In response to impairments associated with nutrients and low dissolved oxygen levels, a local effort was initiated to develop a watershed protection plan (WPP) to improve conditions in the Arroyo Colorado. Working with the TCEQ, the TSSWCB, and other agencies, a local steering committee devised and began implementing strategies to increase dissolved oxygen in the Arroyo and improve its ecological health. With urbanization increasing within the LRGV, the remaining public lands in the region will face pressure to accommodate off-site rainwater discharges from encroaching developments, subdivisions, and planned communities. Incorporating successful best management practices (BMPs) into facility infrastructure and amenities on public lands will optimize the benefits and help reduce the negative impacts from stormwater runoff. Thus, as urbanization continues at a rapid rate, public support for Low impact Development (LID) practices and their use in new construction will be necessary to mitigate the threats of non-point source (NPS) pollution in stormwater runoff and to reduce pollutant loads to the Arroyo Colorado.
Texas A&M University- Kingsville (TAMUK) in partnership with three LRGV Stormwater Taskforce members and one nonprofit organization was awarded $542,930 in Clean Water Act Section 319(h) funds to construct and evaluate LID practices at four sites, develop an education program for local residents, and determine the potential broad application and institutionalization of LID practices in various cities in the LRGV and the Arroyo Colorado Watershed.
The objectives set for the implementation of the project were:
- Design, construct and/or amend facilities with LID practices.
- Provide outreach and education to visitors, the community and public and private land development professionals about LID and good environmental stewardship.
- Assess the costs, functionality, and administrative elements of LID practices.
- Increase the use of LID practices in land development projects.
- Conduct water quality monitoring to assess the potential environmental impact that these LID practices will have on water quality. Reduce the loadings of nonpoint source (NPS) pollutants and thereby bring the receiving water closer to compliance with water quality standards
All the BMPs included in this project were designed by architects, engineers or TAMUK’s staff. Engineering drawings and/or design reports explained the process, rationale and calculations of for each BMP. In addition, the hydraulic and treatment performance of each BMP was estimated using local site conditions and literature values. These estimates were compared to the monitored BMP performance.
The Green Infrastructure BMPs implemented included rainwater harvesting at the City of Alamo Sports Complex, performance monitoring of a biodetention cell designed to treat runoff from a parking lot at South Texas College in McAllen, a demonstration of LID Permeable Pavement implemented at City of La Joya Municipal Library, Texas, and the development, calibration, and validation of several WinSLAMM stormwater models that effectively characterize seven most effective BMPs thus far in the LRGV – three different types of permeable pavements, one biodetention cell, permeable service road, engineered bioswale and rainwater harvesting system. These models will be useful predictive tools to evaluate broad watershed-based programs for green infrastructure or low impact development scenarios designed to improve water quality in the Arroyo Colorado. The program also summarizes the outreach and education components of the project including the LID BMP inventory updates, training and workshops and the Stormwater Report update for the Arroyo Colorado Watershed Protection Plan. Finally, a summary of the effectiveness of BMPs per site in terms of annual load reduction is presented with graphical representations.