IN THIS, OUR SECOND-WETTEST MONTH, when clouds converge to clog the heavens and our days acquire a hue best described as dishwater, the gardens surrounding Mt Tabor Middle School will, quite literally, come rushing to life. The purpose of these plots, brimming with wispy sedges, spiky rushes and other ornamental grasses, is not solely decorative: They will also help keep rainwater from flooding neighborhood basements.

Before the gardens’ arrival, the rain that fell on the school’s four acres of roofing, concrete and asphalt had nowhere to flow but straight into a World War I-era terra-cotta pipe beneath SE Pine St, but the conduit was too narrow to handle the runoff, which ended up overflowing into nearby homes. To combat the soggy siege, the city and Portland Public Schools replaced a chunk of the school’s parking lot with a "rain garden" designed to capture more than 90 percent of the water that falls on school grounds, and to bring Mount Tabor’s impromptu basement pool parties to an end. The success of similar projects around town helped vault storm-water management from good idea to rule of law last April, when the City of Portland passed a Green Streets resolution. Now all city-funded development projects must incorporate methods to manage runoff.

Of course, Mount Tabor’s gardens and the school’s other rainwater collection structures cost about the same as replacing the troublesome pipe—roughly $850,000—but that wouldn’t have been nearly as pretty (the gardens earned a design award from the American Society of Landscape Architects in October). Nor would students have a year’s supply of science lessons just outside their classroom window.