Washington County to build a reservoir and park at Toquerville Ash Creek project would improve existing water system, but is it really needed? (Google Maps) This satellite image shows the area where a proposed reservoir and park could be developed in Washington County. | Updated: 6:15 p.m. A new reservoir could soon be filling near Toquerville where Washington County water officials hope to create a park on federal land where they plan to capture water from Ash Creek, an important Virgin River tributary. The $35 million project is intended to better utilize existing water infrastructure associated with Ash Creek — including a spring that produces millions of gallons of high-quality water that is largely used to water alfalfa — rather than develop new ones, according Zach Renstrom, general manager of the Washington County Water Conservancy District.