Impact/Purpose:

The purpose of this project was to define the current condition of biological communities in headwater streams in the Southern Rocky Mountains Ecoregion and define what proportion of streams are affected streams by high metals loadings. Additional purposes included determining what biological indicators are suitable for detecting metals impacts, what constitutes a reference condition in mineralized areas of the Rocky Mountains and to determine if the EMAP scale be appropriately adjusted to target and analyze problems in this ecoregion.

Description:

Investigators conducted pilot work on indicators in 1993 and the full project, including sampling of biological, chemical, and physical parameters in selected headwater streams, was conducted in 1994 and 1995. The population of interest was streams within the Southern Rocky Mountains Ecoregion, with sampling limited to mineralized areas. During the initial selection process, streams were stratified according to stream size. Seventy-three random sites were sampled over the tow-year period. Additionally, 6 reference and 7 test sites were sampled. The sampling period was limited to August and September to take into account both biological and logistical considerations such as accessibility, lower streams flows for higher metal concentrations and larger macroinvertebrate. Products: Clements, W.H. and D. Carlisle. Date unknown. Development and validation of a regional biotic index to assess the effects of heavy metals on headwater streams of the Southern Rocky Mountain Ecoregion. Final Report to U.S. EPA, Region 8, Denver, CO. Clements, W.H., D. Carlisle, J. Lazorchak, and P. Johnson. 1998. The effects of heavy metals on benthic macroinvertebrate communities in Colorado's headwater streams. Bull. North Amer. Benthol. Soc. 15:165.

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