Frequently Asked Questions

  1. What is aquifer storage and recovery?
  2. Are there other methods to transfer water into an aquifer?
  3. How many aquifer storage and recovery systems are there in Texas?
  4. How many aquifer storage and recovery systems are there in United States?
  5. Can aquifer storage and recovery be used to store any type of water?
  6. How much of the stored water can be withdrawn from an aquifer storage and recovery system?
  7. What is the quality of water recovered from an aquifer storage and recovery system?
  8. What are the main concerns regarding aquifer storage and recovery in Texas?
  9. Can the TWDB provide funds for the construction of an aquifer storage and recovery system?
  10. What is the role of the TWDB in aquifer storage and recovery?
  11. What are the benefits of aquifer storage and recovery?
  12. What are some of the things that aquifer storage and recovery cannot achieve?
  13. What are the most important technical factors needed for aquifer storage and recovery to be a potential water management tool?
  14. Is aquifer storage and recovery considered in the 2012 State Water Plan?
  15. How can I get more information about aquifer storage and recovery?

Answers to Frequently Asked Questions

1. What is aquifer storage and recovery?

Aquifer storage and recovery (commonly referred to as ASR) is the practice of storing water in a suitable aquifer through a well when water is available and recovering the water from the same aquifer when it is needed. Typically, the same well is used for both injection and recovery.

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2. Are there other methods to transfer water into an aquifer?

Yes, two other common methods are spreading basins and vadose zone wells. If the soil between the land surface and the aquifer can transmit water, spreading basins can be used. In spreading basins, water is retained by engineered structures and percolates through the soil to the aquifer. If the soil at the surface is impermeable and the aquifer is shallow, vadose zone wells might be considered. Vadose zone wells typically are large diameter wells that penetrate through an impermeable soil layer to areas where water can infiltrate the soil through the wells and drain into the aquifer.

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3. How many aquifer storage and recovery systems are there in Texas?

Currently, there are three in Texas. The aquifer storage and recovery system at the City of Kerrville began operating in 1998, and the San Antonio Water System’s Twin Oaks facility began operating in 2004. Both systems continue to perform successfully and are viewed by their operators as a beneficial component of their water management plans. El Paso Water Utilities uses what is considered a hybrid aquifer storage and recovery facility established in 1985. In this system, water is added to the aquifer using wells and spreading basins and the stored water is recovered from wells that are not the same as the ones used for injection.

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4. How many aquifer storage and recovery systems are there in the United States?

There are approximately 175 aquifer storage and recovery well fields in the United States. The first aquifer storage and recovery facility in the United States was built in 1969 in Wildwood, New Jersey, and has been operating since then. The implementation of aquifer storage and recovery systems in the nation has accelerated in recent years.

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5. Can aquifer storage and recovery be used to store any type of water?

Yes, stored water may come from a variety of sources. Although surface water is the prevalent source, groundwater from other aquifers or reclaimed water may also be used. In Texas, all three types of water (surface water, groundwater, and reclaimed water) are used. Regardless of the source, in Texas, all water is required to be treated to meet the Federal Safe Drinking Water Act prior to injection.

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6. How much of the stored water can be withdrawn from an aquifer storage and recovery system?

If water is stored in a freshwater aquifer, it is possible to recover 100 percent of that water. If water is stored in a brackish aquifer, some stored water is left in the aquifer to create a buffer zone, ensuring that brackish water is not present in the recovered water. This buffer zone only needs to be established once. After establishing a buffer zone, high recovery efficiencies are possible. If long storage times are expected, flow in the aquifer may pose a risk of the stored water migrating away from the storage site. The potential for migration of stored water should be considered during the planning of an aquifer storage and recovery project.

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7. What is the quality of water recovered from an aquifer storage and recovery system?

In the majority of cases, the recovered water is expected to be of drinking water quality because the water injected is required to meet the Federal Safe Drinking Water Act. In some cases, additional treatment such as pH adjustment or disinfection may be required; water quality and treatment requirements can be site and project specific.

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8. What are the main concerns regarding aquifer storage and recovery in Texas?

A 2011 study conducted for the Texas Water Development Board (TWDB) found that water purveyors who had considered aquifer storage and recovery had the following concerns:

  • Ability to recover the stored water
  • Quality of the recovered water
  • Cost effectiveness of aquifer storage and recovery
  • Potential for others to recover the stored water

While these concerns need to be considered, they have been successfully addressed in the aquifer storage and recovery systems operating in Texas and across the nation.

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9. Can the TWDB provide funds for the construction of an aquifer storage and recovery system?

One of the main functions of the TWDB is to provide financial assistance to support the development of recommended water management strategies in the regional and state water plans, including aquifer storage and recovery. More information about the TWDB’s financial assistance programs is available at http://www.twdb.state.tx.us/financial/index.asp.

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10. What is the role of the TWDB in aquifer storage and recovery?

The statute allows the TWDB to perform studies as the agency deems necessary to evaluate aquifers suitable for aquifer storage and recovery (Texas Water Code§11.155).

In 2015, the 84th Texas Legislature appropriated $1 million to the TWDB to fund grants for demonstration projects for alternative water supplies. We provided funding to the Victoria County Groundwater Conservation District, the Edwards Aquifer Authority, and the Corpus Christi Aquifer Storage and Recovery Conservation District to acquire information about local geological conditions, water quality, aquifer properties, system design, and system operation and maintenance for possible ASR projects.

The TWDB is also mapping and characterizing geologic formations as part of the agency’s Brackish Resources Aquifer Characterization System (BRACS) program. More generally, the mission of the TWDB’s Innovative Water Technologies group is to educate the water community on the use of nontraditional water supplies by participating in research and demonstration projects, developing publications and educational materials, conducting outreach, and actively participating in key water organizations.

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11. What are the benefits of aquifer storage and recovery?

When comparing aquifer storage and recovery systems to surface water reservoirs, there are two main benefits which include no water loss due to evaporation and no loss of storage capacity due to sedimentation. Aquifer storage and recovery can also defer the need for additional capital investment by increasing the use of existing treatment facilities; they can be used in non-peak hours to pretreat aquifer storage and recovery source water for storage.

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12. What are some of the things that aquifer storage and recovery cannot achieve?

Aquifer storage and recovery is not used for flood control, hydropower generation, or recreation. It also requires aquifers that can store and transmit the stored water; these may not exist in all areas of the state. These factors should be considered in planning for an aquifer storage and recovery project.

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13. What are the most important technical factors needed for aquifer storage and recovery to be a potential water management tool?

Four factors of highest importance are:

  • Access to a water source. Aquifer storage and recovery only stores water, it doesn’t create it.
  • Access to an appropriate aquifer in which to store and transmit the stored water at a rate and volume sufficient to meet the need.
  • Design and operation of the aquifer storage and recovery system to minimize or eliminate potential migration of the stored water away from the storage site.
  • Proper controls (institutional or technical) to ensure that the stored water remains under the control of the project operator of the aquifer storage and recovery system.

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14. Is aquifer storage and recovery considered in the 2012 State Water Plan?

In the 2017 State Water Plan, seven regional water planning groups (regions E, F, G, J, K, L, and O) have included aquifer storage and recovery as a recommended water management strategy. Collectively, there are 49 recommended water management strategies in the plan that meet the water needs of water user group. If these strategies are implemented, aquifer storage and recovery would yield an estimated 152,000 acre-feet of new water supply per year by decade 2070, constituting about 1.8 percent of all recommended water management strategies.

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15. How can I get more information about aquifer storage and recovery?

If you have any questions about or need information on the TWDB’s aquifer storage and recovery program, please go to http://www.twdb.texas.gov/innovativewater/asr/index.asp or contact Mr. Matt Webb at 512-463-6929 or matthew.webb@twdb.texas.gov.

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