Anticipating Growth in the Texas Hill Country: Exploration of Potential for Land Application of Treated Wastewater
MetadataShow full metadata
The Texas Hill Country is an iconic landscape known for its unique beauty, including clear-running rivers and streams, and numerous springs both large and small. Given the rapid population growth along the I-35 corridor and west into the Hill Country, water-resource planning and management challenges are emerging that provide opportunity for an integrated or “One Water” approach to problem solving.
First, there is growing demand for drinking water in a region that is also known to be drought-prone and home to many threatened or endangered species that need water too. Secondly, with increased water use comes a proportional increase in treated wastewater effluent production. Absent strong nutrient standards in permitted discharges to prevent cultural eutrophication of Hill Country streams, alternative uses of treated wastewater effluent are available that can reduce withdrawals of surface and groundwater and create new economic opportunities by using wastewater effluent as a resource rather than disposing it as a waste product.
From a larger set of Texas Hill Country cities that were based on their location relative to the Edwards Aquifer, nine were selected in a first phase analysis using a geographic information system and based on weighted criteria including population growth rate, potential site distance from a wastewater treatment plant (WWTP), and a set of land uses deemed suitable for land application of treated wastewater. These nine cities were then evaluated based on their ability to meet four criteria: 1) the target city’s WWTP is located within or upstream of either the contributing or recharge zones of the Edwards Aquifer regulatory boundary, 2) the city’s WTTP has a current or near future need to expand their WWTP based on reported average daily discharge being 75 percent or more of permitted maximum daily discharge, 3) it being early enough in their planning development cycle, either hypothetically or in actual practice, that reuse infrastructure can be carefully examined and planned for at the most efficient time, and 4) having land-use scenarios suitable for land application that are within a 3-mile (maximum) radius of the WWTP. From this analysis, three cities emerged for study: Blanco, Boerne, and Leander.
A second phase of site analysis given to the three study cities is based on weighted criteria that include land use, location relative to the Edwards Aquifer regulatory boundary, distance from WWTP, and percent slope. Among results, the City of Blanco can meet 100 percent of both current and future needs for land application of TWW effluent on highest-quality sites (scores of ten) within a one-mile radius of its WWTP. The City of Boerne, can also meet both current and future needs for land application within a one-mile radius, but will need to include some sites with scores less than a ten and act with a greater sense of urgency given the current/projected growth rate. The City of Leander presents a particular challenge given its current/projected growth rate, large effluent volume expected in the future, and location and will require other reuse strategies to ensure efficient use of water and protection of local/regional water quality.
By applying a replicable methodology using publicly available data, this study shows promise for land application of treated wastewater effluent in the Texas Hill Country. While infrastructure and other cost considerations need to be analyzed in a future study along with refinement of site selection and a collaborative process for its execution, this study highlights the need for community officials and residents to develop a shared vision for their community’s water future. The promise of reusing effluent via land application to help solve growing demand for water must also account for an equal need to protect surface and groundwater quality. Thus, an appropriate level of wastewater treatment must be engineered that fully accounts for specific site characteristics such that land application as a reuse strategy fulfills its promise while avoiding negative impacts on surface and groundwater.