Maffitt Lake is a reservoir in the four corners of Dallas County, Polk County, Warren County, and Madison County, Iowa. It is located at 41.517°N 93.792°W / 41.517; -93.792.
Map of Dale Maffit Reservoir, Iowa 50061, USA
It is owned by the Des Moines Water Works that serves as an emergency water supply for the city of Des Moines, Iowa. In a drought emergency, the level of the Raccoon River could be brought up by draining water from the lake into the river.
Also a nice place to take a walk, as there are a significant number of trails and picnic areas in this parklike setting.
References
Dale Maffitt Reservoir Wikipedia(Text) CC BY-SA