July 22, 2019

Aquifer Storage and Recovery: Opportunities and Practical Considerations

Lucy K. Infeld, Sarah N. Munger, and Rachel K. Roberts

Increasing water demand combined with more extreme weather patterns associated with climate change are straining water resources. Times of plenty are increasingly being followed by times of scarcity. The federal government, states, and localities are seeking innovative solutions to maximize water storage, and aquifer storage and recovery (ASR), although not a new technology, has gained new prominence as a potential response to the expanding water crisis. See, e.g., CDM Fed. Prog. Corp., Methodology for Aquifer Storage and Recovery Benefit Cost Analysis: Prepared for the United States Department of Homeland Security, Federal Emergency Management Agency 1-1 (2016); Colorado’s Water Plan 6-155 (2015); Austin Water, Water Forward Integrated Water Resource Plan: A Plan for the Next 100 Years, § 7.2.1 (2018). Notably, FEMA is encouraging communities to consider ASR as part of its Hazard Mitigation Assistance program to mitigate the increased risks of flood and drought that accompany climate change. Fed. Emerg. Mgmt. Agency, Aquifer Storage and Recovery (2017). It is currently estimated that there are 95 ASR projects in the United States, and that number is expected to grow in the coming years. Tex. Living Waters Proj., Aquifer Storage and Recovery (last visited June 14, 2019).

ASR projects capture and store water in subsurface aquifers during wet seasons for times of need, such as drought. See, e.g., Fred Blumberg et al., State Bar of Texas: Essentials of Texas Water Resources § 26.2 (2018); Fed. Emerg. Mgmt. Agency, supra at 1. Aquifers may be confined, in which case an injection well is necessary for recharge, or unconfined, such that either an injection well or surface water infiltration may be used. Id. Some benefits of ASR compared to traditional reservoirs include “increased protection from evaporation, surface pollutants, and extreme weather events.” CDM Fed. Prog. Corp., supra at 2-1. ASR also has the potential for lower impacts on fish movement than in-channel reservoir construction. Peter G. Scott, Aquifer Storage and Recovery in the Columbia Basin: The Need for Legislative Action, 21 Pub. Land & Resources L. Rev. 35, 39 & n.15 (2000).  

The benefits of ASR as a climate change adaptation tool come with challenges, however. These include possible adverse effects on water quality, potentially complex water rights questions, and a host of siting issues. This article presents a high-level overview of opportunities as well as common challenges related to water rights and water quality. This article does not focus on any one state’s regulatory structure, but identifies several key issues that should be considered when embarking on an ASR project.

1. ASR and Water Rights

As the climate changes and snowpacks shrink, the ability to store available water becomes more important. ASR could provide a lower-impact alternative to dams and surface reservoirs for this increased storage. However, water rights law poses some challenges that will have to be overcome for this to be a viable option.

In particular, the party who stores the water must have a right to divert and store the water in the first place (right to fill); storage may decrease flows downstream (shutting off the tap); and other parties may withdraw stored water from the same aquifer using their wells, particularly unpermitted ones (too many straws).

a. Right to Fill
Entities that embark on this innovative approach may find themselves limited by the extent of their existing water rights. For example, the city of White Salmon, Washington, has been delayed in its attempts to develop an ASR project due to insufficient existing water rights to fill its wellfield to capacity. See Aspect Consulting, City of White Salmon Aquifer Storage and Recovery Feasibility Assessment: Prepared for City of White Salmon 2-2 (2011). In response, the city applied for a new seasonal surface water right. City of White Salmon Agenda Memo (Dec. 5, 2018). An entity interested in developing an ASR project should determine whether its existing water rights provide sufficient water for the project and consider whether additional rights should be obtained through new permitting or purchase. 

b. Shutting off the Tap
Storing runoff decreases flows downstream. This “is particularly true immediately downstream from points of diversion.” Scott, supra at 75, n.226. Decreasing downstream flows may impact users and ecosystems below the point of diversion. See id. at 75–76. On the other hand, in places that rely on mountain snowmelt for water, well-timed ASR has the potential to improve water reliability for both downstream users and fish by capturing spring runoff and releasing stored water during the dry irrigation season. State permitting systems for ASR, such as Washington’s, should be able to address these issues as part of their permitting process. See, e.g., Rev. Code. Wash. Ann. § 90.03.370 (2)(a)(ii); Wash. Admin. Code § 173-157-200(3).

c. Too Many Straws
Multiple wells may overlay the same aquifer that is being used for ASR. Many of these wells may be unregulated. In Washington, wells for domestic or industrial purposes that use less than 5,000 gallons per day are exempt from permitting. Rev. Code. Wash. Ann. § 90.44.050. In California, the majority of groundwater use has traditionally been unregulated. Susan Snyder, Groundwater: Rights and Risks, 36 Energy and Mineral Law Found. § 26.06 (2015). Unpermitted wells, along with natural seepage, may mean that the volume of water that is actually “in the bank” when it comes time to be used is significantly less than expected. As such, prospective projects need to know whether they will retain control over their water once it is in the ground, and if so, how much water they can recover. Some states may use permitting and authorization schemes that could mitigate the impact of “too many straws,” but that limit the amount of recoverable water See e.g., Tex. Water Code § 36.454(c) (stating that, generally, a project “may not recover groundwater by an [ASR] project in an amount that exceeds the volume authorized . . . .”).

ASR has the potential to be a useful and relatively low-impact way to increase storage in the face of decreasing snowpacks and increased spring runoff. Parties interested in pursuing ASR should be cognizant of the need to have a right to fill, mitigate impacts from shutting off the tap, and determine whether too many straws may be in their planned water bank.

2. ASR and Water Quality

While ASR can help to improve water quantity for end users, many states and municipalities face surface water quality issues and challenges in protecting groundwater quality. The major issue for aquifer recharge involves adequate treatment of water before it is used for recharge. See e.g., Stone et al., USGS, Effects of Aquifer Storage and Recovery Activities on Water Quality in the Little Arkansas River and Equus Beds Aquifer (2016). Pretreatment ensures that the new source of water does not contaminate the aquifer, allows the water to meet the requirements for its intended use, and minimizes any mechanical or technical problems in both infiltration of the aquifer and later use of the recharged water.

a. Outside Source Contamination
The largest water quality concern for ASR is potential contamination or degradation of the quality of water within the aquifer from the water being injected. Water injected into ASR wells often includes treated drinking water from public water treatment systems, untreated groundwater and surface water, treated effluent, and reclaimed or recycled water. EPA, Aquifer Recharge and Aquifer Storage and Recovery (last updated Nov. 14, 2018).

If the quality of water injected into ASR wells is of lower quality than the water naturally present in the aquifer, the injection of this lesser quality water can degrade the water quality of the aquifer as a whole. Additionally, any contamination or pathogens present in the injected water could cause pathogens to enter the aquifer. See, e.g., Mary Shaleen-Hansen, Wash. State Dep’t of Ecology, Guidance for Aquifer Storage and Recovery AKART Analysis and Overriding Consideration of the Public Interest Demonstration (2017). Additionally, disinfectants, like chlorine, may become a pollutant and enter the groundwater. Id. Given that aquifers can be naturally occurring sources of incredibly high-quality water, concerns over degradation of quality often go hand-in-hand with the benefits to water quantity through aquifer recharge.

b. Difference in Intended Uses
Small-scale ASR projects created by municipalities may only have one intended purpose for the aquifer, whether drinking water, agricultural, or industrial use. In those instances, it is easier to determine which treatment standard to use. However, as climate change impacts continue to increase the importance of water storage, ASR projects are expanding to cover entire regions and to provide water with multiple intended uses (e.g., residential drinking water, irrigation, and industrial).

Different regulations and water quality concerns exist for each distinct use of ASR wells for water storage. Public drinking water obviously must meet different standards than those for industrial water or irrigation. As such, entities contemplating ASR systems should think carefully about the uses to which the system will, or may, be put. If drinking water is one objective, they will want to consider whether recovered water can be used as drinking water or, more to the point, at what cost. Using one aquifer or ASR project for multiple uses can result in complicated treating techniques or the need for treatment prior to injection of new water sources, as well as post-treatment to ensure that water meets all applicable quality standards.

In areas where ecosystems can be affected by even the slightest change in water quality, these differences can have an enormous impact. For example, an ASR project in the Florida Everglades sparked such concern over impacts to ecosystems and species that the Army Corps of Engineers and Florida state representatives completed a decade-long study on the impacts of ASR to the ecosystem. See U.S. Army Corps of Engineers, ASR Regional Study Fact Sheet (2018) (finding that phased implementation of a regional-scale ASR is feasible but would require risk assessments, testing, and continued evaluation).

c. Mechanical Problems
In addition to concerns about contamination of an aquifer, pretreatment is also necessary to ensure that any suspended fine materials that could clog the well are removed. Without proper separation, fine particles can be trapped together near the well or injection and create a clog. Additionally, without proper treatment, microbes can bloom, clogging the well and making it difficult or impossible to inject new water into the aquifer or, later, withdraw water from the aquifer. Niels Hartog and Pieter J. Stuyfzand, Water Quality Considerations on the Rise as the Use of Managed Aquifer Recharge Systems Widens, MDPI: Water at 2 (2017).

Water quality also can deteriorate during subsurface passage in the aquifer. Heavy metals, such as iron and magnesium can be released as the water moves through the subsurface area of the aquifer. See id. at 2–3. These releases can result in a need to once again treat water when it is withdrawn from the aquifer. Additionally, particulate matter can enter into the well and create risks of well clogging.

Separate from all these factors, another variable that may affect the future of ASR usage in the United States is the U.S. Supreme Court’s disposition of County of Maui v. Hawaii Wildlife Fund, No. 18-260. That case, which will be argued during the October Term 2019, examines a Ninth Circuit decision that municipal injection wells, which caused pollutants to reach the ocean via groundwater, required an NPDES permit because the pollutants were fairly traceable back to point sources—the wells. Significantly, the wells in question already were properly permitted under the Underground Injection Control program of the Safe Drinking Water Act. While sound bases exist to support reversal of the Ninth Circuit’s holding, affirmance would impose an ill-suited regulatory scheme on groundwater recharge and recovery systems and create disincentives for continued investment in these environmentally beneficial water management practices.

In sum, ASR provides a promising management technique for dealing with challenges of water shortages, particularly in areas already suffering from increasing demand on insufficient resources. However, an increased reliance on ASR requires that we recognize and solve new problems involving water quality, both in the aquifer and of the recovered waters, and water rights to ensure that this technology can deliver on its promises. Both technological and regulatory advancements will be necessary to maximize the public and private benefits of this appealing water management strategy.

    Lucy K. Infeld, Sarah N. Munger, and Rachel K. Roberts

    Lucy K. Infeld and Rachel K. Roberts are associates at Beveridge & Diamond’s Seattle, Washington, office, and Sarah N. Munger is an associate at Beveridge & Diamond’s Austin, Texas, office. They wish to thank Richard Davis, principal at Beveridge & Diamond’s Washington, D.C., office, for his support and contributions.