Ecoflows: Developing Indices of Streamflow Alteration

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The Minnesota Pollution Control Agency (MPCA) lists streamflow alteration as a key stressor on aquatic life in many watersheds. However, the MPCA currently does not have the information needed to quantitatively associate metrics from Index of Biological Integrity (IBI) surveys with metrics of streamflow alteration.  We are using USGS streamgage data and MPCA IBI data to develop relations between streamflow alteration and biological responses.

The goal of this study is to quantify relations between altered hydrology and responses of fish and invertebrate communities. The Minnesota Pollution Control Agency (MPCA) will use this information to evaluate watershed conditions and develop plans to restore and protect aquatic ecosystems in the watersheds. This study is being completed in two phases.

 

Red Lake River Bank Sloughing

Red Lake River Bank Sloughing (Credit: Jeffrey Ziegeweid, USGS)

In Phase 1, we used data from long-term USGS streamgages to calculate hydrologic metrics for two time periods (1945-79 and 1981-2015). Time periods were selected based on literature focusing on trends in streamflows. A total of 178 hydrologic metrics were calculated using streamflow records and the EflowStats package in the R Statistical Environment. Metrics were compared between sites with and without observed trends in streamflow in order to identify metrics that could be used as indicators of altered hydrology.

 

 

 

 

 

Agricultural Tile Drain in Rice Creek, South-Central Minnesota

Agricultural Tile Drain in Rice Creek, South-Central Minnesota. (Credit: Jeffrey Ziegeweid, USGS)

In Phase 2, we are comparing metrics used to calculate Index of Biological Integrity scores from fish and invertebrate sampling conducted by the MPCA to hydrologic metrics calculated in Phase 1. Statistical relations between hydrologic and biological metrics will be developed to characterize changes in aquatic communities based on changes to hydrology in rivers throughout Minnesota.

Des Moines River Bank Sloughing and Sediment Depositional Areas

Des Moines River Bank Sloughing and Sediment Depositional Areas. (Credit: Jeffrey Ziegeweid, USGS )

 

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