The city's green roofs and green alleys have garnered attention, but still make up only a small portion of the city's large footprint.
"When it rains like cats and dogs in Chicago, the combined sewers overflow and release stormwater and untreated waste into the Chicago River. As the city's own Web site acknowledges, this hurts the river's health and habitat. The excess stormwater can even flood homeowners' basements. The problem persists despite the presence of the so-called "Deep Tunnel," a massive network of tunnels meant to divert the runoff and move it to surface reservoirs until water reclamation plants can sanitize it. Not only is this stormwater management system unable to handle big rainfalls, it's enormously expensive."