In March, Susan Bryan cooked up thirty-four batches of play dough, dyed them blue and green, and packed them in old yogurt containers. No, she’s not a preschool teacher; she’s the county’s rain garden coordinator. She needed dough, along with some bendy straw “downspouts,” to help thirty would-be Master Rain Gardeners learn how to contour land to retain stormwater.

“Our goal is to make rain gardens commonplace,” says Harry Sheehan, environmental manager at the county water resources office. “We want thousands of people to do this.”

They’ll have their work cut out for them. Through 2010, only about 165 rain gardens had been installed in Ann Arbor. The city is hoping to encourage more, and in doing so, diminish troublesome storm water runoff, by offering discounts to anyone who installs a rain garden, cistern, or rain barrel, or pledges to run a RiverSafe Home (by, for example, properly disposing of hazardous wastes and minimizing use of lawn fertilizers). Do all three and you could save 25 percent on your storm water bill.