Tuesday, May 27, 2008 - 11:30 AM
157

Ecological futures for stream fishes along an intermittent great plains riverscape affected by drought and groundwater withdrawal for irrigation

Jeffrey A. Falke1, Kurt D. Fausch1, Robin Magelky2, Angela Squires2, Deanna Durnford2, Linda Riley2, and Ramchand Oad2. (1) Department of Fish, Wildlife, and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, CO 80523-1474, (2) Department of Civil and Environmental Engineering, Colorado State University, 1372 Campus Delivery, Fort Collins, CO 80523-1372

Across the western Great Plains, groundwater pumping for irrigated agriculture is depleting regional aquifers that sustain stream flow for native fishes.  Simultaneously, the region has undergone a multi-year drought that further reduced stream flow and increased water demands by agriculture.  We surveyed fish habitat quantity and connectivity at the segment and basin scales during spring and summer 2005-2007 to investigate linkages between habitat drying and groundwater dynamics. Based on our empirical observations, along with historical groundwater and stream flow data , we constructed a linked regional and alluvial groundwater model to investigate how irrigation pumping and riparian evapotranspiration affect groundwater stage and fish habitats.  Our model suggests that under the status quo of pumping, habitats for stream fishes are not sustainable into the near future.  Based on minimum habitat requirements, we recommend reduced pumping to maintain habitat quantity above a conservation threshold that will allow persistence of fishes and critical habitats.  Reduced water use mandated by an interstate compact may provide more habitat for native plains fishes in the future.  Our ongoing research is aimed at optimizing habitat by recommending irrigation alternatives in areas of the aquifer that supply groundwater to critical refugia for plains fishes along the riverscape.


Web Page: groundwater, agricultural irrigation, stream fishes