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A MULTI-SCALE SCREENING PROCESS TO IDENTIFY LEAST-DISTURBED STREAM SITES FOR USE IN WATER QUALITY MONITORING
Citation:
Lattin, P. D., L. McAllister, AND P L. Ringold. A MULTI-SCALE SCREENING PROCESS TO IDENTIFY LEAST-DISTURBED STREAM SITES FOR USE IN WATER QUALITY MONITORING. Presented at American Water Resources Association Summer Specialty Conference, Olympic Valley, CA, June 28-30, 2004.
Description:
We developed a four-step screening procedure to identify least-disturbed stream sites for an EPA Environmental Monitoring and Assessment Program (EMAP) pilot project being conducted in twelve western states. In this project, biological attributes at least-disturbed sites are used to characterize a least-disturbed condition for streams located within pre-defined biophysical strata. It is important to describe the least-disturbed condition because the biological condition at these sites is a benchmark used in assessing stream health regionally. The screening procedure consists of four steps: 1) a GIS-based screen to evaluate disturbance levels within nested catchments; 2) a fine screen that uses online orthophotos and topographic maps to examine catchments in greater detail; 3) evaluation by local experts; and 4) aerial and ground verification. In each step, candidate sites and their upstream catchments are evaluated semi-quantitatively based on the presence and severity of human-related disturbances and their likely impacts to the stream. The least-disturbed sites filter through to successive steps. Preliminary analyses suggest that the procedure is an accurate tool for selecting least-disturbed stream sites at a regional scale. The process has been applied in Utah and the Northern Great Plains ecoregion and will be applied in Nevada in 2004. The basic procedure can be adapted for a wide range of ecological applications.