Nation Tribal Jurisdictional Area, base flow decreased by 292,000 acre-feet, or 28 percent. Streamflow in the North Canadian River at the streamflow-gaging station at Shawnee, Okla., decreased during the hypothetical drought by as much as 28 percent, and the mean change in streamflow decreased as much as 16 percent. Streamflow at the Shawnee streamflowgaging station did not recover to nondrought conditions until about 3 years after the simulated drought ended, during the relatively wet year of 2007. Water Use Groundwater demands in the CPN Tribal Jurisdictional Area are predominantly from municipal and domestic wells (Mashburn and others, 2013). Water use is regulated by the Oklahoma Water Resources Board (OWRB) and reported by water-use permit holders as total annual pumping. For this report, monthly time increments of water pumping amounts were used. To convert annual water use from the Central Oklahoma aquifer model to monthly time periods, the OWRB estimate of the monthly percentage of the annual water discharge for different categories of wells pumped by county (Oklahoma Water Resources Board, 2012) was used. Other municipal demands were met through surface-water storage in reservoirs and were not included in this analysis.