Stormwater Control Technology: Reclaiming Urban Watersheds
Editor's Note: This article was written by Nancy Steele for the Switzer Foundation Spring 2009 Newsletter.
The Los Angeles basin relies on imported water for about 60 percent of its water supply – sources which are becoming increasingly restricted and less than reliable. Opportunities for additional surface water storage are limited in the developed Los Angeles basin, but the groundwater aquifers have much unused capacity, over 1million acre-feet in 2006. If the questions surrounding the feasibility of utilizing stormwater runoff for groundwater recharge could be resolved, the result may be greater self-sufficiency for the Los Angeles Basin in terms of water supply reliability.
In 2000, the Los Angeles & San Gabriel Rivers Watershed Council, a non-profit collaboration of government, business, community groups, and academia, convened a group made up of representatives from federal, state, and local agencies to address the potential benefits and barriers to conserving rainfall and runoff. The Los Angeles Basin Water Augmentation Study was designed to assess the water quality implications of infiltrating urban storm water runoff to augment water supplies and to reduce pollution from urban runoff.
Over its history, this study has been funded and managed by eleven public and private partners and has received in addition five competitive grants. After six years of data collection at six sites throughout the LA Basin, the study concluded that pollutants in storm water are efficiently removed as the water moves through the soil and thus infiltration is a safe and effective way to increase water supplies.
Demonstrating Green Streets: Elmer Avenue
Phase III of the study is a neighborhood scale demonstration of retrofitting a neighborhood to capture and infiltrate stormwater. Using a variety of criteria, the partners chose a working-class community in northwest Los Angeles for the demonstration site. The one-block street presently collects run-on from approximately forty acres of urban landscape; there is no storm drain system and the neighborhood suffers from street flooding during storms.
This one-block community enhancement project will use a mixture of strategies to reduce flooding and water pollution, increase local groundwater, and add more green space with an emphasis on native, drought-tolerant landscaping. Some residents will have rain gardens on their properties, and all residents will be taught how to take care of their new landscapes. Strategies to be employed include underground catch basins at the head of the street to divert run-on connected to infiltration galleries running under the street. Infiltration galleries will also be connected to vegetated swales and driveway drains. Residents will gain sidewalks, street lights, and additional trees and green spaces. Native plants gardens will be designed to attract birds and butterflies. The Watershed Council will be installing the private property components and the City is installing all features in the public right of way.
Construction has begun on Elmer Avenue; the anticipated completion date is June 2009, but California’s budget woes have temporarily stalled the project.
For more information about this project, or about Nancy Steele's work with the Los Angeles and San Gabriel Rivers Watershed Coalition, contact her at nancy@lasgrwc.org.
