Publications / Lower Fryingpan River Benthic Macroinvertebrate Study on October 2013 and April 2014

Lower Fryingpan River Benthic Macroinvertebrate Study - October 2013 and April 2014

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Executive Summary

Benthic macroinvertebrate communities serve as indicators of stream and ecosystem
function. Previous work completed on the Fryingpan River by Miller Ecological
Consultants, Inc was used to determine the stream conditions in 2001 through 2003. In
those previous studies, a fall and spring sampling regimen was used to determine changes due to winter flow conditions. This study used the same fall and spring sampling period and two of same locations to update the current condition of the macroinvertebrate community in the Fryingpan River in three locations. Sampling took place at three sites,

  • Site 1 – at Basalt,
  • Site 2 – downstream of Taylor Creek, and
  • Site 3 – downstream of Ruedi Dam.

Site 2 and Site 3 were the same sites sampled during the fishery studies
conducted in 2001 through 2003. Sampling efforts followed the same protocols as the
2001-2003 study. The results from 2013 -2014 provide an update on the stream conditions since the last sampling in 2003. The main evaluation factors of diversity, evenness, taxa richness, EPT and functional feeding groups all provide insight into the current stream conditions.

In general, results of fall 2013 and spring 2014 were similar to results from the previous study in 2001 through 2003; however, some differences were observed in taxa richness, evenness and EPT values. The difference in sample analysis (600 count for 2013-2014 and full count for 2001-2003) may account for some of the difference. Results of the 2013-2014 sampling are most similar to the data from spring 2003 for most metrics. Functional groups
exhibited similar composition during all years with slight variation occurring mostly in the scraper and predator groups. The distribution of the functional feeding groups is similar to the species distribution. There is more complexity in the types of feeding groups in the downstream section of the Fryingpan River compared with the area near the dam.

The current condition of the macroinvertebrate community is similar to conditions
monitored in 2003. The metrics used for the evaluation show that the macroinvertebrate community does not show signs of impairment, especially in the downstream reaches. Taxa richness and EPT values are somewhat lower than those in 2001 – 2003. It may be useful to conduct additional sampling in future years to determine if this signifies a downward trend or is within the natural variability of the river. Overall, the data show that the lower Fryingpan River has the expected stream conditions for a tailwater stream.

The macroinvertebrate community indicates generally good stream conditions, however, the reduced number of taxa may be the result of recent changes in the flow regime. The following recommendations are made to monitor the benthic macroinvertebrate community.

  • Monitor the three sites at least every 2-3 years to track any changes resulting from the late summer flow releases.
  • Continue to monitor water temperatures at all three locations ( dam, Taylor Creek and Basalt).
  • Compile an annual summary of discharge and water temperature for the lower
    Fryingpan River.

Contact Us

Roaring Fork Conservancy

PHONE: (970) 927-1290

PO Box 3349
Basalt, CO 81621

22800 Two Rivers Road
Basalt, CO 81621

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