20 YEARS OF CONTINUOUS WATER-QUALITY MONITORING IN THE CHENEY RESERVOIR WATERSHED, SOUTH-CENTRAL KANSAS

Cheney Reservoir, located in south-central Kansas, is a primary drinking-water source and an important recreational resource for the City of Wichita. Constituents of concern in Cheney Reservoir include nutrients, sediment, and taste-and-odor compounds. Water-supply needs and reliance on Cheney Reservoir are likely to continue to increase with ongoing population growth and urban development. Source-water protection is essential to preserving water-quality conditions and ensuring safe, reliable drinking-water supplies in the future. The U.S. Geological Survey, in cooperation with the City of Wichita, has been collecting continuous water-quality data that are transmitted in near-real time at two sites in the Cheney Reservoir watershed since 1998 using in-situ water-quality monitors equipped with sensors for water temperature, specific conductance, dissolved oxygen, turbidity, chlorophyll and phycocyanin fluorescence, and fluorescent dissolved organic matter. Long-term data and their interpretation are critical to understanding factors influencing water quality, changes in water-quality conditions over time, and developing robust regression models to compute occurrences, concentrations, and loads of constituents of concern. Ongoing data collection provides the long-term data required to document changing water-quality conditions that may be due to best management practice implementation in the watershed. Additionally, these data are used to refine continuous real-time water-quality models that provide notification of changing water-quality conditions and inform decisions by water-treatment operators. The knowledge gained using continuous water-quality monitors assists in the development, implementation, maintenance, and assessment of watershed-management goals and plans to maintain Cheney Reservoir as a public-water supply and recreational resource.