Executive Summary

            This report represents combined results of Year 10 of the New Hanover County Tidal Creeks Project and Year 6 of the Wilmington Watersheds Project.  Water quality data are presented from a watershed perspective, regardless of political boundaries.  The combined programs involved 11 watersheds and 50 sampling stations.  In this summary we first present brief water quality overviews for each watershed from August 2003 – July 2004, and then discuss key results of several special studies conducted over the past two years.

Barnards Creek – There was only one station sampled in this watershed during 2004, lower Barnard’s Creek at River Road.  This site had no algal bloom or BOD problems; it had fair water quality in terms of fecal coliform counts but poor water quality as judged by excess turbidity and low dissolved oxygen.  It also had the highest suspended solids, ammonium, total nitrogen and total phosphorus levels among all the local watersheds. 

Bradley Creek – Turbidity was not problematic during 2003-2004.  Dissolved oxygen was good to fair at all sites except the branch at College Acres (BC-CA) where it fell below 5.0 mg/L on three occasions during summer.  Elevated nitrogen and phosphorus levels enter the creek in both the north and south branches, one minor algal bloom occurred in the south branch (BC-SB) and one major bloom occurred in the creek at College Acres.  Fecal coliform bacterial counts were only sampled at BC-CA, where contamination was excessive during six of the seven samples collected in 2004.

Burnt Mill Creek – A sampling station on Burnt Mill Creek at Princess Place had no turbidity or suspended solids problems, but substandard dissolved oxygen during all visits from May through September.  There was one moderate algal bloom in June 2004.  This station also had poor microbiological water quality, exceeding the standard for human contact in five of seven samples.  The effectiveness of Ann McCrary wet detention pond on Randall Parkway as a pollution control device was poor during 2004.  While the pond led to a significant reduction in fecal coliform bacteria and an increase in dissolved oxygen, it failed to reduce nutrient concentrations including ammonium, nitrate, total nitrogen, orthophosphate and total phosphorus.  Several water quality parameters indicated a subsequent worsening of the creek from where it exited the pond to the downstream Princess Place sampling station.  Fecal coliform bacteria and low dissolved oxygen are the primary problems in Burnt Mill Creek.

Futch Creek – Futch Creek maintained good microbiological water quality, as it has since channel dredging at the mouth occurred in 1995 and 1996.  Algal blooms and turbidity were not problems in 2003-2004.  Dissolved oxygen concentrations periodically decreased below 5.0 mg/L in summer at some upper creek stations, but otherwise this creek continues to display some of the best water quality in the New Hanover County tidal creek system, due to generally low development and impervious surface coverage in its watershed.  However, fecal coliform concentrations have recently shown an increasing trend in some upper and middle creek stations, potentially a result of increasing development in the headwaters areas.

Greenfield Lake – The three tributaries of Greenfield Lake (near Lake Branch Drive, Jumping Run Branch, and Lakeshore Commons Apartments) all suffered from severe low dissolved oxygen problems and the in-lake stations (GL-2340, GL-YD, and GL-P) had low dissolved oxygen periodically.  All three of the tributaries also had frequent high fecal coliform counts, and maintained geometric mean counts in excess of the state standard for human contact waters.  Station GL-P, at the Park, had high fecal coliform counts on three of the seven occasions sampled, and very low dissolved oxygen during summer.  The stream near Lakeshore Commons also maintained high nitrate and phosphate concentrations.  The lake again experienced algal blooms at times, with several blooms exceeding the N.C. State Standard of 40 mg/L of chlorophyll a, and a three-month duckweed bloom near the Park.  In general, Greenfield Lake continues to suffer from fecal coliform bacterial contamination, algal blooms, and low dissolved oxygen problems.

Hewletts Creek – The tidally-influenced stations in this watershed had generally low turbidity levels in 2003-2004.  Two major algal blooms occurred in the north branch (NB-GLR) in summer 2004, with dissolved oxygen concentrations generally good to fair at tidal sites.  Fecal coliform counts were low at the lower sites, moderate at the mid-creek sites, and high in terms of the N.C.human contact standard of 200 CFU/100 mL at the north and middle branches, but moderate at the south branch. 

Since January 2004 five non-tidal sites have been sampled in the Hewletts Creek watershed.  One site is PVGC-9, draining Pine Valley Country Club.  This stream had no dissolved oxygen or turbidity problems, moderate nutrient levels, and had one severe algal bloom in summer 2004.  However, six of the seven months sampled showed excessive fecal coliform counts, a general increase over previous years.  The other sites are being sampled to gain background information on the water quality of streams entering (DB-1, DB-2, DB-3) and exiting (DB-4) a proposed constructed wetland/future park area known as the Dobo site, draining into the headwaters of Hewletts Creek.  The input and output streams to the Dobo site had no turbidity or algal bloom problems, but low dissolved oxygen was an issue at DB-1 and all sites had excessive fecal coliform problems.  DB-1 also had comparatively high ammonium, total nitrogen, and total phosphorus problems.

Howe Creek – Five stations were sampled in Howe Creek in 2003-2004.  The lower creek maintained good water quality.  In the upper creek there were a few problems with low dissolved oxygen and occasional algal blooms.  Fecal coliform bacteria counts were low near the ICW, moderate mid-creek, and high in the uppermost two stations during 2003-2004.  After several years of improving water quality, in 2003-2004 the upper two stations showed a doubling of fecal coliform counts from 2001-2003 levels.  This is a concern especially as Howe Creek was previously designated as an Outstanding Resources Water by the State of North Carolina.

Motts Creek – This creek was sampled at only one station, at River Road.  One major and one minor algal bloom occurred during this sampling period.  Dissolved oxygen was below 5.0 mg/L on all occasions from May through September and there were a few instances of elevated BOD5 in 2004.  Turbidity and suspended sediments were not a problem.  Fecal coliform counts exceeded 200 CFU/100 mL on five of the seven sampling occasions in 2004.

Pages Creek – This creek maintained generally good water quality during 2003-2004.  Nutrient loading was low and algal blooms were not found, even at the most human-impacted stations.  There was periodic low dissolved oxygen in warmer months at some stations draining Bayshore Drive.  Pages Creek was not sampled for fecal coliform bacteria during 2003-2004.  This watershed has some of the lowest development and impervious surface coverage in the New Hanover County tidal creek system.

Smith Creek – Smith Creek (sampled at SC-CH, at Castle Hayne road) had moderate water quality problems as reflected by several parameters.  Turbidity and elevated suspended sediments occurred on occasion, but algal blooms or high BOD were not problematic. Excessive fecal coliform bacteria counts occurred on two of seven sampling occasions in 2004.  Low dissolved oxygen problems occurred during most summer months.

Whiskey Creek – Whiskey Creek had relatively high nutrient loading but generally low chlorophyll a concentrations in 2003-2004.  There were a few incidents of low dissolved oxygen at two of the five stations sampled this year, but high turbidity was not a problem.  Fecal coliform bacteria were not sampled in 2003-2004 in this creek.

Water Quality Station Ratings – The NC Division of Water Quality (NCDEHNR 1996) utilizes an EPA-based system to help determine if a water body supports its designated use (described in Appendix A).  We applied these numerical standards to the water bodies described in this report, based on 2003-2004 data, and have designated each station as good, fair, and poor accordingly (Appendix B).  Our analysis shows that (based on fecal coliform standards for human contact waters) the Barnards Creek station was rated fair water quality.  Two of the three stations in Burnt Mill Creek were rated as poor in 2004, and the other was rated fair.  The one Bradley Creek station sampled for fecal coliforms was rated as poor.  Futch Creek was rated as good for fecal coliform bacteria, including for shellfishing in the lower creek.  The Greenfield Lake tributaries were rated as poor microbiological water quality and the in-lake stations as fair to good.  The lower tidal stations in Hewletts Creek were rated good for fecal coliforms; the middle stations as fair, and upper tidal stations as poor.  The non-tidal freshwater stations in the Hewletts Creek watershed were poor throughout.  The uppermost two stations in Howe Creek were rated poor and the lower three were rated good.  Lower Motts Creek was rated poor, as was lower Smith Creek.  We also list our ratings for chlorophyll a, dissolved oxygen and turbidity in Appendix B.

Phytoplankton productivity in Futch and Hewletts Creeks -  Phytoplankton are microscopic plants found in marine, estuarine and freshwater ecosystems.  Phytoplankton, like other plants, utilize sunlight to convert carbon dioxide into high-energy carbohydrates and release oxygen during the process of photosynthesis.  The rate at which these processes take place is known as primary production.  Collectively, phytoplankton are the foundation of food webs in water systems, providing a nutritional base for zooplankton and commercially important shellfish and finfish.  Phytoplankton production in these tidal creeks is greatest in summer and lowest in winter, showing that light and temperature control the basic seasonal patterns.  Productivity is higher at low tide than high tide, and higher upstream than downstream.  Also, productivity was higher in Hewletts Creek than Futch Creek, demonstrating that the greater nutrient inputs from the more highly developed watershed cause higher phytoplankton productivity rates. 

Our experiments also demonstrate that phytoplankton production in Futch and Hewletts Creeks is high, equal to or greater than that of large eutrophic estuaries such as the Neuse and Pamlico River Estuaries.  However, these tidal creeks have not suffered from the major algal bloom problems, toxic blooms, and fish kills that those larger systems have had.  Phytoplankton biomass and productivity can be greatly reduced due to grazing by zooplankton, shellfish and other predators.  We suspect that intense grazing by invertebrates such as oysters have helped to control excessive growth of algae in these creeks, especially in summer months when phytoplankton production is highest.  This tells us that these creeks are habitats where there is intense food chain activity, supporting the larval and juvenile stages of many species of finfish and shellfish, a major reason why these creeks are considered primary nursery areas for marine life.

Fecal coliform contamination of sediments - Sediments in the Bradley Creek drainage frequently harbored high numbers of potentially-pathogenic microbes including fecal coliform, streptococcus, and enterococcus bacteria, particularly during the warmer times of the year when children are most likely to play in these waters. As other studies have shown, fecal indicator bacteria concentrations in sediments correlate with the presence of other fecal pathogens.  It is important to consider the public health risk associated with this poorly known reservoir of contaminants. Many water-borne diseases are not properly tracked to their sources, so a significant problem may be occurring without real awareness of its cause. Human contact with these contaminated sediments must be considered as a serious problem for heavily developed coastal areas, such as the Bradley Creek watershed.

Given the attributes of the Bradley Creek watershed, it is likely that animals, both wild and domestic, were the most important fecal contamination sources. One conclusion, therefore, is that pet waste management should be addressed for all residential areas in coastal watersheds, not just beach communities. Moreover, a significant population of “wildlife” that actually associates with human communities, eating human garbage and unsecured pet foods, such as raccoons and opossums, likely lives in this watershed and contributes to the fecal contamination problem. Educational efforts can reduce this problem as well. It is important to note that animal wastes can be as dangerous a source of pathogens to humans as human waste, particularly because some animal-derived pathogens, such as infectious protozoans, can cause infections that are difficult to diagnose and treat.

Tidal Creek Benthic Fauna - Settlement and survivorship of oyster spat are the two most important factors determining the development and stability of oyster reefs within any system.  When reefs are constructed of shell hash with low relief high numbers of spat settle on them, because predators like crabs will avoid these open areas to avoid getting eaten by larger fish.  As reefs grow and their architecture becomes more complex, many other species inhabit them and a complex food web develops.  The habitat function of oyster reefs is critical especially in shallow estuarine environments where oysters may represent one of the few structural habitats available.  As oyster reefs develop the number of crevices and the amount of internal space within the oyster matrix increases.  These areas are colonized very quickly by small crabs and shrimp that may in turn prey on newly settled oyster spat.  Thus as oyster reefs begin to provide a more complex refuge the overall survivorship of oyster spat may decline on that reef to a stable level.  This provides an excellent example of biological controls and illustrates how a healthy ecosystem operates.  As the oyster reefs develop they provide more habitat allowing a greater number of species of epifauna (such as crabs and shrimp), these species in turn provide food for many of the commercially and recreationally important finfish, such as drum, blue fish, spots and croaker among others.

Thus, if rapid recolonization of an area by oysters is desired, construction of low reefs of shell hash is likely to provide a boost in oyster colonization and reef expansion.  If the additional benefit of increased habitat for the whole creek community is desired, reefs of mixed complexity show a great deal of potential for the development of oyster reef for habitat restoration and mitigation.