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Upper San Marcos River Watershed Plan: Beginning Implementation

Texas State University implemented management measures including adding a watershed coordinator, installing several demonstration NPS practices, conducting public outreach, reviewing local ordinances affecting water quality, and reviewing monitoring data for water quality trends.


The Upper San Marcos River begins in the City of San Marcos at Spring Lake and flows 4.5 miles to its confluence with the Blanco River. In 2010, the Upper San Marcos River did not meet state water quality standards for total dissolved solids (TDS), but has since met standards. The San Marcos Watershed Initiative formed in 2012 and, together with their stakeholders, developed the Upper San Marcos Watershed Protection Plan (WPP) to address their concerns for TDS, bacteria, nutrients, and sediment and to mitigate future water quality issues in the San Marcos River watershed. The WPP was accepted by the U.S. Environmental Protection Agency in June 2018.

One of the management measures recommended in the WPP is low impact development (LID). LID is a comprehensive approach that incorporates or mimics natural processes (e.g., filtration, sedimentation, evapotranspiration) into site planning, design, or redevelopment with the goal of managing surface water runoff volume and reducing pollution as close to the source as possible. Examples include rain gardens, porous pavement, green roofs, and rainwater harvesting for later use. LID can be an important and effective way to mitigate the water quality problems caused by urbanization. For more information, visit the U.S. Environmental Protection Agency's Low Impact Development web page.

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Project Description

Texas State University implemented best management practices (BMPs) including LID, aimed at managing the quantity of and improving the quality of stormwater in the Upper San Marcos River watershed. LID was incorporated in new development in the watershed and retrofitted into existing development. This will encourage further implementation of BMPs and provide information on cost and effectiveness of BMPs in reducing pollution. Texas State also provided education and outreach, a review of water quality protection ordinances, and coordination of water quality monitoring activities. The project was completed in August 2020.

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For More Information

To find out more about the NPS Program, call 512-239-6682 or e-mail us at

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