Rainstorms are a challenge to clean water. They can cause flooding and potentially damaging runoff . But utilities, landscape architects and others are finding solutions — visible everywhere from the county grounds to your neighborhood ice cream shop. In 2011, MMSD built a large basin on the Milwaukee County Grounds. It's a 17-foot-deep sunken pool with grassy walls that, when full, looks like two connected natural lagoons. The basin can hold up to 315 million gallons of water. » See More Project Milwaukee: Great Lakes, Troubled Waters Reports Tom Chapman, project manager for the Milwaukee Metropolitan Sewerage District (MMSD), says the intent of the project is "to store the water upstream so that it’s not in the flood plains, flooding structures downstream." "Depending on the size of the event, it could take a day or longer to fill up, and then it’s held back here for a number of days and released slowly through an outlet structure on the downstream side of the basin," he says. The