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An Assessment of Condition of Streams and Rivers in EPA Region 8 Using EMAP - West Data

Thomas R. Johnson 1 , Karl A. Hermann 1, and Sarah Spaulding 2

1 U.S. Environmental Protection Agency (USEPA), Region 8, Denver, Colorado
2 U.S. Geological Survey (USGS), Denver, Colorado

The US EMAP-West project has completed an assessment of stream condition of the entire western US based on biota, chemistry, and physical habitat at more than a thousand randomly selected sites sampled from 2000 to 2004. A further goal of the project is to assess condition at smaller geographic scales, including assessments at the individual state level. Of the total number of sites surveyed, 430 sites are within the six states in EPA Region 8 (Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming). The original sampling design created for EMAP-West was developed to specifically allow for this type of state and regional assessment. Staff from the Region 8 state agencies, U.S. Geological Survey, U.S. Environmental Protection Agency (USEPA) Region 8, and the USEPA Office of Research and Development (ORD) are collaborating to assess ecological stream condition with a fine-scale regional approach.

For this analysis, indicators were developed at individual state level or by specific Omernik Level 3 ecoregions. Indicators are composed of Indices of Biotic Integrity (for macroinvertebrates, fish, and periphyton) and predictive models (for macroinvertebrates). A suite of chemical, physical, and biological stressors are being analyzed for natural gradients and their relationship to biotic indicators. Land use metrics obtained from GIS data will also be related to certain stressors. An assessment of the streams in each individual state, a number of ecoregions, the upper Missouri basin, and EPA Region 8 will be published in a single volume with separate chapters by reporting unit. A collaborative assessment approach such as this effort is unique within the EMAP-West study. Benefits of collaboration include sharing reference site data and evaluation, cross training in assessment methods, and consistency of the assessment approach and reporting.

Keywords: ecological assessment, biological indicators, surface water, monitoring, water quality

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