Cleaning Up Runoff

Simple ways to handle stormwater can protect the environment and prevent flooding.

We all want clean, healthy water in our rivers and lakes. Here are some ways to improve water quality and control flooding.

What’s at Stake

Extreme rainfall events are becoming more common, washing pollutants into local streams and lakes. Stormwater carries heavy metals, bacteria, phosphates, and other contaminants. It’s essential that we find ways to control and clean stormwater. When stormwater is captured, it can be filtered, so flood control can double as environmental protection.

A Pinch of Prevention

We can limit the harmful chemicals picked up by rainwater, including road salt. Researchers have only studied the environmental impact of salt for about five years—and, already, we know that it has a serious impact on aquatic ecosystems. The good news is that experts have found innovative ways to keep roads and highways safe in the winter with less environmental damage. A project in upstate New York saved taxpayer dollars, made roads safer, and cut road salt use in half.

See my story about this promising solution, recently published in Undark.

Rain Gardens

More and more cities are subsidizing infrastructure that captures and slows stormwater, allowing it to sink into the ground. Rain-conscious development reduces flooding and prevents toxins from being washed into local rivers and lakes. Rain gardens and bioswales are small depressions that use plants and soil to absorb and filter stormwater. These simple and attractive features can filter 80 percent of bacteria and 60 percent of chemical pollution from stormwater.

See my story about limited impact development in Southwest Dispatch.

Absorbent Parks

Some cities think bigger than rain gardens. Bangkok solved its chronic flooding problem by building a beautiful and innovative park that can absorb up to a million gallons of water during heavy rains. Wuhan, China, is planning a similar park as part of its quest to deal with stormwater.

See more about Bangkok’s park, including detailed illustrations, in this story by Patrick D’Arcy for TED Ideas. Also, see the architects’ renderings of Wuhan’s planned park.  

Whole-City Solutions

Some municipalities are pursuing innovative whole-city solutions, turning themselves into giant sponges. Chicago, Fayetteville, NC, Philadelphia, Oak Creek, WI, and Toronto are on the list of cities capturing stormwater in multiple settings. Those settings include roads, parking lots, rain barrels at residences, and municipal infrastructure.

A great example of municipal infrastructure design is an airport in Singapore that turned rainwater capture into a decorative feature.

See this story focusing on North American cities by T.R. Goldman in Politico. For international examples of cities like Singapore, Berlin, Bangkok, and Wuhan, see this story by Suzie Housley for the StormSensor corporation’s website.

Rain Tower at Jewel Changi Airport in Singapore. Source: Bennv3771, CC BY-SA 4.0, via Wikimedia Commons

Green Roofs

In densely developed areas, rooftop gardens are a great option to capture stormwater. These high-rise gardens feature grass, trees, and groundcover planted in a lightweight soil mix. Moisture barriers protect buildings with green roofs. According to the EPA, green roofs reduce runoff volumes, regulate building temperatures, and reduce urban heat island effects. Green roofs can be 30 to 40 degrees cooler than conventional roofs in summer.

See this website that explains the benefits of green roofs This story by Katie Pyzyk in Smart Cities Dive covers green roofs in D.C., which leads the nation in the number of green roofs.

Green roof in Chicago
A green roof, Chicago City Hall. Source: Conservation Design Forum, CC BY-SA 4.0, via Wikimedia Commons

Replacing Farm Runoff with Clean Energy

Cow manure sometimes escapes from the farm and enters rivers and lakes, especially during heavy rains. That runoff has a negative effect on aquatic ecosystems and makes lakes less savory for swimming.

There’s a clever way to prevent this, turning poop into power. A renewable energy generator called a biodigester converts cow manure into natural gas. The gas runs a turbine to produce electricity. Some states, like Vermont, offer dairy farmers the opportunity to sell manure-generated electricity back to the grid. Vermont’s program is called “Cow Power.”

Dairy farmers can diversify their income and protect local water quality at the same time. Because biodigesters process cow manure, waste isn’t running into streams and lakes, reducing phosphorus pollution in local waterways. Talk about a renewable resource!

Cow Power hasn’t taken off as well as Vermont had hoped because of the high startup cost of the biodigester equipment. But it’s still powering thousands of homes in Vermont, as well as ski resorts and breweries.

See this essay by Sandra Levine in the Rutland Herald, Gaen Murphree's story for the Vermont Land Trust, and this story by David Thill for the Energy News Network.