HomeMy WebLinkAbout2023-2024 Final ReportCPE
NEW HANOVER COUNTY WATER QUALITY MONITORING PROGRAM
2023-2024
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., 2024. New Hanover County Water Quality Monitoring Program: 2023-
2024 Final Report. New Hanover County, North Carolina: Coastal Protection Engineering of North
Carolina, Inc.
December 2024
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EXECUTIVE SUMMARY
This report represents the findings of the New Hanover County Water Quality Monitoring Program for the
period July 2023 through June 2024. 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 within tidal creeks in New Hanover County. The
creeks monitored for the 2023-2024 program year include Barnards, Futch, Lords, Motts, Pages, Prince
George, Smith, and Island.
Across the eight creeks a total of 20 sampling sites are 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. The chart below depicts the overall
water quality for each parameter for each creek based on the rating system described above.
Ratings by watershed during the 2023-2024 reporting period
Parameter Barnards
Creek
Futch
Creek
Island
Creek
Lords
Creek
Motts
Creek
Pages
Creek
Prince
George
Creek
Smith
Creek
Turbidity GOOD GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Dissolved
Oxygen GOOD FAIR POOR GOOD FAIR FAIR POOR GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD GOOD
Enterococci GOOD GOOD GOOD GOOD POOR FAIR FAIR FAIR
General Trends & Observations
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
not changed drastically from year to year which the exception at Futch Creek which saw overall levels go
from “Good” in 2022-2023 to “Fair” for this program year. The long-term data shows that the dissolved
oxygen levels at Futch Creek has varied between “Good” and “Fair” since 2008. The trend of low dissolved
oxygen levels remained during this sampling period 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. Barnards Creek, Lords Creek, and Smith Creek continued to contain good levels of dissolved oxygen
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this year as has been observed in the past. It should be noted that low dissolved oxygen is a negative
indicator of water quality, while high dissolved oxygen is positive for overall water quality.
Enterococci bacteria levels during the 2023-2024 sampling period remained the same as the previous
sampling period for Barnards Creek, Futch Creek, Lords Creek, and Pages Creek while Motts Creek changed
from “Fair” to “Poor” and Prince George Creek and Smith Creek changed from “Good” to “Fair” over the
same time period. Since 2019, Barnard Creek, Futch Creek, and Lords Creek have contained relatively
lower bacteria levels compared to the other creeks.
Monitoring at Island Creek began in 2021 with one monitoring site off Holly Shelter Road with a second
site added in 2022 off Sidbury Road. Over this time, frequent instances of low dissolved oxygen levels have
been observed within both sampling sites. In addition, several samples containing elevated levels of
Enterococci bacteria were collected from the creek. The Island Creek watershed is mostly rural and
undeveloped where the source of bacteria could be from wildlife. There is one subdivision off Sidbury
Road consisting of about 40 homes that rely on septic as well as a subdivision in Pender County off Holly
Shelter. Due to the proximity of these septic systems to the creek, it is possible that they could also be
contributing to the elevated levels.
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 nine 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 four years this
trend has reversed, where orthophosphate was lower at the intake and higher at the outfall of the lake
(Figures 50 & 51). High concentrations of orthophosphate and Nitrite/Nitrate can cause algae growth
leading to algal blooms which can cause low dissolved oxygen and a decline in overall water quality. Since
monitoring began, there had been an incremental trend of increasing amounts of orthophosphate each
year until this past sampling period when these levels declined. A similar trend has been observed for
Nitrite/Nitrate since 2019 where levels have been declining. A more in-depth review of water quality for
Airlie can be found in the Discussion section of this report.
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 the 2015-2016 program year.
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Key Takeaways
• With few exceptions, Futch Creek, Island Creek, and Lords Creek have generally contained low
levels of enterococcus over the entire course of the program.
• Several creeks have improved water quality in terms of enterococcus bacteria over the years:
o At Barnards Creek, the percentage of samples exceeding the standard was 42% between
2008-2012. However, between 2013 to 2019, that percentage was reduced to an average
of approximately 15%. Between 2020 to present, not one sample exceeded the standard.
o At Motts Creek, 53% of samples exceeded the standard between 2008 to 2015. Since
2015, the percentage of samples exceeding the standard dropped to 19%.
o At Prince George Creek, 29% of samples collected between 2008 to 2017 exceeded the
standard. Between 2018 to Present, only 7% of samples exceeded the standard
o At Smith Creek, 31% of samples collected between 2008 to 2018 exceeded the standard.
Between 2019 to Present, only 7% of samples exceeded the standard.
• Since 2007 Pages Creek has continued to demonstrate elevated levels of enterococcus bacteria
where an average of 34% of samples collected exceed the standard. Of the three sites monitored
in Pages Creek, the majority of the samples collected with elevated levels came from two sites
(PC-BDDS and PC-BDUS). It should be noted that the standards for PC-BDDS and PC-BDUS are
different. Parameter standards can be found in Appendix D.
o Since 2007 43% of the samples collected from PC-BDDS exceeded the standard for
enterococci (<500 CFU/100 ml) on an annual basis.
o Since 2007 53% of the samples collected from PC-BDUS exceeded the standard for
enterococci (<276 CFU/100 ml) on an annual basis. It should be noted that over the course
of the past three years (2022-2024), the annual average of exceedances dropped to 23%.
• With few exceptions, Island Creek, Prince George Creek, Smith Creek, and Lords Creek have
generally contained adequate levels of dissolved oxygen over the entire course of the program.
• Futch Creek has improved over recent years. Between 2008 to 2019, 20% of samples contained
dissolved oxygen levels below the standard. However, between 2020 to 2024, only 8% of samples
were below that standard.
• Barnards Creek has had varying dissolved oxygen levels over time. While not one sample was
below the standard on 9 of the 17 years we’ve monitored, there were 4 years where at least 25%
of the samples exceeded the standard (2014, 2015, 2016, 2022).
• Motts Creek has demonstrated relatively stable levels of dissolved oxygen with approximately
10% of the samples exceeding the standard over the entire course of the program.
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Continued Efforts
While monitoring water quality within New Hanover County is the focus of the Water Quality Monitoring
Program there have been efforts in the past to investigate when there has been indication that water
quality has been negatively impacted. Those efforts can be read in more detail in Appendix C of this report.
During this program year, no additional testing, investigation or exploration was conducted however, New
Hanover County continues to monitor water quality and coordinate with Coastal Protection Engineering
the Cape Fear Public Utility Authority (CFPUA) and local residents to address any emerging issues.
There has been efforts this year by both CFPUA and the New Hanover County Soil and Water Conservation
District where CFPUA conducted a video inspection of the sewer infrastructure within the Bayshore
neighborhood. That inspection revealed no deficiencies. In July 2024, the New Hanover County Soil and
Water Conservation District, with help from Moffatt & Nichol, completed the Pages Creek Restoration
Plan. This plan outlines strategies to reduce bacteria and nutrient loading into the creek. It also enables
the county to collaborate with property owners and apply for federal funding to implement projects that
address non-point-source and point-source pollution, as well as mitigate stormwater and flooding
impacts.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY ....................................................................................................................... I
GENERAL TRENDS & OBSERVATIONS .................................................................................................................. I
KEY TAKEAWAYS ............................................................................................................................................III
CONTINUED EFFORTS .................................................................................................................................... IV
INTRODUCTION .................................................................................................................................1
CREEK SUMMARIES ............................................................................................................................1
BARNARDS CREEK .......................................................................................................................................... 1
FUTCH CREEK ................................................................................................................................................ 4
ISLAND CREEK ............................................................................................................................................... 5
LORDS CREEK ................................................................................................................................................ 6
MOTTS CREEK ............................................................................................................................................... 7
PAGES CREEK ................................................................................................................................................ 8
PRINCE GEORGE CREEK .................................................................................................................................. 9
SMITH CREEK ................................................................................................................................................ 9
AIRLIE GARDENS ............................................................................................................................................ 4
DISCUSSION ..................................................................................................................................... 12
PARAMETERS .............................................................................................................................................. 13
AIRLIE GARDENS DISCUSSION ........................................................................................................................ 14
APPENDIX A: ADDITIONAL CREEK DATA ............................................................................................ 16
BARNARDS CREEK ........................................................................................................................................ 16
FUTCH CREEK .............................................................................................................................................. 18
ISLAND CREEK ............................................................................................................................................. 23
LORDS CREEK .............................................................................................................................................. 26
MOTTS CREEK ............................................................................................................................................. 28
PAGES CREEK .............................................................................................................................................. 31
PRINCE GEORGE .......................................................................................................................................... 35
SMITH CREEK .............................................................................................................................................. 39
AIRLIE GARDENS .......................................................................................................................................... 44
APPENDIX B: LONG TERM TRENDS .................................................................................................... 49
DISSOLVED OXYGEN ..................................................................................................................................... 49
TURBIDITY .................................................................................................................................................. 50
CHLOROPHYLL-A .......................................................................................................................................... 51
ENTEROCOCCI ............................................................................................................................................. 52
APPENDIX C: IMPROVEMENT EFFORTS ............................................................................................. 54
APPENDIX D ..................................................................................................................................... 56
WATER CLASSIFICATIONS .............................................................................................................................. 56
PARAMETER DEFINITIONS ............................................................................................................................. 56
STANDARDS ................................................................................................................................................ 59
METHODS .................................................................................................................................................. 62
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 2023 to June
2024. 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, Motts,
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 2023 through June 2024. 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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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
Overall Assessment
Chlorophyll-a levels exceeded the State standard once for
the year. Overall, there were no issues however,
Enterococci levels were generally higher compared to the
previous two years but still below state standards.
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) 2.5 0
Chlorophyll-a (above 40) < 1.0 < 1.0
Turbidity (above 50) < 1.0 0
Enterococci (above 500) 1.05 1
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.
Overall Assessment
While dissolved oxygen levels exceeded the State
standard on six (6) instances, overall, there were no
other issues with Futch Creek for the year.
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) 7.3 1.6
Chlorophyll-a (above 40) 0 < 1.0
Turbidity (above 50) 0 0
Enterococci (above 500) 1.5 0
Parameter FC-4, FC-6, FC-13, FC-FOY
Turbidity (NTU) Good
Dissolved Oxygen Good, Good, Poor, Poor
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.
*Monitoring in Island Creek began in 2021
Overall Assessment
Dissolved oxygen was rated poor with twelve (12)
occurrences below the state standard. There was one
occurrence of elevated chlorophyll-a and two (2) for
enterococci for the year.
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) 9.5 N/A*
Chlorophyll-a (above 40) < 1.0 N/A*
Turbidity (above 50) 0 N/A*
Enterococci (above 500) < 1.0 N/A*
Parameter IC-HS, IC-SID
Turbidity (NTU) Good
Dissolved Oxygen Poor
Chlorophyll-a Good
Enterococci Good
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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.
Overall Assessment
There was only one (1)occurrence of low dissolved
oxygen and turbidity at the River Road site, otherwise
water quality for the year at Lords Creek was good.
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) < 1.0 < 1.0
Chlorophyll-a (above 40) < 1.0 0
Turbidity (above 50) < 1.0 < 1.0
Enterococci (above 500) < 1.0 0
Parameter LC-RR
Turbidity (NTU) Good
Dissolved Oxygen Good
Chlorophyll-a Good
Enterococci Good
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Motts 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.
Overall Assessment
Enterococci levels were elevated again this year comparted
to previous years. There were seven (7) total exceedances
for the year with six (6) at the Normandy Drive site. There
was one (1) exceedance of Chlorophyll-a level observed at
the Normandy Drive site as well.
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) 2.4 2
Chlorophyll-a (above 40) < 1.0 < 1.0
Turbidity (above 50) < 1.0 0
Enterococci (above 500) 8.5 3.8
Parameter MOT-CBR, MOT-ND
Turbidity (NTU) Good
Dissolved Oxygen Fair, Good
Chlorophyll-a Good
Enterococci Good, Poor
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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.
Overall Assessment
Dissolved Oxygen levels were below state standards five
(5) times at PC-BDDS. Enterococci levels were poor at the
PC-BDDS site where chlorophyll-a levels also exceeded
the standard twice. One (1) observation of elevated
turbidity was noted at the PC-BDUS site.
Parameter PC-BDDS, PC-BDUS, PC-M
Turbidity (NTU) Good
Dissolved Oxygen Poor, Good, Good
Chlorophyll-a Good
Enterococci Poor, Fair, Good
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) 7.9 5.60
Chlorophyll-a (above 40) 1 < 1.0
Turbidity (above 50) 0 0
Enterococci (above 500) 12.24 9
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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 along Castle
Hayne Road and N. College Road.
Overall Assessment
Dissolved Oxygen at was below state standards
throughout the year at all three sites. There were three
(3) exceedances for Enterococci at the Castle Hayne Road
site and one (1) at the North College site.
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) 13.7 14.6
Chlorophyll-a (above 40) < 1.0 < 1.0
Turbidity (above 50) < 1.0 0
Enterococci (above 500) 7.1 2.8
Parameter PG-CH, PG-ML, PG-NC
Turbidity (NTU) Good
Dissolved Oxygen Poor
Chlorophyll-a Good
Enterococci Fair, Good, 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.
Overall Assessment
Enterococci bacteria exceeded state standards three (3)
times at the Candlewood Drive site, twice (2) at the
Gordon Road site, and once (1) at the North Kerr sites.
Dissolved oxygen was below the state standard four (4)
times at the Gordon Road site. There was also one (1)
exceedance of chlorophyll-a at the North Kerr site.
Parameter SC-CH, SC-CD, SC-GR, SC-NK
Turbidity (NTU) Good
Dissolved
Oxygen Good, Good, Poor, Good
Chlorophyll-a Good
Enterococci Good, Fair, Fair, Good
Annual Average
Exceedances Lifetime Past 5
Years
Dissolved oxygen (below 4) 3.5 2.6
Chlorophyll-a (above 40) < 1.0 < 1.0
Turbidity (above 50) < 1.0 < 1.0
Enterococci (above 500) 13.2 3.8
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Airlie Gardens
• Location: City of Wilmington.
• 3 Sampling Locations: AG-IN, AG-FD, AG-
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
• 5 (five) occurrences of dissolved oxygen below
State standard
• 22 (twenty-two) occurrences above State
standard for chlorophyll-a
• 0 (zero) occurrences above State standard for
turbidity
*Enterococci is not measured at Airlie Gardens
Overall Assessment
Dissolved oxygen has remained consistent throughout the
lake despite occasional occurrences below the state
standard. Orthophosphate and Nitrate/Nitrate levels
moderated this year following several years of annual
increases. Chlorophyll-a levels have remained elevated
over recent years indicating the presence of algal blooms.
Two small algal blooms were verified this past year by staff
with the New Hanover County Parks & Gardens
department.
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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 steady growth and development over the past several decades
increasing in population by about forty percent from 2000 (160,307) to 2020 (225,702) according to the
United States Census Bureau. 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 some 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 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 in 2020 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 Motts 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. As mentioned, 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 16 years
of monitoring thus far (this does not include data from Island Creek due to the fact monitoring started
just 3 years ago). The one parameter, however, that has been problematic has been Enterococci bacteria.
Of the 3,604 samples collected and analyzed since June 2008, 763 samples (21%) have exceeded the State
standard for this bacterium. This analysis does not include data from Island Creek which has only been
monitored for the past several 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 16 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 six (6) chlorophyll-a samples exceeded the State standard during
the 2023-2024 monitoring period.
Dissolved Oxygen
In general, the dissolved oxygen within Barnards Creek, Lords Creek, Motts 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 six of the past seven years. Futch Creek has maintained a “Fair” rating for ten of
the fifteen years, however improved and maintained a "Good" since the 2020-2021 monitoring period
until it reverted back to “Fair” during the most recent sampling 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 seven of the past eight 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” fourteen of the sixteen 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 3,664 samples collected and analyzed from all the monitoring sites since June 2008
(including those from Island Creek), 765 samples (21%) have exceeded the State standard for this
bacterium. Specifically, Motts 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 43% and 55% of the
time, respectively.
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The Enterococci levels over the course of the first ten years of monitoring were relatively higher, overall,
compared to the levels observed since 2018. Following two years of relatively low levels of Enterococci
within the study area, this most recent year (2023-2024) demonstrated slightly worse water quality in
terms of the indicator species of bacteria. Three creeks (Motts Creek, Prince George Creek, and Smith
Creek) declined in ratings over the course of the past year. It should be noted, however, that no samples
exceeded the State Enterococci standard during this most recent monitoring period from within Lords
Creek, Futch Creek, and Barnards Creek. At Motts Creek, Pages Creek, Smith Creek, Prince George Creek,
and Island Creek, the standard was exceeded 29%, 22%, 14%, 11%, and 8% of the time over the course of
the 2023-2024 monitoring period, respectively.
At Motts Creek, the bacteria levels had moderated over recent years. Prior to the 2016-2017 sampling
effort, Motts Creek had consistently demonstrated “Poor” water quality in terms of bacterial
contamination. Since that time, Motts Creek has demonstrated a “Fair” or “Good” ratings with the
exception of this past year when higher levels of Enterococci were observed resulting in a “Poor” rating
again. There is no clear cause why levels of Enterococci were elevated this year, but continued monitoring
will indicate if any investigation into the source is necessary. As mentioned above, despite this past year’s
increase of bacteria in the watershed, the overall improvement in Enterococci levels was most likely
attributed to the transition of residential homes with failing septic systems to the CFPUA’s sewer system
in the Marquis Hills community (located within the Motts Creek watershed). Since that time the data has
reflected, that bacteria levels have generally been reduced with the number of exceedances around 15%
and less than 10% in years 2020 and 2022, proving the effects of improving wastewater treatment
measures. CFPUA has planned upgrades to the wastewater infrastructure which may further improve
overall water quality in the watershed. New Hanover County in 2019 completed a drainage project to
improve flow where data has shown a reduction in the levels of bacteria and improvements in dissolved
oxygen and chlorophyl-a.
Pages Creek continued to show elevated levels of Enterococci where eight (8) out of thirty-six (36) samples
(22%) exceeded the State standard over the course of the most recent study period. None of the samples
collected from the site at the mouth of Pages Creek (PC-M) exceeded the standard. Of the eight (8)
samples that exceeded the standard, six (6) were from the Pages Creek Down-Stream Site (PC-BDDS) while
two (2) were from the Pages Creek Up-Stream site (PC-BDUS). As mentioned above, since 2008, PC-BDDS
and PC-BDUS exceeded the standard 43% and 55% of the time, respectively. However, over the past 4
sampling years between July 2020 and June 2024, the percentage of exceedances at both sites has
decreased to 40%.
Airlie Gardens Discussion
The results from monthly sampling over the past eight 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 the 2015-2016 program year at the AG-IN site, nitrate/nitrite levels have been relatively
higher on average compared to the other two sites further closer to the outfall and orthophosphate has
been slightly increasing over time across all sites.
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
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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 could facilitate a reduction of algal blooms thereby helping
to maintain appropriate levels of dissolved oxygen. A couple of small algal blooms were confirmed in the
pond at Airlie Gardens this past year. Data from the 2023-2024 sampling period has revealed a reduction
of orthophosphate and nitrate/nitrite levels at all three sites compared to the previous sampling period.
Chlorophyll-a levels, however, have increased at all three sites during the 2023-2024 sampling period
compared to last year. Therefore, the data was able to confirm the presence of algal blooms suggesting
that the nutrients that continue to enter the lake are taken up through plant growth.
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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 2.3 mg/l and 8.6 mg/l with a mean value of 6.3 mg/l
(Table 1). No samples contained dissolved oxygen levels below the State standard of 4.0 mg/l for C Sw
waters at the surface (Figure 3).
Chlorophyll-a ranged between 1.0 ug/l and 70.0 ug/l with a mean value of 9.0 ug/l at BC-CBR (Table 1).
One sample surpassed the 40 ug/l standard.
Enterococci ranged between 20 CFU/100 ml and 288 CFU/100 ml with a geometric mean value of 102
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 24 NTU with a mean value of 7 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) 7 (1-24)
Dissolved Oxygen (mg/l) 6.3 (2.3-8.6)
Chlorophyll-a (ug/l) 1 (1-70)
Enterococci (#CFU/100ml) 102 (20-288)
(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 4.2mg/l and 9.9 mg/l with a mean value of 7.2 mg/l
(Figure 6 – Figure 9, Table 3). Six (6) 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 33.0 ug/l with a mean value of 4.0 ug/l (Table 3). None of
these values approached the 40ug/l chlorophyll-a standard.
Enterococci ranged between 5 CFU/100ml and 31 CFU/100ml with a geometric mean value of 5
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 21 NTU with a mean value of 5 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) 5 (1-21) 3 (0-15) 5 (1-17) 6 (1-21)
Dissolved
Oxygen (mg/l)
7.4 (5.5-9.7) 7.3 (5.1-9.7) 7.0 (4.2-9.9) 7.1 (4.5-9.9)
Chlorophyll-a
(ug/l)
5 (0-33) 3(0-8) 5 (1-13) 3 (0-7)
Enterococci
(#CFU/100ml)
7 (5-10)1 5 (5-10)1 7 (5-30)1 7 (5-30)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 POOR POOR
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 1.1 mg/l and 9.1 mg/l with a mean value of 4.6 mg/l
(Table 5). Twelve (12) 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 0 ug/l and 43 ug/l with a mean value of 7 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 3,610 CFU/100ml with a geometric mean value of 34
CFU/100ml (Table 5, Figures 17 and 18). Two (2) 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 30 NTU with a mean value of 7 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) 7 (2-30) 5 (1-16)
Dissolved Oxygen
(mg/l)
4.9 (1.9-9.1) 4.2 (0.8-7.9)
Chlorophyll-a (ug/l) 5 (1-18) 8 (0-43)
Enterococci
(#CFU/100ml)
43 (5-2,060)1 25 (5-3,610)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 10.4 mg/l with a mean value of 7.1 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 1 ug/l and 35 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 10 CFU/100ml and 75 CFU/100ml with a geometric mean value of 22
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 51 NTU with a mean value of 21 NTU
(Table 7). One (1) sample 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) 21 (4-51)
Dissolved Oxygen (mg/l) 7.1 (3.5-10.4)
Chlorophyll-a (ug/l) 11 (1-35)
Enterococci (#CFU/100ml) 22 (10-75)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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Motts Creek
Sampling was conducted at two (2) sites (MOT-CBR, MOT-ND) within the Motts Creek watershed (Figure
22).
Dissolved oxygen within Motts Creek ranged between1.8 mg/l and 9.1 mg/l with a mean value of 6.0 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 43 ug/l with a mean value of 8 ug/l (Table 9). One (1) sample
exceeded the 40ug/l standard.
Enterococci ranged between 5 CFU/100ml and 6,490 CFU/100ml with a geometric mean value of 118
CFU/100 ml (Table 9). Samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III waters during
seven (7) sampling events during the reporting period (Figure 25 and Figure 26).
Turbidity values were generally good ranging between 1 and 27 NTU with a mean value of 8 NTU (Table
9). 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 Motts Creek Watershed
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Table 9. Mean values of select parameters from Motts Creek. Range in parentheses.
Parameter MOT-CBR MOT-ND
Turbidity (NTU) 5 (1-27) 4 (4-15)
Dissolved Oxygen (mg/l) 5.1 (2.7-7.9) 6.8 (1.8-9.1)
Chlorophyll-a (ug/l) 6 (1-31) 9 (1-43)
Enterococci (#CFU/100ml) 34 (5-620)1 405 (20-6,490)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 Motts Creek
Parameter MOT-CBR MOT-ND
Turbidity GOOD GOOD
Dissolved Oxygen FAIR GOOD
Chlorophyll-a GOOD GOOD
Enterococci GOOD POOR
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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 2.8 mg/l and 11.9 mg/l with a mean value of 7.1
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 while levels remained above the standard at PC-
BDUS and PC-M.
Chlorophyll-a ranged between 0 ug/l and 76 ug/l with a mean value of 10 ug/l (Table 11). Two (2) samples
exceeded the State standard of 40 ug/l for chlorophyll-a.
Enterococci ranged between 5 CFU/100 ml and 2,480 CFU/100 ml with a geometric mean value of 59
CFU/100 ml (Figures 31 – 33, Table 11). Six (6) samples from PC-BDDS and two (2) samples from PC-BDUS
contained levels higher than the NCDEQ standard. Enterococci was within the standard at PC-M during all
twelve (12) sampling events.
Turbidity values were generally good ranging between 1 and 28 NTU with a mean value of 7 NTU (Table
11). One (1) of the observed turbidity values exceeded the State standard of 25 NTU for class SA waters.
Table 12 depicts the ratings for these parameters for the watershed.
Figure 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) 6 (1-10) 10 (1-28) 5 (1-10)
Dissolved Oxygen (mg/l) 6.0 (2.8-9.2) 7.9 (5.4-11.9) 7.3 (5.1-9.5)
Chlorophyll-a (ug/l) 16 (1-76) 9 (1-22) 6 (0-36)
Enterococci (#CFU/100ml) 303 (10-2,480)1 102 (20-404)1 7 (5-36)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 GOOD GOOD
Enterococci POOR FAIR 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 0.4 mg/l and 8.8 mg/l with a mean value of
4.3 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 and PG-ML and six (6) times at PG-CH (Figures
35 – 37, Table 13).
Chlorophyll-a ranged between 1 ug/l and 16 ug/l with a mean value of 4 ug/l (Table 13). No samples from
Prince George Creek exceeded the 40 ug/l standard.
Enterococci ranged between 5 CFU/100ml and 3,870 CFU/100ml with a geometric mean value of 55
CFU/100ml (Table 13). Four (4) samples collected from within Prince George Creek contained Enterococci
levels above the NCDEQ standard of 500 CFU/100ml for Tier III waters (Figures 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) 5.0 (2.4-8.8) 4.9 (3.1-7.7) 3.0 (0.4-6.4)
Chlorophyll-a (ug/l) 4 (1-7) 3 (1-8) 5 (1-16)
Enterococci (#CFU/100ml) 127 (20-3,280)1 61 (10-435)1 21 (10-3,870)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 POOR POOR POOR
Chlorophyll-a GOOD GOOD GOOD
Enterococci FAIR GOOD GOOD
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Smith Creek
Sampling was conducted at four (4) sites (SC-CH, 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 throughout the first half of the year
due to the reconstruction of the bridge along Castle Hayne Road that crosses Smith Creek.
Dissolved oxygen within the creek ranged between 1.1 mg/l and 10.2 mg/l with a mean value of 7.1 mg/l
(Table 15; Figures 42 – 45). Four (4) samples collected were below the State standard.
Chlorophyll-a ranged between 1 ug/l and 47 ug/l with a mean value of 8 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 1,530 CFU/100 ml with a geometric mean value of 104
CFU/100ml (Table 15). Six (6) samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III waters
(Figure 46-49).
Turbidity values were generally good ranging between 1 and 35 NTU with a mean value of 11 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-CH SC-CD SC-GR SC-NK
Turbidity (NTU) 17 (10-35) 7 (1-22) 12 (3-31) 7 (3-12)
Dissolved Oxygen (mg/l) 7.5 (5.1-9.3) 8.3 (6.5-10.2) 5.7 (1.1-9.4) 6.9 (4.6-9.4)
Chlorophyll-a (ug/l) 4 (1-14) 6 (1-22) 6 (1-23) 18 (2-47)
Enterococci (#CFU/100ml) 54 (24-86) 220 (5-906)1 83 (10-826)1 93 (10-1,530)1
(1)Enterococci values expressed as geometric mean
Figure 42. Dissolved Oxygen at SC-CH at surface (DO-S)
Figure 43. Dissolved Oxygen at SC-CD at surface (DO-S)
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Figure 44. Dissolved Oxygen at SC-GR at surface (DO-S)
Figure 45. Dissolved Oxygen at SC-NK at surface (DO-S) and bottom (DO-B)
Figure 46. Enterococci at SC-CH
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Figure 47. Enterococci at SC-CD
Figure 48. Enterococci at SC-GR
Figure 49. Enterococci at SC-NK
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Table 16. Ratings of parameters within sampling sites within Smith Creek
Parameter SC-CH SC-CD SC-GR SC-NK
Turbidity GOOD GOOD GOOD GOOD
Dissolved Oxygen GOOD GOOD POOR GOOD
Chlorophyll-a GOOD GOOD GOOD GOOD
Enterococci GOOD FAIR FAIR 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 50, Table
17).
Dissolved oxygen within the lake ranged between 1.8 mg/l and 18.0 mg/l with a mean value of 7.8 mg/l
(Table 17; Figures 51-53). Five (5) samples were below the State standard for dissolved oxygen.
Turbidity values were generally good ranging between 1 and 49 NTU with a mean value of 10 NTU (Table
17). No samples exceeded the State standard of 50 NTU for Class C waters.
Chlorophyll-a ranged from 2 mg/l to 293 mg/l with a mean value of 63 mg/l. The standard of 40 mg/l was
exceeded twenty-two (22) times.
Figure 50. Airlie Gardens Sampling Sites
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Figure 51. Dissolved Oxygen at AG-IN
Figure 52. Dissolved Oxygen at AG-FD
Figure 53. 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) 9 (1-37) 10 (3-30) 13 (2-49)
Dissolved
Oxygen (mg/l)
6.3 (1.8-13.0) 9.4 (5.4-13.0) 7.6 (3.2-14.0)
Chlorophyll-a
(mg/l)
59 (2-293) 71 (29-178) 58 (5-134)
Orthophosphate 0.07 (0.01-0.28) 0.04 (0.02-0.10) 0.08 (0.01-0.19)
Nitrate/Nitrite 0.10 (0.01-0.44) 0.02 (0.01-0.11) 0.06 (0.01-0.22)
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 54). On average, Chlorophyll-a levels at AG-FD and AG-OUT have been considerably higher than
the levels observed at AG-IN over time. This may indicate that the nutrients entering the lake from
stormwater runoff collected near AG-IN may be taken up by growing vegetation (algae and other aquatic
plant matter) as the water flows towards the outfall in proximity to AG-OUT.
Figure 54. Chlorophyll-a levels at Airlie Gardens Over Time
When examining the levels of nutrients over time within these sampling sites, higher levels of
nitrite/nitrate have been observed at AG-IN compared to the other two sampling sites on an annual basis
since sampling began in 2015 (Figure 55). Over the past nine (9) years, nitrite/nitrate levels have averaged
0.07 mg/l, 0.06 mg/l, and 0.04 mg/l at AG-IN, AG-FD, and AG-OUT, respectively.
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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 across the lake over the past five years (Figure 56). Collectively, over the past nine (9) 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 had been a trend of increasing levels of both nutrients within the lake over recent years.
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, however, these values decreased during the 2023-2024 sampling period (Figure 57). The
increase in levels of Chlorophyll-a over the past year, as previously discussed, may be a result of taking up
some of these available nutrients and converting them to plant matter.
Figure 55. Nitrate/Nitrate Levels in Airlie Gardens Over Time
Figure 56. Orthophosphate Levels in Airlie Gardens Over Time
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Figure 57. Average Nitrite/Nitrate and Orthophosphate Levels in Airlie Gardens
Dissolved oxygen within the lake has been good, on average, through the years within each site with the
exception of AG-IN during the 2015-2016 and the previous2022-2023 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 58). At each site, the dissolved oxygen levels generally increased
during the warmer summer months and increased during the colder winter months.
Figure 58. Dissolved Oxygen in Airlie Gardens Over Time
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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 2024.
Dissolved Oxygen
Figure 59 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 36%, 22%, 15%, and 10%
of the time within Prince George Creek, Pages Creek, and Futch Creek, respectively. Dissolved oxygen was
below the standard 9% of the time from within both Barnards Creek and Motts Creek while Smith Creek
and Lords Creek exceeded the standard 6% and 5% of the time, respectively. Of the 550 samples that fell
below the standard for dissolved oxygen the since 2008, 322 (58%), were observed during June, July, and
August when water temperatures were the highest. It should be noted that low dissolved oxygen is a
negative indicator of water quality, while high dissolved oxygen is positive for overall water quality.
Figure 59. Long-term surface dissolved oxygen data within tidal creeks. Note: The dissolved oxygen standard
within Pages Creek and Futch Creek is 5.0 mg/l while the standard for the other creeks is 4.0 mg/l.
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Turbidity
Figure 60 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 twenty-one (21) times
in total: eight (8) from within Pages Creek, seven (7) from within Smith Creek, two (2) from within Lords
and Prince George Creek, and one time each from within Barnards Creek, Lords Creek and Motts Creek.
Figure 60. Long-term surface turbidity data within tidal creeks. Note: The turbidity standard within Pages Creek
and Futch Creek is 25 NTUs while the standard for the other creeks is 50 NTUs.
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Chlorophyll-a
Figure 61 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.
Figure 61. Long-term chlorophyll-a data within tidal creeks. There is no standard for chlorophyll-a.
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Enterococci
Figure 62 and Table 18 depict the long-term trends in Enterococci within the seven (7) creeks examined
within this long-term study. Of these creeks, Motts 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 Motts 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 55% of the time, respectively.
Since June 2008, samples collected within Motts Creek, Pages Creek, and Smit Creek exceeded the State
standard for Enterococci 37%, 35%, and 24% of the time, respectively Barnards Creek and Prince George
Creek both exceeded the standard 21% of the time. Lords Creek exceeded the standard 8% of the time
while Futch Creek has only exceeded the standard for Enterococci 3% of the time.
Figure 62. Long-term Enterococci data within tidal creeks. See Appendix D for Enterococci standards.
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Table 18. Enterococci ratings for each watershed during all reporting periods.
Study
Period
Barnards
Creek
Futch
Creek
Lords
Creek
Motts
Creek
Pages
Creek
Prince
George
Creek
Smith
Creek
Island
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 GOOD
2022-2023 GOOD GOOD GOOD FAIR FAIR GOOD GOOD GOOD
2023-2024 GOOD GOOD GOOD POOR FAIR FAIR FAIR GOOD
* Monitoring at Island Creek began in program year 2021-2022
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APPENDIX C
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.
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.
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 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.
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. 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.
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
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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 2022-2023 New Hanover County Water Quality
Monitoring Program report.
Since those efforts New Hanover County continues to monitor water quality and keep an open line of
communication with the Cape Fear Public Utility Authority and the residents in the area to “keep an eye”
out for any emerging issues. In the past year the Cape Fear Public Utility Authority has videoed pipe in the
Bayshore community to visually inspect the lines. No deficiencies were found during that inspection
however, a sewer system overflow (SSO) in August of 2024 was reported resulting in the replacement of
a section of pipe. In addition, as part of the Cape Fear Public Utility Authorities Capital Improvement Plan
the pump station located adjacent to the PC-BDUS site is scheduled for a capacity upgrade. Locally,
improvements to infrastructure has proven to decrease bacteria levels as seen in Motts Creek where over
time, the data has shown decreases in overall bacteria levels in that creek.
In July of 2024 the New Hanover County Soil and Water Conservation District with the assistance from
Moffatt & Nichol, completed the Pages Creek Restoration Plan. The plan outlines potential strategies to
help curb bacteria loading into the creek as well as help to reduce nutrient loading into the creek. The
restoration plan now allows for New Hanover County to partner with property owners and apply for
federal dollars to fund implementation projects installed on homeowners’ properties. The idea is to work
with the community and install retrofits that can mitigate non-point-source and point-source pollution
and impacts from stormwater and flooding.
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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APPENDIX D
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, Motts 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
Motts Creek Carolina Beach Road MOT-CBR 34° 08.610 77° 53.830
Motts Creek Normandy Drive MOT-ND 34° 08.373 77° 54.580
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, Motts 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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63
LITERATURE CITED
Byappanahalli MN, Shively DA, Nevers MB, Sadowsky MJ, Whitman RL. Growth and survival of Escherichia
coli and Enterococci populations in the macro-alga Cladophora (Chlorophyta). FEMS Microbiol Ecol.
2003;46(2):203–211.
Green HC, Haugland RA, Varma M, Millen HT, Borchardt MA, Field KG, Walters WA, Knight R, Sivaganesan
M, Kelty CA, Shanks OC. Improved HF183 quantitative real-time PCR assay for characterization of human
fecal pollution in ambient surface water samples. Appl Environ Microbiol. 2014 May;80(10):3086-94. doi:
10.1128/AEM.04137-13. Epub 2014 Mar 7. PMID: 24610857; PMCID: PMC4018914.
Grizzard, T.J., Randall, C.W., Helsel, D.R., and Hartigan, J.P. 1980. Analysis of non-point pollution export
from small catchments. Journal of Water Pollution Control Federation, 52: 780-790.
Howarth, R.W. and Marino, R. 2006. Nitrogen as the limiting nutrient for eutrophication in coastal marine
ecosystems: Evolving views over three decades. Limnology and Oceanography, 51: 364-376.
Kelsey, H., Porter, D.E, Scott, G., Neet, M., and White, D. 2004. Using geographic information systems and
regression analysis to evaluate relationships between land use and fecal coliform bacterial pollution.
Journal of Experimental Marine Biology and Ecology. 298:197-209.
Kwak, T.J. and Zedler, J.B. 1997. Food web analysis of southern California coastal wetlands using multiple
stable isotopes. Oecologia 110: 262–277.
Mallin, M.A., 2010. University of North Carolina at Wilmington, Aquatic Ecologist. Personal
communication regarding findings of water samples obtained within PG-NC.
Mallin, M.A., Ensign, S.H., McIver, M.R., Shank, G.C., and Fowler, P.K. 2001. Demographic, landscape, and
meteorological factors controlling the microbial pollution of coastal waters. Hydrobiologia. 460: 185-193.
Mallin, M.A.; Williams, K.E.; Esham, C.E.; and Lowe, P.R., 2000. Effect of human development on
bacteriological water quality in coastal watersheds. Ecological Applications 10:1047-1056.
Mallin, M.A., Matthew R. McIver, Anna R. Robuck and John D. Barker. 2014. Environmental Quality of
Wilmington And New Hanover County Watersheds. CMS Report 15-01. Center for Marine Science
University of North Carolina Wilmington. 92pp.
Meade, R., Yazyk, T. & Day, T. 1990. Movement and storage of sediment in rivers of the United States and
Canada. In: The Geology of North America, Woman, H. & Riggs, S. R. (Eds.).
Minnesota Pollution Control Agency, 2008. Nutrients: Phosphorus, Nitrogen Sources, Impact on Water
Quality - A General Overview Water Quality/Impaired Waters #3.22 website last accessed August 31,
2020. https://www.pca.state.mn.us/sites/default/files/wq-iw3-22.pdf
Mote BL, Turner JW, Lipp EK. Persistence and growth of the fecal indicator bacteria Enterococci in detritus
and natural estuarine plankton communities. Appl Environ Microbiol. 2012;78(8):2569–2577
NC Division of Commerce, Labor, Economic Data and Site Information. 2015. Thrive in North Carolina,
County Demographics Report. http://accessnc.commerce.state.nc.us/docs/countyProfile/NC/37129.pdf.
Last visited July 8, 2015.
Nshimyimana JP, Ekklesia E, Shanahan P, Chua LH, Thompson JR. Distribution and abundance of human-
specific Bacteroides and relation to traditional indicators in an urban tropical catchment. J Appl Microbiol.
2014 May;116(5):1369-83. doi: 10.1111/jam.12455. Epub 2014 Feb 25. PMID: 24460587; PMCID:
PMC4271309.
CPE
64
Odum, W.E., Smith, T.J., Hoover, J.K., and McIvor, C.C. 1984. The Ecology of Tidal Freshwater Marshes of
the United States East Coast: A Community Profile. U.S. Fish and Wildlife Service FWS/OBS-83/17, 177 pp.
Olivieri AW, Boehm AB, Sommers CA, Soller JA, Eisenberg JN, Danielson R. (2007). Development of a
protocol for risk assessment of separate stormwater system microorganisms. Alexandria: Water
Environment Research Foundation.
Ricks, C., 2011. Cape Fear Public Utility Authority. Personal communication regarding sewage spills in New
Hanover County.
U.S. Census Bureau, 2019. Quick facts: New Hanover County, NC.
https://www.census.gov/quickfacts/fact/table/newhanovercountynorthcarolina
U.S. Environmental Protection Agency. 1984. Health effects criteria for fresh recreational waters. EPA-
600/1-84-004, U.S. Environmental Protection Agency, Washington, D.C.
U.S. Environmental Protection Agency. 1986. Ambient Water Quality Criteria for Bacteria- 1986. EPA-
440/5/84-002, U.S. Environmental Protection Agency, Washington, D.C.