Sustainable groundwater management and its implications for agricultural land repurposing

In this paper, we examine the implications of groundwater sustainability policies on agricultural land retirement and how retired land can be repurposed to minimize social, economic, and environmental harms, while maximizing potential benefits. Globally, as water resources are strained by increasing agricultural demand and biophysical factors, policies are enacted to restrict groundwater pumping for irrigated agriculture in order to stem social, economic, and environmental harm. However, little is known about the implications of land retirement on ecosystems and people, and how this land can be best repurposed. Using Kern County, CA, as a case study, we draw from 23 qualitative interviews with stakeholders in the agricultural, water, and conservation sectors to understand the impacts of sustainable groundwater management policy and options for land repurposing. Stakeholders in our study outlined both positive and negative impacts of such policies across the region, including increased financial costs of agricultural production, crop type switches to perennial crops such as trees and vines, and improved communication and collaboration among stakeholders. Stakeholders discussed options for land repurposing to maximize ecological, social, and economic benefits, including habitat restoration, installation of solar farms, grazing, groundwater recharge, temporary fallowing, and recreation and parks. Finally, we propose recommendations to maximize the benefits and minimize the harms from the retirement and repurposing of agricultural land: (1) increasing regional planning and cross-stakeholder communication for strategic land repurposing, (2) minimizing the burden of policies that may restrict land repurposing options, and (3) ensuring financial incentives exist for landowners to repurpose their land.


Introduction
Global demand for agricultural products has led to an unsustainable use of water for irrigation (Wada et al. 2010).This is particularly true in arid and semi-arid regions of the world that rely on engineered irrigation systems at large scales (Wada et al. 2010).An increasing scarcity of surface water (due to drought, water policies, infrastructure failures, etc.) has led to the expanded use and depletion of groundwater resources for irrigation and associated economic and environmental concerns related to increased pumping costs, decreased water quality, degraded aquatic ecosystems, and severe land subsidence (Konikow and Kendy 2005;Nelson et al. 2016;Rohde et al. 2017;Niles and Wagner 2019;Franklin et al. 2021).Indeed, a world-wide survey of groundwater levels found significant overdraft globally (Rohde et al. 2017;Franklin et al. 2021).In order to manage groundwater resources more sustainably, governments 120 Page 2 of 12 are implementing policies restricting groundwater pumping for irrigation, which are causing extensive agricultural land retirement, land repurposing, and changes in land ownership (Franklin et al. 2021;Linke and Tollefsen 2021).However, the implications for these types of agricultural land use change and their evolving social-ecological dynamics within agricultural regions remain understudied (Meyfroidt et al. 2019;Wartenberg et al. 2022).
California, USA, is no exception.During the 2011-2017 drought, many Californian farms received 0% of surface water allocations for two or more consecutive years (Sugg 2018).Roughly 2⁄3 of the reductions in surface water were replaced with groundwater, while about 202,243 ha (500,000 acres) of land was fallowed (Lund et al. 2018).As the concern of unsustainable groundwater use grew, California passed the Sustainable Groundwater Management Act (SGMA) in 2014 to achieve long-term balance in pumping and aquifer recharge by 2040.While beneficial towards sustainable groundwater use, reaching the mandated water balance under SGMA is projected to require the retirement of hundreds of thousands of acres in California's Central Valley (Hanak et al. 2019;Kelsey et al. 2018).However, while agricultural land use change transitions driven by water scarcity can have important implications for ecological, social, and economic systems, their potential positive or negative impacts are not well understood (Niles and Wagner 2019;Meyfroidt et al. 2019;Wartenberg et al. 2021Wartenberg et al. , 2022)).
In this paper, we examine the implications of groundwater sustainability policies on agricultural land retirement and how retired land can be repurposed to minimize social, economic, and environmental harms, while maximizing potential benefits.Using Kern County, CA, as a case study, we draw from 23 qualitative interviews with key stakeholders in the agricultural, water, and conservation sectors to better understand the implications of SGMA and future directions for land repurposing.To our knowledge, this is the first study to examine stakeholder perspectives of the impacts of SGMA implementation and land repurposing utilizing a qualitative social science approach.This builds on the work by Niles and Wagner (2019) who conducted focus groups with farmers in Yolo County, CA, to broadly explore farmer perspectives on drivers of water use and potential future changes under SGMA.Qualitative approaches are well positioned to understand the lived experiences and perspectives of individuals towards sustainable water management and can highlight nuance and complexity within social-hydrological systems (Quandt 2022).Previous work has alternatively utilized remote sensing and modeling to understand land use change (Wartenberg et al. 2021(Wartenberg et al. , 2022)), or focused on the equity of governance and planning processes for stakeholders under SGMA (Leach et al. 2021).
SGMA calls for the establishment of groundwater sustainability agencies (GSAs), who coordinate the development of groundwater sustainability plans (GSPs) that require difficult decisions about allocating limited water resources (Hanak et al. 2017;Kelsey et al. 2018).Implementation of these groundwater sustainability plans is only just now in the beginning phases, and thus, understanding their implications for land retirement and repurposing is timely and critical to mitigate harms (Dobbin and Lubell 2021).Kern County, CA, located in the southern part of the Central Valley, is one of the most agriculturally productive landscapes in the world producing over $7.4 billion annually yet is designated a critically overdrafted groundwater basin.Because of this context, the insights from this research can contribute to larger conversations about agricultural land use transitions and options for land repurposing globally (Wartenberg et al. 2022).

Land retirement and repurposing
Throughout this paper, we use the term "land retirement" to refer to agricultural land that is permanently or semipermanently taken out of agricultural production.This goes beyond the period for temporary fallowing, which is a common agricultural practice.We use the term "land repurposing" to refer to the process of actively converting retired land to another type of land use other than intensive agricultural production.Agricultural land that is retired, but then simply left untouched, would not fall into our definition of land repurposing.
Given the existing stressors on our global food production systems, such as variable climates, pests, and other environmental and economic pressures, understanding how retiring agricultural lands can either help mitigate or exacerbate these stressors is important (Hanak et al. 2017).For example, there are concerns that retired lands might serve as sources of unwanted weeds and pests for remaining agricultural land, thus leading to greater pesticide use (Larsen and Noack 2017).Alternatively, retired lands could be repurposed to provide valuable habitat for biodiversity such as pollinators and natural pest enemies, reducing the pest burden and increasing crop health on surrounding croplands (Tamburini et al. 2020).Pollinators and generalist predators, such as birds, may forage in crop fields but rely on uncultivated habitat for nesting (Heath and Long 2019).
In addition to the ecological impacts, major shifts in land use can also have significant economic and social impacts.In California's Central Valley specifically, increased land retirement has been projected to lead to substantial GDP declines and job losses, further exacerbating existing socioeconomic inequalities in the region (Flores-Landeros et al. 2021;Greene 2021).Alternatively, groundwater use and land retirement to promote sustainable groundwater management may have positive impacts on existing issues of degraded water quality (Ayres et al. 2021) and the drying Page 3 of 12 120 up of shallow wells for household and municipal water consumption (Bostic 2021).
Globally, several large-scale studies have looked at the issue of water scarcity and changes in land use.For example, Linke and Tollefsen (2021) explored the links between growing season Standardized Precipitation-Evapotranspiration Index (SPEI) values and land ownership rates in 35 African countries.Their results find a 1.38 percentage point reduction in agricultural land ownership rates for every additional dry growing season.This reduction in land ownership may have major implications for local food security, poverty levels, migration, and conflict (Linke and Tollefsen 2021).Land retirement is a concern for policymakers globally, as these areas could become "economic deserts" (Jowit 2008), with implications for food security and even concerns of malnutrition (Lieber et al. 2022).
Thus, given the potential positive and negative ecological, economic, and social impacts of land retirement, how land is retired is important.The repurposing of retired land may help mitigate the potential negative impacts of land retirement if it is done in a way that can benefit the ecosystem services and functions of the region, while also continuing to support local economies.Indeed, there are significant opportunities to repurpose agricultural lands in the region utilizing multi-benefit approaches to water and land management that can enhance groundwater recharge, improve air and water quality, create new recreational opportunities, improve wildlife habitat, and create new revenue streams for private landowners engaging in land repurposing and conservation-oriented land management (Hanak et al. 2019).

Methods
Our research draws from an interpretive constructivist methodological approach to capture the perspectives and experiences of stakeholders in the agriculture, water, and conservation sectors in Kern County, CA.This constructivist approach allows research participants to see and interpret reality through their own lenses and perspectives (Rubin and Rubin 2012;Quandt and Paderes 2022).We acquired Institutional Review Board (IRB) approval from San Diego State University's IRB before any interviews were conducted (Protocol Number: HS-2021-0209).

Study area: Kern County, California
Agriculture in the region of Kern County that falls within the Central Valley (Fig. 1) is acutely dependent on both surface and groundwater (Elias et al. 2015), with prolonged and recurring drought affecting water availability.From 1950 to 2020, the region saw annual average maximum temperatures increase by 1 °F (0.6 °C), and temperatures are projected to increase by 5 to 8 °F (2.7 to 4.4 °C) by the end of the century (Fernandez-Bou et al. 2021).Alongside temperature increases, precipitation is expected to decrease on average by 20%, with more intense rainfall between November and March, alongside decreasing snowpack in the Sierra Nevada Mountains, an essential resource for water storage (Fernandez-Bou et al. 2021).Drought and extensive groundwater pumping has not only led to groundwater overdrafting, but during the 2012-2017 drought, water shortages were reported for domestic and household use as well, leading to issues of social justice (Greene 2021;Lund et al. 2018;State of California 2019).Over the past 30 years, Kern County has demonstrated an average overdraft of about 2 million acre feet of water each year (Pitzer 2019).It is projected that in California's Central Valley, including Kern County, up to 315,000 hectares (ha) (780,000 acres) of land will be retired due to SGMA (Hanak et al. 2019;Kelsey et al. 2018).
Kern County, CA, spans over 21,000 km 2 (8000 square miles) and is home to a population of over 800,000 people.While our focus is on the Central Valley region of Kern County, the entire county spans from the southern sections of the Coast Ranges and Sierra Nevada mountains and into the Mojave Desert.Kern County residents are largely Hispanic (54.6%), while 19.9% are foreign born and 19% live below the poverty line (US Census 2019).As of the 2017 Census of Agriculture, there were 1731 farms covering 928,955 ha (2,295,497 acres), with the average farm size around 537 ha (1326 acres) (USDA 2019).Almonds and pistachios, along with other perennials, comprise approximately 65% of the total land currently under cultivation (see Fig. 1).

Data collection
We conducted 23 qualitative semi-structured interviews.Interviewees were selected via purposive, snowball sampling design methods, which are commonly used in intensive case studies that involve hard-to-find populations (Bernard 2018).We aim to understand our research questions from the perspectives of three major stakeholder groups: conservation practitioners, agricultural stakeholders, and water resource managers.Based on preliminary discussions with a few key stakeholders, these three, often overlapping, groups emerged as the major relevant stakeholders.Thus, using snowball sampling techniques, we contacted stakeholders already within our professional networks and then asked interviewees to recommend stakeholders within their networks that we could contact.
After 23 interviews, we felt that we had reached data saturation in accordance with common practice for the qualitative social sciences (Bernard 2018).In qualitative studies, data saturation of ≤ 5% new information threshold is typically reached after 6-7 interviews (Guest et al. 2020).For example, research by Guest et al. (2006) found that in their 30 interviews, 70% of the themes and ideas extracted from the interviews were discovered in the first six interviews, 19% in the second six interviews, and only 5% in the remaining interviews.Thus, a small sample size is appropriate and effective to uncover the major themes and topics relevant to the research topic and with all three stakeholder groups.The interviews aim to understand the perspectives of stakeholders in depth, instead of covering the entire breadth of perspectives and experiences that likely exist (Rubin and Rubin 2012).
Interviews were conducted through the Zoom Video Conferencing Platform in June and July 2022.Interviews were recorded by Zoom, and each interview lasted between 30 and 90 min.Zoom produced transcripts of the interview texts, which were then reviewed and revised for accuracy.The semistructured interviews followed a guide of eight open-ended questions focused on the impacts of SGMA and land retirement, as well as current and future land repurposing trends and options (see Supplementary Material 1 Interview Questions).

Data analysis
We used QSR NVivo (1.5.1, 940) software as a tool for coding.In grounded theory analysis, we identified analytic categories (or codes) that emerged from within the text (Bernard 2018).We also drew from a priori assumptions about categories based on the discussion topics within the semistructured interview.For inter-coder reliability, three authors separately coded the interviews and then the sets of codes were compared to come up with the final organization of the results as presented here.

Summary of research participants
While no demographic data was collected from interviewees, we did ask about their personal and professional experience in relation to our study.Thus, based on these conversations, in Fig. 2, we classify stakeholders into three groups: conservation practitioners, agricultural stakeholders, and water resource managers.While a few stakeholders very clearly fell into only one group, for most there were significant overlaps between two or more categories.In order to maintain both confidentiality and anonymity, we exclude any details that may reveal the identity of our interviewees.However, to give a general idea of the types of stakeholders interviewed, the conservation practitioners included stakeholders from large land-acquisition and conservation agencies, regional non-profits, national and state government entities, and wildlife researchers; the agricultural stakeholders included producers and leaders from agricultural organizations, agriculture extension, consultants, and land brokers; the water resource managers included stakeholders from surface and groundwater water management groups.These three categories of stakeholders are meant to serve as a guide to interpreting the results, and throughout the "Results and discussion" section, we have indicated where appropriate the type of stakeholder giving a specific quote or any clear trends in stakeholder perspectives.However, as stated above, our research approach did not aim to quantify results and instead aims to provide nuanced perspectives of the research topics.

Implications and impacts of the Sustainable Groundwater Management Act
The stakeholders interviewed outlined various positive, negative, and mixed impacts of SGMA at a variety of overlapping spatial scales (Fig. 3).These impacts interact and often exacerbate the already existing ecological, social, and economic challenges.Many of the negative impacts agricultural stakeholders discussed were financial.One agricultural stakeholder highlighted rising water costs, "Right now, water values, open market water, depending on where you are, is ranging from $800 an acre foot to $2500 an acre foot, but, wow, yeah we just sold some for $2500 an acre foot."As highlighted in this quote, these prices are increasing significantly under SGMA and a lack of surface water.As mentioned by a conservation stakeholder, for those with the resources to pay high water costs, "There's a lot of I think scrambling to see you know, is there any water to buy on the market."These price increases and local and regional water shocks can also have global economic impacts as many products are exported outside the region (Dolan et al. 2021).
According to a variety of interviewees, financial burdens of SGMA were seen as one contributing factor to the loss of generational farming and the increase in "corporate farms."For stakeholders who have lived and worked in Kern County their entire lives, this shift in the farming landscape was concerning.One agriculture stakeholder spoke about how "The small farmers out there are just not going to have resources to deal with SGMA.You know the people that have 20 acres here, 50 acres, I don't see any way they can sustain this going forward."Many stakeholders also discussed how there is a sense that some agricultural operations continue to drill wells and maximize gains until SGMA regulations are fully implemented.For example, a conservation stakeholder mentioned how "We still have people who are putting in pistachios and almond trees and you know, deepening their wells just to see, you know how much more can I get out of it."The increased establishment of tree crops that has occurred throughout the region in the last decade can be seen as a short-term strategy to mitigate some of the rising costs of production (including water and labor) and be caused by market-driven growth of specialty crops (Meyfroidt et al. 2019).One study found that this shift has contributed to a growth in profitability and calorie production in Kern County, with limited increases in soil loss or evapotranspiration (Wartenberg et al. 2021).However, it has also been associated with less long-term flexibility (Mall and Herman 2019) and increases in the opportunity costs of retiring (Franklin et al. 2021).
However, not all the impacts were perceived as negative.Increased collaboration between stakeholders, funding opportunities for land repurposing, improved water use efficiency, and the goal of sustainable groundwater management were discussed as positive impacts.As discussed by one water-focused stakeholder, "SGMA gave a lot of opportunity for local collaboration to take place, it kind of forced the table to be built around this notion of groundwater… But landowners were only one piece of the conversation, disadvantaged communities were also given a very large voice at the table."Indeed, strong connectivity between farmers, non-profits, government organizations, and others can be effective at creating long-term solutions through knowledge sharing.Previous work in the region has found that collaborative governance under SGMA has increased representation of marginalized stakeholders; however, this still lags behind more advantaged stakeholders (Dobbin and Lubell 2021).Additionally, research has highlighted a lack of financial resources to scale-up collaboration and a need for increased coordination of plans among GSAs within the same groundwater basin (Leach et al. 2021).

Stakeholder perspectives on agricultural land repurposing
During our interviews, we discussed different land repurposing options, including potential co-benefits and costs (Fig. 4).In the sub-sections below, we present results and discussion on land repurposing options discussed by more than five stakeholders.Less frequently mentioned land repurposing options included commercial/industrial use, development offsets, residential/urban development, and carbon sequestration.

Habitat restoration
Conservation stakeholders discussed how strategic habitat restoration could increase habitat connectivity across the landscape.For example, one conservation stakeholder discussed how there is a need for identifying "…the existing protected areas and really try to work with landowners that are kind of adjacent to those areas to really create some of those habitat corridors."This type of connectivity can be beneficial for wildlife.McComb et al. (2022) found that during the 2011-2017 drought, an increase in fallowed land led to increased functional connectivity for the San Joaquin kit fox (Vulpes macrotis mutica).Habitat restoration may also help increase pollinator habitat (Stewart et al 2019), which might benefit surrounding agricultural fields, and according to one agriculture stakeholder, " Even small little, like, island buffers around ag have been shown to be really beneficial for pollinators."However, Wartenberg et al. (2022) found that from 2002 to 2018, being located near protected areas did not influence the decision to fallow land.This suggests the need for landscape-level planning for maximizing habitat restoration benefits from fallowing land.As highlighted by one conservation stakeholder, "If we get this right, we end up with you know connected land that has been taken out of agricultural production, but that has ongoing value that is not creating problems with invasives in the land that is still in agricultural production." Habitat restoration may have multiple widespread longterm benefits including groundwater recharge, native grass and shrub reintroduction, revitalized soil, and improved air and water quality (Stewart et al 2019), and stakeholders spoke specifically about the potential for grazing, water recharge, and recreation on restored lands.Conservation easements may be one solution to promote habitat restoration, and stakeholders mentioned The Nature Conservancy and the regional organization the Sequoia Riverlands Trust as already working with landowners in the area on conservation easements.One strategy may be to buy land to convert to habitat restoration (Kelsey et al 2018), although most stakeholders voiced the desire to keep land managed by private landowners as is commonly done in conservation easements.
However, not all viewpoints were positive.Some concerns were voiced about endangered species, weeds, and pests negatively impacting neighboring landowners.Producers might oppose being adjacent to restored habitat because it could bring endangered species onto their land costing them an incidental "take" fee, or unwanted pests could disrupt their crops.Indeed, the Endangered Species Act, both the federal Endangered Species Act and the California Endangered Species Act, were mentioned as sources of regulatory controls that could slow down land repurposing.Some agricultural stakeholders discussed how land should be restored, versus left on its own, which can lead to increased invasive species and dust storms (Kelsey et al. 2018).For example, one agricultural stakeholder was concerned that "if you start putting a whole bunch of unmanaged native like weedy areas in the valley itself, you're not only increasing the number of lygus bugs, but you're increasing their proximity to the field." Lastly, there was a consensus across the three stakeholder types on the importance of financial incentives for landowners to conduct and be compensated for habitat restoration, as highlighted by one of the conservation stakeholders, "I think we should not only cover the costs of doing the restoration, but compensate them [land owners]."Among the agricultural stakeholders, these financial concerns were echoed as, "Habitat is fantastic but a kit fox doesn't necessarily pay the rent."Another agriculture stakeholder told us that, "Farmers are not looking for handouts, but they need the longterm guarantee of financial incentives, and ones that will not go away after only a few years."These financial concerns extended beyond just landowners as one agricultural stakeholder told us "Of course habitat restoration is fantastic, but that doesn't lend to a lot of jobs, either."Indeed, increased land fallowing is predicted to threaten local jobs (Hanak et al. 2019).

Solar
The second most mentioned land repurposing option among stakeholders was large-scale solar farms.Solar farms are already increasing in the Central Valley as Senate Bill 100, passed in 2018, calls for 60% of energy statewide to be from renewable sources by 2030 (SB 100 Joint Agency Report).According to a water stakeholder, Kern County is already the "largest producer of renewables in the state."It is important to note that much of the renewable energy production in Kern County is actually outside the study area -including the Alta Wind Energy Center, which is the largest wind farm in the United States and located in the Tehachapi Pass part of Kern County.Solar has the potential to be either socially and ecologically damaging or beneficial, and ongoing research is exploring the impacts of solar development on ecosystems (Wu et al. 2023).During our interviews, stakeholders often voiced dissenting opinions about solar and its potential co-benefits.As expressed by one agriculture stakeholder, "There's differences of opinion within the agricultural community about should we allow solar to take over farmland." According to some, solar may be the number one choice of farmers because of the financial benefits of leasing land for solar.Leasing uncultivated land to solar companies can be more profitable than farming and allow farmers to move their water to other parts of their farm, as explained by an agriculture stakeholder, "These farmers can see the writing on the wall that they're not gonna have enough water to farm, and so, this solar is a better highest and best use."An agricultural stakeholder told us how, "I don't love more solar, but I understand that it's an exit strategy from irrigated agriculture that has to be considered."Some conservation and agricultural stakeholders discussed how solar farms can be designed in a wildlifefriendly manner and/or be compatible with livestock grazing.One conservation stakeholder spoke about how, "We have been doing a number of studies since 2014 on the use of large solar farms by kit foxes, and they do quite well there.You have certain mitigations that are implemented, like permeable fencing and you know, some amount of vegetation management, no use of rodenticides, things like that."An agricultural stakeholder discussed how they have seen grazing happening on solar farms, "I did find sheep grazing under solar panels… so it's definitely being done and it can be done.Some of it has to do with how high off the ground the solar panels are."Indeed, another conservation stakeholder spoke about how "Solar farms are actually one of the more compatible uses, we can have some economic benefit to the landowner and actually the society as a whole, even some of the endangered species, endangered wildlife, can survive under the solar panels." However, there was no consensus among stakeholders, and others discussed how solar is not compatible with wildlife or grazing due to increased costs and damage from animals.For example, one agricultural stakeholder who has worked closely with large-scale solar companies told us "The goats will chew on just about anything.If you've got your wires on the backside of the solar panels, they're going to chew on them, and so that's why most solar arrays you'll see pretty much fenced."Additionally, many energy companies that lease lands for solar often keep the land under panels bare using chemicals and machinery (Graham et al 2021).Another concern from the agricultural stakeholders about solar is the use of agricultural land for solar as "Some of the solar farms are on prime farm ground."

Grazing
Grazing was another common land repurposing option discussed, either on its own, or as a co-benefit of other land repurposing options, such as habitat restoration, solar, and groundwater recharge.Previous studies have shown that if managed effectively, grazing can be a tool for maintaining a healthy landscape (Beattie et al 2017).As described by one conservation stakeholder, grazing can potentially help reduce weeds and pests on retired land, while cattle provide a source of income from the land, "It's a way for them to continue to make some money off of that property.Weeds or non-native grasses and things like that, they get incredibly intense and that's actually where the cattle grazing helps out."Among all three stakeholder types, there were generally positive perceptions of grazing on retired lands, while allowing landowners to move their water elsewhere.Even if land is only fallowed for a short period of time, grazing can provide some ecosystem benefits as an agriculture 120 Page 8 of 12 stakeholder mentioned that " [Sheep] tend to be managed in fairly tight groups, they get good deposition of urine and fecal material and so you can really sort of build your soil health that way a little faster." Conservation-focused stakeholders also discussed the benefits of grazing.Indeed, grass and shrubbery management is important because native endangered species, like the kit fox, thrive in plains without excessively dense groundcover (Beattie et al. 2017).One conservation stakeholder described how, "once those lands do get retired, and if the intent is to try to make habitat out of them, you know grazing is very compatible with the species as well."Another conservationists discussed the compatibility of grazing and endangered species habitat, "They found that cattle do a good job of keeping the vegetation low for species like blunt-nosed leopard lizards."Overall, repurposing land for grazing was less contentious than other options.

Groundwater recharge
Creating groundwater recharge basins or recharge ponds is one possible repurposing option for retired lands with multiple co-benefits including habitat for pollinators and other species, recreation, and grazing (Bourque et al. 2019).During our interviews, groundwater recharge projects were often encouraged by stakeholders as a win-win option for land repurposing, as long as the financial incentives exist.A conservation stakeholder discussed how " I think one of the more attractive ways to repurpose lands, at least from a grower standpoint, is going to be multi-benefit recharge," while a water management stakeholder stated, "We're hopeful to do multi-benefit recharge in areas."Some stakeholders also discussed how, given the importance of groundwater issues, state funding opportunities for recharge exist right now, making this option more financially feasible.
Groundwater recharge is not new to the area.One longstanding example is the Kern Water Bank, a semi-private groundwater bank operated by the Kern Water Bank Authority that stores water from the State Water Project, Central Valley Project, and the Kern River (Kiparsky et al. 2021).The Kern Water Bank also includes some habitat for endangered and threatened species, highlighting the potential of multi-purpose water recharge projects to also have conservation benefits for migrating bird populations and endangered species.Thus, the Kern Water Bank serves as an example for multi-use groundwater recharge.As envisioned by one conservation stakeholder, groundwater recharge, It's an actual multi-use, so it's got an exercise trail around it, and also it's full of vegetation, and so I think you know when it is flood the potential for habitat for migratory birds and lots of other animals, so that could potentially be another thing that folks could do would be to create opportunities for recharge on their land.
An agriculture stakeholder spoke about the feasibility of groundwater recharge on private lands, " On your farm… you know where you can take 500 acres or 1000 acres and make it a sinking basin, a recharge pond, an ecosystem project to restore bird habitat or wetland habitat, those kinds of things.Yeah, that's one approach that I think will work well here."

Temporary fallowing and/or disking
Many stakeholders discussed the prevalence of leaving land temporarily fallow, largely through a process called "disking" where a tractor pulls a disk through the soil.Disking uncultivated land can prevent weed growth, leave the window open for future cultivation, and maintain water rights tied to the land.As explained by one conservation stakeholder, People just like run over the field like every six months or so to make sure there's no plants, nothing that's going to be like a nice host for species.Farmers are like natural optimists, because if they weren't optimistic they wouldn't be farming.But I think there's like this hope that like next year there will be water and like next year they'll be able to grow.This sentiment that growers might temporarily fallow through disking in order to keep their options open for the future was repeated in many of the interviews.Indeed, temporary fallowing is nothing new and may have agricultural benefits, as stated by one agriculture stakeholder who discussed, "I mean fallowing could have benefits, and when you come back you're gonna have less diseases and less air borne diseases and less nematodes." However, temporary fallowing or disking can lead to potential environmental and human health problems, such as invasive species introduction, growth of agricultural weeds and pests, reduced habitat for pollinators or endangered species, and poor air quality (Kelsey et al. 2018;Bourque et al. 2019).One conservation stakeholder was particularly concerned and discussed, "Yeah, with no interventions we're heading for a dust bowl for sure, and it's going to be hugely detrimental to the valley if 10-20% of land is haphazardly retired."An agriculture stakeholder spoke about how "one group of people will say we need to disk the field and the other group is going to say but that's going to cause dust and dust is an environmental disaster."As stated previously, some stakeholders voiced concerns about leaving farmland unmanaged and unrestored, leading to weedy patches with negative impacts on surrounding agricultural land.

Recreation and parks
Recreation can be a multi-benefit land use in tandem with groundwater recharge, habitat, and grazing (McCole and Vogt 2011).For example, one water stakeholder spoke about an ongoing project, "We have a recharge flood protection basin that we're building there and the idea is to find other government funding to put in recreation there for the community, a play area, maybe some soccer fields."Another water stakeholder spoke about how some of the grant money coming down from the state could "provide, for the benefit of setting up wetlands, some kind of multi-benefit recreational area, habitat ecosystem restoration kind of work." Alternatively, some stakeholders were skeptical about using fallowed land for recreation because of the hot weather throughout the summer months, and that the native vegetation is "not particularly beautiful."Also, stakeholders spoke about concerns producers may have about having recreation trails near agricultural fields such as spraying near trails or dumping/arsen on properties.An agriculture stakeholder explained that, People will say, well, make it a trail, make it recreation, make it you know some kind of place people can come and visit, and it's like yeah you know that works in a few places, but most property owners don't want the public coming in and trumping across their ground.Nobody wants trash and arsonists and all the nuisances that the public bring when they want to hike in private places.You don't see too many farmers that are all excited about letting 300 acres go for a nature preserve or a public trail, bicycle path, you know.

Key takeaways and recommendations
While our study is grounded in a case study of Kern County, CA, the results and recommendations may apply to other locations facing similar challenges with water scarcity and agricultural production.This is important because the social-ecological implications of land use change and land repurposing have been understudied, both globally and in the region (Meyfroidt et al. 2019;Wartenberg et al. 2022).Therefore, the findings presented here aim to fill this gap by providing an in-depth exploration into both the impacts of water scarcity-induced land use change and the possible solutions to repurposing land taken out of agricultural production.The concern and potentially negative impacts of SGMA found here are similar to those in Yolo County in the northern Central Valley (Niles and Wagner 2019).While the study by Niles and Wagner (2019) did not focus specifically on land repurposing, the 137 farmers in their study were in strong support of incentives for farmers to adopt water saving practices (92% of farmers), groundwater recharge credits (83%), and public programs aimed at water savings (82%).These results are in line with our findings as well.
Through our analysis of the impacts of SGMA and the potential land repurposing options discussed by conservation, agriculture, and water stakeholders, we propose three key takeaways and recommendations in order to maximize the benefits and minimize the harms from the repurposing of agricultural land: (1) regional planning and crossstakeholder communication for strategic land repurposing, (2) minimizing the burden of policies that may restrict land repurposing options, and (3) financial incentives for landowners for land repurposing.These recommendations come directly from the stakeholders themselves and are not solely our own.We have chosen the three presented below because each was highlighted by multiple stakeholders and by multiple stakeholder groups.
First, early and strategic landscape-level planning for land repurposing will help balance the benefits and costs, serving as a blueprint for efficient decisions about how land should be repurposed.Many stakeholders expressed concern about land being retired and repurposed in an uncoordinated manner.For example, they discussed how prime agricultural lands with secure access to surface water and fertile soils should be left in agricultural production in order to sustain the regional agricultural economy.Furthermore, certain areas may be prioritized for habitat restoration, with the co-benefits of groundwater recharge, recreation, or grazing, based on their proximity to existing protected areas and lesser suitability for agriculture.Encouragingly, several stakeholders leading local water management groups did mention that creating strategic, landscape-level plans is an active and ongoing goal of their organizations.There have also been previous efforts at landscape-level planning, such as the San Joaquin Valley Regional Blueprint developed from 2006 to 2009 (http:// ice.ucdav is.edu/ proje ct/ sjv_ bluep rint.html), and SGMA provides an opportunity to focus on land use and water in regional planning.While the increased collaboration and communication through the GSAs, as highlighted by the stakeholders, is an important step in coordinated, strategic land repurposing, Dobbin and Lubell (2021) find that representation of small, low-income communities is still lagging behind, and Leach et al. (2021) find that GSAs suffer from conflicting interests among and lack of trust among diverse stakeholders.
Second, to promote successful land repurposing, there need to be solutions to minimize the burden of existing policies that might restrict land repurposing options.There was a concern from many stakeholders that existing policies might restrict land repurposing and/or slow down the repurposing process.In our study, stakeholders brought up two specific policies they were specifically concerned might restrict land 120 Page 10 of 12 repurposing: the federal Endangered Species Act (ESA) and the Williamson Act, also known as the California Land Conservation Act of 1965.Under the ESA, some stakeholders were concerned that restoring land to provide habitat might encourage endangered species to inhabit land still under production, thus leading to land use limitations and/or resulting in "take" of a listed species that can lead to financial penalties of up to $50,000 or imprisonment.As a solution to these issues, several conservation stakeholders discussed the potential of federal Safe Harbor Agreements, which are "a regulatory assurance that encourages landowners to maintain important habitat on their lands by removing the risk of additional regulation in the future" (Kreye et al. 2016) .Additionally, the California State Safe Harbor Agreement Program Act provides landowners with a similar voluntary program meant to promote habitat conservation while protecting landowners.This means that landowners enrolled in these types of Safe Harbor Agreements will not be subject to additional land use restrictions, even if a protected species increases on the landowner's property.Alternatively, under the Williamson Act, land is under 10-year contracts to maintain and protect agricultural landscapes, and thus, this land may not be able to be repurposed to a non-agricultural land use until the contracts are up.While the goal of the Williamson Act to protect prime agricultural land is important, it may restrict innovative and potentially beneficial land repurposing options.
Lastly, we recommend that there be a robust and longterm system of financial incentives for landowners to retire and repurpose their land, as well as support for local agricultural workers and communities that depend upon agriculture.Many of the negative impacts of SGMA have been financial -including higher water prices and land devaluation -leading to a loss of generational farming and growth in corporate farms that can afford higher prices (Wilson et al. 2017).While the drivers of these changes are complex, stakeholders in our study expressed concern that generational, family farms continued to "get squeezed."Stakeholders did provide some possible avenues for providing financial incentives; for example, restoration could be funded by habitat mitigation credits for development projects or groundwater overdraft fees collected by GSAs.However, as increased land retirement is predicted to threaten local jobs (Hanak et al. 2019), it is critical that such incentives extend beyond landowners themselves.Incentives and support programs also need to consider the larger agricultural economy and community that supports landowners, including agricultural workers and the businesses that support growers such as tractor rental companies or processing facilities.Many stakeholders brought up their concerns for the entire agricultural community and not just landowners.Lastly, given the scale of water use and food production within the region, it may be in the larger interest of the state and the country to minimize the potentially devastating economic impacts to the region in order to conserve water and repurpose land.

Conclusions
Agricultural land use change transitions driven by climateor policy-related water scarcity can have important implications for ecological, social, and economic systems.However, their potential positive or negative impacts are not well understood (Meyfroidt et al. 2019;Wartenberg et al. 2021Wartenberg et al. , 2022)).Thus, in this study, we examine (1) the implications of groundwater sustainability policies on agricultural land retirement, and (2) how retired land can be repurposed to minimize social, economic, and environmental harms, while maximizing potential benefits.The success of agriculture in California, and globally, is contingent on supplies of irrigation water, even under increasing climate-and policydriven water scarcity.Using Kern County, CA, as a case study, we utilize 23 qualitative interviews to better understand the implications of groundwater sustainability policies on agricultural land retirement and how retired land can be repurposed to minimize harms and maximize benefits.Water scarcity is dynamic and complex, and the consideration of multi-purpose, multi-sector, and multi-scale solutions is critical to adapting important agricultural systems (Dolan et al. 2021).
Stakeholders in our study outlined a wide variety of SGMA impacts across the region.This included increased financial costs of agricultural production, crop type switches to perennial crops such as trees and vines, and improved communication and collaboration among stakeholders.Stakeholders also discussed numerous options for land repurposing to maximize potential ecological, social, and economic benefits.These included habitat restoration, solar, grazing, groundwater recharge, temporary fallowing, and recreation and parks.For certain land repurposing options, there was a widespread agreement to the benefits, such as groundwater recharge; however, for others, there was less consensus, such as solar.Additionally, some of these options can be integrated to create multi-benefit repurposing options.Lastly, we propose three key takeaways and recommendations in order to maximize the benefits and minimize the harms from the repurposing of agricultural land: (1) strategic regional land use planning and cross-stakeholder communication and collaboration, (2) reducing the burden of policies that may restrict land repurposing options, and (3) financial incentives for landowners for land repurposing.While every context will be different, the insights from this research can contribute to larger conversations about agricultural land use transitions and options for land repurposing globally (Wartenberg et al. 2022).

Fig. 1
Fig. 1 Map of western Kern County by crop type.Kern County extends to the east of what is pictured; however, this study focused on the part of Kern County that falls within the Central Valley

Fig. 2
Fig. 2 Summary of research participants and their area(s) of expertise

Fig. 3
Fig.3Stakeholder perspectives of the impact of SGMA.These impacts have been organized based on scale (on-farm, county-wide, and valley-wide); however, these categories are overlapping and not mutually exclusive.Impacts are color-coded where red is negative, yellow is mixed, and green is positive.These codes are based on the stakeholder interviews

Fig. 4
Fig. 4 Land repurposing options.The options included here were discussed by more than 5 interviewees.Twenty-two stakeholders discussed habitat restoration, 15 solar, 12 grazing, 11 groundwater recharge, 11 temporary fallow/disking, and 6 recreation and parks