Introduction

The interactions between natural water availability and societal water demand and management are complex. In particular, extreme events such as floods and droughts impose management burdens and costs that are not completely understood. Here, we provide an assessment of complex responses to water scarcity during a multi-year drought in California, with a focus on the agricultural and energy sectors.

According to the California Department of Water Resources, water years 2007–2009 made up the 12th driest 3-year period in California’s recorded climatic history (DWR 2010). From a purely hydrological perspective, droughts in the late 1920s, 1970s, and 1980s were more severe (Table 1). The 2007–2009 drought, however, coincided with a period of increased demands for freshwater, changes in operating rules at reservoirs, and increased environmental protections that reduced pumping of water from the Sacramento–San Joaquin Delta to state and federal water users south of the delta (DWR 2010). Among the sectors affected by reduced water availability were agriculture and energy production.

Table 1 Drought severity in the Sacramento and San Joaquin Valleys
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Droughts are severe climatic events through which we may gain insight into our response to both natural climate variability and weather events that are expected to occur as a result of climate change. Climate change research has brought new attention to studies of social and environmental system adaptability. Vulnerability and resilience literature provide a common framework for understanding social and environmental system response to stresses through analysis of “adaptive capacity” (Engle 2011). Due to remaining gaps in empirical research of the adaptive capacity of both social and environmental systems, scholars encourage historical studies of individual climatic events (such as droughts and floods) that are representative of the types of climate stresses that will be faced as a result of longer-term climate change (Engle 2011).

Although defined variously throughout climate change resilience and vulnerability literature, the term “adaptive capacity” refers to the ability of a sector or group to avoid risk; conversely the term “vulnerability” refers to an inability to do so (Ribot 2011; Engle 2011; Smit and Wandel 2006; Smit 1993; Burton 1997). Generally, it is thought that a system more exposed and sensitive to a climate stimulus will be more vulnerable, and a system that has more adaptive capacity will be less vulnerable (Smit and Wandel 2006). Yet, the literature also recognizes that adaptive responses can be “maladaptative” (Smit 1993; Burton 1997). Barnett and O’Neill (2010) define maladaptation as action taken to avoid or reduce vulnerability to climate change that impacts adversely on, or increases the vulnerability of other systems. They provide several characteristics of maladaptive behavior: actions that increase emissions of greenhouse gases, disproportionately burden the most vulnerable, have high opportunity costs, reduce the incentive to adapt, or create path dependencies that limit future generations (Barnett and O’Neill 2010).

Here, we situate our empirical analyses of the responses of the agricultural sector and energy sector to the 2007–2009 California drought within the context of climate change resilience and vulnerability literature. We find that despite both sectors being resilient to the impacts of the drought, in terms of maintaining production levels, they do so by relying on a series of coping strategies that increased the vulnerability of other systems. In particular, drought responses increased emissions of greenhouse gases, had high environmental opportunity costs, and led to a reduced incentive to adapt. We conclude that the responses of the agricultural and energy sectors during the 2007–2009 California drought led to increased vulnerability of ecosystems and social groups that rely on those ecosystems for their health or employment.

Methods

To characterize social and environmental response to drought, we analyze a set of empirical indicators over a period of at least a decade to ensure that we examine the drought within its larger temporal context. For the agricultural sector, we use agricultural acreage, yield, agricultural revenue by county and/or water district, and agricultural employment data collected by the US Department of Agriculture, the California Department of Food and Agriculture, County Crop Commissioners, individual water districts, the US Census, and the California Employment Development Department. Using these data, we examine trends in the agricultural sector, including:

  • gross agricultural revenue,

  • economic productivity of agriculture,

  • economic productivity of agricultural water use, and

  • agricultural employment.

Given the diversity of agricultural water suppliers, and supplies, across the state, we provide an overview of trends in the agricultural sector statewide during the drought period and then focus on a case study of the Westlands Water District (Westlands) to explore local adaptation efforts, such as groundwater pumping. There is no single ‘representative’ agricultural water district in California, due to varied geography, microclimates, and agricultural production. However, Westlands is a useful case study as one of the largest agricultural water users in the state and also as a district that is highly vulnerable to drought impacts.

For the energy sector, we examine trends in:

  • California’s electricity generation (by source),

  • costs to rate payers, and

  • greenhouse gas emissions.

This case study addresses the following questions:

  • How did agricultural and energy production change during the 3-year drought according to the indicators described above?

  • What adaptation efforts were employed in each sector?

  • What components of the observed adaptation were maladaptive, and to what effect?

  • What are the lessons learned about the resilience of freshwater-dependent sectors to more frequent and more intense drought events expected with climate change?

The answers to these questions help us understand resilience to future droughts in California and elsewhere, and are particularly relevant given projections of more frequent and severe water shortages in the future due to climate change (IPCC 2013; DWR 2008). A recent study states that critically dry water years in the Sacramento and San Joaquin Valleys are expected to be about 8 and 32 % more likely by the latter half of the twenty-first century, respectively (Null and Viers 2012).

Results

Agriculture

During droughts, such as the 2007–2009 drought, California’s agricultural sector employs several coping strategies to maintain production and reduce the economic and social impacts of water shortages. These coping strategies include increased reliance on local groundwater, temporary water transfers among users, fallowing farmland, and the alteration of cropping patterns and changes to the types of crops cultivated (Michael et al. 2010). There are few institutional or legal constraints on California groundwater extraction, and as a result the average groundwater depletion (or total extraction volume) doubled during the 2006–2010 time period (Famiglietti et al. 2011).

As a result of these complex factors, the state’s 81,500 farms and ranches generated $34.8 billion in gross revenue for their production in 2009—the third highest year on record and just below the all-time high of $38.4 billion reached during 2008, the second year of the drought (USDA-NASS Agricultural Statistics 2000–2009). The California Department of Food and Agriculture (CDFA 2010) reported that the state’s agricultural sales for 2009 ranked behind only 2008 and 2007 as third highest on record (sales and revenue are adjusted for inflation).

Statewide, harvested acreage has been declining over the past decade, even during periods of more abundant water. The rate of decline in acreage actually slowed between 2007 and 2009 (USDA 2000–2009). In general, annual crop acreage has been gradually decreasing, as annual crops are being replaced by higher-value perennial crops, particularly fruits and nuts (USDA 2000–2009). Based on county crop reports over the last three decades, we conclude that yield or unit of crop per acre has fluctuated from year to year, but only dropped below 2006 (wet year) levels only once during the drought and in a single crop category—in water-hungry and low-value field and seed crops—during the final year of the drought (2009). The average total combined yield of irrigated crops in California was higher during the drought period (2007–2009) than prior to the drought (2000–2006). A closer study of data from county crop reports and irrigation districts reveals varied responses to drought between and within individual counties. For instance, while the total gross revenue of Fresno County agriculture increased by 2 % during the drought years, gross revenue in neighboring Kern and Kings Counties declined by 9 and 19 %, respectively. While Fresno, Kern, and Kings Counties all fallowed land at higher rates during the drought, nearby Tulare County did not. In fact, Tulare County harvested more acres in both 2008 and 2009 than it did in 2006, considered a wet water year.

The drought period coincided with a national and global recession, complicating the analysis of drought impacts. From 2005 to 2009, unemployment almost doubled statewide from 5.4 to 11.3 % (EDD 2011). Michael et al. (2010) found that over the same time period, crop production and agricultural support jobs declined by 1.5 % (2,500 jobs) to 2.3 % (3,750 jobs) in the San Joaquin Valley. However, California Employment Development Department data (2011) indicate that employment sectors other than farming, fishing, and forestry saw the most severe declines in employment in the San Joaquin Valley; employment in farming, fishing, and forestry either remained stable or increased as a percentage of the total jobs available. We note that communities within the San Joaquin Valley have had the highest levels of unemployment and poverty in the state for decades, in both wet and dry years (Villarejo and Redmond 1988).

A case study: the Westlands Water District

California water districts were created over the past century to manage agricultural water rights and water contracts, and to distribute water from state and federal water projects to individual farms. More than 500 water districts currently supply water for agricultural purposes in the state. Importantly, while water district boundaries are often different from county boundaries, watershed boundaries, or groundwater boundaries, their record keeping relates directly to water supply, making them useful for understanding the specific relationship between water use and agricultural production.

Westlands is one of the largest agricultural water districts in the state, serving more than 600,000 acres of farmland on the west side of the San Joaquin Valley in Fresno and Kings Counties. It has the state’s largest federal water contract, and is allocated over one million acre-feet annually, accounting for 30 % of total water exported south of the Sacramento–San Joaquin Delta (Delta Vision Task Force and ENTRIX, Inc. 2008). However, Westlands water contract is relatively “junior” and, therefore, it is often the first region to be affected by water shortages. Furthermore, Westlands lies above the Tulare Basin aquifer, which experienced rapid declines during the drought period (Famiglietti et al. 2011). Thus, Westlands is a useful case study as one of the largest agricultural water users in the state and also as a district that is vulnerable to drought impacts. We note that there are many different types of agricultural water districts and sources of water supply, meaning that both drought impacts and adaptations are varied across the state.

During the 2007–2009 drought, federal Central Valley Project (CVP) water allocations were reduced. During this period, Westlands shifted to other water supply sources, namely groundwater (Fig. 1). For example, Westlands used 315,000 acre-feet groundwater in 2007 (a year during which the district received 50 % of its CVP allocation) and 480,000 acre-feet in 2009 (a year received 10 % of its CVP allocation). This amount of groundwater pumping is just under the levels reached during the severe 1976–1977 drought, when pumping also increased to nearly 500,000 acre-feet (WWD 1996). By utilizing alternate water supplies, particularly groundwater, as a drought response Westlands’ total water supply was only reduced by 3 % in 2006; 13 % in 2007; and 28 % in 2009 (compared to the average water supply between 1993 and 2009). Thus, groundwater pumping allowed Westlands to adapt to reduced CVP deliveries during the drought.

Fig. 1
figure 1

Westlands Water District water supply sources, 2000–2009. Source: WWD (2011a). Water supply is reported in acre-feet. “Net CVP” is CVP allocation adjusted for carryover and rescheduled losses; “Groundwater” is total groundwater pumped by the WWD; “Water User Acquired” includes intra-district transfers between private landowners; “Additional” includes surplus water, supplemental supplies, and other adjustments

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Changes in land use also played a role in drought adaptation. Irrigated crop reports from Westlands summarize cropping patterns within the district between 2000 and 2009 (Fig. 2). These reports show that fallowed acreage increased substantially during the drought in comparison to previous years. In 2000 and 2006 (normal and wet water years, respectively), Westlands fallowed roughly 45,000 and 55,000 acres. During the 2007–2009 drought years, the district fallowed between 99,663 and 156,239 acres annually.

Fig. 2
figure 2

Cropped and fallowed acres in Westlands Water District, 2000–2009. Source: WWD (2011b). There was a significant decline in total cropped acreage over the course of the drought, compared to pre-drought acreage, which remained relatively steady from 2000–2006

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The value of crops produced at the district level is not available from the district crop reports themselves, and is estimated by combining district irrigated crop reports with relevant production value information available at the county level. Here, we use the district’s irrigated crop acreage information and the production values from Fresno County crop reports to generate an approximation of crop values over the drought period compared to past years. The results show that total production values by acreage peaked in 2007 and then slightly declined in 2008 and 2009 (Fig. 3).

Fig. 3
figure 3

Estimated gross revenue, Westlands Water District, 2000–2009. Source: WWD (2011b) and Fresno County Annual Crop Reports (2000–2009), Fresno County Agricultural Commissioner’s Office. Value is estimated by applying the calculated annual crop production value per acre, according to crop type, from Fresno County to annual harvested acreage of the same crop type in Westlands. This method is used because only acreage, not yield, is reported by the district. Although the district also serves a portion of Kings County, the majority of the district’s land is in Fresno County. Values are in 2010 dollars adjusted for inflation

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In 2007, the total value of Westlands’ harvested acreage, in terms of estimated gross revenue from irrigated crops, reached an all-time high of $1.6 billion (using Fresno and Kern County Crop Reports 2000). However, there was a significant decline in annual gross revenue in the district over the course of the drought (2007–2009), compared to the pre-drought period (2000–2006). Yet, the decrease in gross revenue was proportionally less than the drop in total applied water; as a result, there was a significant increase in the annual estimated value per acre-foot (AF) applied water (or the economic productivity of water). During the drought, the economic productivity of water was 30 % higher than during the pre-drought period.

Energy production

California is fortunate to have extensive hydroelectric power capacity. Hydroelectricity is relatively inexpensive compared to almost every other form of electricity generation, it produces few or no greenhouse gas emissions, and is extremely valuable for satisfying peak electricity demands and meeting the needs of daily electricity demand fluctuations. The latter is often the most difficult and costly forms of demand to satisfy. The amount of hydroelectricity that can be generated in any given year, however, is directly related to river runoff and the amount of water stored in California’s reservoirs (Gleick and Nash 1991; Christian-Smith et al. 2011).

During droughts, total hydropower production drops in close relationship to the amount of water flowing in California’s major rivers. Figure 4 shows total hydroelectricity generation in California from 1983 to 2009, plotted together with the unimpaired natural water flows (reconstructed total natural flows excluding diversions and withdrawals) in the Sacramento and San Joaquin Rivers over the same period. The correlation between the two curves is strong: when runoff falls, hydroelectricity production falls, and when runoff is high, hydroelectricity production increases.

Fig. 4
figure 4

California hydroelectricity generation (solid line) from 1983 to 2012 together with unimpaired runoff from the Sacramento and San Joaquin Rivers (dashed line), showing the strong relationship between river flow and hydropower generation. Data on energy generation in California comes from the California Energy Almanac database, at http://energyalmanac.ca.gov/electricity/electricity_generation.html. (Accessed June 2014). Data on unimpaired runoff in the Sacramento-San Joaquin Rivers come from: DWR (2014) California Data Exchange Center. http://cdec.water.ca.gov/water_supply.html. (Accessed June 2014)

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In an average year in California, around 15 % of the state’s electricity (excluding imported power from outside the state) is generated from hydropower facilities. The total fraction of the state’s electricity produced by hydropower has been falling over the past quarter century as demand for electricity has continued to grow, but installed hydroelectric capacity has remained relatively constant (see Fig. 5, which shows the percent of total California electricity generation produced by hydropower plants). The ability to expand California’s hydroelectric capacity is limited. Few undammed rivers, little unallocated water, and growing environmental and economic constraints have all contributed to the difficulty of adding new hydropower capacity.

Fig. 5
figure 5

California electricity production by generating source from 1997 to 2009. Data from the California Energy Commission. (http://energyalmanac.ca.gov/electricity/index.html#table)

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Figure 6 shows total electricity produced for California from 1997 to 2009 by major generating sources. During dry years, hydroelectricity production as a fraction of total state electricity demand can fall to under 10 %. During these periods, lost hydropower is typically made up by burning natural gas and by increasing purchases from out-of-state sources. Because the cost of generating electricity with natural gas is substantially higher than the cost of producing hydropower, droughts lead to a direct increase in electricity costs borne by California ratepayers (Gleick and Nash 1991; Christian-Smith et al. 2011).

Fig. 6
figure 6

California hydroelectricity as a percent of total State electricity generation. The fraction of electricity provided by hydroelectric systems has fallen over the past quarter century as overall electricity production has grown. Data from the California Energy Commission

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Figure 5 demonstrates that the growth in overall electricity production has been dominated by increases in natural gas generation. Hydroelectricity fluctuates with hydrologic conditions, coal generation has declined, and renewable and other in-state production has increased, but at a slower rate than natural gas production.

In the drought years of 2007, 2008, and 2009, hydroelectricity production accounted for only 9, 8, and 10 % of the state’s overall electricity generation, respectively, as compared to an average of 15 % during 1983–2001 (McKinney 2003).

Discussion

Barnett and O’Neill (2010) offer five characteristic maladaptations to climate change: actions that increase emissions of greenhouse gases, have high opportunity costs, disproportionately burden the most vulnerable, reduce the incentive to adapt, and lead to path dependency. Here, we find that several of the adaptive strategies employed by the agricultural and energy sectors during the 2007–2009 California drought indicate maladaptation.

Increasing emissions of greenhouse gases

Using California Energy Commission estimates of hydroelectricity generated in an average year compared to generation during the 2007–2009 drought, it is possible to calculate the extra natural gas burned during the drought. During the drought, approximately 30,000 GWh of lost hydropower were made up with additional natural gas generation. The average levelized cost of California’s in-service combined cycle gas turbines (around 11.5 cents per kWh) compared to the levelized cost of hydroelectric facilities (around 6 cents per kWh) gives an estimate of the added cost to California ratepayers of around $1.7 billion over the course of the drought (Christian-Smith et al. 2011).

In addition to these direct economic costs to consumers, there are indirect environmental costs associated with the additional combustion of natural gas, including increased air pollution in the form of nitrous oxides (NO x ), volatile organic compounds (VOCs), sulfur oxides (SO x), particulate matter (PM), carbon monoxide (CO), and carbon dioxide (CO2), the principal greenhouse gas responsible for climatic change. Using standard emissions factors from the California Air Resources Board and the California Energy Commission (see Table 2) for conventional combined cycle natural gas systems, the drought led to the emissions of substantial quantities of these additional pollutants (see Table 3). In particular, nearly 13 million tons of additional (net over emissions in an average year) carbon dioxide was released during the drought, or roughly a 10 % increase in average annual CO2 emissions from California power plants, along with substantial quantities of NO x , VOCs, and PM. The 0.070 lbs per MWh emissions factors of NO x and 0.208 lbs per MWh VOC represent approximately a 10 % annual increase of these pollutants into local air/watersheds during the drought; NO x and VOC are known contributors to the formation of smog, triggers for asthma, and have other negative impacts on human and environmental health (Gleick and Nash 1991).

Table 2 Criteria pollutant emissions factors (pounds per MWh) for conventional combined cycle natural gas generation
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Table 3 Total air emissions from additional natural gas use during the 2007–2009 drought (tons)
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These estimates are conservative, assuming that all additional natural gas combustion came from more environmentally friendly combined cycle systems. The economic costs of conventional or advanced simple cycle natural gas systems are three to seven times higher than the cost of combined cycles, and emissions are also higher due to lower efficiencies of combustion. Thus, the drought imposed additional direct and indirect impacts to air quality and California ratepayers.

High environmental opportunity costs

The groundwater basins that underlie the Central Valley contain one-fifth of all groundwater pumped in the nation and are, in effect, California’s largest water reservoirs (Faunt 2009). The agricultural sector’s current drought adaptation strategy relies largely on additional groundwater pumping from these basins, which are already stressed; thus increased groundwater pumping represents a high environmental opportunity cost.

A United States Geological Survey (USGS) long-term analysis of groundwater levels in the Central Valley based on GRACE (Gravity Recovery and Climate Experiment) satellite data found significant declines in groundwater levels over the last 40 years (Faunt 2009). These declines have been primarily driven by the overdraft of the Tulare Basin in the southern portion of the San Joaquin Valley. Between 1962 and 2003, an average of 9.1 million acre-feet of water went into storage annually, and an average of 10.5 million acre-feet was removed annually (Faunt 2009), for a net average annual overdraft of about 1.4 million acre-feet. Groundwater overdraft is particularly severe during dry periods, when the data show that not only the Tulare Basin but also the Sacramento Valley and San Joaquin Basins pump more groundwater than is replenished.

Famiglietti et al. (2011) found that groundwater levels in the San Joaquin Basin dropped by 2–6 feet per year from October 2003 to March 2009, while groundwater levels in the Sacramento Basin dropped by a less extreme 0.3–0.5 feet per year over that same time period. Overall, the Sacramento–San Joaquin River Basin lost approximately 25 million acre-feet over the time period—roughly the capacity of Lake Mead, the largest reservoir in the USA (Famiglietti et al. 2011). Westlands’ groundwater conditions report shows that local groundwater surface elevation decreased around 50 feet during the 2007–2009 drought (WWD 2014, Fig. 5).

Given the naturally low rates of groundwater recharge in the San Joaquin Basin, combined with projections of decreasing snowpack (Cayan et al. 2006) and population growth, continued groundwater depletion at the rates estimated are unsustainable, with risks for economic and food security in the USA (Famiglietti et al. 2011). In addition, although not yet quantified, there are increased energy requirements and greenhouse gas emissions associated with increased groundwater pumping from declining groundwater tables.

Reduced incentive to adapt

Farmers have access to emergency aid, loans, and insurance programs that cover part of farmer and rancher losses from drought, floods, and other disasters. Farmers used these programs during the drought to supplement lost farm income due to drought impacts on crops and livestock; we only consider crop losses. Crop insurance policies pay farmers for losses related to either below-average yields (crop yield insurance) or below-average revenue (revenue insurance). With subsidies, most farmers pay around 40–50 % of crop insurance premiums.

Table 4 summarizes California’s drought-related agricultural losses compensated through the USDA Risk Management Agency crop insurance policies, totaling $20 million over the drought period. The vast majority of drought-related crop insurance payments were made for field crops, primarily wheat, oats, and barley. Only in five cases during the drought period were crop insurance payments made for crops other than field crops.

Table 4 USDA drought-related crop insurance payments in California, 2005–2009
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Half of the payments were made during the last year of the drought, indicating that impacts were becoming more severe as the drought persisted. In the final year of the drought, 2009, crop insurance payments in California totaled more than $11 million. Farmers and ranchers in the San Joaquin Valley Counties took out the highest number of drought policies, and received the most in total payment for drought losses between 2007 and 2009.

Looking only at Fresno County, which houses the majority of Westlands Water District acreage, we found declines in harvested acreage, but simultaneous increases in gross revenue during the drought. The total gross revenue of Fresno County agriculture increased 2 % during the drought years, and has increased 35 % since 2000. Despite the relative robustness of Fresno County agriculture, Fresno County farmers and ranchers received the highest total drought-period insurance payments in comparison to other counties. Over 200 drought insurance policies were paid in Fresno County during the drought, totaling $10 million.

Conclusions

California’s agricultural and energy sectors sustained high production levels during the 2007–2009 drought. We find that despite both sectors being resilient to the impacts of the drought, in terms of maintaining production levels, they do so by relying on a series of coping strategies that increased the vulnerability of other systems. In particular, drought responses increased emissions of greenhouse gases, had high environmental opportunity costs, and led to a reduced incentive to adapt.

During this 3-year drought period, California’s hydropower was roughly halved. This lost hydropower was replaced with the purchase and combustion of additional natural gas. We calculate that electricity ratepayers spent $1.7 billion to purchase natural gas over the 3-year drought period, emitting an additional 13 million tons of CO2 (about a 10 % increase in total annual CO2 emissions from California powerplants). The substitution of hydropower with natural gas also released substantial quantities of harmful pollutants, including nitrous oxides, volatile organic compounds, and particulates.

In addition, although total agricultural revenues remained high during the drought, the increased groundwater pumping that in part sustained agricultural production would not provide water security in the face of a longer or more severe drought. The agricultural sector’s increased reliance on groundwater from overdrafted aquifers also increased energy demands and led to drastic declines in groundwater tables. Finally, crop insurance programs under the federal Farm Bill may have reduced the incentive for farmers to adapt by providing subsidized drought insurance for some farms growing water-intensive crops in the Central Valley of California.

We conclude that the responses of the agricultural and energy sectors during the 2007–2009 California drought led to increased vulnerability of ecosystems and social groups that rely on those ecosystems for their health or employment. For California to become more resilient to future drought conditions (as of publication, California had entered into yet another multi-year drought), it will be critical to shift from crisis-driven responses to the development and enactment of long-term mitigation measures.

Crisis-driven responses, such as increased use of fossil fuel-based energy sources, groundwater pumping, and reliance on crop and drought insurance, may harm future generations. Table 5 compares crisis responses with mitigation measures for some of the sectors affected by drought. As this table suggests, a number of mitigation measures are available within different sectors, and mitigation strategies in one sector can have a positive effect on other sectors. For example, improvements in the efficiency of water use in the agricultural sector can minimize that sector’s reliance on the existing supply and reduce unnecessary water use. Therefore, water efficiency improvements can help maximize the current supply and reduce the drought’s impact on other sectors, such as the environment, if water savings are left in-stream or explicitly committed to environmental flow needs (Gleick et al. 2011). Likewise, improving soil moisture management can improve the efficiency of agricultural water use, with benefits for the economy such as increased farm revenues and decreased payouts in the form of federally subsidized crop insurance.

Table 5 Crisis-driven responses and mitigation measures for drought-affected sectors
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