Sweetwater Builds New Reservoir An illustration on this page shows the recently completed Sweetwater, Tex., reservoir dam during construction. It is located about seven and one half miles south of Sweetwater, which is in Nolan County, and it has a capacity of a billion and a quarter gallons. It is filled from a watershed of sixty-five sections and also by numerous springs. The reservoir is high enough for the water to flow into the city and into the mains by gravity. A 12-inch main conveys the water to the distribution system of the city.