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 12 watersheds and 52 sampling stations.  In this summary we first present brief water quality overviews for each watershed from August 2002 – July 2003 (Tidal Creeks) or August 2002 – September 2003 (Wilmington Watersheds), and then discuss key results of special studies conducted over the past two years.

Barnards Creek – There was a fecal coliform bacterial pollution problem at all three of the stations sampled in the Barnard’s Creek watershed, with the highest fecal coliform counts at the station on Carolina Beach Rd.  Lower Barnard’s Creek at River Road had poor water quality as judged by turbidity and low dissolved oxygen, and there was increased loading of nitrogen at all three stations compared with the 2001-2002 study.  However, BOD at the River Road station decreased from the previous year.

Bradley Creek – Turbidity was not problematic during 2002-2003.  Low dissolved oxygen was an occasional problem in brackish waters of the creek during summer and fall.  Elevated nitrogen and phosphorus levels enter the creek in both the north and south branches, but major algal blooms were not seen during the sampling period.  Fecal coliform bacteria were only sampled at the station at College Acres, which proved to be contaminated on 82% of the occasions sampled.

Burnt Mill Creek – A sampling station on Burnt Mill Creek at Princess Place had substandard dissolved oxygen during 50% of the sampling trips.  This station also had very poor microbiological water quality, exceeding the standard for human contact in 11 of 12 samples, with a geometric mean of 1162 CFU/100 mL.  The station just upstream of Ann McCrary pond also had severe fecal coliform contamination, exceeding the standard on 92% of sample occasions.  The effectiveness of Ann McCrary wet detention pond on Randall Parkway as a pollution control device was not good last year.  There were no statistically significant reductions in any of the pollutant parameters due to passage through the pond.  All 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 were not seen in 2002-2003.  Dissolved oxygen and turbidity concentrations were minor problems last year.  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.

Greenfield Lake – The three tributaries of Greenfield Lake (near Lake Branch Drive, Jumping Run Branch, and Lakeshore Commons Apartments) all suffered from low dissolved oxygen problems on numerous occasions, as did all three stations within the lake proper.  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.  The stream near Lakeshore Commons also maintained high nitrate and phosphate concentrations.  However, excessive algal blooms were not recorded in the lake in 2002-2003.  Generally, nutrient loading was highest at a station (GL-2340) located in the south end that receives several urban and suburban inputs.  Fecal coliform bacterial contamination was also prevalent at all in-lake and tributary stations during 2002-2003, increasing over the previous year as a result of the breaking of the drought and increased stormwater runoff.

A large regional wet detention pond on the tributary Silver Stream did a good job of reducing pollutant loads to the lake from this drainage.  Statistically significant reductions in orthophosphate, total phosphorus, and conductivity were all realized.  However, contrary to previous years, nitrogen and fecal coliform bacteria were not significantly reduced, likely because of construction activities occurring along the lower pond.   The design of this pond consists of two interconnected basins containing large amounts of diverse aquatic vegetation, with most inputs directed into the upper basin.  This could serve as a potential model for future large pond design.

Hewletts Creek – This creek received higher nitrate loading in its three upper branches compared with last year, due to the end of the drought.  One major algal bloom exceeding the State standard occurring in the north branch near Greenville Loop Road.  The middle branch had the highest nutrient concentrations, largely derived from two golf courses.  Low dissolved oxygen was not a problem in 2002-2003.  Fecal coliforms were not sampled in Hewletts Creek in 2002-2003, except at a station exiting the Pine Valley Country Club golf course, where the State standard was exceeded 75% of occasions sampled.

Howe Creek – Five stations were sampled in Howe Creek in 2002-2003.  The lower creek maintained good water quality.  A notable decrease in the number of algal blooms has occurred in Howe Creek below Graham Pond since a wetland enhancement was performed in 1998.  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 in mid-creek, and high in the uppermost station during 2002-2003.

Motts Creek – This creek was sampled at only one station, at River Road.  Low dissolved oxygen was a problem on 42% of the sampling occasions in 2002-2003, and turbidity and suspended sediments were a periodic problem.  Fecal coliform pollution was a frequent (58% of the time) problem at this station.  Biochemical oxygen demand (BOD5) and algal blooms decreased from the previous year.

Pages Creek – This creek maintained generally good water quality during 2002-2003.  Turbidity, nutrient loading and phytoplankton growth was low, even at the most anthropogenically-impacted stations.  However, 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 2002-2003.  This watershed has some of the lowest development and impervious surface coverage in the New Hanover County tidal creek system.

Smith Creek – Smith Creek had moderate water quality problems as reflected by several parameters.  Turbidity and elevated suspended sediments occurred on occasion, and an algal bloom exceeding 30 mg/L of chlorophyll a occurred once at the 23^rd St. station.  Low dissolved oxygen problems occurred 33% of the time and 41% of the time at our two Smith Creek stations during 2002-2003.  However, BOD levels declined from the previous year.

Lower Cape Fear Watershed – Sampling was continued in the creek draining Greenfield Lake into the Cape Fear River.  Fecal coliform concentrations exceeded the state standard for human contact waters on 17% of the sampling occasions during 2002-2003.  There was a fish kill here in September 2003 of about 450 individuals. 

Whiskey Creek – Whiskey Creek had relatively high nutrient loading but generally low chlorophyll a concentrations in 2002-2003.  There were several incidents of low dissolved oxygen at two of the five stations sampled this year, but high turbidity was not a problem.  Fecal coliform bacteria counts were high in the upper north and south stations and moderate in the mid-creek station in 2002-2003.

Water Quality Station Ratings – The NC Division of Water Quality utilizes an EPA-based system to help determine if a water body supports its designated use (described in Appendix B).  We applied these numerical standards to the water bodies described in this report, based on 2002-2003 data, and have designated each station as good, fair, and poor accordingly.  Our analysis shows that (based on fecal coliform standards for human contact waters) two of the three Barnards Creek stations were rated poor quality.  All three stations in Burnt Mill Creek were rated as poor in 2002-2003. Futch Creek rated good for fecal coliform bacteria, including for shellfishing throughout the lower creek.  Greenfield Lake and its tributaries rated poor microbiological water quality throughout.  The one station in Hewletts Creek sampled for fecal coliforms last year was rated poor.  The uppermost station in Howe Creek was rated poor, and the middle two were rated fair, respectively, while the lower two were rated good.  Lower Motts Creek was rated poor and both of the Smith Creek stations were rated poor.  The Lower Cape Fear station was rated fair for fecal coliforms.  We also list ratings for chlorophyll a, dissolved oxygen and turbidity in Appendix B, with Greenfield Lake, Smith Creek and Motts Creek having generally poor ratings for dissolved oxygen.

Fecal coliform contamination of sediments - Sediments in the Bradley Creek watershed were sampled for fecal coliform bacteria, and showed a variable but significant population of fecal coliforms at all times and locations sampled. At all sites, suspension of the sediments by physical forces would have sufficed to create water column concentrations of fecal coliforms high enough to mandate closure to shellfishing, and, in several cases, to close these waters to human body contact. Direct body contact with sediments, such as by wading or manual disturbance of the sediments, would likely be particularly hazardous, assuming that sediment fecal coliform concentrations indicate pathogen presence.  When one adds in the fecal coliforms normally suspended in the overlying water as well, then disturbance of the sediments can add a significant health threat to certain water bodies.

Sediment phosphate levels in these samples were not statistically related to fecal coliform bacteria abundance in estuarine sediments.  However, water temperature had  a significant effect on sediment coliform counts.  Coliform counts were lowest at low temperatures and maximal at moderate temperatures, and low at high temperatures.  Fecal coliform contamination of tidal creeks in New Hanover County may be driven by a complex relationship between storm water runoff, animal sources of fecal matter, and a selection of environmental factors.  A much larger study, funded by Sea Grant, is scheduled to occur during 2004-2006.

Tidal Creek Oyster Reef Studies – The health and habitat values of oyster reefs in several tidal creeks were studied.  The results suggest considerable variability in oyster reef characteristics among the New Hanover tidal creeks examined.  In 2001 Pages Creek was described as having “high shell coverage, relatively high densities of live oysters (compared to other creeks examined), and intermediate vertical relief”, while Hewletts Creek was defined as intermediate among the four creeks overall with “relatively high live oyster densities, but low relief”.  As noted previously live oyster densities in Pages and Hewletts Creeks were greater than measurements in Howe or Whiskey Creeks during 2001 but declined in the 2003 measurements.  This is a source of some concern because we also recorded an increase in the amount of shell hash coverage compared to total oyster shell coverage (culms + shell hash).  Our concern here is that this change may reflect a decline in the oyster populations within these areas.  Data from an associated project looking at settlement within the Hewletts Creek system (during late 2002 and early 2003) shows that larvae did recruit to that system, suggesting that factors other than larval supply may be primarily responsible for this pattern.  Measurements of reef complexity were moderate for both Pages and Hewletts Creeks indicating the presence of some high relief culms.  Although these same data showed that the amount of open space within reefs at these two creeks was variable, with some reefs having >50% of the area within the reef as open space.  These data would seem to indicate that reefs in these two systems demonstrate a high degree of variability among years and give some indication of the dynamic nature of oyster reef formation.  In many cases the most complex oyster habitats may be those that provide both oyster structure and open patches within the reef proper.  The question that we must now focus on is at what point do oyster reefs provide the greatest benefits to other organisms (as habitat, refuge, and as system modifiers) while still providing the aggregate needs for healthy oysters and good settlement structure for larvae to maintain the reef integrity.