2022- 2023 Final ReportCPE-NC
NEW HANOVER COUNTY WATER QUALITY MONITORING PROGRAM
2022-2023
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., 2023. New Hanover County Water Quality Monitoring Program: 2022-
2023 Final Report. New Hanover County, North Carolina: Coastal Protection Engineering of North
Carolina, Inc.
November 2023
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EXECUTIVE SUMMARY
This report represents the findings of the New Hanover County Water Quality Monitoring Program for the
period July 2022 to June 2023. 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, Inc. to test water quality at twenty monitoring sites within eight tidal creeks in New
Hanover County. The creeks monitored include Barnards, Futch, Lords, Mott, Pages, Prince George, Smith,
and Island.
New for this program year, a second monitoring site at Sidbury Road (IC-SID) was added in the Island Creek
watershed which creates a linear transect giving a more holistic view of water quality across the entire
watershed. It should be noted that data for this year at Island Creek reflects the combination of two
monitoring sites which resulted in increased occurrences of dissolved oxygen as seen in the table below
and in later sections of this report. The addition of the site will not affect any long-term trends as this is
only the second year of monitoring at Island Creek and baseline data is still being captured as future
development is expected within the watershed. Additionally, a monitoring site at Smith Creek (SC-23) was
removed from the monitoring program to add the site at Island Creek. As a result, there were no changes
in overall watershed rating or to the ratings for each individual site. For long-term trends, New Hanover
County still maintains 4 monitoring sites (SC-NK, SC-GR, SC-CD) at Smith Creek.
Each of the 20 monitoring sites is monitored monthly for physical, chemical, and biological parameters
that, collectively, help determine the 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 quantitative sampling results, an assessment of the water quality is provided in qualitative
terms for each watershed. This 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 was outside the acceptable range of the State standard less than 10% of the times sampled
the watershed received 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 2022-2023 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 GOOD GOOD POOR GOOD FAIR FAIR POOR GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD FAIR FAIR GOOD GOOD
Long Term Trends
Dissolved oxygen, turbidity, and chlorophyll-a levels fluctuate on a seasonal basis where, typically, levels
decrease during the winter and increase during the summer. In general, turbidity and chlorophyll-a levels
over time have not been relatively low within the sampled creeks. Likewise, dissolved oxygen levels have
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not changed drastically from year to year which the exception at Mott Creek which saw overall levels go
from “Good” in 2021-2022 to “Fair” for this program year. The long term data shows an increase in
dissolved oxygen levels at Mott Creek since 2008. However, the trend of low dissolved oxygen levels
remain at Prince George Creek where levels have been consistently low over time. This is likely due to
the creek’s naturally slow water flow, which is more characteristic of swamp-like waters. Slower moving
waters typically contain lower dissolved oxygen levels.
Overall, Enterococci bacteria levels during the 2022-2023 sampling for the majority of the watersheds
remained similar to what has been observed over recent years which includes relatively high levels of
Enterococci bacteria within Mott Creek and Pages Creek. Since 2019, Barnard Creek, Futch Creek, Lords
Creek, and Smith Creek have contained relatively lower bacteria levels compared to the other creeks.
It should be noted that monitoring at Island Creek began in 2021, 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 monitoring at the
lake at Airlie Gardens due to concerns of noticeable algal blooms that have been observed over the years.
The lake drains directly into Bradley Creek, close to the Atlantic Intracoastal Waterway (ICWW). Three
sampling sites are maintained within the lake. They are located where contributing water enters the lake
(intake), in the middle of the lake, and in proximity to the outfall where the water leaves the lake and
enters Bradley Creek.
Since 2015, water quality monitoring results from within the lake at Airlie Gardens 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 within the lake.
Over the past eight years, the levels of the nutrient Nitrite/Nitrate have generally been higher at the intake
compared to the sampling site located at the outfall of the lake. This trend was also observed with the
nutrient orthophosphate during the first three years of monitoring, however, over the past three years
this trend has reversed, where orthophosphate was lower at the intake and higher in the middle and the
outfall of the lake. 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, there has been an incremental trend of increasing amounts of
orthophosphate each year. The same trend has been observed for Nitrate/Nitrate since 2019.
In recent years chlorophyll-a levels have increased throughout the lake with a noticeably higher rate of
increase at the middle and in proximity to the outfall of the lake compared to the sampling location
adjacent to the intake into the lake. High levels of Chlorophyll-a can be indictive of the presence of algal
blooms. In general, chlorophyll-a levels have steadily increased within the lake over time since
chlorophyll-a sampling began in 2016.
Improvement Efforts
While urbanization and development can be factors impacting water quality, 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.
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Efforts made by New Hanover County over the years to improve water quality include property acquisition
using grant and trust fund sources, working with the Cape Fear Public Utility Authority (CFPUA) to test
sewer infrastructure, the installation of stormwater Best Management Practices (BMPs) such as
raingardens, infiltration basins, and impervious surface retrofits, and microbial source tracking. Much of
the effort in recent years has been to investigate and determine the source of bacteria within the Pages
Creek watershed.
Of all of the parameters that are monitored and analyzed, enterococci bacteria is one that poses the most
threat to human and environmental health. While elevated levels have been seen at multiple creeks over
the years, most of the efforts to identify the source of bacteria have been at Pages Creek because of the
number of samples that have exceeded the state standard. Two sites in particular within the Bayshore
community (PC-BDDS and PC-BDUS) have exceeded the standard 43% and 58% of the time since testing
began in 2007. In addition, Pages Creek is designated as a Class SA Water, meaning it is an area prime for
shellfishing. However, Pages Creek is currently “closed” to shellfishing due to the elevated levels of
enterococci bacteria.
This year in June and July of 2023 the county partnered with Coastal Protection Engineering to broaden
the geographic extent of source tracking testing in Pages Creek in an attempt to determine if any
additional areas within the creek contained human-borne bacteria and narrow down locations where
bacteria is entering into the creek. Twenty (20) additional testing sites located throughout the watershed
were sampled twice on a falling tide, once during a dry period and once following a rain event, for a total
of forty (40) samples. This method would provide an opportunity to identify if the contamination was
widespread or concentrated within specific geographic areas in the watershed. After collection, samples
were sent to an analytical laboratory to determine the presence concentration of human-borne fecal
bacteria. This additional testing resulted in the identification of human signatures during both sampling
events which, again, confirmed the presence of human borne bacteria within the creek. The results also
indicated that the location of bacteria entering the creek is limited to an area in proximity to the two long-
term monitoring sites, Pages Creek Up-Stream and Pages Creek Down-Stream (PC-BDUS and PC-BDDS).
The results of the expanded testing can be found in Appendix D of this report.
The additional source tracking from this year follows up on subsequent Microbial Source Tracking (MST)
efforts the county has conducted in over the years. Microbial Source Tracking analyzes the genetic
material in fecal bacteria to determine the specific microorganisms present, and compares that to a
database of known sources, including humans. The first effort in 2008, New Hanover County partnered
with University of North Carolina Wilmington’s Center for Marine Science and CPE to conduct microbial
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, the New Hanover County
Planning & Land Use department partnered with the Cape Fear Public Utility Authority and the New
Hanover County 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 the University of North Carolina Chapel Hill to expand the source
tracking effort testing in three creeks, Mott, Smith and Pages. That study found the presence of a human
signature in the bacteria for all three. Since then, the overall bacteria levels in those creeks have
decreased. In the Mott Creek watershed two completed projects may be contributing to improved water
quality including a creek restoration project performed by the New Hanover County Engineering
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department and a septic to sewer conversion project in the Marquis Hills subdivision where there were
numerous failing septic systems. Major pump rehabilitation projects were also complete at Smith Creek
which could be contributing to improved bacteria levels there. At Pages Creek, which has seen sustained
high levels of bacteria, the Cape Fear Public Utility Authority has concluded video imaging using closed
circuit television where no deficiencies were identified in the sewer system, additional efforts have been
conducted as mentioned below.
In 2019, New Hanover County partnered with the University of North Carolina Wilmington’s Socio-
Environmental Analysis Laboratory and CPE 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, University of North Carolina Wilmington and CPE analyzed the imagery and identified
two areas depicting thermal anomalies in proximity to the two long term monitoring sites. These thermal
anomalies, once ground truthed, revealed several subterranean groundwater seeps entering the creek
from the streambank in the vicinity of sewer lift stations.
As a follow up to the 2019 thermal study, in June and July of 2022, planning staff and the Cape Fear Public
Utility Authority coordinated to perform Microbial Source Tracking analysis of the seep water coming from
the creek bank in two locations that identified Enterococci bacteria in the water. That MST analysis
resulted in the non-detection of a human marker at the Pages Creek up-stream site (PC-BDUS) and the
presence, although unquantifiable amount, from the down-stream site (PC-BDDS). The completion of this
testing resulted in expanded creek wide sampling from this year that had never been conducted prior.
The culmination of the data gathered over the past several years from additional sampling and analysis
suggests that there are no other locations where bacteria is entering into the creek. New Hanover County,
Coastal Protection Engineering and the Cape Fear Public Utility authority will continue to collaborate and
explore next steps to identify the source and formulate recommendations for mitigation of bacteria in
Pages Creek. New Hanover County and Coastal Projection Engineering will also continue to identify and
investigate any other emerging issues within the other sampled watersheds.
Improvement Efforts within Airlie Gardens
At Airlie Gardens to help combat problems associated with eutrophication and overall water quality within
the lake, 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, however, has not indicated a reduction in nutrient loading into the lake.
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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 ........................................................................................................................ 15
APPENDIX A: ADDITIONAL CREEK DATA ............................................................................................ 17
BARNARDS CREEK ........................................................................................................................................ 17
FUTCH CREEK .............................................................................................................................................. 19
ISLAND CREEK ............................................................................................................................................. 24
LORDS CREEK .............................................................................................................................................. 27
MOTT CREEK .............................................................................................................................................. 29
PAGES CREEK .............................................................................................................................................. 32
PRINCE GEORGE .......................................................................................................................................... 36
SMITH CREEK .............................................................................................................................................. 40
AIRLIE GARDENS .......................................................................................................................................... 44
APPENDIX B: LONG TERM TRENDS .................................................................................................... 49
DISSOLVED OXYGEN ..................................................................................................................................... 49
TURBIDITY .................................................................................................................................................. 50
CHLOROPHYLL-A .......................................................................................................................................... 50
ENTEROCOCCI ............................................................................................................................................. 51
APPENDIX C ..................................................................................................................................... 53
WATER CLASSIFICATIONS .............................................................................................................................. 53
PARAMETER DEFINITIONS ............................................................................................................................. 53
STANDARDS ................................................................................................................................................ 56
METHODS .................................................................................................................................................. 59
APPENDIX D: PAGES CREEK SOURCE TRACKING STUDY ...................................................................... 60
LITERATURE CITED ........................................................................................................................... 63
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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 (UNCW) 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 2022 to June
2023. 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 have been
monitored since 2015.
The results described in this report represent the physical, biological, and chemical data collected monthly
from all sampling sites from July 2022 through June 2023. These results are organized by watershed
alphabetically, with the results of the eight 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 can be 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.
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Figure 1: Watersheds Monitored
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Note: While fluctuations occur throughout the year, all levels
for Enterococci at BC-CBR were below state standards.
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
• 1 (one) occurrence 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
While dissolved oxygen did drop below the State standard
once at the Carolian Beach Road site, overall, there were
no issues with Barnards Creek for the year.
Parameter BC-CBR
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good
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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
• 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 Futch Creek for the
year.
Note: While fluctuations occur throughout the year, all
levels for Enterococci at FC-13 were below state
standards.
Parameter FC-4, FC-6, FC-13, FC-FOY
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good
4
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Island Creek
• Location: Northeast New Hanover County and
portions of Pender County (Sidbury Road & Holly
Shelter Road).
• 2 Sampling Locations: IC-HS, IC-SID
• Size: 12,919 Acres
• Drains To: NE Cape Fear River
• Land Use: Mostly undeveloped, low density
residential.
Year at a Glance
• 13 (thirteen) occurrences of dissolved oxygen below
State standard
• 1 (one) 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
Dissolved oxygen was determined to be poor with 13
occurrences below the state standard. There was one
occurrence of elevated chlorophyll-a at the Holly Shelter
site, otherwise all other parameters were good.
Parameter IC-HS, IC-SID
Turbidity (NTU) Good
Dissolved Oxygen Poor
Chlorophyll-a Good
Enterococci Good
• Site IC-SID was added at Island Creek to gain a linear
transect view of water quality, as water moves through
the creek from one location to another.
• Additional occurrences of dissolved oxygen were a
result from adding a monitoring site.
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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
• 1 (one) 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
There was only one occurrence of low dissolved oxygen
at the River Road site, otherwise water quality for the
year at Lords Creek was good.
Note: While fluctuations occur throughout the year, all
levels for Enterococci at LC-RR were below state
standards.
Parameter LC-RR
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good
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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
• 4 (four) occurrence of dissolved oxygen below
State standard
• 0 (zero) occurrence above State standard for
chlorophyll-a
• 0 (zero) occurrence above State standard for
turbidity
• 4 (four) 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 four exceedances at the Normandy Drive
site this year.
Parameter MOT-CBR, MOT-ND
Turbidity (NTU) Good
Dissolved Oxygen Fair, Good
Chlorophyll-a Good
Enterococci Good, Fair
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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
• 7 (seven) occurrences of dissolved oxygen below
State standard.
• 1 (one) occurrence above State standard for
chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
• 5 (five) occurrences above State standards for
Enterococci
Overall Assessment
Dissolved Oxygen levels were below state standards
several times at PC-BDDS & PC-BDUS. Enterococci levels
where lower than last year and only saw elevated levels at
the PC-BDDS site while chlorophyll-a saw 1 exceedance.
Parameter PC-BDDS, PC-BDUS, PC-M
Turbidity (NTU) Good
Dissolved Oxygen Poor, Good, Good
Chlorophyll-a Good, Fair, Good
Enterococci Poor, Good, Good
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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
• 12 (twelve) occurrences of dissolved oxygen
below State standard
• 1 (one) occurrence above State standard for
chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
• 1 (one) occurrence 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 was 1 exceedance for Enterococci
at the Marathon Landing site.
Parameter PG-CH, PG-ML, PG-NC
Turbidity (NTU) Good
Dissolved Oxygen Fair, Fair, Poor
Chlorophyll-a Good
Enterococci Good
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Smith Creek
• Location: Central New Hanover County including
portions of City of Wilmington (Wrightsboro, ILM,
Kings Grant, Coastal Carolina).
• 4 Sampling Locations: SC-NK, SC-GR, SC-CD,
SC-23
• 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
• 3 (three) occurrences of dissolved oxygen below
State standard
• 1 (one) occurrence above State standard for
chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
• 2 (two) occurrences above State standards for
Enterococci
Overall Assessment
Water quality within Smith Creek was generally good with
the exceptions of enterococci bacteria, which exceeded
state standards twice at the Candlewood Drive site and
dissolved oxygen was below the state standard three times
at the Gordon Road site. There was also one exceedance
of chlorophyll-a at the Candlewood Drive site.
Parameter SC-NK, SC-GR, SC-CD
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good, Good, Fair
• Site SC-23 was removed to add a site at Island Creek.
• Site SC-CH data was not available this year due to the
reconstruction of the bridge across Smith Creek.
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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
• 8 (eight) occurrences of dissolved oxygen below
State standard
• 12 (twelve) occurrences above State standard
for chlorophyll-a
• 1 (one) occurrence above State standard for
turbidity
*Enterococci is not measured at Airlie Gardens
Overall Assessment
Dissolved oxygen was lower than the previous year and
saw occurrences below the state standard.
Orthophosphate levels continue to increase. It may take
several years for a trend to emerge after the completion
of recent water quality improvement projects in 2019 and
2020. It is recommended to continue monitoring.
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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
increasing in population by fifty percent from 1990 (120,284) to 2006 (182,591). In 2023, the population
within the county was estimated to be 232,614 with a growth rate of one percent in the past year
according to the most recent United States census data. While long term monitoring suggests that
development and continued growth in New Hanover County may have altered water quality within its
tidal creeks in the past, a more recent assessment of the ratings for many water quality parameters as
depicted in this report show they have seen improvements 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 factor may be the inclusion of state
stormwater controls required for all new development which aims to mitigate stormwater on site. These
stormwater control measures aim to reduce water quantity, which affects water quality. Additionally, the
county has recently created a stormwater services program to help maintain and improve drainage,
primarily in areas developed prior to state stormwater regulations. An increase in stormwater control
measures can contribute to overall water quality and mitigate the effects of stormwater runoff.
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 creeks monitored since 2008 have
experienced good water quality in terms of turbidity and chlorophyll-a levels over the course of 15 years
of monitoring thus far (this does not include data from Island Creek due to the fact monitoring started
just 2 years ago). The one parameter, however, that has been problematic has been Enterococci bacteria.
Of the 3,429 samples collected and analyzed since June 2008, 738 samples (22%) have exceeded the State
standard for this bacterium. This analysis does not include data from Island Creek which has only been
monitored for two years and therefore was not included in the long-term dataset.
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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. Enterococci samples are not collected
at Airlie Gardens as it was determined at that time that bacterial contamination was not an issue.
Biological Parameter Discussion
Chlorophyll-a
Over the past 15 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 for this
program. The dissolved oxygen along with chlorophyll-a and turbidity levels have generally increased
during warmer summer months. The longer summer days allow for increased photosynthetic activity
that, as a result, can lead to phytoplankton blooms. While often problematic in the summer months, algal
blooms are less common in the fall and winter when water temperatures decrease. 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 3 chlorophyll-a samples exceeded the State standard during the
2022-2023 monitoring period.
Dissolved Oxygen
In general, the dissolved oxygen within Barnards Creek, Lords Creek, Mott Creek, and Smith Creek has
been rated “Good” over the course of the entire program with few exceptions. Barnards Creek
experienced a decline in dissolved oxygen between 2014 and 2017, but, since that time, improved to
“Good” again over the five of the past six years. Futch Creek has maintained a “Fair” rating for nine of the
fifteen years, however improved and maintained a "Good" since the 2020-2021 monitoring period. Pages
Creek has demonstrated varying dissolved oxygen levels over time ranging from “Poor” to “Good” over
the years and has been deemed “Fair” during six of the past seven monitoring 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” thirteen of the fifteen 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.
Physical Parameter Discussion
Enterococci
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 3,429 samples collected and analyzed from all the monitoring sites since June 2008,
738 samples (22%) have exceeded the State standard for this bacterium. Specifically, Mott Creek has
exceeded the standard 37% of the time and at Pages Creek, the down-stream site (PC-BDDS) and up-
stream site (PC-BDUS) exceeded the standard 42% and 58% of the time, respectively.
The Enterococci levels over the course of the first ten years of monitoring were relatively higher, overall,
compared to the levels observed since 2018. This year’s data indicates that the bacteria levels have
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continued to moderate since that time as all creeks were rated “Good” with the exception of Mott Creek
and Pages Creek where the rating was “Fair”. No samples exceeded the State Enterococci standard during
this most recent monitoring period from within Lords Creek, Futch Creek, Barnard Creek, and Island Creek.
At Prince George Creek, Smith Creek, and Mott Creek, the standard was exceeded 3%, 6%, and 17% of the
time over the course of the 2022-2023 monitoring period, respectively.
At Mott Creek, the bacteria levels have moderated over the past seven years. Prior to the 2016-2017
sampling effort, Mott Creek had consistently demonstrated “Poor” water quality in terms of bacterial
contamination. Since that time, Mott Creek has demonstrated a “Fair” rating six times over the past seven
years (with a “Good” rating last year). 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 through 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.
Pages Creek continued to show elevated levels of Enterococci where six out of thirty-six samples (17%)
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 six samples that exceeded the standard, five were from the Pages
Creek Down-Stream Site (PC-BDDS) Of the twenty sites included in this program, PC-BDUS has surpassed
the Enterococci state standards the most, however, during the 2022-2023 sampling period the standard
was breached only one time. Historically, however, this station, located at the boat ramp in the Bayshore
community within the Pages Creek watershed, has exceeded the standard 58% of the time since sampling
began in 2008.
In 2008 and 2013 source tracking studies were 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 abandoned 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. 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.
As a result of those investigations, in 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 two locations
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 visualized only at lower tides. Both areas were in proximity to the long-term monitoring
sampling sites of Pages Creek Up-Stream Site (PC-BDUS) and Pages Creek Down-Stream Site (PC-BDDS) in
the Bayshore neighborhood and directly adjacent to CFPUA lift stations. CPE collected water samples
from these areas during the summer of 2022 and sent them to a commercial laboratory who analyzed
them 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
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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 the 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.
2023 Expanded Sampling Discussion
Following the testing of water seeping out of the creek bank, it was decided to broaden the geographic
extent of source tracking testing in Pages Creek in an attempt to determine if any additional areas within
the creek contained human-borne bacteria. In doing so, it may be possible to home in on the precise
location, or source, of contamination within the watershed. Partnering with CPE, 20 additional testing
sites located throughout the watershed were sampled twice on a falling tide, once during a dry period and
once following a rain event, for a total of 40 samples. This method would provide an opportunity to
identify if the contamination was widespread or concentrated within specific geographic areas in the
watershed. After collection, samples were sent to an analytical laboratory to determine the presence of
human-borne fecal bacteria. This additional testing resulted in the identification of human signatures
during both sampling events which, again, confirmed the presence of human borne bacteria within the
creek. The results also indicated that the location of bacteria entering the creek is limited to an area in
proximity to the two long-term monitoring sites (PC-BDUS and PC-BDDS). The culmination of the data
gathered over several years from additional sampling and analysis suggests that there are no other
locations where bacteria is entering into the creek. The results of the expanded testing can be found in
Appendix D of this report.
Overall Watershed Ratings for Enterococci
The long-term trends for Enterococci ratings over the past 15 years have shown that Mott Creek, Pages
Creek, and Prince George Creek maintained “Poor” ratings during much of the time; however, over the
past four years these creeks have demonstrated some improvements. Mott Creek, which was deemed
“Poor” between 2008 and 2016, has been deemed “Fair” six of the past seven years with a “Good” rating
just last year. Similarly, Prince George Creek has demonstrated either “Good” or “Fair” ratings over the
past five years whereas it has been rated “Poor” eight out of the previous ten years. Pages Creek, on the
other hand, has continued to exhibit relatively high levels of Enterococci as it has been rated as “Poor”
twelve of the fifteen years included within this study; the other three years it was rated as “Fair”. Like
Mott Creek and Prince George Creek, Smith Creek has improved over recent years as it has been rated as
"Good" for Enterococci levels over the past five years in a row whereas previous years it contained either
"Poor" or "Fair" levels. Barnards Creek and Lords Creek, meanwhile, have demonstrated varying
conditions since sampling was first initiated while Futch Creek has consistently maintained a “Good”
rating, with two exceptions when it was deemed “Fair”.
Airlie Gardens Discussion
The results from monthly sampling over the past seven 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 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.
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Over the past eight years of sampling, the orthophosphate level within AG-IN and AG-FD have averaged
0.07mg/l while the average level of orthophosphate at AG-OUT was 0.08 mg/l. Nitrite/Nitrate levels have
been 0.07 mg/l at AG-IN while AG-FD and AG-OUT averaged 0.04 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 feet deep by 10 feet wide channels
in the lake, effectively removing approximately 4,000 cubic yards of bottom sediment and material. The
removal of the nutrient-laden sediments should 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. In fact,
average orthophosphate levels have continued to increase annually since monitoring efforts began in
2015. Nitrate/Nitrite levels have also increased, on average, since 2018.
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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 2.7 mg/l and 8.7 mg/l with a mean value of 5.1 mg/l
(Table 1). One (1) sample 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 0.0 ug/l and 3.0 ug/l with a mean value of 1.0 ug/l at BC-CBR (Table 1).
These values did not approach the 40 ug/l standard.
Enterococci ranged between 10 CFU/100 ml and 185 CFU/100 ml with a geometric mean value of 56
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 1 and 23 NTU with a mean value of 5 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.
Figure 2. Water Quality Sites within the Barnards Creek Watershed
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Table 1. Mean values of select parameters from Barnards Creek. Range in parentheses.
Parameter BC-CBR
Turbidity (NTU) 5 (1-23)
Dissolved Oxygen (mg/l) 5.1 (2.7-8.7)
Chlorophyll-a (ug/l) 1 (0-3)
Enterococci (#CFU/100ml) 56 (10-185)
(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
Table 2. Ratings of parameters within sampling sites within Barnards Creek
Parameter BC-CBR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci GOOD
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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 5.4mg/l and 9.0 mg/l with a mean value of 7.0 mg/l
(Figure 6 – Figure 9, Table 3). No 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 9.0 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 5 CFU/100ml and 90 CFU/100ml with a geometric mean value of 8
CFU/100ml. No samples collected within Futch Creek 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 3 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
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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 (1-11) 3 (1-7) 4 (0-14) 4 (1-15)
Dissolved
Oxygen (mg/l)
7.3 (5.7-8.9) 7.2 (5.7-9.0) 6.8 (5.4-9.0) 6.9 (5.4-8.9.0)
Chlorophyll-a
(ug/l)
3 (0-8) 3(0-8) 2 (0-9) 2 (0-9)
Enterococci
(#CFU/100ml)
7 (5-90)1 8 (5-85)1 7 (5-55)1 8 (5-61)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)
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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
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Figure 11. Enterococci at FC-6
Figure 12. Enterococci at FC-13
Figure 13. Enterococci at FC-FOY
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Table 4. Ratings of parameters within sampling sites within Futch Creek
Parameter FC-4 FC-6 FC-13 FC-FOY
Turbidity GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD GOOD GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD
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Island Creek
Sampling was conducted at two (2) sites (IC-HS) within the Island Creek watershed (Figure 14).
Dissolved oxygen at Island Creek ranged between 0.9 mg/l and 8.4 mg/l with a mean value of 4.0 mg/l
(Table 5). Thirteen (13) samples were below the State standard of 4.0 mg/l for C Sw waters during the
sampling period (Figures 15 and 16).
Chlorophyll-a ranged between 1 ug/l and 41 ug/l with a mean value of 9 ug/l (Table 5). One (1) sample
exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 5 CFU/100ml and 146 CFU/100ml with a geometric mean value of 24
CFU/100ml (Table 5, Figures 17 and 18). No samples collected in Island Creek 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
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Table 5. Mean values of select parameters from Island Creek. Range in parentheses.
Parameter IC-HS IC-SID
Turbidity (NTU) 4 (2-8) 5 (1-31)
Dissolved Oxygen
(mg/l)
4.1 (1.7-8.4) 3.6 (0.9-8.0)
Chlorophyll-a (ug/l) 8 (1-24) 11 (1-41)
Enterococci
(#CFU/100ml)
33 (5-146)1 18 (5-130)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. Dissolved Oxygen at IC-SID at surface (DO-S) and bottom (DO-B)
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Figure 17. Enterococci at IC-HS
Figure 18. Enterococci at IC-SID
Table 6. Ratings of parameters within sampling sites within Island Creek
Parameter IC-HS IC-SID
Turbidity GOOD GOOD
Dissolved Oxygen POOR POOR
Chlorophyll-a GOOD GOOD
Enterococci GOOD GOOD
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Lords Creek
Sampling was conducted at one (1) site (LC-RR) within the Lords Creek watershed (Figure 19).
Dissolved oxygen at LC-RR ranged between 3.5 mg/l and 9.8 mg/l with a mean value of 7.4 mg/l (Table 7).
One (1) sample was below the State standard of 4.0 mg/l for C Sw waters during the sampling period
(Figure 20).
Chlorophyll-a ranged between 3 ug/l and 28 ug/l with a mean value of 11 ug/l (Table 7). No samples
exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 5 CFU/100ml and 301 CFU/100ml with a geometric mean value of 20
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 21).
Turbidity values were generally moderate ranging between 4 and 13 NTU with a mean value of 8 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 19. Water Quality Site within the Lords Creek Watershed
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Table 7. Mean values of select parameters from Lords Creek. Range in parentheses.
Parameter LC-RR
Turbidity (NTU) 8 (4-13)
Dissolved Oxygen (mg/l) 7.4 (3.5-9.8)
Chlorophyll-a (ug/l) 11 (3-28)
Enterococci (#CFU/100ml) 20 (5-301)1
(1)Enterococci values expressed as geometric mean
Figure 20. Dissolved Oxygen at LC-RR at surface (DO-S) and bottom (DO-B)
Figure 21. Enterococci Levels at LC-RR
Table 8. Ratings of parameters within sampling sites within Lords Creek
Parameter LC-RR
Turbidity GOOD
Dissolved Oxygen GOOD
Chlorophyll-a GOOD
Enterococci GOOD
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Mott Creek
Sampling was conducted at two (2) sites (MOT-CBR, MOT-ND) within the Mott Creek watershed (Figure
22).
Dissolved oxygen within Mott Creek ranged between 0.8 mg/l and 8.6 mg/l with a mean value of 6.1 mg/l
(Table 9). Four (4) samples collected during the reporting period contained dissolved oxygen levels below
the standard (Figure 23 and Figure 24).
Chlorophyll-a ranged between 1 ug/l and 23 ug/l with a mean value of 5 ug/l (Table 9). No samples
exceeded the 40ug/l standard.
Enterococci ranged between 5 CFU/100ml and 5,490 CFU/100ml with a geometric mean value of 144
CFU/100 ml (Table 9). Samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III waters during
four (4) sampling events during the reporting period (Figure 25 and Figure 26).
Turbidity values were generally good ranging between 2 and 15 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 22. Water Quality Sites within the Mott Creek Watershed
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Table 9. Mean values of select parameters from Mott Creek. Range in parentheses.
Parameter MOT-CBR MOT-ND
Turbidity (NTU) 7 (2-12) 9 (4-15)
Dissolved Oxygen (mg/l) 5.3 (0.8-8) 6.9 (5.1-8.6)
Chlorophyll-a (ug/l) 6 (1-20) 5 (1-23)
Enterococci (#CFU/100ml) 47 (5-315)1 438 (108-5,490)1
(1)Enterococci values expressed as geometric mean
Figure 23. Dissolved Oxygen at MOT-CBR at surface (DO-S)
Figure 24. Dissolved Oxygen at MOT-ND at surface (DO-S)
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Figure 25. Enterococci at MOT-CBR
Figure 26. Enterococci at MOT-ND
Table 10. Ratings of parameters within sampling sites within Mott Creek
Parameter MOT-CBR MOT-ND
Turbidity GOOD GOOD
Dissolved Oxygen FAIR GOOD
Chlorophyll-a GOOD GOOD
Enterococci GOOD FAIR
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Pages Creek
Sampling was conducted at three (3) sites (PC-BDDS, PC-BDUS, and PC-M) within the Pages Creek
watershed (Figure 27).
Dissolved oxygen within Pages Creek ranged between 3.0 mg/l and 8.8 mg/l with a mean value of 6.2 mg/l
(Figures 28 - 30, Table 11). Over the twelve (12) month study period, the dissolved oxygen levels were
below the State standard five (5) times at PC-BDDS and two (2) times at PC-BDUS. Dissolved oxygen was
within the standard at PC-M during all twelve (12) sampling events.
Chlorophyll-a ranged between 0 ug/l and 48 ug/l with a mean value of 6 ug/l (Table 11). One sample
exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 6 CFU/100 ml and 7,270 CFU/100 ml with a geometric mean value of 46
CFU/100 ml (Figures 31 – 33, Table 11). Seven (7) samples from PC-BDDS contained levels higher than the
NCDEQ standard. Enterococci was within the standard at PC-BDUS and PC-M during all twelve (12)
sampling events.
Turbidity values were generally good ranging between 0 and 19 NTU with a mean value of 7 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.
It should be noted that the additional sampling at Pages Creek as part of the ongoing effort to locate the
source of bacteria entering the creek can be found in Appendix D of this report.
Figure 27. Water Quality Sites within the Pages Creek Watershed
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Table 11. Mean values of select parameters from Pages Creek. Range in parentheses.
Parameter PC-BDDS PC-BDUS PC-M
Turbidity (NTU) 7 (3-19) 8 (3-18) 4 (0-11)
Dissolved Oxygen (mg/l) 5.5 (3-8.3) 6.1 (3.3-8) 7.0 (5.1-8.8)
Chlorophyll-a (ug/l) 9 (1-48) 5 (1-17) 3 (0-9)
Enterococci (#CFU/100ml) 289 (20-7270)1 53 (10-437)1 6 (3-24)1
(1)Enterococci values expressed as geometric mean
Figure 28 Dissolved Oxygen at PC-BDDS at surface (DO-S)
Figure 29. Dissolved Oxygen at PC-BDUS at surface (DO-S)
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Figure 30. Dissolved Oxygen at PC-M at surface (DO-S) and bottom (DO-B)
Figure 31. Enterococci at PC-BDDS
Figure 32. Enterococci at PC-BDUS
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Figure 33. Enterococci at PC-M
Table 12. Ratings of parameters within sampling sites within Pages Creek
Parameter PC-BDDS PC-BDUS PC-M
Turbidity GOOD GOOD GOOD
Dissolved Oxygen POOR GOOD GOOD
Chlorophyll-a GOOD FAIR GOOD
Enterococci POOR GOOD GOOD
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Prince George
Sampling was conducted at three (3) sites (PG-CH, PG-ML, and PG-NC) within the Prince George Creek
watershed (Figure 34).
Dissolved oxygen within Prince George Creek ranged between 0.6 mg/l and 8.1 mg/l with a mean value of
4.6 mg/l (Table 13). Surface dissolved oxygen values were below the State standard of 4.0 mg/l for C Sw
on seven (7) occasions during the reporting period at PG-NC, three (3) times at PG-ML, and two (2) times
at PG-CH (Figures 35 – 37, Table 13).
Chlorophyll-a ranged between 1 ug/l and 30 ug/l with a mean value of 5 ug/l (Table 13). No samples from
Prince George Creek exceeded the 40 ug/l standard.
Enterococci ranged between 5 CFU/100ml and 5,493 CFU/100ml with a geometric mean value of 46
CFU/100ml (Table 13). One (1) sample collected from within Prince George Creek contained Enterococci
levels above the NCDEQ standard of 500 CFU/100ml for Tier III waters (Figures 38 – 40).
Turbidity values were generally good ranging between 1 and 8 NTU with a mean value of 3 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 34. Water Quality Sites within the Prince George Creek Watershed
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Table 13. Mean values of select parameters from Prince George Creek. Range in parentheses.
Parameter PG-CH PG-ML PG-NC
Turbidity (NTU) 4 (3-5) 2 (1-3) 4 (2-8)
Dissolved Oxygen (mg/l) 5.1 (2.6-8.0) 5.5 (3.4-8.1) 3.2 (0.6-8.1)
Chlorophyll-a (ug/l) 3 (1-10) 7 (1-30) 5 (1-17)
Enterococci (#CFU/100ml) 72 (10-262)1 76 (20-5,493)1 18 (5-121)1
(1)Enterococci values expressed as geometric mean
Figure 35. Dissolved Oxygen at PG-CH at surface (DO-S) and bottom (DO-B)
Figure 36. Dissolved Oxygen at PG-ML at surface (DO-S)
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Figure 37. Dissolved Oxygen at PG-NC at surface (DO-S) and bottom (DO-B)
Figure 38. Enterococci at PG-CH
Figure 39. Enterococci at PG-ML
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Figure 40. Enterococci at PG-NC
Table 14. Ratings of parameters within sampling sites 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 GOOD GOOD GOOD
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Smith Creek
Sampling was conducted at three (3) sites (SC-NK, SC-GR, SC-CD) within the Smith Creek watershed (Figure
41). It should be noted that site SC-CH data was not available this year due to the reconstruction of the
bridge along Castle Hayne Road that crosses Smith Creek due to the damage from a vehicle accident. In
addition, site SC-23 was removed to add the site IC-SID within Island Creek watershed.
Dissolved oxygen within the creek ranged between 0.8 mg/l and 10.9 mg/l with a mean value of 7.0 mg/l
(Table 15; Figures 42 – 44). Three (3) samples collected were below the State standard.
Chlorophyll-a ranged between 1 ug/l and 47 ug/l with a mean value of 10 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 1,080 CFU/100 ml with a geometric mean value of 86
CFU/100ml (Table 15). Two (2) samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III
waters (Figure 45-47).
Turbidity values were generally good ranging between 1 and 32 NTU with a mean value of 6 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 41 Water Quality Sites within the Smith Creek Watershed
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Table 15. Mean values of select parameters from Smith Creek. Range in parentheses.
Parameter SC-CD SC-GR SC-NK
Turbidity (NTU) 3 (1-7) 12 (2-32) 4 (2-5)
Dissolved Oxygen (mg/l) 8.9 (7.5-10.9) 7.4 (4.1-10) 6.8 (4.1-9.5)
Chlorophyll-a (ug/l) 7 (1-47) 5 (1-31) 16 (1-34)
Enterococci (#CFU/100ml) 336 (132-1,080)1 70 (10-256)1 30 (5-110)1
(1)Enterococci values expressed as geometric mean
Figure 42. Dissolved Oxygen at SC-CD at surface (DO-S)
Figure 43. Dissolved Oxygen at SC-GR at surface (DO-S)
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Figure 44. Dissolved Oxygen at SC-NK at surface (DO-S) and bottom (DO-B)
Figure 45. Enterococci at SC-CD
Figure 46. Enterococci at SC-GR
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Figure 47. Enterococci at SC-NK
Table 16. Ratings of parameters within sampling sites within Smith Creek
Parameter SC-CD SC-GR SC-NK
Turbidity GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD GOOD
Chlorophyll-a GOOD GOOD GOOD
Enterococci FAIR GOOD GOOD
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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 48, Table
17).
Dissolved oxygen within the lake ranged between 2.2 mg/l and 18.0 mg/l with a mean value of 6.3 mg/l
(Table 17; Figures 49-51). Eight (8) samples were below the State standard for dissolved oxygen.
Turbidity values were generally good ranging between 1 and 63 NTU with a mean value of 9 NTU (Table
17), however one (1) sample exceeded the State standard of 50 NTU for Class C waters.
Chlorophyll-a ranged from 1 mg/l to 592 mg/l with a mean value of 63 mg/l. The standard of 40 mg/l was
exceeded twelve (12) times.
Figure 48. Airlie Gardens Sampling Sites
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Figure 49. Dissolved Oxygen at AG-IN
Figure 50. Dissolved Oxygen at AG-FD
Figure 51. Dissolved Oxygen at AG-OUT
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Table 17. Mean values of select parameters from Airlie Gardens. Range provided in parentheses.
Parameter AG-IN AG-FD AG-OUT
Turbidity (NTU) 6 (1-15) 9 (2-32) 12 (3-63)
Dissolved
Oxygen (mg/l)
4.1 (2.2-6.5) 7.5 (4.6-11.1) 7.2 (3.1-18)
Chlorophyll-a
(mg/l)
31 (31-147) 80 (1-426) 79 (1-592)
Orthophosphate 0.15 (0.01-0.31) 0.16 (0.01-0.35) 0.21 (0.03-0.35)
Nitrate/Nitrite 0.13 (0.01-0.60) 0.06 (0.01-0.23) 0.10 (0.01-0.36)
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 monthly 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). Since that time, however, the trend
reversed, and higher levels of Chlorophyll-a was observed at AG-FD and AG-OUT compared to AG-IN
(Figure 52). 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 52. 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 have been observed at AG-IN compared to the other two sampling sites on an annual basis
since sampling began in 2015 (Figure 53). 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.
0
10
20
30
40
50
60
70
80
90
AG-IN AG-FD AG-OUT
Ch
l
o
r
o
p
h
y
l
l
-a
(
m
g
/
l
)
Chlorophyll-a Levels in Airlie Gardens Over Time
2016-2017 2017-2018 2018-2019 2019-2020 2020-2021 2021-2022 2022-2023
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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 sampling periods, however the values have been
similar if not increasing slightly across the lake over the past five years (Figure 54). Collectively, over the
past eight years of sampling, the average orthophosphate levels have been 0.07 mg/l at AG-IN and 0.08
mg/l at AG-OUT. This data suggests that Nitrogen may be the limiting nutrient regulating vegetative
growth within the lake.
Overall, 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 0.10 mg/l and 0.17 mg/l, respectively during the 2022-2023 study period (Figure
55).
Figure 53. Nitrate/Nitrate Levels in Airlie Gardens Over Time
Figure 54. Orthophosphate Levels in Airlie Gardens Over Time
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Figure 55. 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 and the recent 2022-2023 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 56). At each site, the dissolved oxygen levels generally increased
during the warmer summer months and increased during the colder winter months.
Figure 56. Dissolved Oxygen in Airlie Gardens Over Time
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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 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 legacy creeks have been derived from data
obtained between July 2008 and June 2022.
Dissolved Oxygen
Figure 57 depicts the long-term trends in dissolved oxygen within the seven 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%, 15%, 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 520 samples that fell below the standard for dissolved oxygen the
since 2008, more than half (51%), were observed during June, July, and August when water temperatures
were the highest.
Figure 57. 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.
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0
4
8
12
16
Pages Futch Smith Barnards Lords Mott Prince
George
Ch
l
-a
(
u
g
/
l
)
Chl-a Levels in Tidal Creeks Over Time
2008 2009 2010 2011 2012
2013 2014 2015 2016 2017
2018 2019 2020 2021 2022
Figure 59. Long-term chlorophyll-a data within tidal creeks
Turbidity
Figure 58 depicts the long-term trends in turbidity within the seven (7) creeks examined within this study
over the long-term period beginning in 2008. 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 58. 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 59 depicts the long-term trends in chlorophyll-a within the seven 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.
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Enterococci
Figure 60 and Table 18 depict the long-term trends in Enterococci within the seven (7) creeks examined
within this long-term 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 exceeding the
standard 43% and 58% of the time, respectively.
Since June 2008, samples collected within Mott Creek and Pages Creek exceeded the State standard for
Enterococci 37% and 36% of the time, respectively while Smith Creek and Barnards Creek have exceeded
the standard 24% and 23% of the time, respectively and Prince George Creek exceeded standard 21% 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.
Figure 59. Long-term Enterococci data within tidal creeks
0
200
400
600
800
1000
1200
Pages Futch Smith Barnards Lords Mott Prince
Georges
Bayshore
Sites
En
t
e
r
o
c
o
c
c
i
(
C
F
U
/
1
0
0
m
l
)
Enterococci Levels in Tidal Creeks Over Time
2008 2009 2010 2011 2012 2013 2014 2015
2016 2017 2018 2019 2020 2021 2022
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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
2022-2023 GOOD GOOD GOOD FAIR FAIR GOOD GOOD
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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.
Parameter Definitions
Temperature
Thermal pollution can result in significant changes to the aquatic environment. Most aquatic organisms
are adapted to survive within a specific temperature range. Thermal pollution may also increase the
extent to which fish are vulnerable to toxic compounds, parasites, and disease. If temperatures reach
extremes of heat or cold, few organisms will survive.
Thermal pollution may be caused by stormwater runoff from warm surfaces such as streets and parking
lots. Soil erosion is another cause, since it can cause cloudy conditions in a water body. Cloudy water
absorbs the sun's rays, resulting in a rise in water temperature. Thermal pollution may even be caused by
the removal of trees and vegetation which normally shade the water body. In addition to the direct effects
of thermal pollution on aquatic life, there are numerous indirect effects. Thermal pollution results in
lowered levels of dissolved oxygen, since cooler water can hold more oxygen than warmer water.
Salinity
Salinity is a measure of the amount of sodium chloride ions dissolved in water. This is important to
monitor since changes in the levels of salt concentration can impact the ability of salt sensitive species to
survive. An estuary, such as the lower Cape Fear River, usually exhibits a gradual change in salinity
throughout its length, as freshwater entering the estuary from tributaries mixes with seawater moving in
from the ocean. Salinity levels control, to a large degree, the types of plants and animals that can live in
different zones of the estuary. Freshwater species may be restricted to the upper reaches of the estuary,
while marine species inhabit the estuarine mouth. Some species tolerate only intermediate levels of
salinity while broadly adapted species can acclimate to any salinity ranging from freshwater to seawater.
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Conductivity
Specific conductance is a measure of the ability of water to conduct an electrical current. Similar to
salinity, it measures the amount of dissolved ions (including sodium chloride) in the water.
pH
The pH of water is a measurement of the concentration of H+ ions, using a scale that ranges from 0 to 14.
Natural water usually has a pH between 6.5 and 8.5. While there are natural variations in pH, many pH
variations are due to human influences. Unanticipated decreases in pH could be indications of acid rain,
runoff from acidic soils, or contamination by agricultural chemicals.
Turbidity
Turbidity is the amount of particulate matter that is suspended in water. Turbidity measures the scattering
effect that suspended solids have on light: the higher the intensity of scattered light, the higher the
turbidity. During a rainstorm, particles from the surrounding land are washed into 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
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.
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Orthophosphate
Phosphorus is a nutrient required by all organisms for the basic processes of life. Phosphorus is a natural
element found in rocks, soils, and organic material. Phosphorus clings tightly to soil particles and is used
by plants, so its concentration in clean waters is generally very low. However, phosphorus is used
extensively in fertilizer and other chemicals, so it can be found in higher concentrations in areas of human
activity. High levels in the water column can be detrimental to water quality as phosphates can cause algal
blooms resulting in decreased dissolved oxygen levels.
Orthophosphate is sometimes referred to as "reactive phosphorus." Orthophosphate is the most stable
kind of phosphate and is the form used by plants. Orthophosphate is produced by natural processes and
is found in sewage.
Nitrate/Nitrite
Nitrate is highly soluble (dissolves easily) in water and is stable over a wide range of environmental
conditions. It is easily transported in streams and groundwater. Nitrates feed plankton (microscopic plants
and animals that live in water), aquatic plants, and algae, which are then eaten by fish. Nitrite is relatively
short-lived in water because it is quickly converted to nitrate by bacteria.
Excessive concentrations of nitrate and/or nitrite can be harmful to humans and wildlife. If excessive
amounts of nitrates are added to the water, algae and aquatic plants can be produced in large quantities.
When these algae die, bacteria decompose them, and use up oxygen.
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Standards
Water quality standards have been established legislatively for a number of these parameters (Table 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 (Tier Classifications
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.
Parameter Standards
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
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Table 20. Single sample standards for Enterococci as determined by the US EPA
Description Single sample maximum
Designated beach areas < 104 CFU/100 ml
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
Tier Classifications
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
IC-SID Tier III No Adjacent to culvert off Sidbury 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-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
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Sampling Sites & Locations
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
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
Island Creek Sidbury Road IC-SID 34° 20.188 77° 49.032
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 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
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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
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APPENDIX D: PAGES CREEK SOURCE TRACKING STUDY
Over the past fifteen years, New Hanover County has implemented several initiatives designed to identify
the source of Enterococci bacteria that has frequently been observed at two sampling sites (PC-BDUS and
PC-BDDS) within the Pages Creek watershed in proximity to the Bayshore community. First, 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, the New Hanover County Planning & Land Use department
partnered with the Cape Fear Public Utility Authority and the New Hanover County Health department to
search for leaking septic or sewer, however, that investigation did not find the source of contamination.
Later, in 2013 the county partnered with the University of North Carolina Chapel Hill to expand the source
tracking and conducted a study exploring the source of Enterococci bacteria from within Pages Creek,
Mott Creek, and Smith Creek. That study found the presence of a human signature in the bacteria for all
three creeks including from within samples collected at both PC-BDUS and PC-BDDS in Pages Creek.
In an attempt to identify where the bacteria was entering Pages Creek, 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 in 2019 to conduct a thermal imagery scan of two
portions of Pages Creek adjacent to the two long-term monitoring sites that have consistently detected
elevated levels of Enterococci bacteria. Following the flight, UNCW and CPE analyzed the imagery and
identified two areas depicting temperature anomalies which could indicate the geographic source
contaminated water. Ground truthing these areas revealed several subterranean groundwater seeps
entering the creek from the streambank in the vicinity of the sewer lift stations adjacent to PC-BDUS and
PC-BDDS. In June and July of 2022 planning staff, CPE, and the Cape Fear Public Utility Authority
performed additional testing of the seep water coming from the creek bank in these two locations that
identified Enterococci bacteria in the water. 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.
Following these efforts, in 2023 New Hanover County secured funding to expand the extent of the source
tracking investigations to determine if human contamination may be identified in areas within the Pages
Creek watershed beyond proximity to the two long-term monitoring sites at PC-BDUS and PC-BDDS. CPE
collected water samples in replicate from twenty sites located throughout the creek on April 11, 2023
(Figures 61, 62, and 63).
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Figure 61. 2023 source tracking sampling locations. Note: Samples from sites 4-20 were collected during both
sampling events. Samples were also collected from sites 1-3 during the April 11 event only, and sites 21-23 during
the July 6 sampling event.
Figure 62. Zoomed in figure depicting 2023 source tracking sampling locations in proximity to PC-BDUS. Note:
Samples from sites 4-20 were collected during both sampling events. Samples were also collected from sites 1-3
during the April 11 event only, and sites 21-23 during the July 6 sampling event.
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Figure 63. Zoomed in figure depicting 2023 source tracking sampling locations in proximity to PC-BDDS. Note:
Samples from sites 4-20 were collected during both sampling events. Samples were also collected from sites 1-3
during the April 11 event only, and sites 21-23 during the July 6 sampling event.
Samples were collected soon after a full tide such that the water was ebbing. No rain had been recorded
within the area within 48 hours before sampling occurred. The fecal gene marker HF-183 was detected
in both samples collected from Site #11 which is located directly upstream from the long-term monitoring
site PC-BDDS. The marker was also present in both samples at Site #10 which represents the location of
PC-BDDS, however, the signal was lower and not quantifiable (“Detected, Not Quantified”). Three other
sampling sites (#4, #9, and #14) indicated the presence of the fecal gene marker in just one of the two
replicate samples and therefore was classified as a “Non-Detect”. Sites #4 and #9 are located further
downstream from PC-BDDS suggesting that the high signal detected at Site #11 diminished as the water
traveled down the creek. A second sampling event occurred on July 6, 2023 soon after a high tide as the
water began to ebb. Nearly an inch of rain had fallen within the area before sampling occurred. Because
the results from the initial sampling event in April indicated that no fecal gene marker was present within
any of the sampling sites located in proximity to the mouth of the creek, samples were not collected from
sampling sites #1, #2, and #3 during this second event and, rather, additional sites were established in
proximity to PC-BDDS where the fecal gene marker was previously identified. The results of this second
sampling event showed that the human fecal marker was only identified within three sampling sites all in
proximity to PC-BDDS. Specifically, the marker was observed within both replicate samples collected at
Site #18 (the location of PC-BDDS) and immediately downstream at Site #17. Although detected, the level
of signal was relatively low such that the results were marked as “Detected, Not Quantified”. The other
positive “hit” was located further downstream at Site #13. The level of the marker at this location was
higher than the other two sites and therefore was noted as a “Quantifiable Result”.
As described above, the results of the 2023 source tracking effort determined that there was the presence
of the human fecal marker in proximity to both PC-BDUS and PC-BDDS during separate sampling events.
This effort which was the first-time creek-wide sampling had been conducted, also ruled out that bacteria
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could have been entering from other locations within the creek as a creek-wide sampling initiative had
not previously been conducted. New Hanover County, Coastal Protection Engineering and the Cape Fear
Public Utility authority will continue to collaborate and explore next steps to identify the source of bacteria
in Pages Creek in order to formulate recommendations for mitigation.
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