Science

A closer look at the statewide condition of stream biology in Vermont

Comparing nutrients and biological condition across the state, region, and nation

Comparing nutrients and biological condition across the state, region, and nation

Vermont Department of Environmental Conservation (VTDEC) scientists recently completed a large survey to assess the statewide health of Vermont’s rivers and streams. This study involved detailed assessments of 73 randomly selected stream sites, including fish population surveys, macroinvertebrate sampling (i.e. insects and other small creatures that live on the stream bottom), and water chemistry monitoring. This survey builds on a similar study completed by VTDEC five years ago, and coincides with EPA’s National Rivers and Streams Assessment (http://water.epa.gov/type/rsl/monitoring/riverssurvey/).

Our statewide survey produced several interesting results. Overall, the condition of Vermont’s streams is relatively similar to what we saw five years ago. However, there was a noticeable decline in streams with highly rated fish and macroinvertebrate communities. When we looked at the data more closely, we saw that most of this difference was accounted for by streams that were assessed in 2011 and were severely affected by scouring flood flows during Tropical Storm Irene. We have seen biological recovery at most of our long-term monitoring sites in the three years since this storm, but climate change will increase the likelihood of more damaging events of this nature.

While watershed development was relatively low at these randomly selected sites, agricultural use and corresponding nitrogen and phosphorus concentrations did seem to have an effect on biological condition. However, when compared to results from throughout the nation and our Northern Appalachians eco-region (including the rest of New England, and parts of New York, Pennsylvania and Ohio), we see that Vermont is outperforming other areas for both nutrient and biological indicators. In fact, Vermont had 42% of stream miles rated as “Good” for phosphorus using EPA thresholds, compared to only 7% of streams in our eco-region.  Despite significant water quality problems in parts of our state, this is encouraging for our overall ability to protect and maintain stream water quality.

VTDEC plans to continue these surveys every five years, which will provide further insights into patterns in biological condition over time. The final report on this study is available at: http://www.watershedmanagement.vt.gov/mapp/docs/mapp_nrsa_prob2008_2012.pdf

Collecting macroinvertebrates in the Lamoille River below Fairfax Falls (Photo courtesy of Jim Deshler)

Collecting macroinvertebrates in the Lamoille River below Fairfax Falls (Photo courtesy of Jim Deshler)