Stormwater: Problem or Asset?

Urban development greatly increased stormwater runoff in communities. Although ancient civilizations understood the need for sewer systems to collect and carry rainwater, nineteenth- and early twentieth-century city planning was often unconcerned with stormwater effects. Stormwater runoff flows directly into wetlands, lakes, and rivers, picking up trash, waste, nutrients, and chemicals along the way and causing algae blooms and pollution. In 1969 the Cuyahoga River in northeastern Ohio caught fire due to water pollution, sparking nationwide calls for regulation that culminated in the 1972 passage of the Clean Water Act and comprehensive efforts to study, understand, and manage stormwater. Since those early efforts, thinking has shifted from directing stormwater off site simply to reduce flooding toward retaining rain where it falls, minimizing runoff, and increasing infiltration and groundwater recharge. Maplewood's early roads usually had ditches, but as the city matured, curbs, gutters, and storm sewers became part of the urban landscape and quickly moved water away from neighborhoods. Today stormwater is treated as an asset instead of a problem. In 1997 Maplewood's first rain garden was built on Birmingham Street, and rain gardens in yards can capture runoff from roofs, drives, and in some cases boulevards. Rain gardens, shallow depressions typically planted with native flowers and grasses, are a popular way to filter runoff from roofs, sidewalks, and driveways. Most stormwater in this neighborhood historically flowed directly into Lake Phalen with no treatment, but in 2012 Maplewood constructed a two-cell infiltration basin system at Gladstone Savanna to capture and treat a 1.5-inch rainfall event. Runoff from the neighborhood is piped into the northern cell, where sediments settle out and small rain events infiltrate. During heavy rains, water flows beneath the trail into a dry creek bed and spreads into the southern infiltration basin, where stormwater seeps into the soil, microbes break down pollutants, and groundwater aquifers are recharged. In heavy rains, excess water bypasses the Savanna and is piped west to Lake Phalen.

Maplewood, Minnesota · United States