Aquifer Storage and Recovery
Aquifer Storage and Recovery
Aquifer Storage and Recovery (ASR) is a water supply strategy to store available water in a natural aquifer during wet times for later recovery and use. Austin Water is currently studying aquifers in our region to determine the most favorable areas for an Aquifer Storage and Recovery project in the future.
HOW ASR SYSTEMS WORK
When water supplies are plentiful, an Aquifer Storage and Recovery system will store available drinking water from Austin Water in a natural aquifer underground. When our regular water supply becomes low, stored water is pumped out of the aquifer, treated to meet drinking water standards, and distributed to customers. Water collected and stored in an ASR system would be available under Austin’s existing water rights, allowing Austin to maximize local water resources.
PROJECT BACKGROUND
From 2008-2016, a historic drought hit Central Texas, reducing water in the Highland Lakes to historically low levels. In response, Austin Water created Water Forward, an integrated plan to guide Austin’s water future for the next 100 years. The City Council-approved Water Forward plan includes conservation, reuse, and water supply strategies to ensure a diversified, sustainable, and resilient water future for Austin. Aquifer Storage and Recovery is one of the water supply projects included in Water Forward. An ASR project will make Austin’s water supply more resilient to the effects of climate change and drought and could provide a second source of water during emergencies, like freeze events or flooding.
PROJECT UPDATE - APRIL 2025
Austin Water began a scientific study in 2022 for its ASR project. After completing a comprehensive screening evaluation of aquifers within an eight-county area, Austin Water narrowed its study area to Travis, Bastrop and Lee Counties. Additional spatial analysis was then conducted to select a focus area for field testing and further study for the project.
After careful scientific study, the Carrizo-Wilcox Aquifer in Bastrop County was identified as the focus area because it has favorable hydrogeology, is closer to the existing system infrastructure, and is in an area where water can be stored deep in the aquifer well and below levels of local wells. Travis County was thoroughly evaluated but was not identified as the focus area because the hydrogeology is less favorable than Bastrop County, resulting in lower water storage capacity. Austin Water is working with stakeholders in Bastrop County to provide updates about the study results, to discuss safeguards for the aquifer and local communities, and to learn about desired community benefits in Bastrop County.
WHAT'S NEXT
Austin Water wants to work with stakeholders to develop a project that can provide regional benefits. As Central Texas continues to experience rapid population growth and increasing water demands, innovative strategies like ASR will be critical to securing the state’s water future.
The next phase of the project will include exploratory drilling and field testing. In this phase groundwater samples and core samples will be tested in a lab to understand baseline geochemistry and will be tested with Austin Water drinking water to observe and document any interactions. Based on these results, appropriate treatment processes can be designed for the next project phase to prevent adverse reactions and protect the health of the aquifer. Austin Water will provide results and seek feedback.
COMMUNITY OUTCOMES EVALUATION
Austin Water has performed a community outcomes evaluation to understand potential benefits and burdens from the ASR project. This evaluation considers effects on Austin Water customers and communities near ASR project infrastructure and helped to identify project adjustments and mitigation strategies to reduce potential negative impacts.
GET INVOLVED
The project team is available to make presentations to community and professional groups. Please send an email to aw-asr@austintexas.gov to request a presentation.
Frequently Asked Questions
Austin has completed a comprehensive evaluation of numerous aquifers within the region, across eight counties. The Carrizo-Wilcox, which is successfully used for ASR in Bexar County, was determined to be able to meet project goals and provide the storage capacity scale that Austin Water needs.
After careful scientific study, the Carrizo-Wilcox Aquifer in Bastrop County was identified as the focus area because it has favorable hydrogeology, is closer to the existing system infrastructure, and is in an area where water can be stored deep in the aquifer well and below levels of local wells. An area in Bastrop County several miles south of Paige, TX is the current focus area for the next phase of field testing.
Travis County was thoroughly evaluated but was not identified as the focus area because the hydrogeology is less favorable than Bastrop County, resulting in lower water storage capacity.
For more information relating to aquifers and groundwater please refer to the following link, https://www.twdb.texas.gov/groundwater/index.asp
No, Austin’s ASR project will not take native groundwater. The project will store Austin’s existing water supplies for later use. Austin’s ASR project will not take out more volume of water than it puts into the aquifer, per state ASR requirements from the Texas Commission on Environmental Quality.
In the next stages of ASR development, Austin Water will perform field testing to gather core samples and native groundwater samples and test those in a laboratory setting to understand baseline geochemistry and compatibility with Austin Water drinking water. This will allow design of appropriate treatment processes to prevent adverse water quality reactions and protect the health of the aquifer. After this step, Austin Water will develop a small-scale ASR pilot project to further characterize how Austin’s drinking water that will be stored in the ASR may interact with native groundwater. Extensive water quality testing will be done before a decision is made to move to each subsequent phase of the project.
Austin’s ASR project is planned to store water from Austin’s drinking water system. Water for ASR will be treated before it goes in the ground to ensure compatibility with the aquifer and existing groundwater. When ASR water is recovered, it will be treated to be fully compatible with AW’s existing drinking water quality.
The amount of land needed for an ASR project is based on location and aquifer characteristics. We currently estimate that up to approximately 7,000 acres will be needed for the wellfield and a half mile buffer. Only about 200 acres of that amount will be needed for wells, facilities, and aboveground improvements.
To legally protect the stored water, the land above the storage zone must be protected from pumping. Landowners will be compensated for purchase or lease of land and may remain on the land to continue local farming and ranching operations.
Austin Water will seek to operate the ASR wells in a manner that minimizes local well impacts. We understand from other ASR projects that overall water levels for adjacent wells typically increase when water is being added to the ASR and decrease when ASR water is being withdrawn. Austin’s ASR project will not withdraw (or recover) more water than was stored. Austin Water will improve and lower wells where necessary.
Austin Water’s 2024 Water Forward plan has a goal of storing 60,000 acre feet of water in the planned ASR project by 2040 and 300,000 acre feet by 2080.
No, the success of the ASR project is fundamentally tied to the protection of the Carrizo-Wilcox Aquifer system. The area’s drinking water will rely on the health of the aquifer once this project is built. If this project does not protect water quality for the region, then it does not work. The project includes substantial time for field testing and piloting to develop an understanding of water
chemistry in the aquifer and design appropriate treatment processes. The next phase of testing (approximately three years) would involve lab testing of native groundwater interactions with Austin’s drinking water, which is sourced from Lakes Austin and Travis.
No, Austin’s ASR project is not planned to capture flood waters. The ASR project will store drinking water from Austin's core supply source, the Colorado River and Highland Lakes. An ASR project for flood mitigation is not feasible due to infrastructure and storage requirements as well as cost.
Austin Water will pay for this project over a number of years using strategies that allow us to finance large projects while keeping customer rates affordable. Austin Water’s debt management strategies have made it possible to address two competing needs – spending on improvements infrastructure for dependable water service while keeping water rates down and affordable for customers of all incomes. Securing near-zero percent interest loans also helps Austin Water fund major infrastructure projects at a tremendous cost savings for the utility and its customers.
It is a priority for Austin Water to choose a location for the project that will allow us to protect the water that we store. AW will have control of the land above our stored water, but due to the early stage of the project, we have not yet identified specific strategies to achieve that. Other ASR projects, for example, have purchased the land above their stored water to protect it, and leased the land back to farmers or ranchers. Additionally, Texas Commission on Environmental Quality (TCEQ) requirements for ASR state that ASR projects must be able to maintain control over their stored water.
The ASR team will hold community meetings to share information and collect input on the ASR project and will attend meetings in the community throughout the project. Community engagement events will be conducted in the summer of 2022 to receive input on the criteria and weightings that will be used by the project team to evaluate different project alternatives.
We are also developing an Equity and Affordability Road Map and Tool to help implement the ASR project with an equity and affordability lens. These products will help guide our community engagement efforts along with determining potential equity impacts and mitigation options when evaluating ASR project configurations.
*Results of each project phase will be evaluated to determine whether the project will move to the next phase.