Reconnaissance of benthic invertebrates from tributary streams of the Yampa and North Platte River basins, northwestern Colorado

Benthic invertebrates were collected from tributaries of the Yampa River in Routt and Moffat Counties, and tributaries of the North Platte River in Jackson County. Field water-quality measurements of water temperature, specific conductance, pH, dissolved oxygen, and bed material size were also made to aid in assessing stream water-quality conditions. The purpose of the study was to describe and quantify the benthic invertebrate communities in selected streams in coal mining areas. Stream sampling sites were located upstream and downstream from potential, existing, or historical coal mining areas. Sampling was conducted on a near bimonthly basis throughout the growing season, beginning in April and May 1980, and continuing through September 1981. The density of benthic invertebrates generally increased downstream in all streams sampled. Most of the variation in densities and taxa among the stream sites was associated with sampling date differences. There were also some strong correlations of benthic invertebrate densities with measured water-quality constituents and properties. However, a larger sample size (greater frequency of sampling) may influence this relation. (USGS)