South Carolina's Approach to Probability-based Monitoring: Trends and Uses
Robert F. Van Dolah 1, Derk C. Bergquist 1 and David E. Chestnut 2
1 South Carolina Department of Natural Resources, Marine Resources Research Institute, Charleston, South Carolina
2 South Carolina Department of Health and Environmental Control, Bureau of Water, Columbia, South Carolina
The South Carolina Estuarine and Coastal Assessment Program (SCECAP), in cooperation with NCA, have been evaluating the condition of South Carolina’s estuaries for several years. Approximately 50-60 sites are sampled each year in two strata representing tidal creek and larger open water habitats. Integrated indices of condition have been developed and refined for water and sediment quality, and combined with a benthic index of biotic integrity to form an overall index of habitat quality that is adjusted for equal weighting of all three components. The results are reported over two year intervals. The most recent assessment completed for 2003-2004 indicates that 77-80% of the state’s estuarine tidal creek and open water habitat was in good condition and less than 5% of either habitat was in poor condition. When strata were combined and compared annually since 1999, no major changes in overall coastal habitat condition were found, nor were there major trends in the integrated measures of water quality or habitat quality.
However, some parameters such as sediment contaminant concentrations (ERM-Q), have increased significantly since inception of the program in 1999. The amount of estuarine habitat supporting a healthy benthic community has also decreased since inception of the program. Further evaluation of the spatial distribution of sites indicates that the more developed estuarine watersheds have a higher incidence of sites showing some impairment in overall habitat quality compared to less developed watersheds. SCECAP also provides a unique opportunity to compare summer-only (for NCA) versus year-round (for other state-mandated purposes) measures of various water quality parameters. Many of the parameters and the overall Integrated Water Quality Score (IWQS) show a greater proportion of the state’s estuarine habitat in fair to poor condition based on the year-round versus one-time assessment. SCDHEC has begun using the monthly data collected at a subset of the SCECAP sites as part of their 305(b) reporting.