The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Thursday, January 31, 2008 - 8:40 AM
Trends in Surface-Water Quality of an Intermittent Cold-Desert Stream
Christopher A. Ellison1, Quentin D. Skinner1, and Larry S. Hicks2. (1) Renewable Resources, University of Wyoming, 1000 E. University Avenue, Dept 3354, Laramie, WY 82071, (2) Little Snake River Conservation District, PO Box 355, Baggs, WY 82321
Muddy Creek in south-central Wyoming is listed as impaired by the U.S. Environmental Protection Agency due to habitat degradation. The Little Snake River Conservation District, U.S. Bureau of Land Management, Wyoming Game and Fish Department, and the University of Wyoming initiated watershed improvement best-management practices (BMPs) to address Muddy Creek’s unstable stream channels, degraded riparian function, and to satisfy requirements of the Clean Water Act. Despite the enormity of data collected to evaluate watershed BMPs, an analysis encompassing the entire improvement effort has yet to be accomplished. Analysis and interpretation of Muddy Creek’s flow regime, water quality parameters, and chemical constituents from 1985 to 2006 were conducted to determine trends in surface-water quality. Flow analyses identified reductions in percents of flow duration intervals between the impaired stream’s upper and lower boundary monitoring sites and in hydrograph peaks between pre- and post-BMP implementation. Following BMP implementation, reductions in specific conductivity, total dissolved solids, and turbidity among years were observed in the impaired stream section. Further analysis of these data indicates that time-series modeling is superior to simple linear regression in predicting total dissolved solids and turbidity. Linking water quality improvements to specific BMPs are uncertain; however results strongly suggest that positive trends are correlated to BMPs that stabilized stream channels and improved the condition of riparian areas. Naturally erosive conditions in the basin along with anthropogenic impacts elevate the importance of BMP implementation and a long-term monitoring program. Both are needed to evaluate the effectiveness of improvement efforts and to help resource managers develop practical watershed improvement management strategies so that optimum conditions in Muddy Creek basin can be achieved.