
rating from “Fair” to “Good”. In general, the past two years represent an overall improvement in water
quality with respect to Enterococci compared to the preceding study periods.
No samples collected from within four creeks (Lords Creek, Futch Creek, Barnard Creek, and Island Creek)
exceeded the State Enterococci standard during this most recent study period. At Smith Creek, Mott
Creek, and Prince George Creek, the standard was exceeded 7%, 8%, and 11% of the time during this time,
respectively. Pages Creek continued to show elevated levels of Enterococci where eleven (11) out of 36
samples (31%) exceeded the State standard. None of the samples collected from the site at the mouth of
Pages Creek (PC-M) exceeded the standard. Of the eleven (11) samples that exceeded the standard, six
(6) were from the Pages Creek down-stream site (PC-BDDS) and five (5) were from the up-stream sampling
site (PC-BDUS). Of the twenty (20) sites included in this program, the site PC-BDUS has exhibited the
highest rate of Enterococci above state standards. This station, located at the boat ramp in the Bayshore
community within the Pages Creek watershed, has exceeded the standard 62% of the time since sampling
began in 2008.
In 2008 and 2013 source tracking studies was performed identifying a human signature in the bacteria
that was present in the waters at the PC-BDUS site within Pages Creek. In coordination, the New Hanover
County Health Department, and the Cape Fear Public Utility Authority, investigated abandon septic
systems and conducted inspections of sewer infrastructure to determine if those were a contributing
factor to the elevated bacteria levels. These investigations did not reveal any deficiencies. More recently
in 2019, New Hanover County partnered with the University of North Carolina Wilmington’s Socio-
Environmental Analysis Laboratory and Coastal Protection Engineering of North Carolina to conduct a
thermal imagery scan of two portions of Pages Creek in an attempt identify any possible sources of
bacteria entering the creek.
In June and July of 2022, CPE performed additional source tracking efforts within two areas where the
thermal imagery showed temperature differences indicating the presence of point-source effluent
entering the creek. These areas were characterized as groundwater seeps located along the creek’s bank
and visualized only at lower tides. Both areas were in proximity to the long-term monitoring sampling
sites in the Bayshore neighborhood (PC-BDUS and PC-BDDS) and directly adjacent to CFPUA lift stations.
Water samples were collected from these areas on June 13 and July 11, 2022 and were subsequently
analyzed by a commercial laboratory using the most widely applied method for the characterization of
human fecal pollution in ambient surface waters: Quantitative real-time PCR (qPCR) assays that target the
human-associated HF183 bacterial cluster within members of the genus Bacteroides (Green et al., 2014).
A large number of laboratory and field studies have shown that analyses of host-associated molecular
marker genes such as HF183 can identify sources of fecal contamination in waterways with a high degree
of precision. Accordingly, this tool has become an established indicator for human sewage contamination
in temperate environments (Nshimyimana et al., 2014). Both samples collected in proximity to PC-BDUS
resulted in a “Non-Detect” where the host-associated fecal gene biomarker (HF183) were not detected in
one or both test replicates. The two samples collected from the seep located in proximity to PC-BDDS
resulted in “Detected, Not Quantified” where the host-associated fecal biomarker was detected in both
test replicates but in quantities below the limit of quantification.
CPE-NC
15
At Mott Creek, the bacteria levels continue to improve; similar to the results observed during the past
three (3) study periods. During 2021-2022, only two (2) samples were above the state standard while
during the three previous sampling periods , three (3), six (6), and six (6) samples above the standard were
collected, respectively. Prior to the 2016-2017 sampling effort, Mott Creek had consistently demonstrated
“Poor” water quality in terms of bacterial contamination. As mentioned above, part of this improvement
comes from the result of transitioning residential homes with failing septic systems to the CFPUA’s sewer
system in the Marquis Hills community (located within the Mott Creek watershed). Since that time the
data has reflected, that bacteria levels have reduced proving the need for additional septic to sewer
conversions in other watersheds. CFPUA has planned upgrades to the wastewater infrastructure which
may further improve overall water quality in the watershed. New Hanover County has also completed a
drainage project via its Stormwater Services Program to improve flow. Data has shown reduced levels of
bacteria and improvements in dissolved oxygen and chlorophyl-a since the completion of that project in
2019.
Overall Watershed Rating
The long-term trends for Enterococci ratings over the past fourteen (14) years have shown that Mott
Creek, Pages Creek, and Prince George Creek maintained “Poor” ratings during much of the time;
however, over the past three (3) years these three creeks have demonstrated some improvements. Mott
Creek, which was deemed “Poor” between 2008 and 2016, has improved to “Good” for the first time this
year and was deemed “Fair” over the previous five (5) study periods. Similarly, Smith Creek has improved
over recent years as it has been rated as "Good" for Enterococci levels over the past four (4) years in a
row whereas previous years it contained either "Poor" or "Fair" levels. Barnards Creek, Lords Creek, and
Prince George Creek have demonstrated varying conditions since sampling was first initiated. Futch
Creek, meanwhile, has consistently maintained a “Good” rating, with two exceptions when it was deemed
“Fair”.
CPE-NC
16
Airlie Gardens Discussion
The results from monthly sampling over the past seven (7) years 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 (3) sites in Airlie Gardens were generally
low. However, generally speaking, since 2015-2016 at the AG-IN site, nitrate/nitrite levels have been
relatively higher on average compared to the other two sites further south and closer to the outfall and
orthophosphate has been steadily increasing over time across all sites.
Over the past seven (7) years of sampling, the orthophosphate level within all three sampling sites have
averaged 0.06mg/l. Nitrite/Nitrate levels have been 0.06 mg/l at AG-IN while AG-FD and AG-OUT
averaged 0.03 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 macroalgae within the lake. Phosphorus is a particularly
vital nutrient for converting sunlight into usable energy, and essential to cellular growth and reproduction.
Under natural conditions phosphorus is typically scarce in water. In the late 1960s scientists discovered
phosphorus contributed by human activity to be a major cause of excessive algae growth and degraded
lake water quality (MPCA, 2008). The process involving an increase of nutrient loading to a waterbody,
called eutrophication, 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 and overall water quality, Airlie Gardens has
implemented initiatives identified in their stormwater master plan. These initiatives include installing
several aerators in the lake 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 was restored in early
2019 which included the planting of native Cypress and the installation of an engineered wetland BMP.
In 2020 the County completed a dredging operation by excavating 5' deep by 10' wide channels in the
lake, effectively removing approximately 4,000 cubic yards of bottom sediment and material. The removal
of the nutrient-laden sediments will ideally result in decreased levels of orthophosphate and
nitrate/nitrite within the water column which should result in a reduction of algal blooms thereby helping
to maintain appropriate levels of dissolved oxygen. Since these implementation projects were recently
completed, the monitoring data has not shown a reduction on nutrient loading into the lake, but it may
take a couple to several years to see a trend emerge. It is recommended to continue to monitor the lake
to gauge the status of the lake and the effectiveness of the implemented projects.
CPE-NC
17
APPENDIX A: ADDITIONAL CREEK DATA
Barnards Creek
Sampling was conducted at one site (BC-CBR) within the Barnards Creek watershed (Figure 2).
Dissolved oxygen within BC-CBR ranged between 1.1 mg/l and 10.0 mg/l with a mean value of 5.5 mg/l
(Table 1). Two (2) samples contained dissolved oxygen levels below the State standard of 4.0 mg/l for C
Sw waters at the surface (Figure 3).
Chlorophyll-a ranged between 1.0 ug/l and 5.0 ug/l with a mean value of 2.0 ug/l at BC-CBR (Table 1).
These values did not approach the 40 ug/l standard.
Enterococci ranged between 5 CFU/100 ml and 63 CFU/100 ml with a geometric mean value of 21 CFU/100
ml, which is below the NCDEQ standard of 500 CFU/100 ml for Tier III waters (Table 1). None of the twelve
(12) samples collected during this period exceeded this standard.
Turbidity values were generally good, ranging between 2 and 18 NTU with a mean value of 6 NTU (Table
1). No samples exceeded the State standard of 50 NTU for C SW waters.
Table 2 depicts the ratings for these parameters for the watershed.
Table 1. Mean values of select parameters from Barnards Creek. Range in parentheses.
Figure 2. Water Quality Sites within the Barnards Creek Watershed
CPE-NC
18
Parameter BC-CBR
Turbidity (NTU) 6 (2-18)
Dissolved Oxygen (mg/l) 5.1 (1.1-10.0)
Chlorophyll-a (ug/l) 2 (1-5)
Enterococci (#CFU/100ml) 21 (5-63)
(1) Enterococci values expressed as geometric mean
Figure 3. Dissolved Oxygen at BC-CBR at surface (DO-S) and bottom (DO-B)
Figure 4. Enterococci at BC-CB
CPE-NC
19
Table 2. Ratings of parameters within sampling stations within Barnards Creek
Parameter BC-CBR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci GOOD
CPE-NC
20
Futch Creek
Sampling was conducted at four (4) sites (FC-4, FC-6, FC-13, and FC-FOY) within the Futch Creek watershed
(Figure 5).
Dissolved oxygen within Futch Creek ranged between 4.4mg/l and 9.9 mg/l with a mean value of 7.5 mg/l
(Figure 6 – Figure 9, Table 3). Two (2) samples contained dissolved oxygen levels below the State standard
of 5.0 mg/l for SA water
Chlorophyll-a ranged between 0.0 ug/l and 13.0 ug/l with a mean value of 3.0 ug/l (Table 3). None of
these values approached the 40ug/l chlorophyll-a standard.
Enterococci ranged between 1 CFU/100ml and 112 CFU/100ml with a geometric mean value of 7
CFU/100ml. No samples collected within Futch Creek during exceeded the NCDEQ Enterococci standard
of 500 CFU/100 ml for Tier III waters (Figure 10 – Figure 13, Table 3).
Turbidity values were generally low ranging between 0 and 15 NTU with a mean value of 4 NTU (Table 3).
No samples exceeded the State standard of 25 NTU for SA waters during this study period.
Table 4 depicts the ratings for these parameters for the watershed.
Figure 5. Water Quality Sites within the Futch Creek Watershed
CPE-NC
21
Table 3. Mean values of select parameters from Futch Creek. Range in parentheses.
Parameter FC-4 FC-6 FC-13 FC-FOY
Turbidity (NTU) 3 (1-9) 4 (0-9) 6 (0-12) 5 (0-15)
Dissolved
Oxygen (mg/l)
7.8 (5.7-9.6) 7.6 (5.2-9.9) 7.2 (4.4-9.7) 7.5 (5.1-9.9)
Chlorophyll-a
(ug/l)
2 (0-5) 2 (0-5) 3 (1-13) 3 (0-12)
Enterococci
(#CFU/100ml)
6 (1-81)1 6 (1-101)1 8 (1-112)1 8 (1-92)1
(1)Enterococci values expressed as geometric mean
Figure 6. Dissolved Oxygen at FC-4 at surface (DO-S) and bottom (DO-B)
Figure 7. Dissolved Oxygen at FC-6 at surface (DO-S) and bottom (DO-B)
CPE-NC
22
Figure 8. Dissolved Oxygen at FC-13 at surface (DO-S) and bottom (DO-B)
Figure 9. Dissolved Oxygen at FC-FOY at surface (DO-S) and bottom (DO-B)
Figure 10. Enterococci at FC-4
CPE-NC
23
Figure 11. Enterococci at FC-6
Figure 12. Enterococci at FC-13
Figure 13. Enterococci at FC-FOY
Table 4. Ratings of parameters within sampling stations within Futch Creek
CPE-NC
24
Parameter FC-4 FC-6 FC-13 FC-FOY
Turbidity GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD FAIR GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD
CPE-NC
25
Island Creek
Sampling was conducted at one (1) site (IC-HS) within the Island Creek watershed (Figure 14).
Dissolved oxygen at IC-HS ranged between 2.4 mg/l and 10.2 mg/l with a mean value of 5.6 mg/l (Table
5). Three (3) samples were below the State standard of 4.0 mg/l for C Sw waters during the sampling
period (Figure 15).
Chlorophyll-a ranged between 1 ug/l and 9 ug/l with a mean value of 4 ug/l (Table 5). No samples
exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 5 CFU/100ml and 305 CFU/100ml with a geometric mean value of 30
CFU/100ml (Table 5). None of the twelve (12) samples collected over this reporting period contained high
levels of Enterococci beyond the NCDEQ standard of 500 CFU/100 ml for Tier III waters.
Turbidity values were generally moderate ranging between 2 and 8 NTU with a mean value of 4 NTU (Table
5). No samples exceeded the State standard of 50 NTU for C Sw waters in Island Creek during the reporting
period.
Table 6 depicts the ratings for these parameters for the watershed
Figure 14. Water Quality Site within the Island Creek Watershed
CPE-NC
26
Table 5. Mean values of select parameters from Island Creek. Range in parentheses.
Parameter IC-HS
Turbidity (NTU) 4 (2-8)
Dissolved Oxygen
(mg/l)
5.6 (2.4-10.2)
Chlorophyll-a (ug/l) 4 (1-9)
Enterococci
(#CFU/100ml)
30 (5-305)1
(1)Enterococci values expressed as geometric mean
Figure 15. Dissolved Oxygen at IC-HS at surface (DO-S) and bottom (DO-B)
Figure 16. Enterococci at IC-HS
Table 6. Ratings of parameters within sampling stations within Island Creek
Parameter IC-HS
Turbidity GOOD
Dissolved Oxygen FAIR
Chlorophyll-a GOOD
Enterococci GOOD
CPE-NC
27
Lords Creek
Sampling was conducted at one (1) site (LC-RR) within the Lords Creek watershed (Figure 17).
Dissolved oxygen at LC-RR ranged between 4.5 mg/l and 10.9 mg/l with a mean value of 7.8 mg/l (Table
7). No samples were below the State standard of 4.0 mg/l for C Sw waters during the sampling period
(Figure 18).
Chlorophyll-a ranged between 3 ug/l and 39 ug/l with a mean value of 14 ug/l (Table 7). No samples
exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 5 CFU/100ml and 52 CFU/100ml with a geometric mean value of 15
CFU/100ml (Table 7). None of the twelve (12) samples collected over this reporting period contained high
levels of Enterococci beyond the NCDEQ standard of 500 CFU/100 ml for Tier III waters (Figure 19).
Turbidity values were generally moderate ranging between 3 and 21 NTU with a mean value of 10 NTU
(Table 7). No samples exceeded the State standard of 50 NTU for C Sw waters in Lords Creek during the
reporting period.
Table 8 depicts the ratings for these parameters for the watershed.
Figure 17. Water Quality Site within the Lords Creek Watershed
CPE-NC
28
Table 7. Mean values of select parameters from Lords Creek. Range in parentheses.
Parameter LC-RR
Turbidity (NTU) 10 (3-21)
Dissolved Oxygen (mg/l) 7.8 (4.5-10.9)
Chlorophyll-a (ug/l) 14 (3-39)
Enterococci (#CFU/100ml) 15 (5-52)1
(1)Enterococci values expressed as geometric mean
Figure 18. Dissolved Oxygen at LC-RR at surface (DO-S) and bottom (DO-B)
Figure 19. Enterococci Levels at LC-RR
Table 8. Ratings of parameters within sampling stations within Lords Creek
Parameter LC-RR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci GOOD
CPE-NC
29
Mott Creek
Sampling was conducted at two (2) sites (MOT-CBR, MOT-ND) within the Mott Creek watershed (Figure
20).
Dissolved oxygen within Mott Creek ranged between 3.0 mg/l and 10.6 mg/l with a mean value of 6.8
mg/l (Figure 21 and Figure 22, Table 9). One (1) sample collected during the reporting period contained
dissolved oxygen levels below the standard (Figure 21 and Figure 22).
Chlorophyll-a ranged between 1 ug/l and 110 ug/l with a mean value of 11 ug/l (Table 9). One sample
exceeded the 40ug/l standard.
Enterococci ranged between 5 CFU/100ml and 2,310 CFU/100ml with a geometric mean value of 89
CFU/100 ml (Table 9). Samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III waters during
two (2) sampling events during the reporting period (Figure 23 and Figure 24).
Turbidity values were generally good ranging between 2 and 23 NTU with a mean value of 8 NTU (Table
7). No turbidity observations exceeded the State standard of 50 NTU for C Sw waters.
Table 10 depicts the ratings for these parameters for the watershed.
Figure 20. Water Quality Sites within the Mott Creek Watershed
CPE-NC
30
Table 9. Mean values of select parameters from Mott Creek. Range in parentheses.
Parameter MOT-CBR MOT-ND
Turbidity (NTU) 7 (2-23) 10 (5-19)
Dissolved Oxygen (mg/l) 6.2 (3.0-10.6) 7.4 (5.6-10.6)
Chlorophyll-a (ug/l) 16 (1-110) 6 (2-13)
Enterococci (#CFU/100ml) 43 (5-211)1 183 (5-2,310)1
(1)Enterococci values expressed as geometric mean
Figure 21. Dissolved Oxygen at MOT-CBR at surface (DO-S)
Figure 22. Dissolved Oxygen at MOT-ND at surface (DO-S)
CPE-NC
31
Figure 23. Enterococci at MOT-CBR
Figure 24. Enterococci at MOT-ND
Table 10. 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 GOOD FAIR
CPE-NC
32
Pages Creek
Sampling was conducted at three (3) sites (PC-BDDS, PC-BDUS, and PC-M) within the Pages Creek
watershed (Figure 25).
Dissolved oxygen within Pages Creek ranged between 2.8 mg/l and 12.3 mg/l with a mean value of 7.5
mg/l (Figures 26 - 28, Table 11). Over the twelve (12) month study period, the dissolved oxygen levels
were below the State standard four (4) times at PC-BDDS. Dissolved oxygen was within the standard at
PC-BDUS and PC-M during all twelve (12) sampling events.
Chlorophyll-a ranged between 1 ug/l and 80 ug/l with a mean value of 10 ug/l (Table 11). One (1) sample
exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 3 CFU/100 ml and 763 CFU/100 ml with a geometric mean value of 78
CFU/100 ml (Figures 29 – 31, Table 11). Six (6) samples from PC-BDDS and five (5) samples from PC-BDUS,
respectively, contained levels higher than the NCDEQ standard.
Turbidity values were generally good ranging between 0 and 17 NTU with a mean value of 6 NTU (Table
11). None of the observed turbidity values exceeded the State standard of 25 NTU for class SA waters.
Table 12 depicts the ratings for these parameters for the watershed.
Figure 25. Water Quality Sites within the Pages Creek Watershed
CPE-NC
33
Table 11. Mean values of select parameters from Pages Creek. Range in parentheses.
Parameter PC-BDDS PC-BDUS PC-M
Turbidity (NTU) 7 (1-17) 7 (3-11) 4 (0-12)
Dissolved Oxygen (mg/l) 8.9 (5.6-12.3) 6.2 (2.8-9.5) 7.5 (6.0-9.5)
Chlorophyll-a (ug/l) 17 (2-80) 10 (2-37) 3 (1-5)
Enterococci (#CFU/100ml) 471 (134-763)1 143 (25-620)1 7 (3-67)1
(1)Enterococci values expressed as geometric mean
Figure 26 Dissolved Oxygen at PC-BDDS at surface (DO-S)
Figure 27. Dissolved Oxygen at PC-BDUS at surface (DO-S)
CPE-NC
34
Figure 28. Dissolved Oxygen at PC-M at surface (DO-S) and bottom (DO-B)
Figure 29. Enterococci at PC-BDDS
Figure 30. Enterococci at PC-BDUS
CPE-NC
35
Figure 31. Enterococci at PC-M
Table 12. Ratings of parameters within sampling stations within Pages Creek
Parameter PC-BDDS PC-BDUS PC-M
Turbidity GOOD GOOD GOOD
Dissolved Oxygen FAIR GOOD GOOD
Chlorophyll-a GOOD GOOD GOOD
Enterococci POOR POOR GOOD
CPE-NC
36
Prince George
Sampling was conducted at three (3) sites (PG-CH, PG-ML, and PG-NC) within the Prince George Creek
watershed (Figure 31).
Dissolved oxygen within Prince George Creek ranged between 0.5 mg/l and 9.8 mg/l with a mean value of
4.9 mg/l (Table 13). Surface dissolved oxygen values were below the State standard of 4.0 mg/l for C Sw
on eight (8) occasions during the reporting period at PG-NC, three (3) times at both PG-ML and PG-CH
(Figures 33 – 35, Table 13).
Chlorophyll-a ranged between 1 ug/l and 28 ug/l with a mean value of 6 ug/l (Table 13). No samples from
Prince George Creek exceeded the 40 ug/l standard.
Enterococci ranged between 5 CFU/100ml and 3,780 CFU/100ml with a geometric mean value of 56
CFU/100ml (Table 13). Four (4) samples collected from within Prince George Creek contained Enterococci
levels above the NCDEQ standard of 500 CFU/100ml for Tier III waters (Figures 36 – 38).
Turbidity values were generally good ranging between 1 and 11 NTU with a mean value of 4 NTU (Table
13). No samples exceeded the State standard of 50 NTU for C Sw waters.
Table 14 depicts the ratings for these parameters for the watershed.
Figure 32. Water Quality Sites within the Prince George Creek Watershed
CPE-NC
37
Table 13. Mean values of select parameters from Prince George Creek. Range in parentheses.
Parameter PG-CH PG-ML PG-NC
Turbidity (NTU) 5 (3-9) 3 (1-8) 5 (1-11)
Dissolved Oxygen (mg/l) 5.9 (3.1-9.8) 5.9 (0.5-9.7) 3.0 (0.5-8.0)
Chlorophyll-a (ug/l) 7 (2-28) 5 (1-10) 4 (2-7)
Enterococci (#CFU/100ml) 79 (5-2,220)1 67 (5-565)1 33 (5-3,780)1
(1)Enterococci values expressed as geometric mean
Figure 33. Dissolved Oxygen at PG-CH at surface (DO-S) and bottom (DO-B)
Figure 34. Dissolved Oxygen at PG-ML at surface (DO-S)
CPE-NC
38
Figure 35. Dissolved Oxygen at PG-NC at surface (DO-S) and bottom (DO-B)
Figure 36. Enterococci at PG-CH
Figure 37. Enterococci at PG-ML
CPE-NC
39
Figure 38. Enterococci at PG-NC
Table 14. Ratings of parameters within sampling stations within Prince George Creek
Parameter PG-CH PG-ML PG-NC
Turbidity GOOD GOOD GOOD
Dissolved Oxygen FAIR FAIR POOR
Chlorophyll-a GOOD GOOD GOOD
Enterococci FAIR GOOD GOOD
CPE-NC
40
Smith Creek
Sampling was conducted at five (5) sites (SC-CH, SC-23, SC-NK, SC-GR, SC-CD) within the Smith Creek
watershed (Figure 39). The sampling site SC-CH was inaccessible between January and June 2022 due to
construction of the bridge spanning the creek at Castle Hayne Rd and therefore no data was collected
from the site during that timeframe.
Dissolved oxygen within the creek ranged between 3.5 mg/l and 10.2 mg/l with a mean value of 7.0 mg/l
(Table 15; Figures 40 – Figure 44). Two (2) samples collected were below the State standard.
Chlorophyll-a ranged between 0 ug/l and 79 ug/l with a mean value of 6 ug/l (Table 15). One (1) sample
exceeded the State Standard for chlorophyll-a from within Smith Creek.
Enterococci ranged between 5 CFU/100 ml and 2,780 CFU/100 ml with a geometric mean value of 71
CFU/100ml (Table 15). Three (3) samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III
waters (Figure 45 -Figure 49).
Turbidity values were generally good ranging between 2 and 8 NTU with a mean value of 4 NTU (Table
15). No observations exceeded the State standard of 50 NTU for SW class C waters.
Table 16 depicts the ratings for these parameters for the watershed.
Figure 39 Water Quality Sites within the Smith Creek Watershed
CPE-NC
41
Table 15. Mean values of select parameters from Smith Creek. Range in parentheses.
Parameter SC-23 SC-CD SC-CH SC-GR SC-NK
Turbidity (NTU) 10 (6-17) 7 (1-19) 12 (7-17) 7 (2-18) 5 (2-9)
Dissolved Oxygen (mg/l) 7.0 (3.5-10.2) 8.2 (6.9-10.2) 5.7 (3.7-9.9) 7.4 (4.1-10.0) 6.5 (4.2-10.1)
Chlorophyll-a (ug/l) 14 (2-79) 3 (0-9) 4 (1-6) 4 (1-10) 7 (2-15)
Enterococci (#CFU/100ml) 34 (5-1,370)1 159 (5-2,780)1 22 (5-75)1 99 (10-414)1 82 (10-548)1
(1)Enterococci values expressed as geometric mean
Figure 40. Dissolved Oxygen at SC-23 at surface (DO-S) and bottom (DO-B)
Figure 41. Dissolved Oxygen at SC-CD at surface (DO-S)
CPE-NC
42
Figure 42. Dissolved Oxygen at SC-CH at surface (DO-S) and bottom (DO-B)
Figure 43. Dissolved Oxygen at SC-GR at surface (DO-S)
Figure 44. Dissolved Oxygen at SC-NK at surface (DO-S) and bottom (DO-B)
CPE-NC
43
Figure 45. Enterococci at SC-23
Figure 46. Enterococci at SC-CD
Figure 47. Enterococci at SC-CH
CPE-NC
44
Figure 48. Enterococci at SC-GR
Figure 49. Enterococci at SC-NK
Table 16. Ratings of parameters within sampling stations within Smith Creek
Parameter SC-23 SC-CD SC-CH SC-GR SC-NK
Turbidity GOOD GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD GOOD GOOD GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD GOOD
CPE-NC
45
Airlie Gardens
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, and includes a 10-acre freshwater lake. The lake
receives input from several stormwater culverts which serves to manage stormwater in the area. Water
quality monitoring was conducted at three locations within the lake: AG-IN, located on the northern
portion of the lake where stormwater enters the lake; AG-FD, located in a central portion of the lake; and
AG-OUT, located at the southern portion of the lake in proximity to the drainage outfall (Figure 50, Table
17).
Dissolved oxygen within the lake ranged between 2.1 mg/l and 11.4 mg/l with a mean value of 7.1 mg/l
(Table 17; Figures 51 - 53). Three (3) samples were below the State standard for dissolved oxygen.
Turbidity values were generally good ranging between 1 and 26 NTU with a mean value of 6 NTU (Table
17). No samples exceeded the State standard of 50 NTU for Class C waters.
Chlorophyll-a ranged from 5 mg/l to 135 mg/l with a mean value of 38 mg/l. The standard of 40 mg/l was
exceeded twelve (12) times.
Figure 50. Airlie Gardens Sampling Sites
CPE-NC
46
Figure 51. Dissolved Oxygen at AG-IN
Figure 52. Dissolved Oxygen at AG-FD
Figure 53. Dissolved Oxygen at AG-OUT
CPE-NC
47
Table 17. Mean values of select parameters from Airlie Gardens. Range provided in parentheses.
Parameter AG-IN AG-FD AG-OUT
Turbidity (NTU) 5 (1-3) 5 (3-11) 8 (3-26)
Dissolved
Oxygen (mg/l)
5.8 (2.1-9.0) 7.6 (5.1-11.4) 7.8 (4.0-10.8)
Chlorophyll-a
(mg/l)
28 (5-53) 35 (10-88) 51 (16-135)
Orthophosphate 0.11 (0.01-0.42) 0.13 (0.01-0.47) 0.16 (0.01-0.42)
Nitrate/Nitrite 0.08 (0.01-0.41) 0.08 (0.01-0.50) 0.07 (0.01-0.26)
Long Term Trends within Airlie Gardens
Monitoring within three sites in the lake at Airlie Gardens began in the summer of 2015. Since that time,
samples have been collected on a monthly basis for the analysis of orthophosphate and nitrate/nitrite
(two types of nutrients). In the summer of 2016, monthly samples were collected for the analysis of
Chlorophyll-a as well. Over the course of time, some trends have emerged. During the 2016-2017 study
period, Chlorophyll-a levels were similar at all three (3) sampling sites, however, the next year (2017-2018
study period) these levels were relatively higher at AG-IN compared to the two (2) sites situated in the
central portion of the lake (AG-FD) and at the outfall location (AG-OUT). During the two most recent study
periods, however, the trend reversed, and higher levels of Chlorophyll-a was observed at AG-FD and AG-
OUT compared to AG-IN (Figure 53). On average, Chlorophyll-a levels at AG-FD and AG-OUT have been
considerably higher than the levels observed at AG-IN over time. This may indicate that the nutrients
entering the lake from stormwater runoff collected near AG-IN may be taken up by growing vegetation
(algae and other aquatic plant matter) as the water flows towards the outfall in proximity to AG-OUT.
Figure 54. Chlorophyll-a levels at Airlie Gardens Over Time
When examining the levels of nutrients over time within these sampling sites, higher levels of
nitrite/nitrate has been observed at AG-IN compared to the other two sampling sites on an annual basis
CPE-NC
48
since sampling began in 2015 (Figure 54). Over the past seven (7) years, nitrite/nitrate levels have
averaged 0.06 mg/l at AG-IN and 0.03 mg/l at both AG-FD and AG-OUT respectively.
This trend of diminishing nutrient levels across the lake (from the stormwater input to the outfall area)
held true for orthophosphate as well for the first three (3) sampling periods, however the values have
been similar if not increasing slightly across the lake over the past four (4) years (Figure 55). Collectively,
over the past seven (7) years of sampling, the average orthophosphate levels have been 0.06 mg/l at each
site.
Over time, there has been a trend of increasing levels of both nutrients within the lake. During the 2015-
2016 study period, nitrate/nitrite levels averaged 0.03 mg/l and orthophosphate averaged 0.02 mg/l.
These levels increased to 0.08 mg/l and 0.14 mg/l, respectively during the 2021-2022 study period (Figure
56).
Figure 55. Nitrate/Nitrate Levels in Airlie Gardens Over Time
Figure 56. Orthophosphate Levels in Airlie Gardens Over Time
CPE-NC
49
Figure 57. Average Nitrite/Nitrate and Orthophosphate Levels in Airlie Gardens
Dissolved oxygen within the lake has been good, on average, through the years within each site with the
exception of AG-IN during the 2015-2016 study period. The levels at AG-FD and AG-OUT have been
similar to each other each year and have been consistently higher in comparison to the levels observed
at AG-IN (Figure 57). At each site, the dissolved oxygen levels generally increased during the warmer
summer months and increased during the colder winter months.
Figure 58. Dissolved Oxygen in Airlie Gardens Over Time
CPE-NC
50
APPENDIX B: LONG TERM TRENDS
In order to assess the long-term trends in water quality, a database has been created to include the data
collected within the eight (7) tidal creeks sampled. Since this is the first-year reporting on parameters of
Island Creek, long-term trends have yet to be identified so for the purpose of this section, Island Creek
has been omitted. The long-term trends from the seven (7) legacy creeks have been derived from data
obtained between July 2008 and June 2022.
Dissolved Oxygen
Figure 58 depicts the long-term trends in dissolved oxygen within the seven (7) creeks examined within
this study. The data show 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 were below the State standard within surface samples 34%, 22%, 16%, and 10%
of the time within Prince George Creek, Pages Creek, Futch Creek, and Barnard Creek, respectively.
Dissolved oxygen was below the standard 8%, 6%, and 5% of the time within Mott Creek, Smith Creek,
and Lords Creek, respectively. Of the 492 samples that fell below the standard for dissolved oxygen the
since 2008, more than half (53%), were observed during June, July, and August when water temperatures
were the highest.
Figure 59. Long-term surface dissolved oxygen data within tidal creeks. Note: The dissolved oxygen standard
within Pages Creek and Futch Creek is 5.0 mg/l while the standard for the other creeks is 4.0 mg/l.
CPE-NC
51
Turbidity
Figure 59 depicts 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 minor increases over time and seasonal patterns have
emerged. This includes higher turbidity observations during the warmer months and lower turbidity
during the cooler months. Since 2008, the turbidity standard from observations monitored from the
surface waters was only breached nineteen (19) times in total: seven (7) from within Pages Creek and
Smith Creek, two (2) from Prince George Creek, and one time each from within Barnards Creek, Lords
Creek and Mott Creek.
Figure 60. Long-term surface turbidity data within tidal creeks. Note: The turbidity standard within Pages
Creek and Futch Creek is 25 NTUs while the standard for the other creeks is 50 NTUs.
Chlorophyll-a
Figure 60 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 in July 2008, only 38
exceedances of the chlorophyll-a standard were observed of the 3,189 samples collected.
CPE-NC
52
Figure 61. Long-term chlorophyll-a data within tidal creeks
Enterococci
Figure 59 and Table 16 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. The
levels of bacteria in Barnards, Smith, and Mott Creek have moderated over recent years (Table 18). Two
sites in particular within the Bayshore community (PC-BDDS and PC-BDUS) in the Pages Creek watershed
have demonstrated relatively high levels of Enterococci bacteria over time.
Since June 2008, samples collected within Mott Creek and Pages Creek exceeded the State standard for
Enterococci 39% and 37% of the time, respectively while Smith Creek and Barnards Creek have exceeded
the standard 25% and 24% of the time, respectively and Prince George Creek exceeded standard 23% of
the time. Lords Creek exceeded the standard 9% of the time while Futch Creek has only exceeded the
standard for Enterococci 4% of the time.
CPE-NC
53
Figure 62. Long-term Enterococci data within tidal creeks
Table 18. Enterococci ratings for each watershed during all reporting periods.
Study Period 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
2019-2020 GOOD GOOD GOOD FAIR FAIR GOOD GOOD
2020-2021 GOOD GOOD GOOD FAIR POOR FAIR GOOD
2021-2022 GOOD GOOD GOOD GOOD POOR FAIR GOOD
CPE-NC
54
APPENDIX C
Water Classifications
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
Temperature
Thermal pollution can result in significant changes to the aquatic environment. Most aquatic organisms
are adapted to survive within a specific temperature range. Thermal pollution may also increase the
extent to which fish are vulnerable to toxic compounds, parasites, and disease. If temperatures reach
extremes of heat or cold, few organisms will survive.
Thermal pollution may be caused by stormwater runoff from warm surfaces such as streets and parking
lots. Soil erosion is another cause, since it can cause cloudy conditions in a water body. Cloudy water
absorbs the sun's rays, resulting in a rise in water temperature. Thermal pollution may even be caused by
the removal of trees and vegetation which normally shade the water body. In addition to the direct effects
of thermal pollution on aquatic life, there are numerous indirect effects. Thermal pollution results in
lowered levels of dissolved oxygen, since cooler water can hold more oxygen than warmer water.
Salinity
Salinity is a measure of the amount of sodium chloride ions dissolved in water. This is important to
monitor since changes in the levels of salt concentration can impact the ability of salt sensitive species to
survive. An estuary, such as the lower Cape Fear River, usually exhibits a gradual change in salinity
throughout its length, as freshwater entering the estuary from tributaries mixes with seawater moving in
from the ocean. Salinity levels control, to a large degree, the types of plants and animals that can live in
different zones of the estuary. Freshwater species may be restricted to the upper reaches of the estuary,
CPE-NC
55
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 a water body turning
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 a flowing stream, tends to contain a lot of dissolved oxygen, while stagnant
water contains little. Oxygen levels are also affected by the diurnal (daily) cycle. Plants, such as rooted
aquatic plants and algae produce excess oxygen during the daylight hours when they are
photosynthesizing. During the dark hours they must use oxygen for life processes. Bacteria in water can
consume oxygen as organic matter decays. Thus, excess organic material in waterbodies can cause oxygen
deficits. Aquatic life can become stressed or die in stagnant water containing high levels of rotting, organic
material in it, especially in summer, when dissolved oxygen levels are at a seasonal low.
Chlorophyll-a
Chlorophyll-a is a green pigment found in plants. It absorbs sunlight and converts it to sugar during
photosynthesis. Chlorophyll-a concentrations are an indicator of phytoplankton abundance and biomass
in coastal and estuarine waters. High levels often indicate an algal bloom which can induce the depletion
of oxygen in the water column due to the microbial degradation of plant cells. Chlorophyll-a
concentrations are often higher after rainfall, particularly if the rain has flushed nutrients into the water.
Higher chlorophyll-a levels are also common during the summer months when water temperatures and
light levels are high because these conditions lead to greater phytoplankton numbers.
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
CPE-NC
56
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.
CPE-NC
57
Standards
Water quality standards have been established legislatively for a number of these parameters (Table 19).
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/100 ml, 158 CFU/100 ml, 276 CFU/100 ml, and 501 CFU/100 ml 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/100 ml, 276 CFU/100 ml, and 500 CFU/100 ml, respectively (Table 21). A geometric
mean of 35 CFU/100 ml 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 22). Based on this analysis, of the twenty (20) tidal creek
sampling sites, two (2) could be considered Tier II and eighteen (18) could be considered Tier III. All three
(3) of the Airlie Garden sites are considered Tier III.
Table 19. 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
Table 20. Single sample standards for Enterococci as determined by the US EPA
Description Single sample maximum
Designated beach areas < 104 CFU/100 ml
CPE-NC
58
Swimming areas with moderate full body contact < 158 CFU/100 ml
Lightly used full body contact swimming areas < 276 CFU/100 ml
Infrequently used full body contact swimming areas < 501 CFU/100 ml
Table 21. 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/100 ml
Tier II, swimming areas used three days a week during the swimming
season <276 CFU/100 ml
Tier III, swimming areas used on average four days a month during the
swimming season <500 CFU/100 ml
Table 22. Tier Classification for New Hanover County Water Quality Monitoring Sites
Site
Name
Proposed Tier
Classification Boating or Swimming Access Comments
AG-FD Tier III No Central portion of Airlie Gardens Lake
AG-IN Tier III No Northern portion of Airlie Gardens Lake
AG-OUT Tier III No Southern portion of Airlie Gardens Lake
BC-CBR Tier III No Adjacent to culvert off Carolina Beach Road
FC-13 Tier III No Private docks are the only means of direct access
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-FOY Tier III No No clear access points (no docks on Foy branch)
IC-HS Tier III No Adjacent to culvert off Holly Shelter Road
LC-RR Tier III No Adjacent to bridge on River Road
MOT-CBR Tier III No Adjacent to culvert off Carolina Beach Road
MOT-ND Tier III No Adjacent to small bridge on Normandy Drive
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
PC-M Tier II Yes Direct access via Canady's Yacht Basin Marina
PG-CH Tier III No Adjacent to culvert on Castle Hayne Road
PG-ML Tier III No Small boat launch site on private property
PG-NC Tier III No Adjacent to culvert on North College Road
SC-23 Tier III No Adjacent to bridge on 23rd Street
SC-CD Tier III No Narrow, shallow. Adjacent to Candlewood Drive
SC-CH Tier III No Adjacent to bridge on Castle Hayne Road
SC-GR Tier III No Adjacent to culvert on Gordon Road
SC-NK Tier III No Adjacent to bridge on North Kerr
Table 23. List of Tidal Creek Sampling Sites
Creek Name Site Name Site Code Latitude Longitude
Barnards Creek Carolina Beach Road BC-CBR 34° 09.522 77° 54.712
Futch Creek 4 FC-4 34° 18.068 77° 44.760
CPE-NC
59
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
Island Creek Holly Shelter IC-HS 34° 22.172 77° 48.544
Lords Creek River Road LC-RR 34° 05.185 77° 55.275
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
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
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
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
Table 24. 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
CPE-NC
60
Methods
These seven (7) 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 = 0.1 m) and near the creek bottom at sites with depths greater than 0.5 m. 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
CPE-NC
61
APPENDIX D: PAGES CREEK PCR ANALYSIS
Following the thermal imagery study and ground truthing in 2019, Coastal Protection Engineering
identified areas where groundwater was seeping into Pages Creek from the creek’s bank. Adjacent to
sewer infrastructure, the idea was to sample the water from the seeps to understanding if there was any
bacteria being carried by groundwater from the infrastructure into the creek. Two samples of
groundwater were taken, one at each pump station site adjacent to the creek. Those sampling results
indicated the presence of Enterococci bacteria.
After the identification of enterococci bacteria coming from the groundwater seeps, NHC and Coastal
Protection Engineering and Cape Fear Public Utility Authority partnered in order to test if the seep water
contained a human signature or if the bacteria was from another animal such as a dog. The idea this time
was further narrow down geographically the source of bacteria. Four samples were collected from the
same seeps located near to the long-term monitoring sampling sites in the Bayshore neighborhood (PC-
BDUS and PC-BDDS). Water samples were collected from these areas on June 13 and July 11, 2022 and
were subsequently analyzed by a commercial laboratory using the most widely applied method for the
characterization of human fecal pollution in ambient surface waters: Quantitative real-time PCR (qPCR)
assays that target the human-associated HF183 bacterial cluster within members of the genus Bacteroides
(Green et al., 2014). A large number of laboratory and field studies have shown that analyses of host-
associated molecular marker genes such as HF183 can identify sources of fecal contamination in
waterways with a high degree of precision. Accordingly, this tool has become an established indicator for
human sewage contamination in temperate environments (Nshimyimana et al., 2014). Both samples
collected in proximity to PC-BDUS resulted in a “Non-Detect” where the host-associated fecal gene
biomarker (HF183) were not detected in one or both test replicates. The two samples collected from the
seep located in proximity to PC-BDDS resulted in “Detected, Not Quantified” where the host-associated
fecal biomarker was detected in both test replicates but in quantities below the limit of quantification.
CPE-NC
62
LITERATURE C ITED
Byappanahalli MN, Shively DA, Nevers MB, Sadowsky MJ, Whitman RL. Growth and survival of Escherichia
coli and Enterococci populations in the macro-alga Cladophora (Chlorophyta). FEMS Microbiol Ecol.
2003;46(2):203–211.
Green HC, Haugland RA, Varma M, Millen HT, Borchardt MA, Field KG, Walters WA, Knight R, Sivaganesan
M, Kelty CA, Shanks OC. Improved HF183 quantitative real-time PCR assay for characterization of human
fecal pollution in ambient surface water samples. Appl Environ Microbiol. 2014 May;80(10):3086-94. doi:
10.1128/AEM.04137-13. Epub 2014 Mar 7. PMID: 24610857; PMCID: PMC4018914.
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., 2010. University of North Carolina at Wilmington, Aquatic Ecologist. Personal
communication regarding findings of water samples obtained within PG-NC.
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.; 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., 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.
Meade, R., Yazyk, T. & Day, T. 1990. Movement and storage of sediment in rivers of the United States and
Canada. In: The Geology of North America, Woman, H. & Riggs, S. R. (Eds.).
Minnesota Pollution Control Agency, 2008. Nutrients: Phosphorus, Nitrogen Sources, Impact on Water
Quality - A General Overview Water Quality/Impaired Waters #3.22 website last accessed August 31,
2020. https://www.pca.state.mn.us/sites/default/files/wq-iw3-22.pdf
Mote BL, Turner JW, Lipp EK. Persistence and growth of the fecal indicator bacteria Enterococci in detritus
and natural estuarine plankton communities. Appl Environ Microbiol. 2012;78(8):2569–2577
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.
CPE-NC
63
Nshimyimana JP, Ekklesia E, Shanahan P, Chua LH, Thompson JR. Distribution and abundance of human-
specific Bacteroides and relation to traditional indicators in an urban tropical catchment. J Appl Microbiol.
2014 May;116(5):1369-83. doi: 10.1111/jam.12455. Epub 2014 Feb 25. PMID: 24460587; PMCID:
PMC4271309.
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.
Olivieri AW, Boehm AB, Sommers CA, Soller JA, Eisenberg JN, Danielson R. (2007). Development of a
protocol for risk assessment of separate stormwater system microorganisms. Alexandria: Water
Environment Research Foundation.
Ricks, C., 2011. Cape Fear Public Utility Authority. Personal communication regarding sewage spills in New
Hanover County.
U.S. Census Bureau, 2019. Quick facts: New Hanover County, NC.
https://www.census.gov/quickfacts/fact/table/newhanovercountynorthcarolina
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.