Green Stormwater Infrastructure Can Improve Houston’s Water Quality

Report: GSI reduces runoff pollution by cutting amount of runoff by 50-90%

Environment Texas

HOUSTON – Environment Texas released a new report today that describes how Green Stormwater Infrastructure (GSI) can be used to make a significant reduction in both runoff pollution and flood severity in Houston. The advocacy group is partnering with The Galveston Bay Foundation to urge the City Council to develop a comprehensive GSI plan for Houston.

“The name is long but the concept is simple — Green Stormwater Infrastructure is rain recyling,” said Brian Zabcik, Clean Air and Clean Water Advocate at Environment Texas. “That’s because GSI does several functions common to other kinds of recycling. It captures rainwater, it cleanses rainwater, and it reuses rainwater.”

The new report, Catching the Rain: How Green Infrastructure Can Reduce Flooding and Improve Water Quality, shows how both flooding and pollution have increased as rainfall runoff has increased. The report explains how GSI can address these problems by sharply reducing the amount of runoff. 

“Green Stormwater Infrastructure needs to be in the city’s toolbox as we work to mitigate flooding across the city,” said David Robinson, the Houston City Council member for the At Large 2 position. “The solution provided by GSI complements the larger-scale infrastructure investments that the city and county are making throughout the region.” Council Members Robinson and Dave Martin are two of the co-sponsors for the upcoming Flooding and Storm Surge Symposium on April 5th (https://aiahouston.org/v/event-detail/Flooding-and-Storm-Surge-Symposium/10h/)

Green Stormwater Infrastructure refers to a specific set of design elements in buildings and the landscape that capture and rescue rain where it falls. Some elements, like rain harvesting barrels and cisterns, store the water for later use in landscape irrigation. Other GSI elements allow rain to collect or pool so that it can slowly soak into the soil or evaporate into the air. These elements include green roofs and walls; permeable pavements; and plant-lined basins and channels called rain gardens and bioswales.

“Green Storm Water Infrastructure is a cost-effective tool that has been used successfully in numerous cities across the country to decrease pollution and litter in local waterways and help mitigate local flooding,” said Bob Stokes, Galveston Bay Foundation president. “It has only been used sparingly in the Houston area.  Our area builders, developers, and local governments now have an opportunity to implement this technique and make a real difference in improving the health of our rivers and bayous and mitigating local flooding concerns.”

When more land is covered with buildings, streets, and parking lots, the amount of ground that can soak up rain where it falls is reduced. Explosive growth in the Houston area has produced an equally big jump in impervious cover. Satellite data shows that roughly one-third of Harris County is blanketed with impermeable material. As the amount of impervious cover has soared, so has the amount of runoff. This increased runoff has contributed to the decrease in natural water quality in the Houston area. When runoff flow over roofs, parking lots, and streets, it also picks up chemicals, oils, animal waste, and debris. These pollutants are then carried into bayous, rivers, and bays. Reports have found that 80 percent of all major waterways in the greater Houston area are too dangerous for swimming and fishing because of pollution, which has been made worse by increased runoff.

Heavy rains have increased 167 percent in the city of Houston since 1950. The combination of more rainfall, and fewer places for it to drain, has produced a combination that’s been both fatal and costly. The 2015 Tax Day flood, which killed 12 people, was followed by another damaging flood a year later. It’s tempting to treat floods with resignation. As Mayor Houston Sylvester Turner said after the Tax Day flood, “We certainly can’t control the weather.”

But while it’s impossible to control the weather, or prevent all flooding, it’s possible to reduce the damage. Because Green Stormwater Infrastructure reduces runoff, it helps lower both pollution and flooding. Numerous studies have found that GSI systems can absorb 50–90 percent of rainfall on site. Several studies have also found that GSI can trap 45–99 percent of the solid particles that are contained in stormwater.

Some GSI installations can already be found in the Houston area. Bagby Street in Midtown and Birnamwood Drive in Spring are both constructed with green street features. The Houston Branch of the Federal Reserve Bank of Dallas features both a green roof and bioswales. Rain harvesting systems are included at both New Hope Housing’s Sakowitz complex, which has an above-ground cistern, and the city’s Kendall Library, which uses below-ground retention tanks.

Still, Houston’s use of green stormwater infrastructure is low, especially when compared with other cities across the country. Seattle, Chicago, Philadelphia, Nashville, and New Orleans have all created model GSI plans.

Environment Texas and the Galveston Bay Foundation believe that Houston can follow these cities’ example. The City Council can start this process by adopting a resolution that supports the development of a comprehensive green stormwater infrastructure plan. This plan should include the following steps:

• Conduct an inventory of the amount of stormwater handled by existing green infrastructure; set a realistic but ambitious target for increasing this amount; and implement the policies necessary to reach this goal.
• Integrate all aspects of the city’s water management – drinking water, wastewater, stormwater, and natural water sources.
• Encourage developments to retain as much stormwater on-site as possible by using GSI elements such as rain harvesting, green roofs, rain gardens, bioswales, and permeable paving.
• Incentivize homeowners and business by offering rebates or tax credits to cover the cost of installing GSI on their properties.

State Representative Jessica Farrar, who represents parts of Houston, is also pressing Texas to support Green Strormwater Infrastructure with a newly introduced bill. H.B. 1536 would direct the Texas Commission on Environmental Quality to measure current stormwater management across the state, and develop policies to increase the use of GSI.

“Houston has seen increasingly devastating major flooding events in recent years,” Farrar said. “Public leaders must take steps to minimize the impact of flooding on Houston residents. By reducing stormwater runoff and protecting floodplains, green stormwater practices can help manage flood waters in Houston.”

Environment Texas advocates for clean air, clean water, and preservation of Texas’s natural areas on behalf of approximately 4,000 members statewide. 

The mission of the Galveston Bay Foundation is to preserve and enhance Galveston Bay as a healthy and productive place for generations to come. The Foundation was incorporated in 1987, and is a Section 501(c)(3) non-profit organization.