Protected source water is key to the economic production of potable water that meets all local,
state and federal drinking water requirements. 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 Geographic Information Systems (GIS) and the United States 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 U.S. Geological Survey, Bureau of Mines, U.S. 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 tables.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 540 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 4 |
| Published : | 06/16/2002 |
