Green Infrastructure Master Plan | San Antonio River Authority

Through Clean Water Act Section 319(h) Grant Funding from the Environmental Protection Agency (EPA), the Texas Commission on Environmental Quality (TCEQ) and the San Antonio River Authority (River Authority) have entered into the Upper San Antonio River Watershed Protection Plan (WPP) Implementation – Green Stormwater Infrastructure Master Plan contract.

read the full GIS Master Plan report here

Scope of Work

The San Antonio River Authority (River Authority) was awarded a Clean Water Act Section 319(h) Grant by the U.S. Environmental Protection Agency, administered by the Texas Commission on Environmental Quality (TCEQ) to develop a master plan for the use of green stormwater infrastructure (GSI). This grant project builds off recommendations made in the Upper San Antonio River Watershed Protection Plan (WPP) to implement GSI to reduce stormwater runoff pollution and addresses measures in the Texas Non-Point Source Management Program.

Traditional stormwater infrastructure is designed to manage stormwater volume, not stormwater quality. GSI are constructed features that add the stormwater quality component by mimicking the predevelopment hydrology of an area. Examples are bioretention basins (called rain gardens) and swales, extended detention basins, constructed wetlands, vegetated filter strips, cisterns, and permeable pavement and pavers. They are designed to clean and reduce local flooding by capturing and treating stormwater runoff pollution before it enters local creeks and rivers.

Since GSI is still relatively new to the San Antonio River Basin (SARB), the Master Plan aims to guide decision-makers on where and how to apply limited resources in the upcoming years to maximize water quality benefits while addressing local flooding concerns. The River Authority incorporated stakeholder input to identify and build on common goals and investment priorities for implementing GSI.

The River Authority’s watershed scale models have identified sub-basins or small watersheds that have the highest stormwater pollutant load reduction potential. This project used existing data and modeling tools to identify and prioritize sites within those areas that have the highest potential for GSI implementation effectiveness. Properties considered for implementation included public lands, schools, capital improvement projects, city planning areas, and neighborhoods with supportive stakeholders such as homeowner’s association partners.

For the recommended sites, the River Authority developed site-scale models, concept-level designs, and GSI cost estimates. Using an existing model, the River Authority estimated the pollutant load reductions these projects would achieve across the watershed. The GSI Master Plan will include a recommended schedule of implementation, the stakeholder process, costs, funding considerations, and the overall evaluation and prioritization process – all as examples communities can use for their own decision-making. The GSI Master Plan will also include an evaluation of Triple Bottom Line (TBL) benefits (social, environmental, economic). Ultimately, the goal is for the GSI Master Plan to become a template for all sub-basins not meeting water quality standards in the SARB.

To read the full report click here, Upper San Antonio River Watershed Protection Plan (WPP) Implementation - Green
Stormwater Infrastructure (GSI) Master Plan.

Learn more about Green Stormwater Infrastructure Projects by visiting our Sustainability Learning Module.