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Home My WebLink About2020-2021 Final ReportCPE-NC NEW HANOVER COUNTY WATER QUALITY MONITORING PROGRAM 2020-2021 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., 2021. New Hanover County Water Quality Monitoring Program: 2020- 2021 Final Report. New Hanover County, North Carolina: Coastal Protection Engineering of North Carolina, Inc. September 2021 CPE-NC i This report represents the results of the New Hanover County Water Quality Monitoring Program from July 2020 to June 2021. The results and long-term trends presented in this report are described from a watershed perspective. Since 2007 the county has worked with Coastal Protection Engineering of North Carolina to test water quality at nineteen (19) monitoring stations within seven (7) tidal creeks in New Hanover County. The creeks monitored include Barnards, Futch, Lords, Mott, Pages, Prince George, and Smith. Each creek is monitored monthly for physical, chemical, and biological characteristics that depict the overall quality of the water. In addition to the raw sampling results, a general assessment of the water quality is provided for each watershed. The general assessment gives each parameter the rating of either “Good”, “Fair”, or “Poor” depending on the percentage of samples that went above the State standard for turbidity, chlorophyll-a, and Enterococci, or below the State standard for dissolved oxygen. If the recorded value of a parameter went outside the acceptable range of the State standard less than 10% of the times sampled the watershed will receive a “Good” rating, a “Fair” rating 11%-25% of the times sampled, or a “Poor” rating for greater than 25% of the sampling times. Ratings by watershed during the 2020-2021 reporting period Parameter Barnards Creek Futch Creek Lords Creek Mott Creek Pages Creek Prince George Creek Smith Creek Turbidity GOOD GOOD GOOD GOOD GOOD GOOD GOOD Dissolved Oxygen GOOD GOOD GOOD GOOD FAIR POOR GOOD Chlorophyll-a GOOD GOOD GOOD GOOD GOOD GOOD GOOD Enterococci GOOD GOOD GOOD FAIR POOR FAIR GOOD Long Term Trends Dissolved oxygen, turbidity, and chlorophyll-a levels fluctuate on a seasonal basis where levels decrease in the winter and increase in the summer. Generally, dissolved oxygen levels have not changed drastically from year to year and there has been minimal issues with low dissolved oxygen levels with the exception of Prince George Creek where levels in the creek have been consistently low over time. This is due to Prince George Creek’s water flow, which is naturally slow and acts more like swamp-like waters. Slower moving waters are typical of having lower dissolved oxygen levels. Likewise, in general, turbidity and chlorophyll-a levels over time have not been of concern. Overall, Enterococci bacteria levels during the 2020-2021 sampling for the majority of the watersheds remained the same or were slightly lower than last year, with the exception of Pages Creek and Prince George Creek which saw increases. Enterococci bacteria has had a history of elevated levels that have been of carefully monitored over the years within several of the creeks including Mott, Pages, Barnards, Smith, and Prince George. Lords Creek and Futch Creek, on average, have contained relatively lower bacteria levels compared to the other creeks. In addition to monitoring the seven tidal creeks, New Hanover County in 2015 began monthly testing at the lake at Airlie Gardens due to concerns of water quality and noticeable algal blooms that had occurred over the years. The lake drains directly into Bradley Creek close to the Intracoastal Waterway. There are three sampling sites, one where contributing water enters the lake (intake), one in the middle of the lake, and one at the outfall before the water enters Bradley Creek. CPE-NC ii Since 2015 water quality monitoring has shown that dissolved oxygen varies significantly over an annual basis, increasing during the warmer summer months and decreasing during the colder winter months. Overall, there are no current concerns with the dissolved oxygen levels. Over past 7 years, the levels of the nutrient orthophosphate as well as Nitrite/Nitrate has generally been higher at the intake compared to the sampling sites located at the middle of the lake and at the outfall. High concentrations of orthophosphate and Nitrite/Nitrate has been linked to algae growth leading to algae blooms which can cause issues leading to low dissolved oxygen and a decline in overall water quality. Levels of orthophosphate have incrementally increased over the past six years while Nitrate/Nitrite levels have remained relatively stable. Chlorophyll-a levels can also indicate the presence of algal blooms. In recent years levels have increased at the middle of the lake and the outfall and compared to the sampling location in proximity to the intake into the lake. Improvement Efforts In addition to continued monitoring there have been efforts from New Hanover County to improve overall water quality including the purchasing of property with Clear Water Management Trust Funds, working with the Cape Fear Public Utility Authority to test sewer infrastructure, install stormwater BMPs (Best Manage Practices like raingardens, infiltration basins, and impervious surface retrofits), as well as perform additional source tracking. In 2008 New Hanover County partnered with University of North Carolina Wilmington’s Center for Marine Science and Coastal Protection Engineering NC Inc. to conduct an initial DNA source tracking study to identify the origin of the bacteria in Pages Creek. The study showed that the water sampled tested positive for a human source suggesting that the bacteria in the creek was coming from nearby wastewater systems such as septic tanks and/or the municipal sewer system. Following the report, NHC Planning & Land Use partnered with the Cape Fear Public Utility Authority and the NHC Health Department to search for leaking septic or sewer, however, that investigation did not find the source for contamination. In 2013 the County partnered with UNC-Chapel Hill to conduct an extensive study into the source of enterococci bacteria in Mott, Smith and Pages creeks. That study did find the presence of a human signature in the bacteria for all three creeks, with Smith and Pages having the higher counts. In 2019 New Hanover County partnered with the University of North Carolina Wilmington’s Socio- Environmental Analysis Laboratory and Coastal Protection Engineering of North Carolina to conduct a thermal imagery scan of two portions of Pages Creek adjacent to monitoring sites that have consistently detected elevated levels of Enterococci bacteria in an attempt identify any possible sources of bacteria entering the creek. The thermal study consisted of utilizing a thermal sensor (thermal camera) attached to a fixed wing drone. The thermal sensor was flown following a rain event in January of 2021 in order to detect differences in temperature both above and below ground to show anywhere where there maybe uncommon warm spots or patterns that would normally be cold. Following the flight, UNCW and CPE analyzed the imagery to identify uncommon differences in temperature that may be a possible target or areas that may need follow up investigation. The full report from UNCW of the thermal study and a summary from CPE are found in Appendix D and E of this report. Most recently, staff has worked with CPE to perform additional water quality testing in two areas where the thermal imagery showed peculiar temperature differences. Groundtruthing these sites revealed CPE-NC iii several subterranean seeps entering the creek from the streambank. That testing indicated there was Enterococci bacteria in water coming from the seeps in proximity of the two sewage lift stations adjacent to the long-term monitoring sites at Pages Creek. More samples and PCR tracing will be needed in order to make a definitive determination as to whether that ground water contains bacteria and if the bacteria is from a human source. Airlie Gardens To help combat problems associated with 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, 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. Monitoring data from this past year has not shown a reduction on nutrient loading into the lake. It may take a couple to several years for a data trend to emerge. It is recommended to continue to monitor the lake to gauge the status of the lake and the effectiveness of the implemented projects. Program Expansion For this upcoming year, a new watershed and testing site have been added to the program. Island Creek located in the norther portion of the county is segmented by Sidbury Road and is largely undeveloped. The testing site proposed at a culvert that runs under Sidbury Road will provide a baseline for the water quality data in the watershed. The baseline data will be necessary in in order to establish trends as the area is anticipated to develop over time. CPE-NC EXECUTIVE SUMMARY ....................................................................................................................... I INTRODUCTION .................................................................................................................................1 CREEK SUMMARIES ............................................................................................................................3 BARNARDS CREEK .......................................................................................................................................... 3 FUTCH CREEK ................................................................................................................................................ 4 LORDS CREEK ................................................................................................................................................ 5 MOTT CREEK ................................................................................................................................................ 6 PAGES CREEK ................................................................................................................................................ 7 PRINCE GEORGE CREEK .................................................................................................................................. 8 SMITH CREEK ................................................................................................................................................ 9 AIRLIE GARDENS .......................................................................................................................................... 10 DISCUSSION ..................................................................................................................................... 11 PARAMETERS .............................................................................................................................................. 12 AIRLIE GARDENS DISCUSSION ........................................................................................................................ 15 APPENDIX A: ADDITIONAL CREEK DATA ............................................................................................ 16 BARNARDS CREEK ........................................................................................................................................ 16 FUTCH CREEK .............................................................................................................................................. 19 LORDS CREEK .............................................................................................................................................. 24 MOTT CREEK .............................................................................................................................................. 27 PAGES CREEK .............................................................................................................................................. 30 PRINCE GEORGE .......................................................................................................................................... 34 SMITH CREEK .............................................................................................................................................. 38 AIRLIE GARDENS .......................................................................................................................................... 43 APPENDIX B: LONG TERM TRENDS .................................................................................................... 48 DISSOLVED OXYGEN ..................................................................................................................................... 48 TURBIDITY .................................................................................................................................................. 48 CHLOROPHYLL-A .......................................................................................................................................... 49 ENTEROCOCCI ............................................................................................................................................. 50 APPENDIX C ..................................................................................................................................... 52 WATER CLASSIFICATIONS .............................................................................................................................. 52 PARAMETERS .............................................................................................................................................. 52 STANDARDS ................................................................................................................................................ 55 METHODS .................................................................................................................................................. 58 APPENDIX D: PAGES CREEK THERMAL STUDY SUMMARY .................................................................. 59 APPENDIX E: UNCW PAGES CREEK THERMAL SURVEY PROJECT REPORT ............................................ 75 LITERATURE CITED ........................................................................................................................... 84 CPE-NC 1 New Hanover County’s (NHC) location is unique as it is surrounded by water on three sides by the Cape Fear River, Northeast Cape Fear River and the Atlantic Ocean. It is a coastal county containing many creeks, streams, and water bodies that provide a wide range of recreational activities for thousands of local citizens and visiting tourists each year. 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 habitat 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). 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 to water quality in tidal creeks from adjacent septic systems. An increase in the closure of tidal creeks for shellfishing became an early concern of the citizens of New Hanover County and was a topic included in early land use plans. The ongoing water quality conversation within the community lead to a number of watershed plans which led to a county/city water quality monitoring program. In 1993, New Hanover County and the City of Wilmington partnered with the University of North Carolina Wilmington to conduct a long-standing water quality monitoring program. In 2007, New Hanover County began a separate water quality monitoring program focused on water quality in the tidal creeks within just the unincorporated portion of the County. Coastal Protection Engineering of North Carolina, Inc. (CPE) began monitoring seven (7) tidal creeks within New Hanover County monthly starting in November 2007. The information presented in this report focuses on the results of this monitoring from July 2020 to June 2021. The creeks included in this study are Pages and Futch, which drain into the Atlantic Intracoastal Waterway (ICW) and Lords, Mott, Barnards, Smith, and Prince George, which drain into the Cape Fear River (Figure 1). In addition to the continued sampling from the seven tidal creeks, three sampling sites from within Airlie Gardens were added to the program during the 2015-2016 sampling efforts. The results described in this report represent the physical, biological, and chemical data collected from all sampling sites monthly from July 2020 through June 2021. These results are organized by watershed alphabetically with the results of the seven (7) tidal creeks presented first followed by the results from Airlie Gardens. All raw data, including parameters not summarized in this section, from the tidal creeks sampling sites and the Airlie Garden sampling sites are found in Appendixes A, B, and C. In addition to the raw data, a quick-glance assessment of the water quality within a particular sampling station or watershed has been created to give a general rating for a parameter. This 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 Appendix A of this report. CPE-NC 2 Figure 1: Watersheds Monitored CPE-NC 3 Barnards Creek • Location: South central New Hanover County and a portion in the City of Wilmington. (Monkey Junction, Echo Farms, Carriage Hills). • 1 Sampling Location: BC-CBR • Size: 4,234 Acres • Drains To: Cape Fear River • Land Use: Low and medium density residential, commercial, and retail uses along Carolina Beach Road, S. 17th Street, and S. College Road Year at a Glance • 1 (one) occurrence of dissolved oxygen below State standard • 0 (zero) occurrences above State standard for chlorophyll-a • 0 (zero) occurrences above State standard for turbidity • 0 (zero) occurrences above State standards for Enterococci Overall Assessment Overall, there were no issues with Barnards Creek for the year. However, dissolved oxygen did drop below the State standard one time during July. Parameter BC-CBR Turbidity (NTU) Good Dissolved Oxygen Good Chlorophyll-a Good Enterococci Good CPE-NC 4 Futch Creek • Location: Northeast New Hanover County and a portion of Pender County (Porters Neck, Scotts Hill). • 4 Sampling Locations: FC-4, FC-6, FC-13, FC-FOY • Size: 3,429 Acres • Drains To: Intracoastal Waterway • Land Use: Low density residential and some commercial/retail uses along U.S. 17. Year at a Glance • 0 (zero) occurrences of dissolved oxygen below State standard • 0 (zero) occurrences above State standard for chlorophyll-a • 0 (zero) occurrences above State standard for turbidity • 0 (zero) occurrences above State standards for Enterococci Overall Assessment Overall, there were no issues with Futch Creek for the year. In fact, not one sample exceeded the standards for turbidity, dissolved oxygen, Chlorophyll-a, or Enterococci during the study period. Parameter FC-4, FC-6, FC-13, FC-FOY Turbidity (NTU) Good Dissolved Oxygen Good Chlorophyll-a Good Enterococci Good CPE-NC 5 Lords Creek • Location: Southwest New Hanover County (Veterans Park, River Road). • 1 Sampling Location: LC-RR • Size: 1,076 Acres • Drains To: Cape Fear River • Land Use: Low density residential and commercial/retail uses along Carolina Beach Road. Year at a Glance • 0 (zero) occurrences of dissolved oxygen below State standard • 0 (zero) occurrences above State standard for chlorophyll-a • 0 (zero occurrences above State standard for turbidity • 0 (zero) occurrences above State standards for Enterococci Overall Assessment Overall, there were no issues with Lords Creek for the year. However, Dissolved Oxygen from August to November were noticeably lower than the rest of the year. Additionally, there was one spikes of Enterococci bacteria in August but was well below the State standard. Parameter LC-RR Turbidity (NTU) Good Dissolved Oxygen Good Chlorophyll-a Good Enterococci Good CPE-NC 6 3 Mott Creek • Location: South central New Hanover County (Monkey Junction, Silver Lake, Piner Road). • 2 Sampling Locations: MOT-ND, MOT- CBR • Size: 2,906 Acres • Drains To: Cape Fear River • Land Use: Low to Moderate density residential with commercial and retail along Carolina Beach Road and S. College Road. Year at a Glance • 0 (zero) occurrences of dissolved oxygen below State standard • 1 (one) occurrence above State standard for chlorophyll-a • 1 (one) occurrence above State standard for turbidity • 3 (three) occurrences above State standards for Enterococci Overall Assessment Overall, there was little concern with Mott Creek for the year. While Enterococci levels have decreased over the years, there were three exceedances at the Normandy Drive site (MOT-ND). Parameter MOT-CBR, MOT-ND Turbidity (NTU) Good Dissolved Oxygen Good Chlorophyll-a Good Enterococci Good, Fair CPE-NC 7 Pages Creek • Location: Norteastern New Hanover County. (Middle Sound, Ogden, Porters Neck). • 3 Sampling Locations: PC-BDUS, PC- BDDS, PC-M • Size: 4,124 Acres • Drains To: Intracoastal Waterway Land Use: Low density residential and some commercial/retail uses along U.S. 17. Year at a Glance • 9 (nine) occurrences of dissolved oxygen below State standard. • 0 (zero) occurrences above State standard for chlorophyll-a • 0 (zero occurrences above State standard for turbidity • 13 (thirteen) occurrences above State standards for Enterococci • The Pages Creek Thermal Imagery Study was completed this year. Please see Appendix D and E for the related reports. Overall Assessment Dissolved Oxygen levels were below state standards a few times throughout the year at all sites while Enterococci levels remained elevated at the upstream and down stream sites. Parameter PC-BDDS, PC-BDUS, PC-M Turbidity (NTU) Good Dissolved Oxygen Poor, Fair, Fair Chlorophyll-a Good Enterococci Poor, Poor, Good CPE-NC 8 Prince George Creek • Location: North New Hanover County (Castle Hayne). • 4 Sampling Locations: PG-CH, PG-ML, PG-NC • Size: 10,875 Acres • Drains To: Northeast Cape Fear River Land Use: Low density residential, agricultural, and some commercial/retail uses Castle Hayne Road and N. College Road. Year at a Glance • 20 (twenty) occurrences of dissolved oxygen below State standard • 0 (zero) occurrences above State standard for chlorophyll-a • 0 (zero) occurrences above State standard for turbidity • 5 (five) occurrences above State standards for Enterococci Overall Assessment Dissolved Oxygen at all sites were below state standards throughout the year with the most at the North College site (10). There were also 5 exceedances of state standards for Enterococci during the summer months spread across all sites. Parameter PG-CH, PG-ML, PG-NC Turbidity (NTU) Good Dissolved Oxygen Fair, Fair, Poor Chlorophyll-a Good Enterococci Fair, Fair, Good CPE-NC 9 Smith Creek • Location: Central New Hanover County including portions of City of Wilmington (Wrightsboro, ILM, Kings Grant, Coastal Carolina). • 5 Sampling Locations: SC-CH, SC-23, SC- NK, SC-GR, SC-CD • Size: 17,535 Acres • Drains To: Cape Fear River Land Use: Moderate density residential within the city, light industrial around the airport, some agricultural along Kerr Avenue, and some commercial/retail uses along U.S. 17. Year at a Glance • 0 (zero) occurrences of dissolved oxygen below State standard • 0 (zero) occurrences above State standard for chlorophyll-a • 0 (zero) occurrences above State standard for turbidity • 6 (six) occurrences above State standards for Enterococci Overall Assessment Overall, there were no concerns with Smith Creek for the year. However, Enterococci bacteria did exceed state standards six (6) times across 5 of the 6 sites. Parameter SC-CH, SC-23, SC-NK, SC-GR, SC-CD Turbidity (NTU) Good Dissolved Oxygen Good Chlorophyll-a Good Enterococci Good, Fair, Good, Fair, Good CPE-NC 10 Airlie Gardens • Location: City of Wilmington. • 4 Sampling Locations: AC-IN, AC-AD, AC- OUT • Size: 10 Acre Freshwater Lake • Drains To: Bradley Creek Land Use: On a conservation site surrounded by low density residential. Year at a Glance • 0 (zero) occurrences of dissolved oxygen below State standard • 13 (thirteen) occurrences above State standard for chlorophyll-a • 1 (one) occurrence above State standard for turbidity *Enterococci is not measured at Airlie Gardens Overall Assessment Overall, the lake has had no issue with dissolved oxygen or turbidity. However, Chlorophyll-a, Nitrate/Nitrite, and orthophosphate levels have shown to be increasing over the years. While recent projects were completed in the lake to improve water quality it make take several years for a trend to emerge based on the improvements. It is recommended to continue monitoring the lake for those trends. CPE-NC 11 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. One of the greatest threats to water quality in this area that experts have identified is stormwater runoff created by increased impervious surface coverage (Mallin et al., 2000). Due to many of the contaminants found in stormwater runoff, adverse effects can be imposed upon plants, fish, animals, and people. Excess nutrients can cause algal blooms while bacteria and other pathogens can wash into swimming areas and create health hazards. New Hanover County has experienced rapid growth and development over the past several decades. In 1990, the population within the County was 120,284. By 2006, the population grew over 50% to 182,591 (U.S. Census Bureau, 2006). Furthermore, the County’s population as of July 2014 was 216,995 and was 234,473 as of July 2019 (U.S. Census Bureau, 2019), which reflects a growth rate of 8.0% over that five- year time period. Along with this population growth came increased stormwater runoff, aging wastewater infrastructure, and other issues that potentially impacted the water quality within the County’s creeks. Over the course of decades of rapid growth, New Hanover County’s water quality within its tidal creeks has become altered. Despite the continuation of development and its associated increase of impervious surface within the County, the ratings for many water quality parameters as depicted in this report have improved over the past several years. While there are no clearly identifiable factors that may be facilitating this trend, several notable efforts maybe contributing to these improvements. In 2017, the Cape Fear Public Utility Authority (CFPUA) completed work to provide the Marquis Hills subdivision within the Mott Creek watershed with sewer service providing a more reliable way to treat sewage. Additionally, the CFPUA through their capital improvement plan, identifies and prioritizes projects to upgrade aging infrastructure like pumpstations, and programs like “Find it and Fix it” to maintain the integrity of the sewer system. The County, meanwhile, continues to work toward preventing further deterioration and loss of public uses in surface water through initiatives such as the implementation of best management practices (BMPs) and promoting low impact development. With this in mind, it is important to monitor the water quality of these local systems to determine potential impacts to both human health and ecosystem function. The long-term water quality monitoring results suggest that the seven (7) creeks have experienced good water quality in terms of turbidity and chlorophyll-a levels over the course of the twelve (12) year study thus far. The one parameter, however, that has been problematic has been Enterococci bacteria. Of the 2,967 samples collected and analyzed since June 2008, 705 samples (24% of all samples) have exceeded the State standard for this bacteria. CPE-NC 12 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 bacteria. At the Airlie Gardens sampling locations, the same physical parameters were collected in addition to chemical parameters including orthophosphate and nitrate/nitrite. It was determined at that time that bacterial contamination was non problematic, Enterococci samples are not collected at Airlie Gardens. Physical Parameter Discussion Over the past twelve years of water quality monitoring within these seven (7) creeks, some trends have emerged. Typically, water quality degrades as the water temperature increases and oxygen is not as readily dissolved in the water column. This phenomenon has been observed while investigating the long- term trends of water quality in this study. The dissolved oxygen along with chlorophyll-a and turbidity levels generally increased during the warmer summer months. The longer summer days allow for increased photosynthetic activity that, as a result, allows for an increase in phytoplankton blooms. While often problematic in the summer months, algal blooms are less common in the fall and winter when water temperature decreases. High levels of chlorophyll-a and nutrients along with increases in pH and turbidity may indicate the presence of an algal bloom. Throughout the course of this study, pH values and turbidity measurements were generally found to be within acceptable ranges while only one (1) chlorophyll-a sample exceeded the State standard during the 2020-2021 study period. Overall Watershed Rating In general, the dissolved oxygen within Barnards Creek, Lords Creek, Mott Creek, and Smith Creek has been rated “Good” through the course of this long-term study with few exceptions. Barnards Creek had declined in term of dissolved oxygen in recent years, however it improved to “Good” again over the past four (4) years. Futch Creek has maintained a “Fair” rating for nine (9) of the twelve (12) years, however improved to "Good" during the 2020-2021 study period. Pages Creek has demonstrated varying dissolved oxygen levels over time ranging from “Poor” to “Good” over the years. Prince George Creek has demonstrated the worst long-term dissolved oxygen levels compared to the other creeks in the study as it has been designated as “Poor” ten (11) of the twelve (12) years. Of the 22 samples that fell below the standard for dissolved oxygen during the 2019-2020 study period, thirteen (13), or 59%, were observed during June, July, and August when water temperatures were the highest. 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. The most notable change with respect to dissolved oxygen occurred within Futch Creek where not a single sample fell below the standard during the 2020-2021 study period. Biological Parameter Discussion While several creeks have exhibited relatively low levels of bacteria throughout the lifetime of the program (namely Futch Creek and Lords Creek), other creeks have proven to show elevated levels of Enterococci. Of the 2,967 samples collected and analyzed from all of the monitoring sites since June 2008, 705 samples (24% of all samples) have exceeded the State standard for this bacteria. Specifically, Mott CPE-NC 13 Creek has exceeded the standard 41% of the time and PC-BDDS and PC-BDUS within Pages Creek have exceeded the standard 44% and 61% of the time, respectively. During last year's study period (2019-2020), the collective bacteria levels within the creeks were observed to be much less than what had been noted during previous years including from within Mott and Pages creeks. During the 2020-2021 study period, the bacterial levels increased within several creeks. No samples collected from within three creeks (Lords Creek, Futch Creek, Barnard Creek) exceeded the State Enterococci standard. At Smith Creek, Mott Creek, and Prince George Creek, the standard was exceeded 10%, 13%, and 14% of the time during the study period respectively. Pages Creek continued to show elevated levels of Enterococci where thirteen (13) out of 36 samples (36%) exceeded the State standard. None of the samples collected from the site at the mouth of Pages Creek (PC-M) exceeded the standard. Of the thirteen (13) samples that exceeded the standard, eight (8) were from the Pages Creek up-stream site (PC-BDUS) and five (5) were from the down-stream sampling site (PC-BDDS). Of the nineteen (19) sites included in this program, the site PC-BDUS has exhibited the highest rate of Enterococci above state standards. This station, located at the boat ramp in the Bayshore community within the Pages Creek watershed, has exceeded the standard 61% of the time. In 2008 and 2013 source tracking studies was performed identifying a human signature in the bacteria that was present in the waters at the PC-BDUS site within Pages Creek. In coordination, the New Hanover County Health Department, and the Cape Fear Public Utility Authority, investigated abandon septic systems and conducted inspections of sewer infrastructure to determine if those were a contributing factor to the elevated bacteria levels. These investigations did not reveal any deficiencies. More recently in 2019, New Hanover County partnered with the University of North Carolina Wilmington’s Socio- Environmental Analysis Laboratory and Coastal Protection Engineering of North Carolina to conduct a thermal imagery scan of two portions of Pages Creek in an attempt identify any possible sources of bacteria entering the creek. Staff is currently working with CPE to continue to investigate and perform additional water quality testing in two areas where the thermal imagery showed peculiar temperature differences. The full report from UNCW of the thermal study and a summary from CPE are found in Appendix D and E of this report. It should be noted that regular boating activity in the vicinity of the boat ramp facilitates the resuspension of bottom sediments. Studies have implicated streambed sediment and its resuspension as sources and principal transport vectors for bacteria (Meade et al. 1990). Bottom sediment, including those in brackish waters, may act as a reservoir for prolonging Enterococci survival due to the resuspension of sediments and could be contributing to the overall levels of bacteria in the creek. At Mott Creek, the bacteria levels continue to improve; similar to the results observed during the 2019- 2020 study period, only three (3) samples were above the state standard during the 2019-2020 study period compared to six (6) during the two previous study periods. Prior to the 2016-2017 sampling effort, Mott Creek had consistently demonstrated “Poor” water quality in terms of bacterial contamination. As mentioned above, the CFPUA installed a centralized sewer system in the Marquis Hills community (located within the Mott Creek watershed) several years ago and septic tanks have been removed. Additionally, the main force main pumpstation is scheduled to be replaced in the watershed and together could lead to further improvements in overall water quality. CPE-NC 14 Overall Watershed Rating The long-term trends for Enterococci ratings over the past twelve (12) years have shown that Mott Creek, Pages Creek, and Prince George Creek maintained “Poor” ratings during much of the time; however, over the past two years these three creeks have demonstrated some improvements. Mott Creek, which was deemed “Poor” between 2008 and 2016, has improved to “Fair” over the past five (5) study periods. The most noted improvement has been within Smith Creek where it was rated as "Good" for Enterococci levels over the past three (3) years whereas previous years it contained either "Poor" or "Fair" levels. Barnards Creek, Lords Creek, and Prince George Creek have demonstrated varying conditions since sampling was first initiated. Futch Creek, meanwhile, has consistently maintained a “Good” rating, with two exceptions when it was deemed “Fair”. CPE-NC 15 Airlie Gardens Discussion The results from monthly sampling over the past seven (7) years have provided some insight into the water quality within the lake. There are no State or federal standards for nutrients including the two monitored within Airlie Gardens (orthophosphate and nitrate/nitrite). That said, the levels of orthophosphate and nitrate/nitrite observed within the three (3) sites in Airlie Gardens were generally low. However, generally speaking, since 2015-2016 at the AG-IN site, nitrate/nitrite levels have been relatively higher on average compared to the other two sites further south and closer to the outfall and orthophosphate has been steadily increasing over time across all sites. Over the past seven (7) years of sampling, the orthophosphate level within AG-IN has have averaged 0.05 mg/l while AG-FD and AG-OUT have averaged 0.05mg/l and 0.04 mg/l, respectively. Nitrite/Nitrate levels have been 0.06 mg/l at AG-IN while AG-FD and AG-OUT averaged 0.03 mg/l and 0.02 mg/l respectively. This suggests that the nutrient-rich stormwater runoff delivered to the lake at AG-IN are ultimately taken up by aquatic plants and macroalgae within the lake. Phosphorus is a particularly vital nutrient for converting sunlight into usable energy, and essential to cellular growth and reproduction. Under natural conditions phosphorus is typically scarce in water. In the late 1960s scientists discovered phosphorus contributed by human activity to be a major cause of excessive algae growth and degraded lake water quality (MPCA, 2008). The process involving an increase of nutrient loading to a waterbody, called eutrophication, can lead to algae blooms. As the vegetation dies off and the plant matter decomposes, bacteria take up the oxygen in the water column, which can be harmful to fish and other aquatic life. To help combat problems associated with this eutrophication and overall water quality, Airlie Gardens has implemented initiatives identified in their stormwater master plan. These initiatives include installing several aerators in the lake to increase the dissolved oxygen levels. In addition, the tributary that delivers stormwater runoff into the lake just upstream from the AG-IN sampling location was restored in early 2019 which included the planting of native Cypress and the installation of an engineered wetland BMP. In 2020 the County completed a dredging operation by excavating 5' deep by 10' wide channels in the lake, effectively removing approximately 4,000 cubic yards of bottom sediment and material. The removal of the nutrient-laden sediments will ideally result in decreased levels of orthophosphate and nitrate/nitrite within the water column which should result in a reduction of algal blooms thereby helping to maintain appropriate levels of dissolved oxygen. Since these implementation projects were recently completed, the monitoring data has not shown a reduction on nutrient loading into the lake, but it may take a couple to several years to see a trend emerge. It is recommended to continue to monitor the lake to gauge the status of the lake and the effectiveness of the implemented projects. CPE-NC 16 Barnards Creek Sampling was conducted at one site (BC-CBR) within the Barnards Creek watershed (Figure 2). Dissolved oxygen within BC-CBR ranged between 2.5 mg/l and 9.7 mg/l with a mean value of 6.1 mg/l (Table 1). One (1) sample contained dissolved oxygen levels below the State standard of 4.0 mg/l for C Sw waters at the surface (Figure 3). Chlorophyll-a ranged between 1.0 ug/l and 10.0 ug/l with a mean value of 3.0 ug/l at BC-CBR(Table 1). These values did not approach the 40 ug/l standard. Enterococci ranged between 5 CFU/100 ml and 173 CFU/100 ml with a geometric mean value of 52 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 21 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 CPE-NC 17 Table 1. Mean values of select parameters from Barnards Creek. Range in parentheses. Parameter BC-CBR Turbidity (NTU) 7 (1-21) Dissolved Oxygen (mg/l) 6.1 (2.5-9.7) Chlorophyll-a (ug/l) 3 (1-10) Enterococci (#CFU/100ml) 52 (5-173) (1) Enterococci values expressed as geometric mean Figure 3. Dissolved Oxygen at BC-CBR at surface (DO-S) and bottom (DO-B) Figure 4. Enterococci at BC-CB CPE-NC 18 Table 2. Ratings of parameters within sampling stations within Barnards Creek Parameter BC-CBR Turbidity GOOD Dissolved Oxygen GOOD Chlorophyll-a GOOD Enterococci GOOD CPE-NC 19 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 4.9 mg/l and 11.4 mg/l with a mean value of 6.1 mg/l (Figure 6 – Figure 9, Table 3). No samples contained dissolved oxygen levels below the State standard of 5.0 mg/l for SA water Chlorophyll-a ranged between 1.0 ug/l and 6.0 ug/l with a mean value of 3.0 ug/l (Table 3). None of these values approached the 40ug/l chlorophyll-a standard. Enterococci ranged between 1 CFU/100ml and 249 CFU/100ml with a geometric mean value of 10 CFU/100ml. No samples collected within Futch Creek during exceeded the NCDEQ Enterococci standard of 500 CFU/100 ml for Tier III waters (Figure 10 – Figure 13, Table 3). Turbidity values were generally low ranging between 0 and 31 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 CPE-NC 20 Table 3. Mean values of select parameters from Futch Creek. Range in parentheses. Parameter FC-4 FC-6 FC-13 FC-FOY Turbidity (NTU) 4 (1-10) 5 (0-28) 6 (0-28) 6 (1-31) Dissolved Oxygen (mg/l) 7.7 (5.5-9.3) 7.6 (5.4-9.1) 7.7 (5.1-11.4) 7.5 (4.9-9.2) Chlorophyll-a (ug/l) 3 (1-5) 2 (1-5) 3 (1-6) 3 (1-5) Enterococci (#CFU/100ml) 9 (1-67)1 7 (1-91)1 18 (1-122)1 13 (1-249)1 (1)Enterococci values expressed as geometric mean Figure 6. Dissolved Oxygen at FC-4 at surface (DO-S) and bottom (DO-B) Figure 7. Dissolved Oxygen at FC-6 at surface (DO-S) and bottom (DO-B) CPE-NC 21 Figure 8. Dissolved Oxygen at FC-13 at surface (DO-S) and bottom (DO-B) Figure 9. Dissolved Oxygen at FC-FOY at surface (DO-S) and bottom (DO-B) Figure 10. Enterococci at FC-4 CPE-NC 22 Figure 11. Enterococci at FC-6 Figure 12. Enterococci at FC-13 Figure 13. Enterococci at FC-FOY CPE-NC 23 Table 4. Ratings of parameters within sampling stations within Futch Creek Parameter FC-4 FC-6 FC-13 FC-FOY Turbidity GOOD GOOD GOOD GOOD Dissolved Oxygen GOOD GOOD GOOD GOOD Chlorophyll-a GOOD GOOD GOOD GOOD Enterococci GOOD GOOD GOOD GOOD CPE-NC 24 Lords Creek Sampling was conducted at one (1) site (LC-RR) within the Lords Creek watershed (Figure 14). Dissolved oxygen at LC-RR ranged between 4.2 mg/l and 10.5 mg/l with a mean value of 7.5 mg/l (Table 5). No samples were below the State standard of 4.0 mg/l for C Sw waters during the sampling period (Figure 15). Chlorophyll-a ranged between 2 ug/l and 29 ug/l with a mean value of 10 ug/l (Table 5). No samples exceeded the State standard of 40 ug/l for chlorophyll-a. Enterococci ranged between 5 CFU/100ml and 225 CFU/100ml with a geometric mean value of 20 CFU/100ml (Table 5). None of the twelve (12) samples collected over this reporting period contained high levels of Enterococci beyond the NCDEQ standard of 500 CFU/100 ml for Tier III waters. Turbidity values were generally moderate ranging between 5 and 20 NTU with a mean value of 12 NTU (Table 5). No samples exceeded the State standard of 50 NTU for C Sw waters in Lords Creek during the reporting period. Table 6 depicts the ratings for these parameters for the watershed. Figure 14. Water Quality Site within the Lords Creek Watershed CPE-NC 25 Table 5. Mean values of select parameters from Lords Creek. Range in parentheses. Parameter LC-RR Turbidity (NTU) 12 (5-20) Dissolved Oxygen (mg/l) 7.5 (4.2-10.5) Chlorophyll-a (ug/l) 10 (2-29) Enterococci (#CFU/100ml) 20 (5-225)1 (1)Enterococci values expressed as geometric mean Figure 15. Dissolved Oxygen at LC-RR at surface (DO-S) and bottom (DO-B) Figure 16. Enterococci Levels at LC-RR CPE-NC 26 Table 6. Ratings of parameters within sampling stations within Lords Creek Parameter LC-RR Turbidity GOOD Dissolved Oxygen GOOD Chlorophyll-a GOOD Enterococci GOOD CPE-NC 27 Mott Creek Sampling was conducted at two (2) sites (MOT-CBR, MOT-ND) within the Mott Creek watershed (Figure 17). Dissolved oxygen within Mott Creek ranged between 3.4 mg/l and 10.0 mg/l with a mean value of 7.3 mg/l (Figure 18 and Figure 19, Table 7). One (1) sample collected during the reporting period contained dissolved oxygen levels below the standard (Figure 18 and Figure 19). Chlorophyll-a ranged between 1 ug/l and 107 ug/l with a mean value of 10 ug/l (Table 7). One sample exceeded the 40ug/l standard. Enterococci ranged between 20 CFU/100ml and 1,050 CFU/100ml with a geometric mean value of 136 CFU/100 ml (Table 7). Samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III waters during three (3) sampling events during the reporting period (Figure 18 and Figure 19). Turbidity values were generally good ranging between 3 and 18 NTU with a mean value of 8 NTU (Table 7). No turbidity observations exceeded the State standard of 50 NTU for C Sw waters. Table 8 depicts the ratings for these parameters for the watershed. Figure 17. Water Quality Sites within the Mott Creek Watershed CPE-NC 28 Table 7. Mean values of select parameters from Mott Creek. Range in parentheses. Parameter MOT-CBR MOT-ND Turbidity (NTU) 7 (3-14 10 (4-18) Dissolved Oxygen (mg/l) 6.8 (3.4-9.9) 7.8 (5.8-10.0) Chlorophyll-a (ug/l) 4 (1-5) 14 (1-107) Enterococci (#CFU/100ml) 101 (20-399)1 184 (20-1,050)1 (1)Enterococci values expressed as geometric mean Figure 18. Dissolved Oxygen at MOT-CBR at surface (DO-S) Figure 19. Dissolved Oxygen at MOT-ND at surface (DO-S) CPE-NC 29 Figure 20. Enterococci at MOT-CBR Figure 21. Enterococci at MOT-ND Table 8. Ratings of parameters within sampling stations within Mott Creek Parameter MOT-CBR MOT-ND Turbidity GOOD GOOD Dissolved Oxygen GOOD GOOD Chlorophyll-a GOOD GOOD Enterococci GOOD FAIR CPE-NC 30 Pages Creek Sampling was conducted at three (3) sites (PC-BDDS, PC-BDUS, and PC-M) within the Pages Creek watershed (Figure 22). Dissolved oxygen within Pages Creek ranged between 1.2 mg/l and 12.8 mg/l with a mean value of 6.5 mg/ (Figure 23 through Figure 25, Table 9). Of the three (3) sites monitored over the twelve (12) month study, the dissolved oxygen levels were below the State standard four (4) times at PC-BDDS, three (3) times at PC-BDUS, and two (2) times at PC-M. Chlorophyll-a ranged between 1 ug/l and 34 ug/l with a mean value of 4 ug/l (Table 9). No samples exceeded the State standard of 40 ug/l for chlorophyll-a. Enterococci ranged between 1 CFU/100 ml and 5,480 CFU/100 ml with a geometric mean value of 84 CFU/100 ml (Figure 26 – Figure 28), Table 9). Five (5) samples from PC-BDDS and eight (8) samples from PC-BDUS, respectively, contained levels higher than the NCDEQ standard. Turbidity values were generally good ranging between 1 and 19 NTU with a mean value of 7 NTU (Table 9). None of the observed turbidity values exceeded the State standard of 25 NTU for class SA waters. Table 10 depicts the ratings for these parameters for the watershed. Figure 22. Water Quality Sites within the Pages Creek Watershed CPE-NC 31 Table 9. Mean values of select parameters from Pages Creek. Range in parentheses. Parameter PC-BDUS PC-BDDS PC-M Turbidity (NTU) 8 (3-18) 7 (3-13) 6 (1-19) Dissolved Oxygen (mg/l) 7.1 (3.0-12.8) 5.5 (1.2-8.6) 6.8 (1.8-9.5) Chlorophyll-a (ug/l) 3 (1-10) 7 (1-34) 2 (1-5) Enterococci (#CFU/100ml) 415 (16-5,480)1 273 (1-1,620)1 5 (1-10)1 (1)Enterococci values expressed as geometric mean Figure 23. Dissolved Oxygen at PC-BDS at surface (DO-S) Figure 24. Dissolved Oxygen at PC-BDUS at surface (DO-S) CPE-NC 32 Figure 25. Dissolved Oxygen at PC-M at surface (DO-S) and bottom (DO-B) Figure 26. Enterococci at PC-BDDS Figure 27. Enterococci at PC-BDUS CPE-NC 33 Figure 28. Enterococci at PC-M Table 10. Ratings of parameters within sampling stations within Pages Creek Parameter PC-BDUS PC-BDDS PC-M Turbidity GOOD GOOD GOOD Dissolved Oxygen POOR FAIR FAIR Chlorophyll-a GOOD GOOD GOOD Enterococci POOR POOR GOOD CPE-NC 34 Prince George Sampling was conducted at three (3) sites (PG-CH, PG-ML, and PG-NC) within the Prince George Creek watershed (Figure 29). Dissolved oxygen within Prince George Creek ranged between 0.4 mg/l and 9.4 mg/l with a mean value of 4.9 mg/l (Table 11). Surface dissolved oxygen values were below the State standard of 4.0 mg/l for C Sw on ten (10) occasions during the reporting period at PG-NC, five (5) times at PG-NC, three (3) times at PG- CH, and two (2) times at PG-ML (Figure 30 – 32, Table 11). Chlorophyll-a ranged between 1 ug/l and 39 ug/l with a mean value of 5 ug/l (Table 11Table 11). No samples from Prince George Creek exceeded the 40 ug/l standard. Enterococci ranged between 5 CFU/100ml and 19,900 CFU/100ml with a geometric mean value of 73 CFU/100ml (Table 11). Five (5) samples collected from within Prince George Creek contained Enterococci levels above the NCDEQ standard of 500 CFU/100ml for Tier III waters (Figure 33 – Figure 35). Turbidity values were generally good ranging between 1 and 15 NTU with a mean value of 4 NTU (Table 11). No samples exceeded the State standard of 50 NTU for C Sw waters. Table 12 depicts the ratings for these parameters for the watershed. Figure 29. Water Quality Sites within the Prince George Creek Watershed CPE-NC 35 Table 11. Mean values of select parameters from Prince George Creek. Range in parentheses. Parameter PG-CH PG-ML PG-NC Turbidity (NTU) 5 (1-15) 4 (2-9) 4 (2-7) Dissolved Oxygen (mg/l) 5.5 (3.1-9.3) 5.5 (0.4-9.4) 3.7 (0.4-8.8) Chlorophyll-a (ug/l) 4 (2-11) 4 (1-8) 7 (2-39) Enterococci (#CFU/100ml) 52 (5-417)1 74 (20-22)1 17 (1-121)1 (1)Enterococci values expressed as geometric mean Figure 30. Dissolved Oxygen at PG-CH at surface (DO-S) and bottom (DO-B) Figure 31. Dissolved Oxygen at PG-ML at surface (DO-S) CPE-NC 36 Figure 32. Dissolved Oxygen at PG-NC at surface (DO-S) and bottom (DO-B) Figure 33. Enterococci at PG-CH Figure 34. Enterococci at PG-ML CPE-NC 37 Figure 35. Enterococci at PG-NC Table 12. Ratings of parameters within sampling stations within Prince George Creek Parameter PG-CH PG-ML PG-NC Turbidity GOOD GOOD GOOD Dissolved Oxygen FAIR FAIR POOR Chlorophyll-a GOOD GOOD GOOD Enterococci FAIR FAIR GOOD CPE-NC 38 Smith Creek Sampling was conducted at five (5) sites (SC-CH, SC-23, SC-NK, SC-GR, SC-CD) within the Smith Creek watershed (Figure 36). Dissolved oxygen within the creek ranged between 3.7 mg/l and 9.9 mg/l with a mean value of 7.2 mg/l (Table 13; Figure 37 – Figure 41). No samples collected were below the State standard. Chlorophyll-a ranged between 1 ug/l and 25 ug/l with a mean value of 5 ug/l (Table 13). No samples exceeded the State Standard for chlorophyll-a from within Smith Creek. Enterococci ranged between 5 CFU/100 ml and 24,200 CFU/100 ml with a geometric mean value of 72 CFU/100ml (Table 12). Six (6) samples exceeded the NCDEQ standard of 500 CFU/100 ml for Tier III waters (Figure 42 -Figure 46). Turbidity values were generally good ranging between 1 and 87 NTU with a mean value of 12 NTU (Table 13). No observations exceeded the State standard of 50 NTU for SW class C waters. Table 14 depicts the ratings for these parameters for the watershed. Figure 36. Water Quality Sites within the Smith Creek Watershed Table 13. Mean values of select parameters from Smith Creek. Range in parentheses. CPE-NC 39 Parameter SC-23 SC-CD SC-CH SC-GR SC-NK Turbidity (NTU) 9 (1-28) 14 (5-65) 12 (4-30) 17 (3-87) 8 (3-17) Dissolved Oxygen (mg/l) 6.6 (4.2-9.8) 8.2 (6.2-9.8) 6.5 (3.9-9.9) 8.0 (6.2-9.6) 6.7 (3.7-9.7) Chlorophyll-a (ug/l) 8 (5-25) 3 (1-11) 4 (1-14) 3 (1-7) 7 (1-24) Enterococci (#CFU/100ml) 32 (5-1,130)1 273 (5-24,200)1 21 (5-122)1 128 (5-9,800)1 84 (5-3,440)1 (1)Enterococci values expressed as geometric mean Figure 37. Dissolved Oxygen at SC-23 at surface (DO-S) and bottom (DO-B) Figure 38. Dissolved Oxygen at SC-CD at surface (DO-S) CPE-NC 40 Figure 39. Dissolved Oxygen at SC-CH at surface (DO-S) and bottom (DO-B) Figure 40. Dissolved Oxygen at SC-GR at surface (DO-S) Figure 41. Dissolved Oxygen at SC-NK at surface (DO-S) and bottom (DO-B) CPE-NC 41 Figure 42. Enterococci at SC-23 Figure 43. Enterococci at SC-CD Figure 44. Enterococci at SC-CH CPE-NC 42 Figure 45. Enterococci at SC-GR Figure 46. Enterococci at SC-NK Table 14. Ratings of parameters within sampling stations within Smith Creek Parameter SC-23 SC-CD SC-CH SC-GR SC-NK Turbidity GOOD GOOD GOOD GOOD GOOD Dissolved Oxygen GOOD GOOD GOOD GOOD GOOD Chlorophyll-a GOOD GOOD GOOD GOOD GOOD Enterococci GOOD FAIR GOOD FAIR GOOD CPE-NC 43 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 47, Table 15). Photographs of each sampling site are found in Appendix A. Raw data from the tidal creeks sampling sites and the Airlie Garden sampling sites are found in Appendix B and Appendix C, respectively. Dissolved oxygen within the lake ranged between 2.8 mg/l and 12.9 mg/l with a mean value of 7.3 mg/l (Table 15; Figure 48 - Figure 50). Three (3) samples were above the State standard for dissolved oxygen. Turbidity values were generally good ranging between 1 and 103 NTU with a mean value of 9 NTU (Table 15). One observation exceeded the State standard of 50 NTU for Class C waters. Chlorophyll-a ranged from 3 mg/l to 130 mg/l with a mean value of 34 mg/l. The standard of 40 mg/l was exceeded thirteen (13) times. Figure 47. Airlie Gardens Sampling Sites CPE-NC 44 Figure 48. Dissolved Oxygen at AG-IN Figure 49. Dissolved Oxygen at AG-FD Figure 50. Dissolved Oxygen at AG-OUT CPE-NC 45 Table 15. Mean values of select parameters from Airlie Gardens. Range provided in parentheses. Parameter AG-IN AG-FD AG-OUT Turbidity (NTU) 6 (1-23) 16 (2-103) 6 (1-12) Dissolved Oxygen (mg/l) 6.1 (2.8-11.6) 8.1 (3-12.9) 7.6 (5.8-11.4) Chlorophyll-a (mg/l) 18 (3-54) 40 (4-130) 43 (3-117) Orthophosphate 0.08 (0.01-0.29) 0.09 (0.02-0.29) 0.09 (0.01-0.26) Nitrate/Nitrite 0.06 (0.01-0.17) 0.05 (0.01-0.26) 0.04 (0.01-0.23) Long Term Trends within Airlie Gardens Monitoring within three sites in the lake at Airlie Gardens began in the summer of 2015. Since that time, samples have been collected on a monthly basis for the analysis of orthophosphate and nitrate/nitrite (two types of nutrients). In the summer of 2016, monthly samples were collected for the analysis of Chlorophyll-a as well. Over the course of time, some trends have emerged. During the 2016-2017 study period, Chlorophyll-a levels were similar at all three (3) sampling sites, however, the next year (2017-2018 study period) these levels were relatively higher at AG-IN compared to the two (2) sites situated in the central portion of the lake (AG-FD) and at the outfall location (AG-OUT). During the most recent study periods, the trend reversed, and higher levels of Chlorophyll-a was observed at AG-FD and AG-OUT compared to AG-IN (Figure 51). On average, Chlorophyll-a levels at AG-FD and AG-OUT have been roughly double 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 51. Chlorophyll-a levels at Airlie Gardens Over Time CPE-NC 46 When examining the levels of nutrients over time within these sampling sites, higher levels of nitrate/nitrate has been observed at AG-IN compared to the other two sampling sites on an annual basis since sampling began in 2015 (Figure 52). Over the past six (6) years, nitrite/nitrate levels have averaged 0.06 mg/l at AG-IN and 0.03 mg/l and 0.02 mg/l at AG-FD and AG-OUT respectively. This trend of diminishing nutrient levels across the lake (from the stormwater input to the outfall area) held true for orthophosphate as well for the first three (3) sampling periods, however the values have been similar at all three (3) sites over the past three (3) years (Figure 53). Collectively, over the past six (6) years of sampling, the average orthophosphate levels within each sampling site are similar- AG-IN and AG-FD have averaged 0.05 mg/l while AG-OUT has averaged 0.04mg/l. Figure 52. Nitrate/Nitrate Levels in Airlie Gardens Over Time Figure 53. Orthophosphate Levels in Airlie Gardens Over Time CPE-NC 47 Dissolved oxygen within the lake has been good, on average, through the years within each site with the exception of AG-IN during the 2015-2016 study period. The levels at AG-FD and AG-OUT have been similar to each other each year and have been consistently higher in comparison to the levels observed at AG-IN (Figure 54). At each site, the dissolved oxygen levels generally increased during the warmer summer months and increased during the colder winter months. Figure 54. Dissolved Oxygen Levels in Airlie Gardens Over Time CPE-NC 48 In order to assess the long term trends in water quality, a database has been created to include the data collected within the seven (7) tidal creeks under current investigation. The long-term trends from these creeks have been derived from data obtained between July 2008 and June 2021. Dissolved Oxygen Figure 55 depicts the long-term trends in dissolved oxygen within the seven (7) creeks examined within this study. The data show a distinct seasonal pattern including higher dissolved oxygen during the cooler winter months and lower dissolved oxygen during the warmer summer months. Generally speaking, the dissolved oxygen levels within each creek have not changed drastically from year to year. Since 2008, dissolved oxygen levels were below the State standard within surface samples 34%, 23%, 17%, and 10% of the time within Prince George Creek, Pages Creek, Futch Creek, and Barnard Creek, respectively. Dissolved oxygen was below the standard 8%, 6%, and 5% of the time within Mott Creek, Smith Creek, and Lords Creek, respectively. Figure 55. 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. Turbidity Figure 56 depicts the long-term trends in turbidity within the seven (7) creeks examined within this study. In general, the long-term trend of turbidity has remained fairly constant within each creek on an annual basis, however several creeks have experienced minor increases over time and seasonal patterns have emerged. This includes higher turbidity observations during the warmer months and lower turbidity during the cooler months. Since 2008, the turbidity standard from observations monitored from the surface waters was only breached nineteen (19) times in total: seven (7) from within Pages Creek and Smith Creek, two (2) from Prince George Creek, and one time each from within Barnards Creek, Lords Creek and Mott Creek. CPE-NC 49 Figure 56. Long-term surface turbidity data within tidal creeks. Note: The turbidity standard within Pages Creek and Futch Creek is 25 NTUs while the standard for the other creeks is 50 NTUs. Chlorophyll-a Figure 57 depicts the long-term trends in chlorophyll-a within the seven (7) creeks examined within this study. In general, the long-term trend of chlorophyll-a has remained fairly constant within each creek. Contrary to the trend observed with dissolved oxygen, chlorophyll-a levels appear to increase during the warmer months and decrease during the cooler months. Since sampling began in July 2008, only 35 exceedances of the chlorophyll-a standard were observed of the 2,967 samples collected. Figure 57. Long-term chlorophyll-a data within tidal creeks CPE-NC 50 Enterococci Figure 59 and Table 18 depict the long-term trends in Enterococci within the seven (7) creeks examined within this study. Of these creeks, Mott Creek, Pages Creek, Smith Creek, and Prince George Creek have maintained relatively higher levels of bacteria over time compared to Lords Creek and Futch Creek. The levels of bacteria in Barnards, Smith, and Mott Creek have moderated over recent years (Table 18). Two sites in particular within the Bayshore community (PC-BDDS and PC-BDUS) in the Pages Creek watershed have demonstrated relatively high levels of Enterococci bacteria over time. Since June 2008, samples collected within Mott Creek and Pages Creek exceeded the State standard for Enterococci 41% and 38% of the time, respectively. Smith Creek and Barnards Creek have both exceeded the standard 26% of the time while Prince George Creek exceeded standard 23% of the time. Lords Creek exceeded the standard 10% of the time while Futch Creek has only exceeded the standard for Enterococci 4% of the time. Figure 58. Long-term Enterococci data within tidal creeks CPE-NC 51 Table 16. Enterococci ratings for each watershed during all reporting periods. Study Period Barnards Creek Futch Creek Lords Creek Mott Creek Pages Creek Prince George Creek Smith Creek 2008-2009 POOR GOOD FAIR POOR POOR FAIR POOR 2009-2010 POOR GOOD POOR POOR POOR POOR POOR 2010-2011 POOR GOOD GOOD POOR FAIR POOR POOR 2011-2012 POOR GOOD GOOD POOR POOR POOR POOR 2012-2013 POOR GOOD FAIR POOR POOR POOR POOR 2013-2014 GOOD GOOD GOOD POOR POOR POOR FAIR 2014-2015 GOOD GOOD GOOD POOR POOR POOR FAIR 2015-2016 POOR FAIR FAIR POOR POOR POOR FAIR 2016-2017 GOOD GOOD GOOD FAIR POOR GOOD FAIR 2017-2018 FAIR FAIR POOR FAIR POOR POOR POOR 2018-2019 FAIR GOOD FAIR FAIR FAIR GOOD GOOD 2019-2020 GOOD GOOD GOOD FAIR FAIR GOOD GOOD 2020-2021 GOOD GOOD GOOD FAIR POOR FAIR GOOD CPE-NC 52 Water Classifications The State of North Carolina has employed a series of classifications that apply to all waters in the State including streams, rivers, and lakes (NC Administrative Code, section 15A NCAC 2B .0200). These classifications are meant to protect the specified uses within waterbodies. These include aquatic life survival and reproduction, secondary recreation, primary recreation, shellfishing, and water supply. The classifications that apply to the creeks examined in this study are: C: Waters: Protected for uses such as secondary recreation, fishing, wildlife, fish consumption, aquatic life including propagation, survival and maintenance of biological integrity, and agriculture. Secondary recreation includes wading, boating, and other uses involving human body contact with water where such activities take place in an infrequent, unorganized, or incidental manner. This includes the lake within Airlie Gardens. C Sw: Freshwater that is protected for aquatic life and secondary recreation uses. The “Sw” supplemental classification indicates that these are swamp waters, and so are likely to have lower dissolved oxygen and pH than non-swamp streams due to natural conditions. However, a majority of the sites, including Lords Creek, Mott Creek, Barnards Creek, Smith Creek, and Prince George Creek, designated as C Sw by the State, are tidally influenced and have a brackish salinity range. SA: Saline water bodies that are protected for shellfishing uses. This use requires a more stringent standard for fecal coliform. Areas protected for shellfishing are also subject to the protection requirements for the less stringent classifications of SC and SB, which include aquatic life, secondary recreation, and primary recreation. This designation applies to Futch Creek and Pages Creek. Parameters Temperature Thermal pollution can result in significant changes to the aquatic environment. Most aquatic organisms are adapted to survive within a specific temperature range. Thermal pollution may also increase the extent to which fish are vulnerable to toxic compounds, parasites, and disease. If temperatures reach extremes of heat or cold, few organisms will survive. Thermal pollution may be caused by stormwater runoff from warm surfaces such as streets and parking lots. Soil erosion is another cause, since it can cause cloudy conditions in a water body. Cloudy water absorbs the sun's rays, resulting in a rise in water temperature. Thermal pollution may even be caused by the removal of trees and vegetation which normally shade the water body. In addition to the direct effects of thermal pollution on aquatic life, there are numerous indirect effects. Thermal pollution results in lowered levels of dissolved oxygen, since cooler water can hold more oxygen than warmer water. Salinity Salinity is a measure of the amount of sodium chloride ions dissolved in water. This is important to monitor since changes in the levels of salt concentration can impact the ability of salt sensitive species to survive. An estuary, such as the lower Cape Fear River, usually exhibits a gradual change in salinity throughout its length, as freshwater entering the estuary from tributaries mixes with seawater moving in CPE-NC 53 from the ocean. Salinity levels control, to a large degree, the types of plants and animals that can live in different zones of the estuary. Freshwater species may be restricted to the upper reaches of the estuary, while marine species inhabit the estuarine mouth. Some species tolerate only intermediate levels of salinity while broadly adapted species can acclimate to any salinity ranging from freshwater to seawater. Conductivity Specific conductance is a measure of the ability of water to conduct an electrical current. Similar to salinity, it measures the amount of dissolved ions (including sodium chloride) in the water. pH The pH of water is a measurement of the concentration of H+ ions, using a scale that ranges from 0 to 14. Natural water usually has a pH between 6.5 and 8.5. While there are natural variations in pH, many pH variations are due to human influences. Unanticipated decreases in pH could be indications of acid rain, runoff from acidic soils, or contamination by agricultural chemicals. Turbidity Turbidity is the amount of particulate matter that is suspended in water. Turbidity measures the scattering effect that suspended solids have on light: the higher the intensity of scattered light, the higher the turbidity. During a rainstorm, particles from the surrounding land are washed into 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. CPE-NC 54 Enterococci Enterococci are distinguished from fecal coliform bacteria by their ability to survive in saltwater, and in this respect, they more closely mimic many pathogens than do the other indicators. Enterococci are typically more human-specific than the larger fecal streptococcus group. EPA recommends Enterococci as the best indicator of health risk in saltwater used for recreation and as a useful indicator in freshwater as well. In 2004, Enterococci took the place of fecal coliform as the new federal standard for water quality at public beaches. It is believed to provide a higher correlation than fecal coliform with many of the human pathogens often found in sewage (Jeng, et al., 2004). Results indicated that Enterococci might be a more stable indicator than fecal coliform and, consequently, a more conservative indicator under brackish water conditions. Orthophosphate Phosphorus is a nutrient required by all organisms for the basic processes of life. Phosphorus is a natural element found in rocks, soils, and organic material. Phosphorus clings tightly to soil particles and is used by plants, so its concentration in clean waters is generally very low. However, phosphorus is used extensively in fertilizer and other chemicals, so it can be found in higher concentrations in areas of human activity. High levels in the water column can be detrimental to water quality as phosphates can cause algal blooms resulting in decreased dissolved oxygen levels. Orthophosphate is sometimes referred to as "reactive phosphorus." Orthophosphate is the most stable kind of phosphate and is the form used by plants. Orthophosphate is produced by natural processes and is found in sewage. Nitrate/Nitrite Nitrate is highly soluble (dissolves easily) in water and is stable over a wide range of environmental conditions. It is easily transported in streams and groundwater. Nitrates feed plankton (microscopic plants and animals that live in water), aquatic plants, and algae, which are then eaten by fish. Nitrite is relatively short-lived in water because it is quickly converted to nitrate by bacteria. Excessive concentrations of nitrate and/or nitrite can be harmful to humans and wildlife. If excessive amounts of nitrates are added to the water, algae and aquatic plants can be produced in large quantities. When these algae die, bacteria decompose them, and use up oxygen. CPE-NC 55 Standards Water quality standards have been established legislatively for a number of these parameters (Table 17). 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 19). A geometric mean of 35 CFU/100 ml within Tier I swimming areas may also be utilized if at least five samples are collected within 30 days. The creeks and the lake in Airlie Gardens included in this study have not been classified within the RWQ tier system; however, an analysis of accessibility as an indicator of swimming and boating usage has been performed (Table 20). Based on this analysis, of the nineteen (19) tidal creek sampling sites, two (2) could be considered Tier II and seventeen (17) could be considered Tier III. All three (3) of the Airlie Garden sites are considered Tier III. Table 17. 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 CPE-NC 56 Table 18. 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 19. Single sample standards for Enterococci as determined by the NC DEQ Recreational Water Quality Program Description Single sample maximum Tier I, swimming areas used daily during the swimming season <104 CFU/100 ml Tier II, swimming areas used three days a week during the swimming season <276 CFU/100 ml Tier III, swimming areas used on average four days a month during the swimming season <500 CFU/100 ml Table 20. Tier Classification for New Hanover County Water Quality Monitoring Sites Site Name Proposed Tier Classification Accessible for Boating or Swimming Comments MOT-CBR Tier III No Adjacent to culvert off Carolina Beach Road MOT-ND Tier III No Adjacent to small bridge on Normandy Drive LC-RR Tier III No Adjacent to bridge on River Road BC-CBR Tier III No Adjacent to culvert off Carolina Beach Road SC-CH Tier III No Adjacent to bridge on Castle Hayne Road SC-23 Tier III No Adjacent to bridge on 23rd Street SC-CD Tier III No Narrow, shallow. Adjacent to Candlewood Drive SC-NK Tier III No Adjacent to bridge on North Kerr SC-GR Tier III No Adjacent to culvert on Gordon Road PG-ML Tier III No Small boat launch site on private property PG-CH Tier III No Adjacent to culvert on Castle Hayne Road PG-NC Tier III No Adjacent to culvert on North College Road FC-4 Tier III No Private docks are the only means of direct access FC-6 Tier III No Private docks are the only means of direct access FC-13 Tier III No Private docks are the only means of direct access FC-FOY Tier III No No clear access points (no docks on Foy branch) PC-M Tier II Yes Direct access via Canady's Yacht Basin Marina PC-BDDS Tier III No Private docks are the only means of direct access PC-BDUS Tier II Yes Public boat ramp off Bayshore Drive AG-IN Tier III No Northern portion of Airlie Gardens Lake AG-FD Tier III No Central portion of Airlie Gardens Lake AG-OUT Tier III No Southern portion of Airlie Gardens Lake CPE-NC 57 Table 21. List of Tidal Creek Sampling Sites Creek Name Site Name Site Code Latitude Longitude Mott Creek Carolina Beach Road MOT-CBR 34° 08.610 77° 53.830 Mott Creek Normandy Drive MOT-ND 34° 08.373 77° 54.580 Lords Creek River Road LC-RR 34° 05.185 77° 55.275 Barnards Creek Carolina Beach Road BC-CBR 34° 09.522 77° 54.712 Smith Creek Castle Hayne Road SC-CH 34° 15.541 77° 56.325 Smith Creek 23rd Street SC-23 34° 15.472 77° 55.178 Smith Creek Candlewood Drive SC-CD 34° 17.438 77° 51.332 Smith Creek North Kerr SC-NK 34° 15.744 77° 53.256 Smith Creek Gordon Road SC-GR 34° 16.639 77° 52.037 Prince George Creek Marathon Landing PG-ML 34° 21.088 77° 55.349 Prince George Creek Castle Hayne Road PG-CH 34° 20.675 77° 54.217 Prince George Creek North College PG-NC 34° 20.331 77° 53.607 Futch Creek 4 FC-4 34° 18.068 77° 44.760 Futch Creek 6 FC-6 34° 18.178 77° 45.038 Futch Creek 13 FC-13 34° 18.214 77° 45.451 Futch Creek Foy Branch FC-FOY 34° 18.405 77° 45.358 Pages Creek Mouth PC-M 34° 16.209 77° 46.270 Pages Creek Bayshore Drive Down Stream PC-BDDS 34° 16.685 77° 47.673 Pages Creek Bayshore Drive Up Stream PC-BDUS 34° 16.623 77° 48.104 Table 22. List of Airlie Gardens Sampling Sites Site Name Site Code Latitude Longitude Airlie Gardens In AG-IN 34° 21749 77° 82873 Airlie Gardens Floating Dock AG-FD 34° 21549 77° 82796 Airlie Gardens Out AG-OUT 34° 21336 77° 82713 CPE-NC 58 Methods These seven (7) tidal creeks included within this study and the lake in Airlie Gardens are primarily located in the unincorporated portion of New Hanover County. Sampling sites were accessed from land, generally near a bridge or culvert crossing, or by boat. Each tidal creek site was sampled one time per month during a high ebb tide. Tides were determined utilizing the National Oceanic and Atmospheric Administration’s (NOAA) Tides and Currents website (http://tidesandcurrents.noaa.gov/). The sites sampled within Airlie Gardens are not influenced by the tide and therefore no efforts were made to associate the timing of sampling with the tidal stage in the surrounding waters. Due to time constraints, monthly sampling events were conducted on three subsequent days each month. Sites within Airlie Gardens, Lords Creek, Mott Creek, and Barnards Creek were visited on the first sampling day while Smith Creek and Prince George Creek were visited the second day. Futch Creek and Pages Creek were visited on the third day. Rainfall totals for the 24 hours prior to each sampling event were obtained from observations recorded at Wilmington International Airport as reported by NOAA’s National Weather Service web site (http://www.srh.noaa.gov/data/RAH/RTPRAH). Physical Parameters All physical measurements (temperature, salinity, conductivity, turbidity, dissolved oxygen, and pH) were taken in situ utilizing a 6820 YSI Multiparameter Water Quality Probe linked to a YSI 650 MDS display unit. The YSI Probe was calibrated each day prior to use. Physical measurements were taken from the surface at all sites (depth = 0.1 m) and near the creek bottom at sites with depths greater than 0.5 m. Following each sampling trip, the YSI Probe was post-calibrated following each sampling date to ensure that the physical parameters measured were within an acceptable range. Chemical and Biological Parameters Water samples were obtained for the laboratory analysis of chemical (nitrate/nitrite and orthophosphate) and biological (Enterococci and chlorophyll-a) parameters. These grab samples were collected in sterile bottles during a high ebb tide from the surface at each site (depth = 0.1m). Water samples were placed on ice immediately following collection and were delivered in coolers to Environmental Chemists, Inc. of Wilmington, North Carolina for analysis. All analyses performed by Environmental Chemists, Inc. were conducted utilizing the following standard EPA approved methods: • Orthophosphate: SM 4500E • Nitrate/Nitrite: EPA 353.2 • Chlorophyll-a: SM 10200H • Enterococci: EnterolertE CPE-NC 59 Since 2008 New Hanover County has conducted water quality monitoring in 7 tidal creeks (Barnards, Futch, Pages, Prince George, Mott, Smith) within the unincorporated portion of the county. The overall health of the creeks has been tracked by measuring multiple parameters on a monthly basis. The parameters include physical traits like temperature and salinity and biological indicators like dissolved oxygen, chlorophyll-a and Enterococci bacteria. One advantage for tracking the creeks for the same parameters for 13 years is the development of long-term trends. These trends are important when evaluating whether changes in parameters are short-term or long-term and are natural or if there are irregularities causing changes in water quality. For example, dissolved oxygen and chlorophyl-a fluctuate seasonally between summer and winter and show short-term changes. While these changes are known, long term trends are uses full at looking at fluctuations that are uncommon or out of the norm. Any abnormal changes in water quality especial with those that could negatively affect the natural environment or are cause for human health concern are monitored closely to see if the trend continues. After evaluating the long-term trend in Pages Creek, water quality monitoring has indicated elevated levels of Enterococci bacteria exist in the upper and middle portions of the creek. Past investigations of the bacteria had concluded that the bacteria were from a human source and not from other animals in the area. In addition, an investigation of septic systems and sewer infrastructure came back inconclusive. In January 2021 New Hanover County partnered with the University of North Carolina Wilmington’s Socio- Environmental Analysis Laboratory and Coastal Protection Engineering of North Carolina to conduct a thermal imagery scan of portions of Pages Creek to identify any possible sources of Enterococci bacteria entering the creek. A summary of UNCW’s report written by CPE begins on the next page (page 59). The report from UNCW detailing the study area, methods and technical aspects are found in Appendix E. CPE-NC 60 Pages Creek Source Tracking Investigation Utilizing an Unmanned Aerial Vehicle (UAV)-Based Thermal Survey Prepared by: Coastal Protection Engineering of North Carolina, Inc. Marine Scientist: Brad Rosov, M.Sc. Introduction Located in northeastern New Hanover County and encompassing 5,025 acres, Pages Creek watershed drains into the Intracoastal Waterway, north of Middle Sound Loop Road. Development within the watershed is predominately low density residential, with commercial and retail uses along Market St/Highway 17. Since 2007, water quality monitoring within Pages Creek has been performed monthly within three sampling sites (Figure 1). The long-term data set has documented recurring elevated levels of Enterococci bacteria levels within the two monitoring sites located within the Bayshore neighborhood (PC-BDDS and PC-BDUS). In consideration of the human health risks associated with these high levels of bacteria, in 2009 and 2013, New Hanover County funded source tracking studies to determine the origins of the bacteria loading within the waters of Pages Creek in proximity to the Bayshore community. The results of those efforts revealed that water samples collected from both sites contained Enterococci bacteria that originated, in part, from human sources. Despite these efforts to identify the pathway(s) of this bacterial contamination into the creek, its origins remained unknown. Figure 1. Water Quality Sites within the Pages Creek Watershed CPE-NC 61 In 2021, New Hanover County coordinated a renewed effort to determine the source of the human-borne bacterial contamination within portions of Pages Creek. Working with Coastal Protection Engineering of North Carolina, Inc. (CPE) and researchers from UNCW's Socio-Environmental Analysis Lab, a methodology using thermal imaging sensors mounted on an unmanned aerial vehicle (UAV), or drone, was employed to obtain images that depicted significant temperature differences within the study area. The UAV was flown on January 11, 2021 which was approximately 48 hours after a significant (0.64") rainfall. Acquiring data after a rainfall helps to ensure that non-point source (NPS) and/or groundwater discharge locations with temperature differentials or anomalies could be discerned in the resultant thermal images. Furthermore, data acquisition during the winter months is optimal because deciduous trees have shed their leaves allowing for better penetration of the thermal sensor through the tree canopy. Following data acquisition and processing, the images were qualitatively examined, and georeferenced target areas were then groundtruthed, where feasible. Material and Methods Field Methods: On January 11, 2021, a UAV was deployed from a private residence in proximity to the study area. The study area included two polygons surrounding two branches of Pages Creek within the Bayshore neighborhood. These branches were designated as "PC-BDUS" (Pages Creek - Bayshore Drive Upstream) and "PC-BDDS" (Pages Creek - Bayshore Drive Downstream) and includes the long-term water quality monitoring site with the same name, respectively (Figure 2). Each polygon was designed to extend into the headwaters and include a buffer of no less than 50' of land surrounding the shoreline of the creek. The UAV used for this study was a senseFly eBee plus fixed wing drone equipped with a thermoMAP thermal sensor. This thermal camera features a 0.3-megapixel sensor recording infrared wavelength from 7,500-13,500 nm, with a sensor resolution of 0.1°C. Inflight sensor calibration is done as soon as the eBee reaches its designated altitude. Prior to the flight, ground control points (GCPs) and a survey grade RTK system were established and deployed. GCPs are locations on the ground within the flight plan that are used to assist in georeferencing the collected imagery to their correct real-world locations on the Earth’s surface and are used to constrain the thermal imagery. As there is no standard for how GCPs should be created, the ones used in this study are square cardboard cut outs wrapped in aluminum foil. Wrapping GCPs in aluminum foil allows the thermal sensor to “sense” as aluminum acts as a blackbody due to its very low emissivity value. A total of six GCPs were placed in conspicuous locations within the study area. Permissions from local stakeholders were obtained prior to placing the GCPs in their respective locations. CPE-NC 62 Figure 2. Pages Creek Thermal Imaging Study Area including PC-BDUS and PC-BDDS. Lab Methods: Pix4DMapper was used to process thermal imagery collected by the eBee. Within Pix4D, a preference of processing parameters has been applied to obtain the highest quality orthomosaic. Before thermal imagery can be used, it must be radiometrically calibrated. However, the eBee does this calibration in flight in a circular pattern for around 5 minutes and therefore that step is not needed during data processing. Upon opening Pix4D, the thermoMAP template is selected to produce a reflectance map and thermal index map. Pix4D is where GCPs are aligned with imagery collected, thus producing constrained imagery. Pix4D can still process imagery for the most part without the use of GCPs. However, inclusion of GCPs into imagery significantly increases horizontal and vertical accuracy. Symbology parameters are subsequently applied in ArcGIS that allows for easier visual analysis. Within ArcGIS, both TIFF images original color scheme was changed from grayscale to green/red. This color scheme allowed for easier interpretation of temperature visualizations. A standard deviation stretch was applied to create a linear sketch between the values defined by its corresponding N value. Dynamic range adjustment (DRA) was applied in addition to standard deviation. DRA uses statistics from current display extent. Zooming in or out to certain areas of interest visualizes statistical differences among the display extent. These parameters allow to see greater visual difference in pixel values. CPE-NC 63 Results Scientists at UNCW's Socio-Environmental Analysis Lab and CPE utilized the DRA tool in ArcGIS to examine the processed thermal imaging data. Nine discrete locations revealing significant temperature differentials within to two study areas (PC-BDUS and PC-BDDS) were identified (Figures 3-11). Of these, five were located in the PC-BDUS branch and four were located within the PC-BDDS branch. GPS coordinates of these targeted areas were then obtained from the georeferenced images (Table 1). Using Google Earth, three of the targets containing temperature differentials were revealed to be marsh vegetation (Figures 5, 6, and 7) and therefore do not warrant any additional investigation. Four targets are located on private property (Figures 3, 8, 9, and 11) where permission to access the sites from the property owners, would be needed for an on the ground investigation. However, following additional investigation based on updated 2021 aerial imagery and confirming sewer service to those residences, those 4 targets were ruled out at this time. Two targets, however, were identified to be on public property in proximity of the two sewage lift stations adjacent to the long-term monitoring sites at PC-BDUS and PC- BDDS (Figures 4 and 10). Groundtruthing these sites revealed several subterranean seeps entering the creek from the streambank adjacent to each lift station (Figures 12 and 13). New Hanover County Planning staff has worked with CPE to perform additional water quality testing in two areas where the thermal imagery showed peculiar temperature differences. This testing has indicated Enterococci bacteria in water coming from the seeps mentioned above. More samples and PCR tracing will be needed in order to make a definitive determination as to whether that ground water contains bacteria and if the bacteria is from a human source. CPE-NC 64 Targets Located within PC-BDUS Figure 3. Temperature differential located between 336 and 338 Bayshore Drive. CPE-NC 65 Figure 4. PC-BDUS Lift Station. CPE-NC 66 Figure 5. 366 Shore Point Drive CPE-NC 67 Figure 6. 324 Bayshore Drive CPE-NC 68 Figure 7. 394 Shore Point Drive CPE-NC 69 Targets Located within PC-BDDS Figure 8. 517 Trace Drive CPE-NC 70 Figure 9. 540 Bay Cove Lane CPE-NC 71 Figure 10. PC-BDDS Lift Station CPE-NC 72 Figure 11. 522 Scenic Circle CPE-NC 73 Figure 12. Seep located in proximity to the sewage lift station at PC-BDUS. CPE-NC 74 Figure 13. Seep located in proximity to the sewage lift station at PC-BDUS. Table 1. GPS locations for all targets Figure Number Description Latitude Longitude 3 336 and 338 Bayshore Drive 34° 16' 36.01" N 077° 48' 01.31" W 4 PC-BDUS lift station 34° 16' 38.00" N 077° 48' 07.66" W 5 366 Shore Point Drive 34° 16' 34.28" N 077° 48' 00.73" W 6 324 Bayshore Drive 34° 16' 37.11" N 077° 48' 05.38" W 7 394 Shore Point Drive 34° 16' 38.04" N 077° 48' 01.43" W 8 517 Trace Drive 34° 16' 57.53" N 077° 47' 41.39" W 9 540 Bay Cove Lane 34° 16' 49.72" N 077° 47' 31.00" W 10 PD-BDDS lift station 34° 16' 53.35" N 077° 47' 39.40" W 11 522 Scenic Circle 34° 16' 52.55" N 077° 47' 36.84" W CPE-NC 75 PAGES CREEK THERMAL SURVEY PROJECT REPORT December 2020 – January 2021 Ogden, North Carolina University of North Carolina Wilmington, Socio-Environmental Analysis Lab Dr. Narcisa Pricope Graduate assistant: Jesse Scopa CPE-NC 76 1. Mission Plan and Implementation Overview 1.1 Drone – SenseFly eBee Plus RTK i. We will conduct Thermal imagery collection using the SenseFly ThermoMap sensor aboard the eBee Plus RTK along with ground-based GCPs whose location is to be determined (will likely be placed along roads in the two sub-watersheds) 1.2 The area to be surveyed is not in restricted airspace according to DJI GEOZONE map. The yellow rectangle shows our proposed flight area 1.3 Launch and Recovery Site – 516 Bay Cove Ln (with permission from Beth Eckert) Distance from take-off to upstream flight AOI (bottom left polygon) – 2600ft Distance from take-off to downstream flight AOI (Top polygon) – 500ft CPE-NC 77 Launch & Recovery Site Continued 1.4 Flight parameters for both flights (will be conducted concomitantly) i. Height – 74.1m ii. Lateral Overlap – 75% iii. Longitudinal Overlap – 92% iv. Area covered – 2.9 ha, v. Estimated number of photos –356 vi. Estimated flight time 10:06 vii. Estimated Flight Distance. – 7143m 1.5 Personnel i. Pilot in Command -Dr. Narcisa Pricope (FAA license 3973893) ii. Person maintaining line of sight – undergraduate student TBD iii. Ground Control Points - Jesse Scopa and one more UNCW graduate RA a. Anticipate factors that would affect placement b. Create Matching coordinate system for RTK unit (UTM Zone) CPE-NC 78 2. Materials and Methods 2.1 Study Area Pages Creek, residing in Ogden, North Carolina drains a 5,025-acre watershed composed of 17.8% impervious surface coverage into the Intracoastal Waterway (Figure 1). All flights have been conducted using a senseFly eBee plus fixed wing drone equipped with a thermoMAP thermal sensor. This thermal camera features a 0.3-megapixel sensor recording infrared wavelength from 7500-13,500 nm, with a sensor resolution of 0.1°C. Inflight sensor calibration is done as soon as the eBee reaches its designated altitude. A single flight with the specified take off and landing location was able to capture both the upstream and downstream inlet as delineated by Brad Rosov. Figure 58. Pages Creek Upstream Thermal Orthomosaic Overview. (A) Inset map displaying the study area in relation to North Carolina. (B) Inset map displaying spatial reference of study area in relation to Pages Creek Watershed. (C) Thermal orthomosaic (in degrees C) of Pages Creek Upstream Inlet measure in °C with inclusion of GCP’s denoted by blue circle and label CPE-NC 79 2.2 Field Methods Ground control points (GCPs) and a survey grade RTK system were used to constrain the thermal imagery. GCPs are locations on the ground within your flight that are used to assist in georeferencing the collected imagery to their correct real-world locations on the Earth’s surface. As there is no standard for how GCPs should be created, the ones used in this study are square cardboard cut outs wrapped in aluminum foil. Wrapping GCPs in aluminum foil allows the thermal sensor to “sense” as aluminum acts as a blackbody due to its very low emissivity value. A total of six GCPs were placed down before the January 11 2021 flight, divided into three GCPs for each tidal inlet (Figure 1). Permissions from local stakeholders were obtained prior to placing the GCPs in their respective locations. Flights were flown after a large precipitation event to maximize potential of capturing non-point source discharge. 2.3 Lab Methods Pix4DMapper was used to process thermal imagery collected by the eBee. Within Pix4D, a preference of processing parameters has been applied to obtain the highest quality orthomosaic. Before thermal imagery can be used, it must be radiometrically calibrated. However, the eBee does this calibration in flight in a circular pattern for around 5 minutes and therefore that step is not needed during data processing. Other thermal cameras such as the brand FLIR would have to calibrate their data manually. Upon opening Pix4D, the thermoMAP template is selected to produce a reflectance map and thermal index map. Pix4D is where GCPs are aligned with imagery collected, thus producing constrained imagery. Pix4D can still process imagery for the most part without the use of GCPs. However, inclusion of GCPs into imagery significantly increases horizontal and vertical accuracy. Symbology parameters are subsequently applied in ArcGIS that allows for easier visual analysis. Within ArcGIS, both TIFF images original color scheme was changed from grayscale to green/red. This color scheme allowed for easier interpretation of temperature visualizations. A standard deviation stretch was applied to create a linear sketch between the values defined by its corresponding N value. Dynamic range adjustment (DRA) was applied in addition to standard deviation. DRA uses statistics from current display extent. Zooming in or out to certain areas of interest visualizes statistical differences among the display extent. These parameters allow to see greater visual difference in pixel values. CPE-NC 80 3. Anomalies of Interest 3.1 Pages Creek Upstream 366 Shore Point Drive 324 Bayshore Drive xdcs CPE-NC 81 394 Bayshore Drive CPE-NC 82 3.2 Pages Creek Downstream 540 Baycove Lane Lift Station CPE-NC 83 522 Scenic Circle CPE-NC 84 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. Grizzard, T.J., Randall, C.W., Helsel, D.R., and Hartigan, J.P. 1980. Analysis of non-point pollution export from small catchments. Journal of Water Pollution Control Federation, 52: 780-790. Howarth, R.W. and Marino, R. 2006. Nitrogen as the limiting nutrient for eutrophication in coastal marine ecosystems: Evolving views over three decades. Limnology and Oceanography, 51: 364-376. Kelsey, H., Porter, D.E, Scott, G., Neet, M., and White, D. 2004. Using geographic information systems and regression analysis to evaluate relationships between land use and fecal coliform bacterial pollution. Journal of Experimental Marine Biology and Ecology. 298:197-209. Kwak, T.J. and Zedler, J.B. 1997. Food web analysis of southern California coastal wetlands using multiple stable isotopes. Oecologia 110: 262–277. Mallin, M.A.; Williams, K.E.; Esham, C.E.; and Lowe, P.R., 2000. Effect of human development on bacteriological water quality in coastal watersheds. Ecological Applications 10:1047-1056. Mallin, M.A., Ensign, S.H., McIver, M.R., Shank, G.C., and Fowler, P.K. 2001. Demographic, landscape, and meteorological factors controlling the microbial pollution of coastal waters. Hydrobiologia. 460: 185-193. Mallin, M.A., 2010. University of North Carolina at Wilmington, Aquatic Ecologist. Personal communication regarding findings of water samples obtained within PG-NC. 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.). Michael A. Mallin, Matthew R. McIver, Anna R. Robuck and John D. Barker. 2014. Environmental Quality of Wilmington And New Hanover County Watersheds. CMS Report 15-01. Center for Marine Science University of North Carolina Wilmington. 92pp. 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. 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. CPE-NC 85 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.