california drought 2015 case study

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Drought May Cost California's Farmers Almost $3 Billion In 2015

Sam Sanders

A row of newly planted organic tomatoes on April 23, 2015 in Firebaugh, Calif. Some farmers are moving tomato production to the north of the state where water supplies are better. Justin Sullivan/Getty Images hide caption

A row of newly planted organic tomatoes on April 23, 2015 in Firebaugh, Calif. Some farmers are moving tomato production to the north of the state where water supplies are better.

California's drought isn't just turning green lawns brown or #droughtshaming into a trending topic. It's taking a multi-billion dollar toll on the state's agricultural industry as well.

The University of California, Davis is out with a new report , and some of the numbers are steep. The study found that in 2015 alone, the drought will cost the state's farmers industry $2.7 billion and more than 18,000 jobs, with 564,000 acres fallowed.

And that's just for one year. "This study does not address long-term costs of groundwater overdraft, such as higher pumping costs and greater water scarcity," it reads. "The socioeconomic impacts of an extended drought, in 2016 and beyond, could be much more severe."

But Richard Howitt , a professor emeritus at UC Davis, and one of the authors of the study, says the situation for farmers could be worse.

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"Despite really big cuts — 60 percent in the surface water supplies — access to underground water has allowed [farmers] to compensate for at least 70 percent of that," Howitt tells The Salt. "So the net cut is around 8 percent of total water."

But groundwater is now running low as well, especially in the Central Valley of California, the heart of California farm country. "This is concentrated in those areas that don't have access to underground water," Howitt says. "These places are in what we call the Central Valley, the San Joaquin Valley. The impacts are hitting small farmers and farm workers [there]."

Big Ag, Howitt says, has reserves to deal with the ongoing drought in a way that smaller farmers do not.

Howitt does say the agricultural industry is finding creative ways to deal with the drought. "It's significantly worse than last year, but people have come up with cleverer ways of offsetting the effects ," he said. "The ... thing that surprised us a bit was how much the farmers are modifying and adapting to this situation."

For example, he says, they are moving crops around, like tomatoes. They are normally are grown in the south, but farmers are shifting production north, to where there are better water supplies. Howitt says farmers are also trying to focus on the highest value crops — like fruits, nuts and vegetables.

The report comes in the same week that statewide mandatory water cutbacks took effect , requiring a net 25 percent reduction in water use for California cities and towns.

But the state's agriculture industry is exempt from those mandatory cutbacks. And Howitt says that's appropriate. "Ag has got a very, very bad supply," he notes. "They've taken their cuts, and overall they're taking a bigger cut than 25 percent."

Nevertheless, some California farmers are already agreeing to voluntarily cut their water use. A group of farmers in the Central Valley has agreed to reduce water use by 25 percent from 2013 levels, or fallow 25 percent of their land. California's State Water Board said in a statement it welcomes the farmers' proposal.

Howitt says UC Davis will update its study in July, with predictions for what he calls a "worst-case scenario."

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• California drought

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A retrospective study of the 2012–2016 California drought and its impacts on the power sector

Jordan D Kern 1 , Yufei Su 2 and Joy Hill 2

Published 18 August 2020 • © 2020 The Author(s). Published by IOP Publishing Ltd Environmental Research Letters , Volume 15 , Number 9 Citation Jordan D Kern et al 2020 Environ. Res. Lett. 15 094008 DOI 10.1088/1748-9326/ab9db1

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1 Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695, United States of America

2 Department of Environmental Science and Engineering, University of North Carolina-Chapel Hill, Chapel Hill, NC 27516, United States of America

Yufei Su https://orcid.org/0000-0002-0133-4593

• Received 6 March 2020
• Accepted 17 June 2020
• Published 18 August 2020

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Method : Single-anonymous Revisions: 1 Screened for originality? Yes

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Over the period 2012–2016, the state of California in the United States (U.S.) experienced a drought considered to be one of the worst in state history. Drought's direct impacts on California's electric power sector are understood. Extremely low streamflow manifests as reduced hydropower availability, and if drought is also marked by elevated temperatures, these can increase building electricity demands for cooling. Collectively, these impacts force system operators to increase reliance on natural gas power plants, increasing market prices and emissions. However, previous investigations have relied mostly on ex post analysis of observational data to develop estimates of increases in costs and carbon dioxide (CO 2 ) emissions due to the 2012–2016 drought. This has made it difficult to control for confounding variables (e.g. growing renewable energy capacity, volatile natural gas prices) in assessing the drought's impacts. In this study, we use a power system simulation model to isolate the direct impacts of several hydrometeorological phenomena observed during the 2012–2016 drought on system wide CO 2 emissions and wholesale electricity prices in the California market. We find that the impacts of drought conditions on wholesale electricity prices were modest (annual prices increased by $0–3 MWh −1 , although much larger within-year increases are also observed). Instead, it was an increase in natural gas prices, punctuated by the 2014 polar vortex event that affected much of the Eastern U.S., which caused wholesale electricity prices to increase during the drought. Costs from the drought were very different for the state's three investor owned utilities. Overall, we find that increased cooling demands (electricity demand) during the drought may have represented a larger economic cost ($3.8 billion) than lost hydropower generation ($1.9 billion). We also find the potential for renewable energy to mitigate drought-cased increases in CO 2 emissions to be negligible, standing in contrast to some previous studies.

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1. Introduction

There is growing interest in understanding the effects of hydrometeorological variability, and especially drought, on the economic and environmental performance of bulk power systems and electricity markets (van Vliet et al 2012 ; van Vliet et al 2016b , Voisin et al 2016 ). In the United States (U.S.), California is particularly vulnerable to drought due to its reliance on in-state and imported hydropower (California Energy Commission 2017a ). Over the period 2012–2016, California experienced a drought considered to be one of the worst in state history (Griffin and Anchukaitis 2014 , Belmecheri et al 2016 , Lund et al 2018 ). During this time, hydrometeorological impacts included extremely low precipitation, snowpack, and streamflow, along with elevated temperatures (Aghakouchak et al 2014 , Mote et al 2016 ). The drought is estimated to have caused 10 billion dollars in economic damages across the state (Lund et al 2018 ).

The lone estimate of the drought's negative economic impact on California's electric power grid is $2.45 billion (Gleick 2017 ), a number that reflects the estimated market value of hydropower that was 'lost' over the years 2012–2016. On average, California relies on in-state hydropower to provide 13% of its electricity needs, with most of this generation coming from dams located in the Sierra Nevada Mountains. In the worst year of the drought (2015), in-state hydropower generation decreased to 41% of average (California Energy Commission 2017b ), helping to meet only 6% of California's electricity needs (California Energy Commission 2017a ).

This estimated $2.45 billion in lost hydropower revenues was reported widely (Fracassa 2017 , Kasler 2017 ), but it likely does not represent the full cost of the drought to electric utilities and their customers. Drought can also impact electricity demand. For example, if drought is associated with elevated air temperatures that increase residential and commercial cooling needs, it can increase the amount of electricity utilities need to purchase on the wholesale market or produce from self-owned resources. Overall, electricity demand in California appears to have increased mostly along a linear growth trajectory over the years 2010–2018, including during the drought (California Energy Commission 2019 ). However, the effects of the drought on demand varied across sectors, and across end-uses within sectors. For example, in the residential and agricultural sectors (the second and fourth largest consumers of electricity in California, respectively (California Energy Commission 2019 )), many utilities reported decreased electricity consumption during the drought years, even as elevated air temperatures increased cooling demands and irrigation (pumping) requirements on a per crop basis. This has been attributed to reduced water consumption during the drought, which in turn reduced energy requirements for water treatment and distribution (Spang et al 2018 ).

An additional mechanism for drought to impact costs for utilities is by altering the wholesale price of electricity. In particular, the combination of reduced hydropower availability (supply) and increased cooling requirements (demand) that can occur during drought in California may increase wholesale prices by forcing the market to rely on higher marginal cost generators (i.e. more expensive natural gas power plants) (Boogert and Dupont 2005 ). If the 2012–2016 drought caused wholesale electricity prices in California to increase, it would have mitigated some financial pain for hydropower-owning utilities; hydropower production, although greatly reduced, would have been more valuable. At the same time, however, higher market prices could have made it more expensive for utilities to meet demand via purchases from the wholesale market. Wholesale electricity prices in California did increase during the middle of the drought, reaching an apex in 2014 (figure 1 ). However, there has been no attempt to understand how supply and demand effects from the drought might have contributed to this increase (especially compared to other factors known to affect market prices, like natural gas prices); nor has there been an attempt to quantify how increased prices influenced the cost of the drought for California utilities.

Figure 1.  Comparison of historical daily electricity prices in the CAISO market during the 2012–2016 drought (green) alongside prices simulated by the CAPOW model (black). The model is able to capture a significant portion of the variation in daily prices, but struggles in some instances to capture very large price spikes. Note that prices generally increased during the first half of the drought, reaching an apex in 2014, before declining during the last two years.

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Another open question from the 2012–2016 drought has to do with the role of the state's growing reliance on variable renewable energy (wind and solar) in mitigating the environmental impacts of drought. In particular, the substitution of natural gas generation for hydropower during drought is known to increase carbon dioxide (CO 2 ) emissions in California (Fulton and Cooley 2015 , Hardin et al 2017 , Herrera-Estrada et al 2018 ). Previous studies have pointed to the state's growing fleet of wind and solar capacity as a counterbalancing force that was able to mitigate increases in CO 2 emissions that would have occurred during the 2012–2016 drought due to a loss of hydropower (Hardin et al 2017 , Zohrabian and Sanders 2018 , He et al 2019 ). In fact, carbon dioxide (CO 2 ) emissions from California's electric power sector actually decreased over the years 2012–2016 (California Air Resources Board 2019 ).

On the surface, these data seem to support the idea that wind and solar power can help reduce the drought-vulnerability of power systems—an idea that has gained more attention in recent years (van Vliet et al 2016a , He et al 2019 ). However, the role wind and solar play in reducing drought-caused increases in emissions deserves further examination. Previous studies have relied exclusively on historical data from 2012–2016 to evaluate the California grid's response to drought without accounting for the confounding effects of year-to-year changes in the generation mix. From 2012 to 2016, installed capacity of wind and solar in the state more than doubled, and generation from those resources partially offset losses in hydropower generation, in turn reducing the amount of 'replacement' generation needed from natural gas plants. This may (falsely) give the impression that future grid configurations with greater installed wind and solar capacity will be better equipped to replace lost hydropower during a drought, and thus avoid associated increases in carbon emissions. Here, we develop a more nuanced understanding of the role that renewable energy in California plays in mitigating CO 2 increases caused by drought.

In this study, we use newly developed grid simulation software to perform a series of controlled computational experiments that identify the direct influence of drought (and its hydrometeorological constituents) on CO 2 emissions, wholesale electricity prices, and costs for utilities in California. We test different underlying generation mixes, varying the penetration of variable renewable energy, in order to better understand how the presence of renewable energy affects the magnitude of drought-caused increases in CO 2 emissions. Our results provide new insights and important context regarding the economic and environmental impacts of the 2012–2016 drought, its effect on the California grid, and the vulnerability of California's power system to drought in the future under alternative grid configurations.

2.1. Modeling approach

We make use of the California and West Coast Power system (CAPOW) model (Su et al 2020 ), an open source stochastic simulation tool designed specifically for evaluating hydrometeorological risks in the U.S. West Coast bulk power system. The model accurately reproduces historical daily price dynamics in California's wholesale market (figure 1 ), although it sometimes fails to capture the highest observed peak prices due to its use of publically available natural gas 'hub' price data. These data are averages of contracted gas prices experienced by market participants. It is likely that during high demand periods, certain power plants experience gas prices much higher than the hub price, causing spikes in the wholesale electricity price that our model does not capture.

The model's geographical scope covers most of the states of Washington, Oregon and California and the operations of the region's two wholesale electricity markets, the Mid-Columbia (Mid-C) market in the Pacific Northwest and the California Independent System Operator (CAISO) in California. Within the CAISO market, we focus on the service areas of the state's three main investor owned utilities, Pacific Gas & Electric (PG&E), Southern California Edison (SCE), and San Diego Gas & Electric (SDG&E).

CAPOW simulates power system operations using a multi-zone unit commitment and economic dispatch (UC/ED) model formulated as a mixed integer linear program. The model's objective function is to minimize the cost of meeting demand for electricity and operating reserves in the two major markets represented, subject to constraints on individual generators, the capacity of transmission pathways linking zones, and others. CAPOW takes as inputs time series of air temperatures and wind speeds at 17 major airports from the NOAA Global Historical Climatological Network (National Oceanic and Atmospheric Administration 2019 ); solar irradiance at 7 different National Solar Resource Database sites (Sengupta et al 2018 ); and streamflow at 105 different gauges throughout the West Coast (Bonneville Power Administration (BPA) 2019 , CDEC 2019 ). Air temperatures and wind speeds are used to simulate daily peak electricity demand via multivariate regression; hourly values are conditionally resampled from the historical record. It is important to note that in this paper we do not directly account for the effects of reduced water consumption during drought on electricity demand. There is limited data available that would allow for parameterization of a tight model coupling among hydrologic triggers, water conservation policies, and electricity demand.

We use daily wind speeds to simulate aggregate zonal wind power production, and daily solar irradiance to simulate zonal solar power production (both via multivariate regression), before conditionally resampling down to an hourly time step. Time series of daily streamflow are forced through hydrologic mass balance models of major hydroelectric dams in the Federal Columbia River Power System (Pacific Northwest), Willamette River basin (Oregon), Sacramento, San Joaquin and Tulare Lake basins (California). Hydropower availability is calculated on a daily basis across every zone in the model, then dispatched optimally on an hourly basis by the UC/ED model. Model outputs include the least cost generation schedule identified down to the individual generator level, hourly zonal electricity prices ($/MWh), and plant level emissions of CO 2 (tons).

For this study, we collected historical daily temperature, solar irradiance, and streamflow data over the period 1970–2017, and wind data over 1998–2017. Missing wind data (1970–1998) at each site were filled by bootstrapping from the historical record, conditioned on daily temperatures. For the purposes of placing the 2012–2016 drought within the larger context of stationary hydrometeorological uncertainty, we also make use of a 1000-year stochastic dataset of air temperatures, wind speeds, solar irradiance and streamflow created by the authors and described in a separate paper (Su et al 2020 ).

Figure 2 compares drought hydrometeorology (2012–2016) with the full 1970–2017 observed record (black) and the 1000-year synthetic dataset (gray). Data shown are averages across all weather and streamflow monitoring stations. The drought years experienced historically low stream flows and elevated temperatures, relative to the recent observed record and the synthetic dataset, while wind speeds and solar irradiance were relatively normal. Even compared alongside the expanded, 1000-year synthetic dataset, modeled hydropower availability and electricity demand for 2012–2016 (and especially 2014–2015) indicate extraordinary conditions (figure 3 ). Note again that demand data shown are modeled purely as a function of hydrometeorological data being passed through statistical models. These estimates thus represent scenarios in which reductions in energy consumption by the water sector do not occur.

Figure 2.  Comparison of historical drought year hydrometeorology (2012–2016) with the longer observed record (1970–2017) (black) and the 1000-year synthetic dataset (gray). While stream flows reached historical lows (B) and temperatures were elevated (A), the 2012–2016 drought experienced relatively normal wind speeds (C) and irradiance (D).

Figure 3.  Joint density function of total CAISO hydropower production and average CAISO peak demand for the 1000-year synthetic dataset (green) and the 2012–2016 drought years (pink). Historical data shown is purely a function of observed hydrometeorological data passed through statistical estimation of electricity demand and reservoir operations models. No policy feedbacks (reduced water use) are considered when predicting electricity demand.

3. Results and discussion

3.1. effects of drought on market prices and emissions.

First, using the 1000-year synthetic dataset, we calculate an average, 365-d profile for every streamflow gauge, wind/temperature station, and solar irradiance site used in the CAPOW model. We pass these average profiles through the CAPOW model, which first translates them into to corresponding time series of available hydropower, wind and solar power production, as well as electricity demand. Then the UC/ED component of the CAPOW model simulates the operation of much of the West Coast grid, including the CAISO market. Representing 'non-drought' hydrometeorological conditions in this manner is unrealistic, in that the 365-d profile does not exhibit any within-year extremes (which do occur even in non-drought years). However, it does allow for easy assessment of within year anomalies caused by the drought, as well as comparison of the timing of these anomalies with the timing of extreme prices.

Figure 4 compares daily CAISO prices calculated using the 365-d average hydrometeorological profile (turquoise) alongside prices modeled using observed weather and streamflow data from the 2012–2016 drought (magenta). Comparing these two series within a given panel (year), we see significant differences in daily price dynamics, especially in late spring/summer during the worst years of the drought (2013–2015), when prices in the drought simulations are as much as $10 MWh −1 greater than 'average' conditions. Underlying these higher prices in the drought simulations are a lack of snowmelt (hydropower) and elevated temperatures (increased demand), which cause scarcity in the CAISO market.

Figure 4.  Daily wholesale electricity price dynamics in the CAISO market, 2012–2016. Different colors represent different hydrometeorological scenarios. Natural gas price fluctuations are responsible for most observed within year price dynamics and year-to-year differences. The large price spike in early 2014, at the height of the drought, was not caused by drought conditions in the California. Instead, this was caused by extreme cold conditions in the Eastern U.S. that increased the price of natural gas across the entire U.S.

Nonetheless, compared to price differences observed between 'average' and drought conditions within a given year, the differences are much greater across years (e.g. 2013 vs. 2014). This suggests that within year electricity price dynamics, as well as differences in prices across years, are driven more by fluctuations in the price of natural gas than by weather and streamflow conditions. Natural gas prices varied continuously over the period 2012–2016, increasing sharply during 2014, especially at the beginning of the year, when a polar vortex event drastically increased heating demands in the Eastern U.S., causing natural gas shortages and a spike in the price of fuel across the entire country (U.S. Energy Information Administration 2014 ). Note that during this period, there is close agreement between estimated prices in 'average' and drought conditions. This strongly suggests that this other hydrometerological extreme—extreme cold weather occurring thousands of miles away in the Eastern U.S.—was the primary cause of the very high wholesale electricity prices experienced in early 2014 at the height of the drought. This is particularly interesting given evidence (Wang et al 2014 ) that both dry conditions in California during 2014 and the occurrence of the polar vortex in the Eastern U.S. were caused by the synoptic climate event—a jet stream pattern that created a persistent high pressure 'ridge' over the Western U.S. If these atmospheric conditions become more frequent and/or severe as a result of climate change (Swain et al 2014 ), it could add a significant, new dimension to the vulnerability of California's grid in the future.

We can also isolate the effects of the individual hydrometeorological constituents of droughts on both prices and emissions (figure 5 ). In the top panel, yellow bars show daily CAISO prices under a 365-d average hydrometeorological profile calculated from the 1000-year synthetic dataset. One-by-one, we then add in constituents of the 2012–2016 drought, beginning with historically low streamflow in California, then observed streamflow in the Pacific Northwest (which typically exports a significant amount of hydropower down into California), elevated air temperatures, and finally wind speeds and solar irradiance. The time series labeled 'Historical' represent results from the full historic 2012–2016 weather and streamflow dataset.

Figure 5.  Additive effects of individual hydrometeorological constituents of drought on average electricity prices in the CAISO market (top panel) and CO 2 emissions (bottom panel). Results confirm that year-to-year changes in the price of natural gas (i.e. comparing across years) leads to much more significant changes in price than weather and streamflow conditions (i.e. comparing across scenarios within a single year). In the bottom panel, we see that low streamflow and high temperatures in California result in the largest relative increases in power sector CO 2 emissions.

Power sector CO 2 emissions (bottom panel) appear more sensitive to drought conditions than prices (top panel). Comparing emissions under average hydrometeorology with emissions under 2012–2016 conditions, we see large increases, particularly during the two hottest and driest years, 2014–2015. There are clear differences in the strength of the effect across individual drought constituents. In most years, the two largest contributors to increased emissions are very low streamflow in California (i.e. reduced in-state hydropower production) and high air temperatures (i.e. increased electricity demands for cooling).

Note as well that the bar graphs in figure 5 indicate standard errors associated with each price and emissions estimate. For each hydrometeorological scenario (e.g. average conditions + historical CA streamflow), identical weather and streamflow inputs are used in multivariate regression models to create five separate records of power system inputs (time series of wind power, solar power, etc). For a given scenario (bar) shown in figure 5 , the standard errors measure the (limited) influence of randomness in regression residuals on the results.

3.2. The cost of drought to electric utilities

A first step in measuring the cost of the 2012–2016 drought for electric utilities in Calfironia is to quantify impacts on market prices in CAISO. In figure 6 (top panel), we compare the electricity price in CAISO under average hydrometeorology (solid bars) and historical 2012–2016 hydrometeorology (white bars). We also compare electricity prices resulting from two different model choices regarding the price of natural gas: (1) a static, average natural gas price of $3.5/MMBtu (orange bars); and (2) the historical 2012–2016 natural gas price regime (pink bars). The price impacts from drought are equal to the delta of each solid/white bar pair; these results are then plotted in the bottom panel of figure 6 .

Figure 6.  Top panel: Comparison of CAISO electricity prices under historical meteorology (white bars) and average conditions (solid bars), and under historical natural gas prices (pink bars) and average natural gas prices (orange bars). Bottom panel: The drought likely caused wholesale prices to increase between $0–3 MWh −1 , depending on the year. We also find that the co-occurrence of high natural gas prices (brought about by the polar vortex in the Eastern U.S.) and drought conditions in California caused the biggest price impacts in 2014, even though 2015 experienced the lowest hydropower and highest cooling demands.

We find that the drought likely caused average market prices in CAISO to increase between $0–3 MWh −1 , depending on the year, although within-year price differences could be much greater (see figure 4 ). Figure 6 also indicates that natural gas prices influence how the market experiences the effects of drought. For example, in the bottom panel, if a constant, average price of natural gas is assumed for each year (orange bars), the most significant impacts from drought occur in 2015. This is consistent with our findings that, in terms of lost hydropower generation and increased cooling demands, 2015 was the 'worst' year during the 2012–2016 drought (see figure 3 ). In reality, the combination of extreme drought conditions in 2014, coupled with high natural gas prices (including those caused by the 2014 polar vortex) actually made 2014 the worst drought year, in terms of increased wholesale prices.

Table 1 further explores the potential costs of drought in the service areas of the three main investor owned utilities in California (PG&E, SCE and SDG&E). The first economic cost to grid participants that we consider is the 'net' value of lost hydropower. In table 1 , we estimate this as the difference between summed daily hydropower revenues (production in MWh multiplied by market price in $ MWh −1 ) under average hydrometeorological conditions and each drought year. This allows us to capture losses from reduced hydropower production, as well as the benefits to hydropower producers from experiencing higher market prices during the drought. In general, we find that increased prices do relatively little to make up for a loss in hydropower production. Across the three utility service areas considered, the net value of lost hydropower over 2012–2016 is approximately $1.9 billion. The only previous estimate of the value of lost hydropower generation during the drought is $2.45 billion (Gleick 2017 ). Our estimate is likely lower due to a few different factors. First, we only assess hydropower that directly participates within the CAISO market. A smaller, but still significant amount of hydropower capacity is operated by other utilities (e.g. Los Angeles Department of Water and Power, Sacramento Municipal Utility District, San Francisco Public Utility Commission, PacifiCorp). Lost hydropower in those areas is not considered. We also directly account for the economic benefits to hydropower producers from increased market prices, which helps offsets lost production somewhat.

Table 1.  Evaluation of the costs of drought in the CAISO market. Higher temperatures increased modeled electricity demand while low streamflows reduce hydropower. The combined effects are an increase in market prices. PG&E and SCE are shown to be the most strongly affected, with PG&E impacted more by a loss of hydropower, and SCE affected more by a modeled increase in demand.

		Average hydrometeorological conditions			Drought impacts			Hydropower revenues			Demand costs
		Demand (GWh)	Hydro (GWh)	Price ($ MWh )	Demand increase (GWh)	Lost hydro (GWh)	Price increase ($ MWh )	Average conditions ($M)	Drought year ($M)	Lost hydro value ($M)	Average conditions ($M)	Drought conditions ($M)	Increased demand costs ($M)	Net drought impact ($M)
PG&E	2012	117 653	24 082	34.70	2411	4882	0.16	784	657	127	4109	4218	108	235
	2013	117 623	24 082	43.33	3173	8887	1.57	1037	685	352	5115	5451	336	688
	2014	117 838	24 082	49.71	3913	11 228	2.39	1207	671	536	5887	6383	495	1031
	2015	118 331	24 082	32.30	2028	12 926	1.58	759	375	384	3862	4133	272	656
	2016	118 250	24 082	29.35	2378	8438	1.03	659	466	194	3512	3721	208	402
SCE	2012	119 994	4268	34.70	4890	988	0.16	139	106	32	4215	4421	207	239
	2013	118 270	4268	43.33	6107	1498	1.57	185	127	58	5152	5621	469	528
	2014	119 294	4268	49.71	7954	2290	2.39	213	105	108	5969	6694	725	832
	2015	121 210	4268	32.30	4723	2598	1.58	137	55	81	3974	4350	376	457
	2016	120 521	4268	29.35	3715	1550	1.03	118	77	41	3606	3858	252	293
SDG&E	2012	25 318	0	34.70	635	0	0.16	0	0	0	885	916	31	31
	2013	24 901	0	43.33	773	0	1.57	0	0	0	1082	1157	75	75
	2014	25 180	0	49.71	1269	0	2.39	0	0	0	1258	1389	130	130
	2015	25 315	0	32.30	1055	0	1.58	0	0	0	825	906	81	81
	2016	25 370	0	29.35	568	0	1.03	0	0	0	753	801	48	48
							Total ($M)	5238	3325	1913	50 206	54 019	3814	5726

Next, we determine the costs associated with higher electricity demand due to elevated air temperatures during the drought. In table 1 , we estimate these additional costs as the difference between summed daily electricity costs (electricity demand in MWh multiplied by the market price in $ MWh −1 ) under average hydrometeorological conditions and each drought year. We find that, in the absence of secondary economic/policy feedbacks (e.g. water conservation efforts in urban areas), increased electricity demand driven by higher air temperatures could have increased costs for utilities by more than $3.8 billion—representing a significantly greater cost than the loss of hydropower.

We also find major differences in how the three investor-owned utilities likely faired during the drought. For example, in the case of PG&E, which is the largest private owner of hydropower capacity in the U.S., the value of lost hydropower represents a greater cost than increased consumption. The opposite is true for SCE, which owns less hydropower capacity and has electricity demands are more sensitive to temperature extremes.

3.3. Renewable energy and drought-caused emissions increases

The second major objective of this paper is to evaluate the potential for variable renewable energy to mitigate increases in CO 2 emissions caused by drought. To answer this question, we measure the response of two different versions of the CAISO grid to drought. In one version we assume 2012 levels of installed wind and solar capacity, and in another we assume 2015 levels of installed wind and solar capacity (more than double 2012 levels). Figure 7 compares the performance of these two versions of the model when simulated under 2015 hydrometeorological conditions (arguably the most extreme year of the drought). Panel A tracks daily differences in fossil fuel generation over the entire year, confirming that a version of the grid with greater (2015) levels of installed wind and solar power relies on less generation from fossil fuels to meet demand. Nonetheless, having increased wind and solar power capacity in place does not prevent the drought conditions from causing an uptick in the use of fossil fuels.

Figure 7.  (A) Changes in fossil fuel generation during 2015 attributable to more than doubling installed wind and solar capacity. (B) Crought caused changes in emissions for the two renewable energy scenarios (2012 (orange) and 2015 (black dotted line)). Differences between these two series are appear to mostly be due to random model errors (C). The presence of more renewable energy does very little to prevent increased reliance on fossil fuel generation during drought.

In panel B, we track daily differences in fossil fuel generation caused by drought conditions in 2015 (i.e. relative to average hydrometeorology) under two different levels of installed wind and solar capacity, 2012 (black) and 2015 (orange). Drought conditions in 2015 appear to cause nearly identical responses (increases) in fossil fuel generation under the two different capacity mixes, despite the fact that double the amount of renewable energy capacity is installed in 2015. This is confirmed by panel C, which plots the difference of the two series shown in panel B. The result approximates a stationary noise process, suggesting that differences between the two renewable energy scenarios is due primarily to stochastic model residuals created by CAPOW when translating hydrometeorological time series into corresponding records of wind and solar power production, electricity demand, etc (see error bars in figure 5 ).

Figure 8 confirms that the presence of more renewable energy does very little to prevent increased CO 2 emissions during drought. We track total CO 2 equivalents emitted by power plants in CAISO under historical drought conditions (open bars) and an 'average' hydrometeorological year (solid bars). We also control for installed renewable capacity. Black bars represent CO 2 emissions in a version of the model that assumes 2012 renewable energy levels. Green bars assume historical capacity levels, which gradually increase over the 5-year period (purple dotted line).

Figure 8.  Top panel: CO 2 emissions under historical 2012–2016 hydrometeorology (open bars), average hydrometeorology (solid bars), 2012 renewable energy capacity (black bars) and historical 2012–2016 renewable capacity (green bars), which gradually increase over the 5-year period. Bottom panel: CO 2 emissions increases during the 2012–2016 drought are actually slightly lower under 2012 renewable energy capacity. This is likely due to greater reliance on higher emission natural gas combustion turbine units when there is more renewable energy installed.

As installed renewable energy capacity increases from 2012–2016 (open bars), emissions are mostly steady before declining in the last year of the drought; they would have decreased faster under average hydrometeorological conditions (solid bars). However, the deltas in emissions between average and historical hydrometeorology look very similar for the two different renewable energy scenarios. The bottom panel confirms this; in fact, we see that drought-caused increases in CO 2 emissions are actually lower in most years if we assume static 2012 installed renewable energy capacity. This could be a sign that the model is relying more on higher emission natural gas combustion turbine units (as opposed to slightly less flexible combined cycle units) when there is more renewable energy installed. If the latter proves to be true, in the short term it raises the possibility that increased renewable energy capacity in CAISO could in fact lead to more severe (larger) emissions responses during drought.

4. Conclusion

In this paper, we closely examine the impacts of the 2012–2016 drought on California's electricity grid. For the first time, we isolate the drought's hydrometeorological constituents and perform a series of controlled experiments in order to understand how weather, streamflow, fuel prices, and renewable energy individually and collectively affected grid outcomes. We first explore the impacts of the drought on wholesale prices for electricity, finding that the drought increased prices on average by between $0–3 MWh −1 , with the biggest underlying causes being a decrease in streamflow (hydropower generation) and elevated temperatures (modeled electricity demand). While an important impact, our results also make clear that natural gas prices were the dominant driver of higher electricity prices experienced during the drought, especially during early 2014 when natural gas prices spiked nationwide due to extremely cold weather in the Eastern U.S. These high gas prices caused a spike in wholesale electricity prices at the height of the drought. Interestingly, the incidence of extreme cold in the Eastern U.S. and extreme drought in California were driven by the same synoptic climate event—a persistent high pressure ridge over the U.S. West Coast.

Our estimates of the cost of the drought in the CAISO system are on the same order of magnitude as the lone previous estimate. However, we find that the cost of the drought in the electric power sector could have been much higher than previously reported, with utilities experiencing significantly increased demand due to higher air temperatures and cooling demands. A limitation of this work, however, is our failure to account for feedbacks from policies aimed and reducing water consumption, which actually reduced electricity demand in some sectors. Improving understanding in this area remains an outstanding challenge. We find essentially no evidence supporting the idea that the presence of greater variable renewable energy capacity before a drought begins will help mitigate associated increases in CO 2 emissions caused by water scarcity and higher temperatures. The results of our controlled experiments show that even when renewable energy capacity more than doubles from 2012 to 2015 levels, the CAISO grid experiences the same increase in fossil fuel generation and CO 2 emissions during drought years. In fact, there is some evidence that drought-caused emissions increases may be more severe under higher installed renewable energy capacity. This could be caused by increased reliance on flexible but inefficient natural gas combustion turbines to help integrate renewables.

Acknowledgments

This research was supported by the National Science Foundation INFEWS programs, awards #1639268 (T2) and #1700082 (T1).

Data availability

The data that support the findings of this study are available upon reasonable request from the authors.

• Geography Review
• Drought and water security: a case study from California

Smart cities

Negative greenhouse-gas emissions, drought and water security, a case study from california.

In 2015 and 2016 California faced one of its most severe droughts on record. This article looks at the challenge of climate change in the context of the Californian drought and its impact on local biodiversity. It is relevant to topics on the water cycle and water security, climate change and ecosystems under stress

• Volume 31, 2017/ 2018
• Climate change
• Resource security
• Water and carbon cycles/Earth’s life support systems

Francesca Quinn

The last ice age ended 11,000 years ago and since then, Earth’s climate has been relatively stable at approximately 14ºC. Over recent decades evidence of higher average temperatures, changing rainfall patterns, increasing sea levels, retreating glaciers and melting of sea ice and ice sheets has been recorded. Extreme weather events, including droughts, have become more frequent.

In 2015 the US state of California experienced one of the worst droughts in its history. This led to real concerns about longterm water security in the region. In October 2016, a quarter of California was lifted out of drought by autumn rains and by spring of 2017 the drought was largely over.

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Modern History Review

A guide to California's drought and water crisis

by Brad Plumer

The roots of California’s water crisis go back decades

California saw this drought coming. Even if people in the state didn’t know it would be this bad — now the worst in recorded history — they’ve known that dry years are inevitable and had all sorts of ideas for how to deal with them.

But for all that planning, California’s current drought has been a disaster . Reservoirs are drying up. Crops are wilting in the fields. For the first time ever, towns and cities will face a mandatory 25 percent cut in their water use.

THE UNDERLYING PROBLEM IS BIGGER THAN ALMONDS OR GOLF COURSES

The problem isn’t that no one foresaw the drought. The problem is that no one has been able to solve an underlying issue that is simultaneously less scary and also much harder than a dry spell: California’s convoluted water system and intractable water politics.

Designed piecemeal over the last century, going back to a time when Los Angeles had one-sixth its current population, California’s system for managing water doesn’t just make it tough to deal with shortages — in some ways, it encourages inefficiencies and waste. This is partly an engineering issue and partly a political one, but it’s become a huge dilemma for a state struggling to adapt to unprecedented drought.

Much of the bickering today around California’s water crisis can be traced back to this underlying systemic issue. Many people accuse farmers — especially its almond growers and cattle ranchers — of using too much water. Farmers, in turn, blame environmentalists for placing undue restrictions on water use. Others fault golf courses and overwatered lawns. Economists say California could better manage its water if only it were priced properly.

There’s some truth to all these points. But it’s worth understanding California’s incredibly complex water system in order to grasp why all these conflicts have arisen — and why fixes are so difficult.

California’s water comes from the north and is used in the south

Perhaps the most fundamental water fact about California is that, historically, water was extremely scarce in the southern two-thirds of the state. The vast majority of precipitation occurs up north , mainly in the winter.

So during the 20th century, both the state and the federal government built an elaborate system of canals, aqueducts, and reservoirs to bring water south:

California’s extensive network of reservoirs, canals, and aqueducts facilitates water marketing. ( Public Policy Institute of California /Vox)

Key parts of this system include:

• The Central Valley Project , built by the federal government in the 1930s, brings water down to the Central Valley, which has now become a key hub for California’s agriculture.
• The State Water Project , built by the state in the 1960s, brings water down to San Francisco and Los Angeles, as well as to the Central Valley.
• The Colorado River Aqueduct , built in the 1930s, brings water from the Colorado River to southern California. Water from this river is divvied up between California, Wyoming, Nevada, Utah, Colorado, New Mexico, Arizona, and Mexico according to rules dating to 1922 .

Today, 75 percent of California’s water supply originates in the northern third of the state, above Sacramento, while 80 percent of water users live in the southern two-thirds of the state. The system that makes this possible operates under a complex thicket of rules managed by federal, state, and local agencies. But for decades, it helped California bloom.

California’s water supply can fluctuate by 40 million acre-feet depending on the year

Rainfall and snow have never been constant in California. In any given year, some part of the state is usually in drought. And for a long time, the water system has been able to deal with at least some oscillations.

In an average year, California gets about 200 million acre-feet of water from rain, snow, and imports from other states. Roughly half of that is absorbed by native plants, evaporates, or flows into the sea. The other half is managed by humans — in the water system described above — and is known as the “developed water supply.”

However, this precise amount can vary a lot year to year. The Department of Water Resources refers to “dry years,” “average years,” and “wet years.” Historically, the state’s developed water supply can fluctuate between roughly 60 million acre-feet in a dry year and 100 million acre-feet in a wet year:

( Legislative Analyst's Office )

The importance of different sources also shifts. During dry years, delivery systems like the Central Valley Project and the Colorado River Project are called on to transport more water to cities and farms. Farmers also compensate by relying more heavily on water pumped from underground aquifers during dry years (they then let those aquifers recharge in wet years).

California is now suffering the worst drought in history, and its water system is cracking under the stress

Now, however, this system has reached a breaking point. This current drought, which started in 2012, is worse than anything California has endured in its history. Virtually the entire state is facing “severe,” “extreme,” or “exceptional” drought:

( California Drought Monitor )

Not only has precipitation been abnormally low, but the state has endured exceptionally warm temperatures that have sped up evaporation. Global warming likely deserves some blame for that latter aspect.

According to one metric from the National Weather Service, those two factors have combined to make this the worst dry spell since at least 1895 — and likely long before:

( National Weather Service Hanford )

The strains on the system can be seen everywhere. Reservoirs like Lake Oroville and Lake Shasta, key nodes in the state’s water storage and delivery system, have been well below capacity. The Central Valley Project has been reducing water deliveries to users — and even cutting off some farmers. Last year, farmers had to let 400,000 acres go fallow and have been depleting underground aquifers to compensate for the lack of surface water.

This winter, things got even worse. One-third of California’s water supply typically comes from snow on the mountains that melts in the spring. But because of a warm winter, little snow fell this year. On April 1, snowpack in the Sierra Nevada mountains was just 6 percent of normal. That’s absurdly low: the previous record for this time of year was 25 percent, set in 2014.

That means there’s going to be a huge water crunch in California this summer. Roughly 41 percent of California’s farmland will face deep water cuts , and 620,000 acres are expected to go fallow, with economic losses of some $5.7 billion. That sets the stage for fierce conflicts between different users.

Humans use over half of California’s developed water supply (and leave the rest in the environment)

( Public Policy Institute of California )

California’s developed water supply is divided between three main sectors. In an average year, about 40 percent of the state’s developed water is used by agriculture. Another 10 percent is used by towns and cities. (The oil and gas industry uses some water for fracking, but a negligible amount.)

The other 50 percent is generally left to protect and restore the environment. That is, the water is allowed to keep flowing through streams and watersheds in order to maintain ecosystems, keep the fish alive, preserve water quality, and so on. As the chart above shows, however, the precise amount left over for this purpose fluctuates a lot between wet and dry years. During droughts, there’s far less water flowing through California’s streams and rivers.

IN SOME PLACES, RULES PREVENT HUMANS FROM TAKING EVERY LAST DROP OF WATER

More than half of this “environmental” water is located up in the rainy north, remote from population centers and not really usable. But there are also places in California where laws prevent cities and farms from taking every last drop of water. Sometimes this is done to benefit other humans further downstream or to maintain water quality. Sometimes it’s done to protect fish or other species.

This can, at times, lead to conflict. In 2007, for example, a federal court ordered the Banks pumping plant near Livermore to reduce water deliveries to towns and farms to ensure there was enough water flowing in the Sacramento–San Joaquin Delta for the endangered Delta smelt .

The current drought will likely lead to new battles. Some farmers, faced with shrinking water deliveries, have expressed frustration at limits placed on water use by various environmental rules. Environmentalists, meanwhile, point out that some streams and ecosystems are now facing dangerously low water levels, putting fish and other species at risk of extinction .

Farms account for 80% of water use (cities are 20%)

( The Hamilton Project )

If you’re looking at human consumption, then farmers are the dominant water users in the state. There’s a reason for this: California plays a pivotal role in US agriculture.

The state is responsible for roughly one-third of the country’s vegetables and two-thirds of its fruits and nuts. The fertile soil and temperate climate are ideal for things like pistachios, broccoli, tomatoes, and lettuce.

The crops that get the most attention are almonds, which now account for roughly 11 percent of California’s human water use — especially since almond consumption is absolutely soaring . But a lot of water is also used for alfalfa — grown as feed for cattle (14 percent) — pasture for livestock (9 percent), rice (7 percent), and so on.

Complex laws govern how farmers get water — and when they get cut off

California’s farmers get their water from a couple of different places. Some rain falls directly on crops. But a huge chunk of water for irrigation comes from California’s elaborate delivery system, which is fed by both rainfall in the north and melting snow from the mountains.

THE CENTRAL VALLEY PROJECT IS NOW CUTTING SOME FARMERS OFF

The laws around which farmers get how much water from these systems are absurdly complex and are often based on historical rights. There are “riparian rights,” which gives access to those who are physically next to waterways. There are laws of “prior appropriation,” which give senior rights to those who first diverted the water for beneficial use, tracing back decades. For those who have water rights, the price of water is usually quite low.

During dry years — like the current drought — those water rights become important. This year, for the second year in a row, the federal Central Valley Project will initially deliver no water to farmers with junior rights. Some users will get their full allotment of water; others will get none. That’s why some farmers are expected to let some 650,000 acres of land go fallow.

But not everyone can let their land go fallow. Almond farmers, for instance, can’t just skip watering their trees for a year; the trees will die. That’s why many farmers, particularly almond growers, have been seeking out another controversial source: groundwater.

In drought, farmers start depleting groundwater — a risky move

When there’s less surface water during droughts, many farmers shift instead to pumping water from underground aquifers — water that’s built up over many decades.

Unlike in other western states, the rules on pumping water from California’s aquifers have long been pretty loose: anyone can draw as much as they want, as long as it’s for a useful purpose. During the current drought, one 2014 UC Davis study found, California’s farmers have been replacing about three-fourths of lost rainfall with groundwater.

As a result, satellite surveys have shown, California’s groundwater has been vanishing at a shocking rate:

Maps of dry season (September–November) total water storage anomalies (in mm equivalent water height; anomalies with respect to 2005–2010) in the western United States. ( Famiglietti et al, 2014 )

This groundwater pumping has helped farmers stave off immediate disaster. But there’s a longer-term problem here. These underground aquifers aren’t easily refilled, since they were built up over many years. What’s more, as these aquifers get drained, the land above them starts sinking , which means they can’t hold as much water in the future.

Add it all up, and farmers are losing a crucial buffer against both this drought, if it persists, and future droughts.

California is finally starting to address this problem, but only sort of. Last year, amid heavy opposition from agricultural interests, the state legislature approved new restrictions on groundwater pumping. But some experts have lamented that these restrictions are fairly flimsy, and will only be phased in gradually between 2020 and 2040.

Farming in California is getting more efficient — but still has some big problems

The share of California’s water used for agriculture has actually declined since 1980 — in part because farmers are using more efficient irrigation techniques and planting crops that generate more value with less water. In the current drought, many farmers are genuinely working hard to conserve.

That said, as a recent paper co-authored by Robert Glennon of the University of Arizona details, there are still a fair number of odd inefficiencies and weird incentives around agricultural water use, in part because of the elaborate rules around usage and in part because water is often artificially cheap.

RULES AGAINST WATER TRADING CAN CREATE PERVERSE INCENTIVES

An example: In the summer, when temperatures soar and water is scarce, many farmers in southern California still use enormous quantities of water to grow alfalfa, a fairly low-value crop that gets shipped abroad for use in dairy industries. (Remember, 14 percent of California’s water use goes toward alfalfa.)

Why is that? In some cases, farmers have to use the water they get or they lose the rights to it. So they may as well grow something. Plus it’s not always easy for farmers to sell their water rights to other people who might find better use for it — there are still quite a few barriers standing in the way of routine water trading. So farmers use cheap water to grow alfalfa, even though it’s sort of a waste.

Water prices for farmers vary widely across the state

Water isn’t free. But what’s striking about California is that the price of water varies wildly from region to region — and is often incredibly cheap for farmers.

Farmers in the Central Coast and South Coast pay roughly as much for water as residential users do. But farmers everywhere else only pay about one-sixth that amount:

Why the disparity? As the Legislative Analyst’s Office explains , the South Coast and Central Coast are served by the State Water Project, which has a higher cost of delivery. The other parts are served by federal water systems, which are largely paid off. Complex water contracts also affect the price.

This varied pricing helps shape what crops are grown where. The Central Coast and South Coast have pricier water, so they tend to grow higher-value crops such as artichokes, strawberries, avocados, and citrus (the soil and climate are also right in these areas). In areas where water is cheaper, you’re more likely to find lower-value row crops like cotton, corn, or tomatoes.

There are also big differences in water efficiency from region to region for the exact same crop. An acre of tomatoes in the Colorado River region uses twice as much water , on average, as an acre of tomatoes in the Central Coast. Climate conditions affect that, but so do prices.

California’s households use a lot of water — though they’ve been cutting back

As we’ve seen, cities and towns only account for 20 percent of California’s human water consumption. But that doesn’t mean they’re conserving as much as humanly possible, either.

CALIFORNIA'S PER-CAPITA WATER USE IS DROPPING — BUT IT COULD STILL FALL FURTHER

The map above, from the Hamilton Project , is striking. Back in 2005, the average person in California’s towns and cities used 124 gallons of water per day — more than twice as much water as the average person in Maine. Why? Lawn watering, mainly. “Whereas residents in wetter states in the East can often rely on rainwater for their landscaping,” the report notes, “the inhabitants of Western states must rely on sprinklers.” (Within the state, water use varies widely , with residents in Beverly Hills using 165 gallons per day and residents in San Francisco using just 46.)

Now, in fairness, California’s per-capita household water use has been declining in recent years — and overall urban water use has stayed flat , even as the population soared past 38 million. That’s thanks to measures to promote water-saving technologies, such as restricted-flow showerheads and low-flow toilets. During the current drought, many cities and towns have been cracking down further on lawn watering.

Even so, some water analysts think there’s a lot further to go. For reference, California’s cities use about twice as much water per capita as Sydney, Australia, which is in a similarly dry climate. Economists also point out that the price of water varies a lot from city to city , with little relationship to scarcity. And wasteful water use is likely to continue so long as water is underpriced.

In March 2015, Governor Jerry Brown announced the first-ever mandatory water restrictions, which will force cities and towns to reduce their water usage by 25 percent in the coming year (varying from town to town). Some water utilities will be encouraged to put “conservation pricing” in place, although many of the cuts will likely come through blunt regulations.

California’s drought problems could get much, much worse

Back in 2008, the Legislative Analyst’s Office pointed out that over the next few decades, as the population grows, California is on track to face significant water shortfalls during “dry” years, unless major changes are made.

IN THE ANCIENT PAST, "MEGA-DROUGHTS" HAVE LASTED FOR DECADES

And there’s a real risk that global warming will worsen those water woes. As the world heats up, California is expected to face higher temperatures. That means less snowpack in the mountains, more evaporation, and a higher risk of severe droughts in the years ahead.

There’s also the dreaded “mega-drought” scenario. Historical evidence from tree rings suggests that in the very distant past, California has endured droughts that lasted many, many decades. It’s unclear if the state is currently in such a dry spell. One recent study, however, led by NASA’s Benjamin Cook, warned that mega-droughts will be more likely this century if greenhouse gas emissions keep rising.

The state isn’t ready for this. “California has no contingency plan for a persistent drought like this one (let alone a 20-plus-year mega-drought), except, apparently, staying in emergency mode and praying for rain,” wrote NASA water scientist and University of California-Irvine professor Jay Famiglietti in a widely circulated op-ed in March .

There’s no simple solution to California’s water woes

Okay, so what’s the answer? Let’s run down some of the proposed fixes in California so far, none of which fully solve California’s water crisis:

Mandatory cuts: Governor Jerry Brown has ordered cities and towns to cut their water use by 25 percent. One flaw? This move does nothing to address agriculture, which consumes four times as much water as urban areas do.

Water-recycling projects or desalination: Back in 2014, California voters approved a $7.5 billion water bond to fund new water recycling, desalination, and drought-preparedness projects. That could help, but those will take time to get underway.

There are plenty of innovative technologies that could help conserve water, though they tend to be quite costly. San Diego is building a desalination plant to make 50 million gallons a day of salty water usable, though it will cost $1 billion, use a large amount of energy, and only supply about 7 percent of the region’s water.

Groundwater pumping restrictions: The state legislature has also approved restrictions on groundwater pumping from agriculture, which will help conserve a vital and limited resource. But those won’t take effect for another five years and will then be phased in gradually between 2020 and 2040. And even those weak rules were fought by many of California’s farming interests.

And what about outside proposals?

Consumer changes: Some people have suggested that California would be better off if we all stopped eating almonds , which are using a ton of the state’s water. (And since almond trees can’t be fallowed for a year, they’re consuming a lot of that scarce groundwater.) Or perhaps we could eat less meat , which also requires a lot of water. It’s true it’d be a huge boon for the planet if we all ate less meat , but unfortunately neither of those things would fix the complex thicket of rules and water pricing in California that encourage inefficient water use.

Water pricing: Some economists have called for better water pricing to encourage more efficient use of water among both households and farmers. The Hamilton Project has offered some suggestions on how California and the West might do this. The hitch? More efficient pricing strategies aren’t always easy to implement, given the complexity of the system. They also don’t fully solve the tension between human and environmental uses of water.

Bolster water markets: In a similar vein, the University of Arizona’s Robert Glennon has called on California to bolster water markets and allow even more water trading among farmers, improving efficiency. (California already does allow farmers to trade the rights to surface water, although the approval process can be cumbersome.)

It wouldn’t take much to have a big impact — if farmers could boost water efficiency by just 4 percent, it would increase the amount of water for cities and businesses by 50 percent. See here for an overview of how California’s water markets currently work and how they might be expanded. Australia has very robust water markets — in which the government buys up water for conservation —though they’re also contentious among some farmers .

But if water markets are so wonderful, why aren’t they more widespread? Last fall, John Fleck, a journalist for the Albuquerque Journal who does a fantastic job of covering water issues, notes that these proposals keep coming up again and again. But the obstacles are formidable.

"This is not for lack of smart scientists and policy people pointing out that the problem is deeper and requires stronger action," Fleck noted on his blog . "This rather reflects a shortcoming of the political system that has left us at with a sub-optimal equilibrium because of the ability of individual players, acting in their own short-term interest, to block progress toward a more socially optimal solution."

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California drought, visualized with open data

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Reservoir Storage

Drought reduces snowpack and results in decreased reservoir volume.

Here, the effect of drought on 56 of California's more than 700 reservoirs is shown through time.

Reservoir volume as a percent of total capacity

Reservoir volume (as a percent of total capacity)
	California reservoirs sorted by elevation

Percent total reservoir volume animated since 2011. Bar widths are proportional to maximum capacity. On the map, circles are proportional to reservoir volume. Data providers: U.S. Drought Monitor , U.S. Bureau of Reclamation , U.S. Army Corps of Engineers , and more ; reservoir data accessed from the CA Data Exchange .

Estimated reservoir surface area loss using USGS's Landsat satellite

Data providers: u.s. geological survey and national aeronautics and space administration.

Changes in reservoir volume impact the surface area of reservoirs. Above, Landsat imagery was used to estimate the change in surface area from August 2011 to August 2014 for two of California's largest reservoirs, Shasta Reservoir and Trinity Lake , both located just under 200 miles northwest of Sacramento, CA. The outlets of the two reservoirs are located approximately 15 miles apart. These reservoirs provide water for irrigation, hydroelectric power, drinking water, ecosystem management, and flood control.

Drought, snowpack, and reservoir storage

Snowpack in California is the primary source of water to reservoirs that serve drinking water, agriculture, and hydroelectric needs.

For any given year, less wintertime snowpack results in lower reservoir levels, and less water for consumptive use.

In 2014, California received only a fraction of its normal precipitation and snow pack, with the State now facing three years of devastating drought ( California Department of Water Resources ).

Drought, snowpack, and reservoir storage (2010 vs 2014)

Snow data provider: u.s. natural resources conservation service snotel, drought also affects flow in streams and rivers.

The current and historical streamflow in unregulated rivers and streams (those without upstream reservoirs or control structures) are shown in the graph.

Current vs historical streamflow

Data providers: u.s. geological survey gagesii and nwis.

Current streamflow (y-axis) is plotted against the historical (since 1980) median streamflow (x-axis) for this day of year. Axes are log-scaled . Mouse over streams on the plot (blue circles), and on map (colored according to flow; red is well below normal flow, dark blue is well above normal flow) for more information.

Water withdrawals

In 2010, the most recent year for which water use was comprehensively estimated, irrigation, thermoelectric power supply, and public supply withdrawals were the biggest uses of freshwater in California ( U.S. Geological Survey ).

Water withdrawals in California (2010)

Data provider: u.s. geological survey, drought and food prices.

Agriculture represents the largest fraction of freshwater withdrawals( 1 ).

For the first time in history, some agricultural areas are not receiving any water for irrigation which is resulting in devastation of historically productive areas. The agricultural output for the state could fall by $3.5 billion this year ( 3 ).

Drought and food price anomalies (2011-2014 differences from the 5-year average)

Droughts, Explained

Uc davis associate professor samuel sandoval solis busts four myths about drought..

• by Narimes Parakul
• January 18, 2022

Drought is back in California. Samuel Sandoval Solis, an associate professor at UC Davis and UC Cooperative Extension specialist, is an expert in water resources management who aims to create better strategies for coping with droughts. Here, he answers some common questions and clarifies some myths about droughts.

What is a drought? A drought is a prolonged period of water shortage. For the past two years, California has been experiencing a meteorological drought, which results from a year of below-average rainfall.

This year, the state is also faced with hydrological and agricultural droughts. A hydrological drought refers to when the lack of precipitation affects rivers and aquifers. Due to above-average rainfall two years ago, reservoirs filled higher in the first year of the drought. Currently, the reservoirs are empty and unable to supplement river flow, thus raising a new issue of a hydrological drought.

An agricultural drought is mostly related to food production, and in 2020, the state lacked enough water to keep agricultural soil wet. While this shortage was covered by water releases from reservoirs last year, reservoirs and aquifers are both severely lacking water this year.

Myth #1: The drought is not my problem.

Drought is everyone’s problem. On average, water use in California is 50 percent environmental, 40 percent agricultural and 10 percent urban, according to the Public Policy Institute of California. But reducing usage will fall to everyone, Sandoval Solis said. “Unfortunately this rhetoric of ‘people who use more water are the only ones responsible for cutting their water use’ is not beneficial. All of us can contribute; all of us should feel that we are part of the problem, and thus part of the solution,” Sandoval Solis said.

He added that everyone can be mindful of indoor water usage and try to save water. For outdoor usage, make sure your irrigation system is not wasting water, and select what part of your landscape you want to protect (such as trees) and what part is expendable (such as ornamentals).

Myth #2: California will never run out of water because it borders the ocean.

Some proposed solutions include using ocean water to supplement the lack of water in the drought. However, this is not a viable option. “It is very expensive, it will pollute the oceans, and it is not sustainable,” Sandoval Solis said.

Myth #3: We need more dams.

“Dams don’t make water. The dams that we need are already built. We just need to manage them better,” said Sandoval Solis.

Myth #4: We need more regulation.

Approved in 2012, Assembly Bill 685 states that every person in California has the right to clean, affordable water. However, approximately 1 million Californians currently live without water, and 10 million Californians are at risk. “We don’t need more regulations; we need to better execute the ones we already have,” Sandoval Solis said. The ineffective implementation of current policies has resulted in entire communities living without water for months, sometimes years.

In fact, he added, with this drought, many of those who ran out of water last time will face the same issue again. “It also depends on systematic advantages or disadvantages,” Sandoval Solis said. “Some of these communities are the ones with the lowest incomes.”

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