Drought – Public Policy Institute of California

Why the Big Drop in California’s Colorado River Water Use?

In 2019, California’s use of the Colorado River—a major water source for Southern California’s cities and farms—dropped to the lowest level in decades. We asked John Fleck—director of the University of New Mexico’s Water Resources Program and a member of the PPIC Water Policy Center research network—about the ongoing changes in California’s use of this water, and what it means going forward. He is the author, with Eric Kuhn, of the new book Science Be Dammed: How Ignoring Inconvenient Science Drained the Colorado River Basin.

PPIC: What are the main reasons Californians are using less Colorado River water?

JOHN FLECK: The biggest reason for the recent drop is that Metropolitan Water District (MWD)—the state’s biggest urban user of the river—didn’t need to take as much water in 2019. But this decline also reflects a longer term trend. Prior to the early 2000s, MWD generally took the maximum it could from the Colorado River, usually more than a million acre-feet per year. In recent decades, it has substantially reduced its dependence on the Colorado, only taking a full supply in years of State Water Project shortage. Water conservation has been an enormous success in Southern California. There was a lot of progress in conservation during the latest drought, and even after it ended. We’re seeing a lot more effective use of water in the basin, with a growing emphasis on groundwater recharge, stormwater capture, and reuse efforts. The excellent snowpack in the Sierra in 2019 meant the agency got a good water allocation from the State Water Project, meaning it needed less from the Colorado.

The other part of this story is the conservation success in the Imperial Irrigation District (IID)—the largest user of Colorado River water in the entire basin. On-farm water conservation was part of transfer agreements with Southern California’s urban water suppliers. IID is now using 600 thousand fewer acre-feet per year than before those transfers took place. The agricultural community took cuts and was compensated for them. Farmers have adapted well: revenue has held up even as they’re irrigating less land. What we’ve seen is an increase in acreage in high-dollar crops like winter lettuce and vegetables, and a reduction in alfalfa and forage crops, which bring in less revenue per unit of water and area of land.

PPIC: Do you expect similar drops in coming years in California or the six other basin states?

JF: We’re going to have ups and downs—especially because MWD use of Colorado River water tends to go up when its supplies from the Sierra are low. But California has really demonstrated that it needs less Colorado River water. It’s taken awhile, but it’s been a really successful adaptation. Scarcity is the norm now in the basin, so the fact that California can succeed in using less imported water is incredibly important. It shows how we can find opportunities for more flexible problem-solving going forward.

We’re seeing similar things going on across the basin. California isn’t giving up water so others can use more. Nevada is using substantially less than they used to—their use peaked in the early 2000s and has dropped since then. Arizona’s use is down, too. And we’re seeing really flat to declining use in all the other basin states. So the notion that economic and population growth means an increase in water use just isn’t the case in the basin.

PPIC: What does this change mean for efforts to bring the basin into balance?

JF: Because we made mistakes over a century ago in allocating more water than the river can provide, these successes are important, but not enough. We’ll need to see more reductions, especially in the lower basin states.

The next steps require renegotiating the rules that govern the basin’s water allocation to solve the basin’s problems. The Bureau of Reclamation is spending 2020 reviewing how the current rules are working, with the expectation that negotiations on new rules will begin soon after that review is complete. There will be a lot of give and take in how that will play out, and we have to let that happen. Once farmers and communities have a clear idea on how much water they will get, they’re pretty good at figuring out what steps are needed to work within those limits. Various options that might come into play include compensating farmers to use less water, additional conservation, and more expensive options like increasing the use of recycled water and building desalination plants. The negotiations will be hard, but the successes we’ve seen in California and elsewhere around the Colorado River Basin suggest that we have the tools needed to respond to the challenges to come.

Video: A Path Forward for California’s Freshwater Ecosystems

“The current approach for ecosystem management is not working. We’re proposing an alternative path,” said Jeff Mount, senior fellow at the PPIC Water Policy Center, at a public briefing in Sacramento last week. He described two ways the current path is failing: in preserving the broad economic and social benefits associated with healthy ecosystems and in reversing the long-term downward trend in native biodiversity and ecosystem conditions. “The Endangered Species Act misses all that. It’s emergency room treatment” of a chronic problem, he added.

The event launched a new report that proposes managing more broadly for ecosystem health while still protecting species at risk of extinction. “We need diverse, complex, and varied ecosystems to recover species,” he noted.

A panel of experts brought real-world experience to the discussion. Panelists have worked on a plan to protect habitats for multiple species in the Upper Santa Ana watershed, a program to restore the San Joaquin River, and the effort to remove dams on the Klamath River, among others.

Heather Dyer, an endangered species biologist with the San Bernardino water district, said that in the Upper Santa Ana watershed, a large group of stakeholders is seeking to “reestablish a community of species” rather than solely focusing on one or two endangered species. She noted that improving the health of ecosystems requires planning at larger scales—and with the full landscape of regulators and stakeholders coming together to work things out.

Ali Forsythe of the Sites Reservoir Project noted that the hardest lift for large-scale projects is building trust among diverse stakeholders—especially when the project has had a long history of litigation behind it, as the San Joaquin River restoration did.

Lester Snow, now with the Klamath River Renewal Corporation, raised the issue of urgency for improving the health of the state’s freshwater ecosystems. Noting that the Klamath dam removal is already at the 13-year point with the four dams still standing, he said, “It’s these lead times that I think are killing us. Climate change and the change of our natural resource system are moving faster than we’re responding,” with grave implications for water supply reliability and ecosystem health. “We cannot have two decades of litigation and negotiation to address a problem that is critical today.”

We invite you to watch the event video.

Video: Preparing California’s Water System for Climate Extremes

Climate change is stressing water management across California. This week the PPIC Water Policy Center hosted its annual half-day workshop in Sacramento to discuss how state and local leaders can help prepare California’s water system and ecosystems for greater climate volatility.

“California has the most variable year-to-year climate of any state in the lower 48,” said Ellen Hanak, director of the PPIC Water Policy Center. “This is expected to increase, with drier dries and wetter wets.” Water management of the future will “need to start managing our droughts for floods and our floods for droughts,” she added, because greater volatility will make it harder to manage multipurpose reservoirs for both floods and droughts at the same time. Flexible, multi-benefit approaches—and solutions that are aligned across agencies—are going to be increasingly important in tackling these complex challenges.

The first panel focused on managing fast- and slow-moving disasters—floods, fires, and droughts. Panelists discussed the impacts of the recent fires on communities and local water systems, and the types of tools and partnerships that can help minimize risks. Tim Ramirez of the Central Valley Flood Protection Board described the significant and increasing flood risk in the San Joaquin Valley and called for a flood bypass to protect the growing Stockton region. And Michael Thompson of Sonoma Water called for funding from the state to support the “collaborative infrastructure” that will enable agencies to work together more effectively.

A panel on safe drinking water summarized the current status of the problem and discussed how to best use the new Safe and Affordable Drinking Water Fund to ensure that the water delivery system works for everyone. “I think that in five years we want to see every child in California has safe drinking water in their home,” said Jonathan Nelson of the Community Water Center. “The way we do that will be through multiple strategies, but that’s the vision we want to work toward, and ideally, as quickly as we can.”

Darrin Polhemus of the State Water Board said small water systems pay more for their systems and supplies, have a lack of management and technical capacity, and are particularly hard hit by water contamination and shortages. He noted that “we have to change this whole paradigm” to help improve how small water systems operate.

The final panel brought key state officials to the stage to discuss the governor’s water resilience portfolio, now being developed to address the challenges of a more volatile climate. Wade Crowfoot, secretary of the California Natural Resources Agency, said a top priority is to make it easier to help the environment and get multiple benefits out of water projects. “Permitting wetlands restoration is the exact same process as permitting a strip mall,” he said. “So while we’re threatened by climate change and our ecosystem is under unprecedented threat, state government makes it really expensive and slow to get [such projects] done.” He said his agency is committed to cutting “green tape” that slows ecosystem restoration projects.

Sounding a particularly hopeful note, Karen Ross, secretary of the California Department of Food and Agriculture, said we have “an opportunity of a lifetime for farmers to step up and identify how they can be part of the solution to climate change.” She noted that farm practices can sequester carbon while also building resiliency to help farms weather droughts and floods.

We invite you to watch the videos from this event:

Managing Urban Water During Dry Times: The California Example

This article was posted on Meeting of the Minds on October 7, 2019.

California’s drought-prone climate, diverse and decentralized landscape of urban water suppliers, and complex water system make it something of a laboratory for testing ways to manage water scarcity. The state’s urban water suppliers have become particularly adept at managing drought, and this sector has become a leader in water use efficiency, recycling, supply diversification, and integrated management.

But the 2012–16 drought revealed that California’s urban areas must continue innovating to ensure water systems are resilient to climate change. Unusually severe, this drought included the driest four-year stretch in 120 years of record keeping. Record-high temperatures and record-low precipitation reduced water stored in mountain snowpack and intensified drought conditions in other ways—making it more like droughts of the future that are expected to result from a changing climate. The lessons learned from this research have relevance for other urban areas facing drought.

Read the full article on meetingoftheminds.org

The Russian River: Managing at the Watershed Level

This is part of a series on issues facing California’s rivers.

Water managers across the state face new and more extreme challenges as the climate warms—from balancing the sometimes conflicting needs of urban, agricultural, and environmental water users to reducing risks from fires, floods, and droughts. We talked to Grant Davis, general manager of the Sonoma County Water Agency, about how his agency is approaching these challenges comprehensively, at the scale of the entire watershed.

PPIC: In your experience, what does it mean to manage at the watershed level?

Grant Davis: At its core, managing the Russian River watershed requires careful consideration of different land uses, stakeholders, water demands, environmental regulations, and ecosystem needs. We have to balance the competing needs of our 600,000 customers, a number of endangered species, recreational users, and a thriving farm community. In practice, we’ve changed our management considerably over the years. For example, we now intentionally release water from our two major reservoirs to improve estuary and fisheries management, while still meeting water supply needs.

In 2008, we began implementing what is known as a “biological opinion” designed to protect three endangered species—coho, Chinook and steelhead. An important element is restoring habitat on Dry Creek, a major tributary below our major drinking water reservoir. The idea is to slow water released from the reservoir to provide refuge for the fish. In the short run, it will likely make water deliveries harder, but it’s key to operating our system sustainably long term. When complete, we’ll have 6 miles of restored habitat out of a 14-mile stretch. It’s a multi-million-dollar effort—and a major undertaking in cooperation. Our agency has worked very closely with the regulating agencies and private landowners, who granted easements that enabled this restoration to occur.

PPIC: How do you use data sources to help you manage this watershed?

GD: We’re establishing information networks that bring multiple benefits. For example, we’re collaborating with the US Geological Survey on an integrated rainfall and stream gage network, which can help us evaluate whether storms might cause flash floods after fires. The rainfall data also helps with ecosystem management. In a changing climate, rainfall data is the primary input for understanding our watershed.

Since the Tubbs fire, we’ve begun working with more parties to leverage our respective data needs. For example, working with emergency responders, we’ve established a network of fire cameras that inform a text alert system. And working with PG&E, we’re looking at installing equipment to forecast atmospheric rivers and fire weather at the same weather stations.

It’s also critical that we use science to better understand atmospheric rivers, which will in turn allow us to better manage reservoirs as the climate warms. These large storms contribute to most flooding in California, and up to 95% of floods in our watershed. And the lack of atmospheric rivers leads to drought. We’re now working with the US Army Corps of Engineers, NOAA (the National Oceanic and Atmospheric Administration), the Scripps Institute of Oceanography, the Department of Water Resources, and other colleagues to study this phenomenon. Together, we’re developing a joint project that uses improved forecasting of atmospheric rivers to better manage water releases from reservoirs. We’ve built a coalition with other water agencies—including those in Orange County, Turlock, and Yuba—that are interested in exploring these same issues in their rivers. Data from the project will help us improve how we manage water supply, floods, and the environment.

PPIC: Talk about how the interaction between surface water and groundwater has affected Russian River water management.

GD: Our watershed is ground zero for efforts to understand the links between groundwater and surface water, and to better manage both together. In 2014, Mark West Creek was selected as one of five priority creeks as part of the California Water Action Plan. The creek goes through a depleted groundwater basin, which has affected its flows. The Department of Fish and Wildlife is now developing recommended flow levels to protect and restore the creek’s critical habitat. The project will also quantify human needs within the watershed.

In places like Mark West Creek, groundwater recharge can play a critical role in addressing the “timing divide” for maintaining freshwater fisheries—because the question is not always whether water is available, but when it’s available. A pilot project in the town of Sonoma will use Russian River surface water in wet winters to recharge the aquifer. We can then pump it when it’s needed in dry summer months for critical uses.

Thanks to Jay Jasperse and Carlos Diaz, both of the Sonoma County Water Agency, for their contributions to this article.

Preparing California’s Rivers for a Changing Climate

This is part of a series on issues facing California’s rivers.

California’s rivers and streams have experienced enormous changes over the past 150 years, and a warming climate brings new challenges. We talked to Ted Grantham—a river scientist at UC Berkeley and a member of the PPIC Water Policy Center research network—about the state of the state’s rivers. Grantham was recently appointed as the first PPIC CalTrout Ecosystem Fellow. Thanks to the donors that helped us launch this program: Gary Arabian, the Morgan Family Foundation, Nick Graves, John Osterweis, and the Rosenberg Ach Foundation.

PPIC: Talk about the changes affecting California’s rivers and streams.

Ted Grantham: California’s rivers and streams have experienced so much change since European settlement that they’re considered “novel ecosystems.” Gold mining and logging brought a massive amount of sediment into rivers. Riparian forests that lined Central Valley rivers and extensive wetlands on the valley floor have mostly been converted to farming. Non-native species have been introduced to most of California’s rivers, lakes, and estuaries, which prey upon or compete with native species. Urban rivers across the state have been channelized. And essentially every major river and stream in the state is impacted by a dam. Dams aren’t just barriers to migratory fish, they also alter downstream flows.

We’ve also prevented rivers from being able to move. Rivers are not static features; when given the opportunity, they will dynamically respond to changes in climate. This dynamism is inherent to how rivers work—it’s how habitat is created and maintained for many species. And it’s what makes these systems resilient over time.

Given all these fundamental changes, it’s remarkable that most of the state’s native fish species are still with us, although many are at risk of extinction.

PPIC: How are the state’s rivers expected to respond to climate change?

TG: The most direct change is increasing temperatures. Our rivers and streams will continue to heat up in a warming climate. Even if average precipitation stays the same, we’ll also experience more extremes, with both drought years and wet years more likely to occur. While increasing floods pose risks to some river ecosystems, it’s drought we’re most concerned about. Drought not only reduces the amount of water available for the environment, it also intensifies competition with other water users, making it harder to protect freshwater ecosystems.

Climate change is particularly problematic for cold-water fish such as salmon. In the short term, large dams have the potential to limit warming to some degree because they hold reserves of cold water. For example, Shasta Dam is managed to sustain salmon populations downstream through cold-water releases. But if water gets too warm over time, our ability to sustain cold-water reserves in the reservoir will decline. In the long term, redesigning dams to allow for fish passage or strategically removing dams will give salmon access to cold water in higher elevation streams.

PPIC: How can we prepare rivers for a changing climate?

TG: There are several promising management strategies that are gaining traction and could help build climate resilience in our rivers. Two important ones are securing environmental flows and restoring floodplains.

“Environmental flows” refers to the quantity, quality, and timing of water needed to maintain healthy rivers and ecosystem services that people rely on. In the past, little consideration was given to water needs of the environment. But that is changing and we’re seeing a growing effort to establish legally protected water allocations for environmental benefits. For example, I’m currently involved in the California Environmental Flows Framework, a program to support the development of environmental flow standards in rivers and streams throughout the state.

We’re also seeing more interest in multi-benefit approaches to floodplain management. Most of California’s rivers are disconnected from their floodplains, which have been converted to agriculture and urban uses. This has had huge impacts on fish populations and other species. As the likelihood of extreme floods increases with climate change, reconnecting floodplains is a cost-effective way to reduce flood risk. What’s exciting is that floodplain restoration can be compatible with agriculture and can also provide productive habitats. For example, the Yolo Bypass is primarily managed to protect Sacramento from flooding, but it also supports seasonal agriculture and habitat for birds and fish. Bringing water back to our floodplains can even help replenish groundwater, which is a critical water source in drought years.

The LA River and the Trade-Offs of Water Recycling

This is part of a series on issues facing California’s rivers.

After a very wet winter, California has been declared drought free. But planning for future water shortages has continued. In Los Angeles, Mayor Eric Garcetti recently announced a goal of 100% wastewater recycling by 2035 to help make city supplies drought proof.

While recycling wastewater helps cities adapt to a changing climate and prepare for droughts, it can have unintended consequences for local watersheds. In some cases, the growing use of recycled water could minimize or even eliminate flows from wastewater treatment plants into local rivers and streams and reduce ecological and recreational benefits. The Los Angeles River exemplifies this kind of trade-off: expanded water recycling will reduce the amount of treated wastewater flowing into this increasingly revitalized urban waterway.

The lower stretch of the river, which was converted into a concrete flood channel in the mid-1900s, is changing. Concrete has been removed from large stretches of the river and public parks and bike paths have been built along its banks, encouraging recreational use and increasing public interest in the river’s restoration. The river was declared a navigable water in 2010 and opened to kayaking the following year. It provides a vital refuge to a variety of riparian species that lost most of their habitat to channelization and urban development.

Last year, researchers from the Southern California Coastal Water Research Project (SCCWRP) launched a study to document the effects of reductions of treated wastewater on vulnerable species and habitats along the highly urbanized, 45-mile stretch of the lower river, as well as on recreational uses of the river. One of the project’s goals is to determine how these impacts could be offset by investments in river restoration and upstream mitigation projects.

The SCCWRP researchers plan to develop recommended seasonal flow targets for each section of the LA River. They will consider the balance between protecting the river’s ecological and recreational uses and local agencies’ desire to capture, divert, and recycle more water in the watershed. The study will also help inform a number of planning efforts, including One Water LA and the LA River Revitalization Master Plan.

Eric Stein, principal scientist with SCCWRP, emphasized that the project’s success is dependent on its collaborative nature. “We are bringing together agencies, municipalities, nonprofit organizations, and community groups to help explore alternative future scenarios and find innovative ways to balance potentially competing demands for water in the LA River,” he said.

The LA River watershed is only one example where a conflict between recycled water investments and downstream users is emerging. As the demand for recycled water grows and local agencies consider new projects, other watersheds could benefit from similar efforts to better understand the impacts of water recycling on the local ecology and downstream users.

Learning the Language of Groundwater

groundwater (ground·wa·ter \-wȯ-tər, -ˌwä-\ Water beneath the land surface that fills pore spaces in underlying soil or rock.

Groundwater is a critical part of California’s water supply—on average, underground aquifers provide nearly 40% of the water used by the state’s farms and cities, and more in dry years. But after decades of unsustainable pumping in many basins, the state is undergoing major changes in how it manages this resource. The Sustainable Groundwater Management Act (SGMA) requires water users to develop plans to bring their basins into balance in coming years and encourages wide public participation in the planning process. Knowing some of the vocabulary is key to engaging in the conversation. This glossary will get you started.

Adjudication: A lack of clarity over how much groundwater individuals can pump has caused conflict in some places. In more than two dozen basins, mostly in Southern California, the courts have been asked to settle—adjudicate—disputes over groundwater pumping rights. Adjudicated basins must report how much water is being pumped, but most other basins are not yet required to do so.

Conjunctive use: The coordinated management of surface water and groundwater to make the best use of surface water during wet periods and groundwater during dry periods. Expanding this practice can require changing how surface reservoirs are operated, to allow the release of more water during the fall to replenish aquifers and increase reservoirs’ capacity to hold winter runoff.

Conveyance: The infrastructure needed to move surface water to where it can be used, including to areas suitable for recharging aquifers. In some parts of the state, this infrastructure is in poor condition or is missing links, creating barriers to getting more water into underground storage.

Glide path: A gradual approach to implementing SGMA, to give water users time to adjust and prevent major disruptions in the regional economy. Most groundwater sustainability agencies in the San Joaquin Valley—where overdraft is a major issue—are likely to adopt this approach. The result is that groundwater levels will continue to decline, but at a decreasing rate, until they reach long-term balance.

Groundwater sustainability agencies (GSAs): Local agencies formed to develop groundwater sustainability plans to manage their resources for the long run. More than 250 GSAs in 140 “priority basins” (which account for most of California’s groundwater use) have been formed.

Overdraft: When groundwater extraction exceeds what is being replenished (also called “groundwater mining”). Its repercussions can include drying wells, sinking lands, reduced streamflow, degraded water quality, and higher energy use from pumping water from deeper depths.

Recharge: Taking action to replenish underground aquifers with surface water (also known as “managed recharge” to distinguish it from natural recharge). This water can come from a variety of sources, including flood- and stormwater, treated wastewater, and spare surface water. Recharge usually involves spreading water on the land. Some water districts have dedicated recharge basins, but individual farms can also help by recharging on their lands. “In lieu” recharge is when farmers enable the aquifer to replenish naturally by pumping less and using surface water instead. One challenge is coming up with ways to compensate farmers who recharge shared basins under their land.

Safe or sustainable yield: The amount of water that can be withdrawn from a groundwater basin without causing problems—such as a significant drop in water levels, harm to groundwater-dependent ecosystems, land subsidence, and saltwater intrusion, to name a few.

Saltwater intrusion: Many coastal aquifers—for example, those on the Central Coast—are overdrafted, which reduces groundwater flow toward the sea and allows saltwater to move in.

Subsidence: Land surfaces can sink in overdrafted basins, which damages infrastructure such as bridges, reservoirs, and water canals. Parts of the San Joaquin Valley have been sinking by more than half a foot annually. Subsidence has reduced capacity in the Friant-Kern Canal, the Delta Mendota Canal, and the California Aqueduct.

Sustainable Groundwater Management Act: Requires water users in most groundwater basins to develop and implement groundwater sustainability plans to bring groundwater use and recharge into balance by the early 2040s. The challenges are particularly big in the San Joaquin Valley and the Central Coast.

White areas: Areas that rely entirely on groundwater for drinking water and irrigation supplies. Water users in these areas—which are shown in white on irrigation district maps—are particularly susceptible to groundwater quality problems and falling water tables, and are vulnerable to pumping restrictions with the implementation of SGMA.

What Does the Colorado River Drought Plan Mean for California?

A much-anticipated plan to address chronic water shortages in the Colorado River Basin was recently signed into law by President Trump. This drought contingency plan (DCP) aims to slow the long-term decline in Lake Mead’s water levels caused by over-allocation of Colorado River water and 19 years of drought, as well as address future water shortages in the basin.

The DCP is the fruit of a decade of negotiations among the seven basin states to resolve the over-allocation problem through cuts and water storage. (Mexico receives water from the river but is not part of this plan.) California has the largest share of the Colorado, with senior rights to more than a quarter of the river’s average annual flow.

Lake Mead is a water source for 600,000 acres of farmland and 19 million people in Southern California. California agencies can also store up to 250,000 acre-feet of water in Lake Mead.

Without the DCP, Lake Mead’s water level could drop too low to allow releases from Hoover Dam. As the lake nears this threshold, senior water right-holders in California might be tempted to withdraw their water before it becomes inaccessible. While such a move would be permissible, it would accelerate the drop in the lake level and affect future deliveries for junior water right-holders in the other lower-basin states.

The DCP eliminates this concern and delivers an orderly and mutually agreed upon method to manage shortages until 2026. It provides assurance against curtailments for water stored behind the dam. This is especially important for the Southern California water agencies, whose ability to store water in Lake Mead is crucial for managing seasonal demands.

Some significant challenges must still be addressed, however. The Imperial Irrigation District, the largest Colorado River water user, opted out of the plan due to a dispute over funding to restore the shrinking Salton Sea. The district also filed a lawsuit that calls for the DCP to be suspended until an environmental review of the plan is completed.

The lawsuit alleges that the Metropolitan Water District (MWD), which would contribute most of the water required to fulfill California’s obligations under the DCP in times of system-wide shortage, unlawfully approved the DCP. IID claims that MWD did not consider the “sources of water that would be necessary for [it] to fulfill its commitment and the environmental effects associated with obtaining water for those sources.” The outcome of this lawsuit is uncertain.

Currently, the Colorado supplies about a third of all water used in Southern California’s urban areas. The region’s water agencies are taking steps to develop more local supplies and increase water efficiency to help them meet water demand if DCP cuts are triggered during a future water shortage.

The plan won’t cause immediate water cuts. This year’s wet winter means that Lake Mead’s elevation, currently 1,090 feet above sea level, may remain above the 1,045-foot threshold at which the mandate is triggered for California. But the basin states now have a plan in place to address the next dry spell.

Commentary: How Better Wastewater Management Can Help California Adapt to Climate Change

This commentary was published on CALmatters on May 9, 2019.

Our public health relies on wastewater management to treat sewage and remove pollutants coming from our homes and businesses.

This system is fundamental to protecting our health. In California, treated wastewater also is a critical source of water for the environment, and, increasingly, a source for recycled water. Climate change is worsening water scarcity and flood risks. Advancements in engineering and technology can help prepare wastewater agencies for a changing climate. But significant shifts in policy and planning are needed to address these challenges.

Wastewater agencies must reliably remove pollutants even as the quantity and quality of the water they treat declines during droughts, and when large storms push their equipment to the breaking point.

In February, an atmospheric river storm—the type that is expected to become more common as the climate warms―inundated Healdsburg’s wastewater treatment facility and pushed more than five times the normal flow of wastewater and runoff into Santa Rosa’s treatment plant.

In a drought, reduced flows to wastewater plants can hamper agencies’ ability to comply with treatment standards, damage equipment, increase costs, and shrink revenue. Lower inflows also reduce the volumes available for recycled water, often considered a “drought-proof” supply.

The drought of 2012–16 brought all of these problems to the fore. Many wastewater agencies are now changing their operations, infrastructure, or finances in response to the challenges they experienced. Our new study recommends sector-wide changes in three areas to help build the sector’s climate resilience:

Maintain water quality in the face of reduced indoor water use. Short-term water conservation during droughts and longer term reductions in water use from indoor efficiency measures challenge wastewater management. All wastewater agencies should assess their vulnerability to major climate pressures, and plan for future droughts. Better coordination and information sharing with suppliers about indoor water conservation and efficiency efforts are also key.
Make smart recycled water investments. Coordination among wastewater and water supply agencies is needed to address the demand for recycled water. Regional planning for recycled water projects can result in investments that are more responsive to changing water use and an increasingly volatile climate, bringing financial and environmental benefits.
Balance conflicting objectives within watersheds. Many wastewater treatment plants discharge treated water into inland watersheds.

Meeting increased demand for recycled water may fuel conflict over the use of treated discharge to support ecosystems and downstream users. Rivers and streams are expected to experience lower flows and higher temperatures, which will heighten threats to aquatic ecosystems. Resources are needed to identify areas most at risk of conflict over the use of treated wastewater, and to develop tools to evaluate the impacts of water recycling projects on the environment and downstream water users.

The state can help wastewater managers make these adaptations, which are critical to building a more integrated and resilient water system. The State Water Board should align its policies on water use, wastewater, recycled water, and environmental protection to better manage for these multiple objectives.

Forging new partnerships to tackle the full range of climate-related risks will help wastewater agencies determine the best adaptations and improvements needed to prepare wastewater management—and California’s water system as a whole—for a more volatile future.