Upper Trinity River-Dallas: Implementing TMDLs through Low Impact Development

Background

LID is a comprehensive approach to site planning, design, and pollution prevention strategies that, when combined, create a more economically sustainable and ecologically functional landscape. LID features work with nature to manage stormwater as close to its source as possible.

LID treats stormwater as a resource, rather than a waste product, and integrates hydrologic and water quality functions into all aspects of the urban landscape and infrastructure. The result is functional and appealing site drainage that restores the ecological integrity of receiving waters, promotes the natural movement of water within an ecosystem or watershed, and reduces construction, maintenance, and inspection costs. Examples of LID management approaches and technologies include rain gardens, porous pavements, green roofs, and rainwater harvesting for later use.

While recent studies have evaluated the effectiveness of LID practices in various regions of the United States, there is still a need to evaluate their performance. There is also little data on the possible effects of adopting LID at a watershed level.

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Project Description

The goal of this project was to improve the quality of stormwater from a site that is typical of commercial development in the Upper Trinity and White Rock Lake watersheds. The focus, as part of the implementation of the Dallas County TMDLs for legacy pollutants, was on removal of chlordane from stormwater runoff. An additional goal was reducing the total and peak flows of stormwater and reducing nutrient and sediment loads from stormwater entering area streams.

The project designed and built several LID features at the Texas A&M AgriLife Research and Extension Center in Dallas and monitored the volume and quality of stormwater entering and leaving these features. Continuing demonstration of these practices after the project ended is showing how LID can be integrated in new developments or retrofitted to existing ones.

Five LID practices were examined in this project: permeable pavements, bio-retention areas, rainwater harvesting, green roofs, and extended detention ponds. Multiple versions of these practices were compared, including alternate irrigation strategies for the rain water harvesting practices.

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For More Information

To find out more about the NPS Program, call 512-239-6682 or e-mail us at nps@tceq.texas.gov.

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