CodeNext Can Be Used To Reduce Austin Flooding

Report: Green Stormwater Infrastructure Helps Cut Runoff by 50–90%; CodeNext Offers Opportunity to Implement New GSI Policies

Environment Texas

AUSTIN – Environment Texas released a new report today that describes how Green Stormwater Infrastructure (GSI) can be used to make a significant reduction in both flood severity & water pollution in Austin. The advocacy group is calling on the City Council to develop a comprehensive Green Stormwater Infrastructure plan. As part of that plan, GSI provisions should be included in CodeNEXT, the current revision of the city’s Land Development Code.

“Rain is one of Austin’s most precious resources, but it’s also linked to some of our most serious problems—flooding, pollution, and drought,” said Cyrus Rautman, campaign organizer with Environment Texas. “Green Stormwater Infrastructure can help with each of these problems by catching more rain where it falls, and discharging less as runoff.”

Environment Texas’s 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 Green Stormwater Infrastructure can address these problems by sharply reducing the amount of runoff.

“Green Stormwater Infrastructure can be very effecting in reducing runoff,” said Austin City Council Member Ann Kitchen. “It is a critical strategy that we need to embrace in Austin and surrounding Central Texas communities in light of our growing populations.”

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.

Eleanor McKinney, a leading landscape architect in Austin and a member of the city’s Code Advisory Group, noted that Green Infrastructure is one of the eight priority programs of the Imagine Austin plan, which was adopted in 2012.

McKinney added, “At the city level, urban forests and parks provide stormwater management. At the site level, green roofs, rain water harvesting, rain gardens, and green streets can all serve to mitigate the often disastrous effects of downstream flooding while integrating nature into the city.”

Floods have been a constant problem since Austin’s founding, but they have been exacerbated by bigger and more frequent storms. The city has seen a 67 percent increase in heavy rains since 1950. Four Austin residents died in a 2013 flood on Onion Creek. Another flood on Onion Creek two years later led the Austin City Council to approve a buyout program for some area homeowners. During the 2015 Memorial Day flood, a key stretch of Lamar Boulevard below Shoal Creek was submerged with water.

Austin’s floods aren’t just exacerbated by increased rainfall, however, but also by increased runoff. As more land in the city has been covered with buildings, streets, and parking lots, the amount of ground that can soak up rain where it falls has been reduced. The result has been a rise in the amount of runoff that flows into stormwater drains and then into creeks, rivers, and lakes.

This increased runoff is also responsible for the decrease in natural water quality in the Austin area. When runoff flow over roofs, parking lots, and streets, it also picks up chemicals, oils, animal waste, and debris. Ten creeks in Austin have been designated by the State of Texas as unsafe for swimming and fishing. Additionally, swimming in Lady Bird Lake has been prohibited due to pollution concerns.

Because Green Stormwater Infrastructure reduces runoff, it can help reduce both flooding and pollution. 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.

A few GSI installations can be seen around Austin, including at City Hall and at the new UT/Dell Medical School. In addition, the city’s WaterWise program gives rebates to homeowners and businesses to cover part of the cost of installing GSI elements.Still, the use of green stormwater infrastructure in Austin is low, especially when compared with other cities across the country. Seattle, Chicago, Philadelphia, Nashville, and New Orleans have all created model GSI plans.

The Austin City Council can start this process, however, by supporting a resolution that calls for the development of a comprehensive green stormwater infrastructure plan. In particular, the Council should ensure that GSI requirements for both new developments and redevelopments are included in the Land Development Code as it is revised during CodeNEXT. Recommendations for the beneficial use of stormwater have already been included in the Imagine Austin. CodeNEXT should update those goals and put them in writing.

“Green Infrastructure is a key piece of the rewrite of the Land Development Code, ensuring that Austin has a green, livable environment for generations to come,” McKinney noted.

Rautman added, “We know that Austin will keep growing. But if we can make sure that future development is green, we will have not only a larger city, but a better one too.”

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