INVER GROVE HEIGHTS (AP) - Some Minnesota cities are using rain gardens and other green infrastructure to keep stormwater from polluting lakes and rivers.

Many of them are small efforts, but a large-scale system in Inver Grove Heights has become somewhat of a national example. The rain garden, which spans more than 3,000 acres in one of the city's commercial development sites, was among eight engineering projects this year to receive top awards from the American Council of Engineering Companies.

Engineer Brett Emmons, whose firm helped design the five-year-old system, says it's performing better than expected and shows green infrastructure's potential.

Other stormwater projects in the Twin Cities area have been equally successful.