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Technical Report

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Illinois River Watershed, Vision, Water Quality, Watershed Conditions


Understanding how water quality conditions change along a land use gradient and over time is important for sustainable watershed management. Therefore, a volunteer monitoring program was created to measure water chemistry at 37 established sites within the Upper Illinois River Watershed and to evaluate changes in water chemistry over the past 15 years. The Illinois River Watershed Partnership (IRWP), a non‐profit organization subcontracted with the Arkansas Water Resources Center at the University of Arkansas, to manage the volunteer monitoring project, train volunteers to collect samples following EPA approved methods, and to analyze the collected samples. The AWRC trained 27 volunteers to collect water samples at 37 sites that were previously sampled in 1993 and 1994. Samples were collected during baseflow conditions during September and December 2008 and February and May 2009 and analyzed for soluble reactive phosphorus, nitrate‐nitrogen, sulfate, chloride, fluoride, total phosphorus, total nitrogen, total suspended solids, and turbidity. Geomean concentrations were calculated and compared to the concentrations observed during the 1993‐1994 study. Overall, total phosphorus and soluble reactive phosphorus concentrations significantly increased at 14% and 11% of the sampled sites, respectively, between the previous and current studies, while respective concentrations significantly decreased at 8% and 16% of sampled sites. The greatest reductions in phosphorus concentrations occurred at sites downstream of effluent discharges, and both total phosphorus and soluble reactive phoshporus concentrations were positevely correlated to pasture and urban land use within the catchment (R²= 0.11, P=0.045; R²= 0.16, P=0.015, respectively). Similarly,both total nitrogen and nitrate‐nitrogen concentrations were positvely correlated to urban and pasture land use (R²= 0.38, P <0.0001; R²=0.29, P=0.0006, respectively), and 5% and 14% of the sampled sites significantly increased in total nitrogen and nitrate nitrogen concentrations, respectively, between the two study periods. Overall, very few significant changes in water quality (i.e., water chemistry) were observed over the last 15 years; those changes that were most noticeable resulted from either improvements in the phosphorus mangement of waterwater treatment facilities or the introdiction of effluent discharge into a new receiving stream. Volunteer monitoring programs are an excellent way to promote environmental education and stewardship, and these programs can be useful in documenting changes in watershed conditions over time.

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