Monday, November 5, 2007
19-15
Langford Creek Stream Assessment.
Eric Buehl, Center for the Inland Bays, 39375 Inlet Road, Rehoboth Beach, DE 19971 and Bruce Allison, Environmental Science, Wesley College, 120 N. State St., Dover, DE 19901.
The land in a watershed and how it is used affects surface water quality. Poorly managed soil easily erodes and can affect water quality by reducing light penetration and smothering bottom-dwelling organisms, and when transported into receiving waters, fertilizers from farms and lawns can cause increased growth in algae, creating low dissolved oxygen conditions. The ability to utilize online models in tandem with a visual stream assessment offers a timely and efficient alternative to costly long-term monitoring and detailed watershed analysis. The objective of this project was to determine the water quality status of Langford Creek utilizing web-based computer models/databases and infield observations. Land use, land cover, and soils data were developed using ArcView version 3.X geographic information system software and the USDA Natural Resources Conservation Service's (NRCS) Web Soil Survey. Methods to evaluate water quality included the use of the computer models InterWET and Long-term Hydrologic Impact Assessment (L-THIA) and NRCS's Visual Stream Assessment Protocol. InterWET and L-THIA were used to estimate nutrient and sediment loads and surface runoff based on site conditions. Pollutant loads calculated with InterWET and L-THIA were compared with data developed by the Chesapeake Bay Program (CBP). Modeled water quality data were then compared with several elements of the visual stream assessment of West Langford Creek utilizing the NRCS Protocol. The computer simulations, the CBP data, and the Visual Stream Assessment Protocol elements indicated that West Langford Creek was in poor condition and was stressed by excess sediment and nutrient loads due to surrounding land use and land cover. Being able to use these methods to rapidly assess water quality can benefit site designers, planners, and concerned citizens.