How homeowners can manage stormwater sustainably
North Texas Municipal Water District (NTMWD) recently installed green stormwater infrastructure (GSI), also called low-impact development, at a building and parking lot near its administrative offices in Wylie. GSI projects are designed to slow fast-moving stormwater using methods that mimic the natural environment.
NTMWD services some of the fastest-growing counties in the United States. The rapid growth brings miles of new roads and thousands of new roofs every year, and these impervious surfaces change how stormwater flows across our watersheds. Most infrastructure is built to move water off the roads and into storm drains as quickly as possible, preventing the gradual absorption of stormwater into the soil. 
According to David Cowan, NTMWD Watershed Manager, fast-moving stormwater can increase erosion and cause water quality issues.
“With heavy rains, all the water that lands on impervious surfaces is going to rush into a storm drain,” he said. “It's going to flow into a stream, and the erosion that takes place is much greater than if you have, let's say, a field with native grasses.”
Erosion is not the only concern. Rushing stormwater isn’t naturally filtered by the soil before entering streams and, eventually, our lakes.
“With that erosion comes a wide array of pollutants,” Cowan said. “For example, a parking lot collects oil and grease and other pollutants that affect water quality. But you also have things like nitrogen and phosphorus--fertilizer that we like to use on our lawn to make it grow. These nutrients can cause algal blooms in the lakes.”
The NTMWD GSI elements are a 2,700-gallon capacity cistern, a rain garden, and a bioretention basin, near its Wylie administrative buildings. The GSI projects will help manage some of the stormwater runoff from the buildings and demonstrate how businesses and homeowners can use GSI on their properties.
The cistern collects rain from the roof of an administration building. The collected rainwater will be released into the rain garden, and the bioretention basin will capture excess water from the parking lot that will drain into a creek.
Rain gardens and bioretention features are built by digging a depressed area in the ground, layering it with soil, planting native or climate-adapted plants, and adding mulch. When it rains, stormwater is captured, slowing the flow of water and allowing time for particles to settle. Water gradually seeps into the soil where plants’ root systems absorb excess nutrients.
According to Cowan, some GSI projects like rain barrels or rain gardens are scalable, making it possible for people with nearly any size yard or skill level to help protect our watersheds. A rain garden built on a residential property can be as simple as a path of rocks leading from a downspout to a small depression planted with drought-resistant flowers, grasses, or shrubs. While it might be necessary to water the plants soon after planting, they can withstand dry Texas summers and wet conditions after they are established.
As with any project, planning is the key to success. Resources provided by Texas A&M AgriLife Extension can help determine the best area in your yard for a rain garden, how to construct it, and which plants would thrive.