Anita Milman is an Associate Professor in UMass Amherst’s Department of Environmental Conservation and Affiliated Investigator with the Northeast Climate Adaptation Science Center. Michael Kiparsky is Director of the Wheeler Water Institute within the Center for Law, Energy & the Environment at the UC Berkeley School of Law. Together they are guest editors of a new special collection of case studies on managed aquifer recharge (MAR)—The Institutional Dimensions of Groundwater Recharge—which was recently published in UC Press’s journal Case Studies in the Environment.

UC Press: Congratulations on the publication of The Institutional Dimensions of Groundwater Recharge, and thank you for this contribution to Case Studies in the Environment!

AM/MK: Thank you. We are quite excited about the special collection. It is one of the only collections of case studies specifically focused on institutions and incentives for managed aquifer recharge, an important and understudied topic for addressing today’s and future water challenges. It was exciting to put the collection together both because of how we did it and what we found. Our team worked directly with water policy-makers and practitioners to anchor the case studies in the on-the-ground realities of this emerging area of water management. Participants in the case studies, along with other experts, then joined us for a major symposium we hosted on the topic, adding more depth of understanding to the analysis of each case and the collection overall. Participant comments and contributions also reinforced to us that institutions and incentives constitute a key bottleneck for both scholarly understanding of MAR and for its implementation in practice.

Pajaro Valley Water Management Agency (PVWMA) Harkins Slough Managed Aquifer Recharge Basin (MAR) in Watsonville, CA. USDA photo by Lance Cheung.

UC Press: First off, for our lay readers, what is managed aquifer recharge, and why is it important?

AM/MK: Groundwater recharge occurs when water percolates into an aquifer, filling storage space created by pumping or subsurface flows. Managed aquifer recharge (MAR) is when humans take actions to increase flows into an aquifer. MAR may mimic natural processes, such as when humans augment water infiltration through natural ponds or channels, or can involve injection of water into an aquifer through wells.

MAR is important because it can help to reduce the all-too-common impacts of groundwater mismanagement that have occurred in many places around the world. Groundwater has been depleted in many or most aquifer systems in the world, negative consequences of which include reductions in the amount of water in storage, degraded water quality, subsidence of the land surface, and impacts on connected rivers and streams. MAR can help address these impacts by augmenting flows of water into the aquifer. MAR can also provide other benefits, such as increasing the amount of groundwater in storage, retiming of surface water flows, and support of groundwater dependent ecosystems.

MAR projects very often embody a multi-benefit approach, in which single projects or schemes result in outcomes across a range of interests, from agriculture supply to urban water reliability to water quality to environmental improvements

UC Press: Your collection presents nine detailed case studies from managed aquifer recharge projects around the US. What was your motivation for launching this collection, and who should read the articles?

AM/MK: Increasing reliance on groundwater, growing recognition of a global trend in groundwater depletion, and climate change have sparked interest in MAR. To date much of the focus of academics and practitioners has been on improving knowledge of the technical aspects of MAR—engineering projects, tracking flows, ensuring water quality, etc. Those contributions are quite important. Yet water is deeply embedded in the social and institutional contexts in which it is governed and used. Over and over again, we heard from water managers that the legal, regulatory, and administrative environment and processes that set the stage for water and land management, combined with complexity of multiple stakeholders and interests, were crucial factors influencing whether or not they were able to implement recharge projects. So our objective was to improve knowledge of the institutional context for MAR in order to start to address this underappreciated bottleneck. Since MAR has many forms and can provide many benefits, the institutional context cannot be examined without also looking at the motivations and specific objectives for implementing MAR.

Our intended audience is quite wide and includes water managers, landowners, agency staff, and anyone else interested in implementing MAR; policy-makers involved in supporting MAR; regulators tasked with overseeing MAR; and researchers seeking to better understand MAR.

UC Press: Can you tell us about some of these projects, and what insights were made?

AM/MK: Each of the projects in the case study collection illustrates crucial aspects of MAR—we chose them for their individual significance, and for the range of geographical settings and motivations they represent. In some cases they show the cutting edge of what can be accomplished in water management.

One we find quite fascinating is the Heyborne Ponds Recharge project—because it illustrates the multi-benefit nature of MAR and, consequently, the potential for partnering in development of MAR. In this project, river water is diverted to wetlands during the winter months, providing habitat for migratory birds. The water in the ponds then percolates through the aquifer, returning to the river and making water available for diversions and ecosystems during the summer months. Another key insight from this project is that Colorado’s well-defined legal and administrative processes for tracking and accounting for recharge facilitated quantifying and allocating the benefits from the project, which helped to make this project possible.

The case studies of the Kern Water Bank and Arizona Water Banking Authority illustrate examples of large scale water banks. Groundwater banking is often discussed as a potential incentive for recharge, where multiple parties can put excess water into the ground with the expectation that they will have access to it later during times of greater need. These case studies clarify some of the immense challenges in moving from a promising concept to a functional banking system, including, as with the Heyborne Ponds project, addressing entitlements for recharge, and accounting.

Other case studies showed the diversity of effective motivations for MAR, ranging from addressing seawater intrusion, to reducing conflicts between groundwater and surface water users, and even reducing nutrient discharges to surface water. These case studies also illuminate how institutional structures related not only to water, but to other environmental conditions, can serve both as facilitators and barriers to MAR.

Ultimately, while the definition of MAR may seem simple on its surface, this collection highlights the range of reasons that MAR is actually put in practice, and shows how crucial these motivations, and the attendant institutional aspects of MAR project design, are in determining the future of MAR.

UC Press: What are the most important overall messages the collection as a whole conveys about recharge?

AM/MK: We think the biggest takeaway is that even though there is a wide diversity of projects, there are similarities in the institutional aspects. Across all of the cases, we see the need for entitlements for use of water for recharge, permitting and approvals for conducting recharge, governance of water in the aquifer, and systems for tracking or accounting for recharge. How these manifest in each case depends on the specifics of the projects; nonetheless, attention to these and other institutional details is essential for project success. In sum, the special collection illustrates that physical design of a project is a necessary but far from sufficient condition for MAR success.

Another key takeaway is the fact that MAR projects very often embody a multi-benefit approach, in which single projects or schemes result in outcomes across a range of interests, from agriculture supply to urban water reliability to water quality to environmental improvements. If this aspect of MAR is to reach its potential in a greater range of projects, it needs to be reflected by diverse institutional involvement and collaboration.

UC Press: Thank you again for spearheading this important project!

AM/MK: It was an exciting effort. We and our many collaborators are delighted to see the articles published!

Case Studies in the Environment is a journal of peer-reviewed case study articles and case study pedagogy articles. The journal informs faculty, students, researchers, educators, professionals, and policymakers on case studies and best practices in the environmental sciences and studies.
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