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Green Infrastructure…It’s Hip

May 24, 2016

According to an Environmental Protection Agency survey, much of the nation’s waters (55% of assessed rivers and streams, and 70% of assessed lakes) fail to meet federal and state water quality standards. Addressing many of these problems will require expanded treatment of sewage and industrial discharges. The sources for most of the impairments are farm fields, urban spaces, and other “nonpoint sources” of pollution.

Nonpoint source (NPS) pollution comes from many sources. As our country has urbanized, the volume of nonpoint source pollution has grown. Buildings, pavement and compacted landscapes do not allow rain and snow melt to soak into the ground. This greatly increases the volume and velocity of stormwater runoff. Stormwater drains through gutters, storm sewers, and other engineered collection systems, discharging into nearby water bodies. 

Pollutants from urban runoff include sediment; oil, grease, toxic chemicals, and heavy metals from vehicles and other sources; pesticides and nutrients from lawns and gardens; and road salts.  If left uncontrolled, this water pollution can lead to the destruction of fish, wildlife, and aquatic life habitats; a loss in aesthetic value; and threats to public health due to contaminated food, drinking water supplies, and recreational waterways. 

Climate change is increasing the impact of urban runoff. Flood events in the Northeast have risen in association with increases in precipitation, particularly extreme events, with a 74% increase in the heaviest 1% of all precipitation events since 1958. As more frequent and damaging storms associated with climate change occur, communities in the Northeast are adversely impacted. Higher runoff flows resulting from heavy rains can cause erosion and flooding in urban streams, damaging habitat, property, and infrastructure. And, of course, the higher runoff flows result in more pollutants entering our waters.

Green infrastructure incorporates compost and soils; plants, trees, and other types of vegetation; and other elements (such as stones) and practices to restore or mimic the natural processes required to manage water and improve urban environments. Green infrastructure includes the use of compost for soil building and natural landscaping to prevent streambank erosion; adoption of low cost practices such as rain gardens in business and neighborhood areas; revitalization of vacant lots through soil remediation and urban gardening; the use of permeable pavements, infiltration planters, trees and tree boxes; and more.

The incorporation of green infrastructure in stormwater management isn’t a new concept. It has been adopted by a number of communities over the past few decades. It offers a cost-effective, resilient approach to managing wet weather impacts that provides many community benefits. Conventional “gray” stormwater infrastructure comprised of piped drainage and water treatment systems is designed to carry urban stormwater away from the built environment. Making improvements to these systems is costly.

Green infrastructure offers a relatively low cost way of reducing and filtering stormwater at its source. By retaining, degrading, and absorbing pollutants, green infrastructure effectively improves the quality of runoff and significantly reduces the quantity of flow that ends up in our stormwater systems. Moreover, it’s scalable—from rain gardens at home, buffer strips in parking lots, and green roofs, to regional approaches such as conservation of large tracts of open land and woodlands. Combined with gray infrastructure, interconnected networks of green infrastructure help to build community resiliency by increasing water supplies, improving water quality, reducing flooding, aiding in carbon sequestration, and decreasing urban heat island effects.

So compost, cleaner water, lower costs…what’s not to love?!

By Athena Lee Bradley

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