Reference site selection for monitoring and assessment of intermittent streams in the Northern Glaciated Plains Ecoregion of South Dakota

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Intermittent streams are defined as those stream channels which flow for only a portion of the year. These streams have well defined bed and bank features and typically display seasonal flow during spring and early summer before drying toward the middle and end of the growing season. Recent emphasis has been placed on monitoring and assessment of intermittent streams. Ephemeral and intermittent channels contribute the bulk of the nation’s stream network and contribute greatly to downstream water quality, habitat conditions, and biotic integrity. Clearer understanding of the importance of these small catchments to downstream water quality, habitat, and biotic integrity has fueled demands to expand protection and monitoring up into these headwater catchments. This project has defined intermittent, headwater stream reference sites and provided supporting field data for the Northern Glaciated Plains (NGP) ecoregion (LIII Ecoregion 46) of South Dakota. The objectives of this proposed effort were to 1) define candidate intermittent stream reference sites within the NGP; 2) conduct field sampling to characterize natural, intermittent reference stream water quality, physical habitat, and biological conditions; 3) define optimal macroinvertebrate metrics for monitoring headwater intermittent prairie streams; 4) define the appropriate index period for macroinvertebrate sampling within headwater intermittent prairie streams; and 5) validate selection of intermittent stream reference sites against random and targeted intermittent drainages within the NGP. Results of this effort demonstrate the utility of the U.S. EPA ATtILA ArcView extension as a screening tool to identify reference monitoring sites. The process used in this study to screen and score landscape metrics successfully established watershed scores falling along a gradient of human disturbance. Most of the variation in watershed scores of ecoregion 46 could be attributed to differences in agricultural development at both watershed and reach scales. Little variation was explained by urban development, road density, or human population density in this ecoregion. Macroinvertebrate communities inhabiting headwaters were very diverse and displayed differences both among LIV ecoregions and site classes. Results suggest that headwater invertebrate communities are sensitive to the human disturbance gradient in this ecoregion (as defined by ATtILA).

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ELECTRONIC FILE - Zoology

Final project report submitted to the U.S. Environmental Protection Agency, Western Ecology Division, Corvallis, OR