Upper San Marcos River: Developing a Watershed Protection Plan
The headwaters of the Upper San Marcos River around Spring Lake are fed by springs from the Edwards Aquifer. The Upper San Marcos River is on the TCEQ 2010 303(d) List due to elevated concentrations of total dissolved solids (TDS). Development and changing land uses are presenting new pressures and additional water quality concerns related to bacteria, nutrients, and sediment.
The Upper San Marcos Coordination Group is helping stakeholders develop a WPP to address the TDS impairment and the additional water quality concerns for the river, with a focus on Spring Lake. The first phase of the project was a watershed characterization using existing water quality monitoring data and land use information as well as the results from additional targeted monitoring. Texas State University-Meadows Center calculated a nutrient budget for Spring Lake to determine the nutrient load contributed by each of the major sources flowing into the lake. Stakeholders are examining potential linkages between present and future land use practices and water quality in the lake.