AWWA SRC57801

As part of the California Department of Health Services Drinking Water Source Assessment and Protection (DWSAP) Program, Black & Veatch completed a joint Sanitary Survey Update and Source Water Assessment for Nevada Irrigation District (NID) and Placer County Water Agency (PCWA) using tools including ArcView GIS and the US Environmental Protection Agency's (EPA's) Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) 3.0 computer program. The sixteen treatment plants NID and PCWA maintain are fed by watersheds located on the western slope of the Sierra Nevada mountains with an area totaling approximately 350 square miles. The complex relationship between topography, land use, pollution sources and other watershed-scale factors is extremely difficult to characterize with traditional tools such as tables containing data on pollution sources or charts of historic water quality data. EPA's most recent version of BASINS uses tools to rapidly combine EPA-provided GIS data from various sources, including the US Geological Survey, Bureau of Mines, US Army Corps of Engineers and the Federal Emergency Management Agency, with external, project-specific data obtained by the user. The resulting product allows the user to develop an appreciation for the watershed as a whole which is crucial for an accurate assessment. The output data was verified and used as a guide for more detailed aerial and foot surveys of high risk areas including freeways, railroads, grazing areas and other probable sources of contamination. The BASINS/GIS-based approach expedited access to the nationwide databases maintained by the EPA resulting in the efficient location and identification of point and nonpoint sources throughout the watershed. Data products derived from the system included land use maps, topographic maps, point source location maps as well as more traditional tabular data. When correlated with historic water quality data, data from the GIS based assessment method resulted in the recognition of potential water supply contaminants and their relative risk. This innovative approach allowed the agencies to develop management plans to ensure reliable delivery of clean source water to the sixteen system treatment plants. Includes 8 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

01/19/2003

Number of Pages:

10

File Size:

1 file , 440 KB