Drought, Fish, and Water in California


Pit River in Modoc County, August 21, 2014.  Drying pools contained mainly non-native fishes.

by Peter Moyle

With a big collective sigh of relief, Californians rejoiced that we have largely recovered from 2012-2016 drought[1].  Streams are flowing.  Reservoirs are full. Crops are watered. Native fishes are reproducing   But this not a time for complacency; if the 2012-2016 drought, the hottest and driest on record, had lasted another year or longer, California ‘s farms, cities, and ecosystems would have been in a dire state, with water in short supply everywhere (Mount et al., 2017, 2018).  This should thus be a time to develop new and better strategies for reducing impacts of severe drought on both natural and developed systems, following the California Water Model (Pinter et al. 2019) of “resilience through failure.”  California has a history of learning from past failures of water management, especially floods, and of avoiding repeating mistakes as a consequence.

Drought, of course, is not confined to California, but is a global problem, which is increasing as the planet warms.  Fish and other aquatic organisms bear the brunt of drought because severe competition with people for water destroys their habitats.  Worldwide, they are facing extinction at increasing rates. This is one lesson from a review of drought effects on freshwater fishes from Canada, California, and Australia (Lennox et al. 2019).  This review shows how fish responded to drought in natural and highly altered waterways worldwide to gain insights into how to keep native fish from going extinct as droughts become more severe. California’s fishes provide especially good insights because most are highly adapted for persisting through long natural droughts; however, many are now threatened with extinction because of actions that exacerbate drought impacts.

To make our review more accessible, we condensed our findings into a list of maxims or aphorisms.  These maxims contain general truths to help managers deal with the enormity of fish conservation problems in an increasingly drought-stricken world. Here are the maxims, somewhat modified from Lennox et al. (2019).

  1. Future droughts will be longer, more frequent, and more severe, creating more stressful conditions for freshwater fishes.
  2. Climate change and human alteration of aquatic ecosystems combine to increase the negative effects of drought.
  3. Fishes survive natural droughts in their native waters through physiological and behavioral adaptations, but all have limits.
  4. Different species respond to drought in different ways, so post-drought fish assemblages are hard to predict, especially in highly altered habitats.
  5.  When natural environmental variability is suppressed by human activity, aquatic ecosystems become homogenized, dominated by a few drought-tolerant fish species, often non-native.
  6. Fish survive droughts by dispersal or migration to other habitats or by finding refuges in remnant habitats where conditions are physiologically suitable.
  7.  The most abundant stream fishes in regions with frequent natural droughts are those with the ability to rapidly disperse and recolonize as both adults and juveniles.
  8. The best drought refuges are usually large rivers, lakes, spring-fed streams, and deep permanent stream pools with ground water inflow.
  9. The bigger and more diverse structurally the drought refuge, the more fishes it can shelter.
  10. Connectivity among habitats is essential for recovery of fish faunas in streams and lakes stricken by drought.
  11. Ground water is essential for maintaining stream refuges through drought.
  12.  Human activity often produces perpetual drought conditions in streams through surface and groundwater removal.
  13. Poor water quality, especially low dissolved oxygen and high temperatures, followed by predation, are primary causes of fish mortality in drought refuges.
  14. Changes in severity or frequency of drought alter fish assemblages, with the effects of the changes depending on the history and physical characteristics of the system.
  15. Fisheries will decrease if human-mediated drought results in habitats unable to support large populations of harvestable fish.
  16. Translocation of species to new waters and artificial propagation are desperation measures unlikely to ameliorate the ecosystem effects of human-expanded drought.

These maxims point to the need to have some aquatic ecosystems in California that are managed largely for native fishes, in ways that make them drought-resistant.  California’s native fishes are actually adapted for surviving severe droughts, but they evolved in large, inter-connected river systems where there were always refuges somewhere.  We cannot bring back those large river systems as habitat but we can create refuges that are closely monitored and managed, with native fishes and the aquatic ecosystems they represent, getting a fair share of the water (Mount et al. 2017).


Oristimba Creek, Merced County, during 2012-16 drought.  Most of creek was dry but there were a few native fish refuges where groundwater  seeped into bedrock pools.  Unfortunately, the pools contained non-native green sunfish which were consuming the native fishes. Photos by P. Moyle.

Further Readings

Lennox R.J., D.A. Crook, P. B.  Moyle, D. P. Struthers, and S. J. Cooke 2019. Toward a better understanding of freshwater fish responses to an increasingly drought-stricken world. Reviews in Fish Biology and Fisheries 29:71-92  https://doi.org/10.1007/s11160-018-09545-9.\  Open Access.

Mount, J., B. Gray, C. Chappelle, G. Gartrell, T. Grantham, P. Moyle, N. Seavey, L. Szeptycki, and B.Thompson. 2017. Managing California’s Freshwater Ecosystems: Lessons from the 2012-16 Drought. Public Policy Institute of California 52 pp.

Mount, J. B. Gray, and 28 others. 2018.  Managing Drought in a Changing Climate: Four Essential  Reforms. San Francisco: Public Policy Institute of California. 30 pp.

Pinter, N., J. Lund, and P. Moyle. 2019.  The California water model: resilience through failure. Hydrological Processes 2019: 1–5. https://doi.org/10.1002/hyp.13447





Peter Moyle is Distinguished Professor Emeritus at the University of California, Davis and is Associate Director of the Center for Watershed Sciences.

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Sustaining integrated portfolios for managing water in California

FY 2018 Reliability Pie Chart

by Jay Lund

Summary:  This post reviews some lessons from portfolio water management in California and identifies roles for state government in facilitating development and implementation of effective portfolios.  To better align state regulations and funding with these goals, a more adaptable structure for state planning is suggested.  Effective integration of local, regional, and state water management goals must more flexibly employ regulations to support environmental operations as components of local, regional, and state water management portfolios.

Recently Governor Newsom issued a call for a state portfolio of actions to manage water under rapidly changing climate and other conditions.  Portfolio approaches attempt to integrate and balance a variety of actions (supply and demand management, surface water and aquifers) for single purposes (water supply, floods, safe drinking water) and often for multiple benefits, involving multiple interests.  A previous essay reviewed the successes and limitations of portfolio approaches to water management in California.  Overall, where applied well, mostly at local and regional levels for single purposes, portfolio approaches have been quite successful.

Portfolio approaches are especially good for adding flexibility to water management infrastructure and institutions.  Like a diversified financial portfolio, water management portfolios employ a broader range of options to improve stability, adaptability, and performance.  Moreover, the thinking and discussions needed to establish and manage portfolios is a good basis for improving integration within and among water agencies and preparation and adaptability for inevitable extreme events and major changes.

Many of California’s local and regional agencies have developed highly effective and cost-effective portfolios of activities for water management.  The 2012-2016 drought’s limited economic impacts (despite some difficult local impacts and some devastating ecosystem impacts) illustrate the effectiveness of local water supply portfolios of water supply and demand actions since the 1987-1992 drought (Lund et al. 2018).  State efforts and funding have helped support local and regional water management portfolios (such as IRWMPs), but overall, state agencies have been less effective (and less well funded) in developing effective portfolio approaches for managing ecosystems and other areas of water management.

Outside of California, the Louisiana coastal master plan is particularly good at taking a multi-time scale approach and the European Union’s Water Framework Directive basin plans provides diverse examples of developing multi-benefit plans for locally-adaptable regulatory frameworks.

How might California better employ water management portfolio approaches, expanding on local and regional successes for single purposes to broader multi-purpose successes regionally and statewide?  This essay summarizes some lessons and useful roles for State activities regarding water portfolio management, and makes a modest proposal for modernizing and integrating State and regional water planning.

Some lessons

  1. Portfolio management employs a range of supplies and demand management activities in an integrated and balanced way. Diversification usually brings flexibility, adaptability, and value.
  2. Most newer portfolio elements, such as water conservation, conjunctive use, interties, and water reuse, are better implemented locally and regionally. State roles for these newer efforts are important, but more in supportive roles of regulatory and technical support than instigation and implementation leadership.
  3. Portfolios of actions (especially preparations for extremes) commonly involve outside water agencies and partners, both nearby and far away. Portfolio management gives opportunities to make and keep friends.
  4. Analytical efforts are important, despite being always approximate. MWDSC, SDCWA, and other local and regional agencies base their portfolios on modeling efforts often more sophisticated than state efforts. Statewide portfolio modeling shows good promise (CALVIN).  These efforts rest on well-organized and available data.
  5. Areas lacking in portfolio management (such as for ecosystems and rural drinking water) have been performing more poorly than areas that have performed comparatively well (such as urban and agricultural water supplies). This may require major changes in thinking, funding models, and perhaps legislation.
  6. Adaptability will be needed for California to prepare for unavoidable changes in climate, population, economic structure, ecosystems, and technology, as well as normal and increasing extreme wet and dry years. Resistance to change and extremes is futile, and portfolio approaches prepare for changes and opportunities in water management.
  7. Integrating regulatory and system planning and operations into a broader portfolio is promising for accomplishing diverse water system purposes. This seems especially important for successful ecosystem management. The Delta’s co-equal goals and voluntary settlement agreements for environmental flows are efforts in this direction.  Continuing separation of infrastructure and operation plans from environmental management seems far less effective and increasingly untenable.

State Roles in Water Portfolio Management

Important state functions in portfolio water management include:

  1. Supporting local and regional fund-raising legally and administratively. Water management and infrastructure are expensive, and local governments have considerable ability and accountability for funding such projects.  State funding can rarely have more than a nudging role.  Propositions 218 and 26 are examples of how State policies can undermine self-funding of local and regional efforts.
  2. Common water accounting, science, and technical support across state agencies, is a foundation for public discussions, coherent management, agreements among agencies, and water trading. This includes integration of local and regional data collection efforts (often using SCADA systems) with state and federal water data collection, management, modeling, and analysis. Texas, Colorado, and other western states act more centrally in these roles.
  3. Bringing statewide interests in sustaining ecosystems and public health into local and regional water management portfolios. Historical state reliance on environmental regulations and permits have not brought desirable levels of environmental progress and rural drinking water supply.  Additional means are needed.
  4. Integrating portfolios across regions and agencies. Establish frameworks and incentives for local agencies to work together regionally, and for state agencies to cooperate in such efforts.  This includes facilitating flexibility in operations and projects, including trades and transfers, in operational, planning, and policy contexts. SGMA, environmental flow management and the Delta are examples where better organized state water planning could usefully parallel regional organization of local agencies and interests.

Separating environmental regulations from water infrastructure, operations, and management has not been successful enough.  Environmental management must become more than regulations, to become more operationally focused on the active operation and development of habitats and water for ecosystems, often involving land owners and other agencies.  Environmental regulations are a central part of state, regional, and local water management portfolios.  If environmental regulations are not shaped to be compatible with other actions, such as infrastructure design and operations and the management of water demands, then the collective portfolio will be at best sub-optimal and at worst a failure.

A Modest Proposal

The state needs a new vision for the California Water Plan, compatible with SGMA/groundwater planning, voluntary environmental agreements, Prop 1 storage project implementation, drought preparedness, and the many other well-intended state and regional efforts.  Under the current state planning and regulatory framework all these efforts face a brutal, expensive, and impossibly slow incrementalism that impedes effective portfolio development and implementation.

Figure 1 shows a potential framework for water and regulatory planning in California. This new framework would place development and approval of a statewide interagency plan under the California Water Commission, perhaps modestly reconstituted, with the plan becoming part of the budget process for the major state agencies involved.  In recent years, the California Water Commission has developed a reputation and role as a neutral party crossing agency and stakeholder lines.  This interagency plan would also become a nexus for reconciling regulatory actions and rolling up local and regional plans.

Supporting this interagency plan, and the activities of state agencies would be a common California Water Science and Technical Program.  The isolated development of science and technical work in separate agencies and programs has not been serving California well.  A common science and technical program is needed to support, integrate, and balance agency efforts, the administration of multi-agency plans for SGMA and groundwater, the Delta, and ecosystems.

Most of a new California Water Plan would consist of multi-agency regional plans for 11 hydrologic regions.  These plans would involve the SWRCB, RWQCBs, DWR, CDFW, CDFA, and local counties and water agencies, focusing on regional coordination of local plans as well as coordinated regional plans for state interests in ecosystems, economic development, and public health.  Regional integrated water plans would be a framework for neighboring agencies to work together; the pairing of the Santa Ana Watershed Project Authority with the State’s Regional Water Quality Control Board 8 (Santa Ana) is perhaps today’s closest equivalent.  Regional offices of state water agencies would be re-aligned for this purpose.  These regional planning efforts would be supported by regional water science and technical efforts to support local and regional SGMA, water quality, ecosystem, and environmental justice plans and efforts.

This approach would preserve what local, regional, and state agencies are already doing well, while bringing agencies together to make improvements and better address areas that lack integration and well-developed portfolios.  Each state role in portfolio planning would be strengthened.

Portfolio water plan.png

Figure 1. Integrating Local, Regional, and State Water Plans, supported by public science

Areas where portfolios have lagged include: environmental management; integration across water management purposes; groundwater; and safe rural drinking water. Extending portfolio planning to and across these areas should help, although it may require changes in how agencies view planning and operations. Regional integration is most important, particularly for obtaining multiple benefits and integrating projects and regulations with portfolios.  Common science and technical information are fundamental here.

Implementation of the Sustainable Groundwater Management Act and new environmental flow regulations together provide an excellent opportunity for modernizing California’s water planning and regulation functions into a more integrated portfolio-based framework.  Some fundamental changes in state regulation and planning would better prepare California for developing and operating effective water management portfolios in an era of rapid change.

Further Readings

Central Valley Joint Venture. http://www.centralvalleyjointventure.org/partnership/what-is-the-cvjv

Escriva-Bou, A., H. McCann, E. Hanak, J. Lund, B. Gray (2016), Accounting for California’s Water. Public Policy Institute of California, San Francisco, CA.

Hanak, E., J. Lund, A. Dinar, B. Gray, R. Howitt, J. Mount, P. Moyle, and B. Thompson (2011), Managing California’s Water:  From Conflict to Reconciliation, Public Policy Institute of California, San Francisco, CA.

Lund, J. (2019), “A water portfolio planning report card for California,” 26 May, CaliforniaWaterBlog.com

Lund, J. (2019), “Portfolio Solutions for Safe Drinking Water – Multiple Barriers,” 7 April, CaliforniaWaterBlog.com

Lund, J. (2019), “Portfolio Solutions for Water – Flood Management,” 3 March, CaliforniaWaterBlog.com

Lund, J. (2019), “Portfolio Solutions for Water Supply,” 10 March, CaliforniaWaterBlog.com

Lund, J.R., J. Medellin-Azuara, J. Durand, and K. Stone, “Lessons from California’s 2012-2016 Drought,” Journal of Water Resources Planning and Management, October 2018. (open access)

Pinter, N., J. Lund, and P. Moyle (2019), “The California water model: Resilience through failure,” Hydrologic Processes, March, and blog post.

Bruun, B. (2017), “The regional water planning process: a Texas success story,” Texas Water Journal, Volume 8, Number 1.

White, Gilbert (1966), Alternatives in Water Management, Publication 1408, National Academy of Sciences – National Research Council, Washington, DC, 52pp.

Jay Lund is a Professor of Civil and Environmental Engineering at the University of California, Davis.

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Flood Mapping in California: The Good, the Bad, and the Ugly

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Figure 1. The first FEMA flood maps were based on modeling run on mainframe computers (Maeder, 2015). Flood modeling has evolved far, but many FEMA maps remain based on early methods.

by Kathleen Schaefer and Nicholas Pinter

FEMA flood insurance rate maps (FIRMs) are the principle tool for managing the National Flood Insurance Program (NFIP).  They identify properties whose owners may be required to purchase flood insurance and help set flood insurance premiums across the US.

FEMA is required to assess FIRMs at least every five years, with revisions when necessary.  However, for almost half of California’s communities, the engineering studies supporting FIRMs are over 20 years old.  Less than 30,000 miles of the State’s 180,000 stream miles have been mapped by NFIP and less than 23% of the flood mapped river miles are designated as ‘Valid’.  A 2013 California Department of Water Resources (DWR) assessment, funded by FEMA, estimated the cost to bring California FIRMs into ‘Valid’ status using current methods to be over $406 million.  Most California communities are unlikely to ever get a new FEMA study.

History of US Flood Mapping

The first US FIRMs used topographic information collected by surveyors using measuring rod and surveying level, a time-consuming and sometimes dangerous process.  Water-surface elevations and floodplain boundaries were hand-drafted onto topographic base maps.  Starting in the 1980s, computer modeling improved the process, but FEMA map production remained an expensive and time-consuming.

In California, from 1973 to 1983, FEMA issued new FIRMs to 376 communities.  But it became apparent that FEMA would not meet Congressionally mandated deadlines to provide all flood-prone communities with detailed flood information.  In 1985, FEMA initiated a new method to reduce the cost and time required for new flood studies.  From 1983 to 1993, FEMA issued new FIRMs to 103 California communities using this revised method.

Beginning in 1986, Congress required NFIP to pay program expenses from insurance premiums.  Without outside federal appropriations, new flood studies lagged, and existing paper maps across the US continued to age (FEMA 2006).  For the past 20 years, an average of just 7-8 new flood studies have been completed each year in California.

By 2015, California flood maps were translated into a seamless digital flood layer.  This meant that anyone could pull up a map and determine if their home touched the floodplain boundary.  By making digital maps readily available to the public, Map Mod transformed many 40-year old, hand-drafted mapping into a digital product perceived to be accurate to within inches.

Age of California Flood Maps

The Community Status Book (FEMA 2018a) lists, by political jurisdiction, the dates of the first map and the date of current effective map.  If a single map panel is updated for any reason, the effective date for that community is updated.  For example, the current effective date for the City of Los Angeles is December 21, 2018, meaning that at least one map panel in Los Angeles was updated then.

FIRM ages

Figure 1.  Number of 532 California communities with a river study by year.  New Flood Insurance Studies (FISs) peaked in the late 1980s and early 1990s.  For the past decade, an average of 7-8 communities per year have received new studies.

On January 1, 2019, the Community Status Book listed 2012 as the average year of the current effective map for California’s 532 jurisdictions.  Most of these updates were small alterations, not formal re-analyses.  This information gives the perception that the modeling that supports the maps average just 6 years old.  The actual average date of the most recent FEMA modeling study underlying California FIRMs is 1993.

Flood-Risk Mapping Today

In 2009, FEMA developed a new plan to manage its inventory of flood maps, entitled Risk Mapping, Assessment, and Planning (Risk MAP).  The Risk MAP vision is for FEMA’s flood mapping program to become database-driven.  Additional meetings and mapping products mandated by the Risk MAP program add cost and time to complete a new study.  Since 2015 at least five new Risk MAP projects have not yet led to a final product (E. Curtis, written comm., May 4 2019).  What will it cost to upgrade the maps using the Risk MAP process?

In 2013, FEMA asked DWR to assist in developing a Mapping Master Plan (DWR 2013) to: (1) assess funding needs for Risk MAP, and (2) provide a road map for meeting the Risk MAP NVUE and deployment metrics.  The plan found that producing a Risk MAP product for each of California’s 532 communities would cost an estimated $445 million (inflation adjusted to 2019).  The Plan also showed that some communities in California may never again receive a new flood map funded by FEMA.

How does flood map age affect NFIP claims?

Over time, economic development and natural processes including climate change alter the hydrology and hydraulics of rivers and watersheds, changing flood risk.  Almost half of the FIRMs in California are based on studies over 20 years old.  This observation leads to several questions:

  • Do older flood maps lead to more flood damages and a greater proportion of flood insurance claims?
  • Do aging flood maps allow development or perhaps deter mitigation in ways that impact flood claims?

Accurate and up-to-date maps are needed to guide wise development on floodplains.

Conclusions and Recommendations

Several observations stand out from this analysis.

  • Less than 30,000 miles of California’s estimated 180,000 stream miles have been mapped by the National Flood Insurance Program (NFIP).
  • Less than 23% of California’s 30,000 NFIP mapped stream miles are designated as ‘Valid’ in FEMA’s asset management system.
  • Of the 22,138 California flood mapped stream miles not characterized as ‘Valid,’ FEMA currently has plans to study only a small fraction.
  • Most of California’s FIRMs are based on studies from the 1970s and early 1980s, when mapping and computing technology was significantly less accurate.
  • The conversion of paper FIRMs to digital format can give the public and policy makers false perceptions of map accuracy and flood risk.
  • The cost of updating all of California’s outdated FIRMs using the Risk MAP process ($445 million dollars) would be almost $2000 per current California NFIP policyholder (inflation adjusted to 2019).
  • Many California communities may never again receive a new flood study funded by FEMA.

The original mandate of NFIP was to update flood maps at least every five years.  In actuality, map updates are unusual and the nation’s inventory of flood maps has become “out-of-date, using poor quality data or methods and not taking account of changed conditions” (Horn 2018).

Flood maps continue to age faster than they are updated.  New mapping and map updates have become more expensive and time-consuming.  NFIP has run up a $36 billion structural deficit.  California can lead in using new technologies to quantify and communicate flood risk.  Several private companies already market models that assess flood risk throughout the US.  These models are arguably less accurate than a detailed site-specific model, but they calculate flood hazard as a continuous parameter, not just in or out of a 100-year line.  These risk-based models can better quantify and incorporate uncertainty.  Risk-based modeling also can easily and quickly be updated to reflect changing hydrologic, hydraulic, and climatic conditions over time.

California should consider making improvements to how flood risks are assessed, mapped, and updated.

Further Readings

California Department of Water Resources (DWR), 2013.  California Deployment and Mapping Master Plan (Draft). Prepared under Mapping Activity No. 3 executed in 2010 by Atkins.  Sacramento, CA: CA Department of Water Resources.

Congressional Budget Office (CBO), 2017.  “The National Flood Insurance Program: Financial Soundness and Affordability. Congressional Budget Office Report.  Washington D.C.: Congressional Budget Office.  https://www.cbo.gov//system//files//115th-congress-2017-2018//reports//53028-nfipreport2.pdf..

FEMA, 2018a.  Community Status Book, FEMA Database.  The National Flood Insurance Program Community Status Book.  2018.  https://www.fema.gov/national-flood-insurance-program-community-status-book.

Horn, D.P.,  2018.  “National Flood Insurance Program: Selected Issues and Legislation in the 115th Congress. Report to Congress R45099.  Washington DC: Congressional Research Service.  https://fas.org/sgp/crs/homesec/R45099.pdf.

Kelly, J.V.  2017.  FEMA Needs to Improve Management of Its Flood Mapping Programs. OIG Report OIG-17-110.  Washington D.C.: Office of the Inspector General, Department of Homeland Security.  https://www.oig.dhs.gov/sites/default/files/assets/2017/OIG-17-110-Sep17.pdf.

Kathleen Schaefer is a PhD student in Civil Engineering at the University of California, Davis and a former FEMA administrator.  Nicholas Pinter is a Professor at the UC Davis Department of Earth and Planetary Sciences.


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Economic Tradeoffs in Groundwater Management During Drought

by Kathleen Stone and Rob Gailey

Domestic well users in some areas were greatly impacted by additional agricultural groundwater pumping during California’s 2012-2016 drought, which substantially compensated for reduced surface water supplies. Implementation of the 2014 Sustainable Groundwater Management Act (SGMA) should improve long-term groundwater availability during drought for all system users by requiring groundwater management to avoid significant and unreasonable impacts of decreased groundwater levels.

To evaluate the economic impacts of local groundwater policy alternatives on two sometimes conflicting user groups in a local groundwater system, we analyzed agricultural and domestic groundwater use in Tulare County, California (Figure 1) during the 2012-2016 drought (Gailey et al., 2018; Gailey et al., 2019; Stone, 2019).

Figure 1 map.png

Figure 1. Study area in Tulare County, California

Using hydrologic and crop production data from the drought, agricultural surface water deliveries, crop water demands, and groundwater usage were estimated for much of the Tulare County valley floor. With these data, an agricultural-groundwater profit maximization model was created to relate groundwater use, agricultural profit, and resulting agricultural costs from potential groundwater use regulations. A similar relationship for domestic groundwater users was obtained from an existing domestic well costs model (Gailey et al., 2019). By defining alternative groundwater policies as depth-to-groundwater (DTGW) pumping limits, the models estimated agricultural opportunity and domestic well costs, respectively.

To reflect the need to mitigate results of level declines during drought under SGMA, we further added a groundwater recovery fee or cost for agricultural users, Cw, ranging from $0-$900 per acre-ft. This cost simulates future groundwater recovery costs from either importing replacement surface water or reducing future water use by fallowing lower-valued crops after the drought, to resupply drought groundwater drawdown, as required by SGMA.

The collection of these policy-related economic impacts on users forms a trade-off curve of impacts to the agricultural and domestic well users (a Pareto curve) for the range of drought drawdown policies. The groundwater policy which maximizes the total economic welfare for the region (both groups) was then identified (Figure 2).

Figure 2 plots

Figure 2. (a) Agricultural cost curves ($B) and domestic well users’ cost curve ($M), (b) User economic impact trade-off curves

Limiting drought-related drawdown increases agricultural costs and reduces domestic well user costs. Agricultural costs increase because reduced groundwater availability reduces crop production and profits. Domestic well costs decrease because supply shortages and accompanying costs from groundwater drawdown are reduced (Gailey et al., 2019). With increasing groundwater recovery costs, the agricultural cost curves and welfare-maximizing policies reach thresholds in which the recovery costs to pump more groundwater exceed the profit gained from additional groundwater pumping. With SGMA implementation, represented by a penalty for excess groundwater pumping, drawdown and domestic well costs are reduced substantially and the historical ratcheting-down of groundwater levels over the series of droughts is avoided.

Since agricultural profit greatly exceeds domestic well costs incurred during drought, opportunities should exist for compensating domestic well user costs from the additional profits preserved from agricultural pumping. The compensation provided by agricultural users might involve negotiations among user groups and regulatory authorities. Consistent with Gailey et al. (2019), one potential method to estimate a socially-equitable cost allocation is to model the groundwater drawdown caused by agricultural and domestic users and allocate costs proportionally to drawdown impacts, respectively. One method to implement cost allocation is to create a compensation fund with revenues from excess pumping fees.

Additional agricultural groundwater pumping during the drought, to compensate for reduced surface water supplies, greatly impacted domestic well users in some areas. Economically, these impacts on domestic well users were much less than the economic benefits of this additional pumping to agricultural users. SGMA policy implementation to achieve sustainability, requiring groundwater management to avoid significant and unreasonable impacts of decreased groundwater levels, will improve long-term groundwater availability to all system users, but some compensation and preparations for domestic well users could be usefully incorporated into local groundwater sustainability plans.

Further Reading

Gailey, R. M. and Lund, J. R. 2018. “Managing Domestic Well Impacts from Overdraft and Balancing Stakeholder Interests.” https://californiawaterblog.com/2018/05/20/balancing-ag-and-domestic-well-interests-during-groundwater-overdraft/

Gailey, R. M., Lund, J. R., & Medellín-Azuara, J. (2019). Domestic well reliability: evaluating supply interruptions from groundwater overdraft, estimating costs and managing economic externalities. Hydrogeology Journal 27(4): 1159-1182. https://doi.org/10.1007/s10040-019-01929-w

Stone, K. (2019). Economic Tradeoffs in Groundwater Management During Drought: Tulare County, California. (MS Thesis) University of California, Davis. Retrieved from https://watershed.ucdavis.edu/shed/lund/students/KStone_Thesis2019.pdf

Kathleen Stone recently completed her masters degree in Civil and Environmental Engineering at the University of California, Davis.  Rob Gailey less recently completed his PhD in Civil and Environmental Engineering at the University of California, Davis and has returned to professional consulting.

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Some common questions on California water (Part II)

by Jay Lund and Josué Medellín-Azuara

This is the second installment of answers to some common questions regarding water problems in California.  Part I examined some common questions on water supplies (questions 1-5).  Part II looks more at common questions on water uses and demands.

6. Wouldn’t more agricultural water use efficiency end California’s water problems?

Irrigated crops are about 80% of human water use in California, so it is an obvious target for conservation attention.  This irrigation supports about $50 billion/year in agricultural production, about 4% of the state’s economy, with a much larger share for many poorer counties.

Water applied to crops for irrigation evapotranspires from the crop to the atmosphere, or runs off to nearby streams, or infiltrates to groundwater. (A tiny amount of water is harvested with the crop’s biomass.) The percent of irrigation water evapotranspired by the crop is often called irrigation efficiency.  Irrigation efficiency can increase with more expensive irrigation technology, such as drip irrigation, which require less water application and often improves crop yields and quality.

For most of California, increasing surface water irrigation efficiency mostly comes from reducing infiltration to groundwater needed to support agriculture and rural residents during drought. Much of current recharge in California’s Central Valley comes from irrigation. Increasing irrigation efficiency also often leads farmers to expand irrigated acreage with the “saved” water, leaving to greater losses of water to the atmosphere, and less water for downstream users and aquifer recharge.  Most promising irrigation efficiency improvement is reduces non-beneficial evaporation from soil and non-recoverable return flows.

Because improving irrigation efficiency mostly comes from reducing the amount of water available for recharge or other uses, saving real water in agriculture mostly means reducing agricultural production (crop evapotranspiration), which has real and sometimes inevitable costs to rural areas.

Grafton, R. Q. et al. (2018), “The paradox of irrigation efficiency,” Science, 24 Aug 2018.

Lund, J., E. Hanak, R. Howitt, A. Dinar, B. Gray, J. Mount, P. Moyle, B. Thompson (2011), “Taking agricultural conservation seriously,” CaliforniaWaterBlog.com, 15 March 2011.

7. Wouldn’t ending water subsidies for farmers save a lot of water?

The short answer is no.  Water subsidies in California are remarkably rare today.  Historically, the biggest water subsidies in California were for construction of federal (USBR and Army Corps of Engineers) reservoirs and canals.  These largely ended decades ago.  Farmers benefited from these projects with cheaper and more reliable water supplies, which increased the economic value of their lands.  Most original farmers have since sold their lands to other farmers, pocketing most of the federal subsidies in the sale price of their farmlands.  Federal expenditures today for agricultural water supplies in California are now much diminished.

State water project deliveries are now, and have almost always been, entirely funded by the project’s water users.  Some local water agencies, urban and agricultural, have benefited from state water bonds funding some of their capital projects.  It is sometimes argued that these projects would often be built anyway by local and regional water agencies.

Perhaps the biggest water subsidies are the mutual subsidies that come from the economies of scale for larger water supplies and coordinated projects.  When people work together in water, costs are lower, even without external subsidies.

A similar question is, “Would ending federal farm subsidies reduce agriculture and save water in California?”  Our suspicion is that California’s agriculture is profitable enough that ending crop subsidies might change the mix of crops, but would not greatly increase agricultural land fallowing that would reduce actual net water use.  (Also, most of the more profitable fruit, vegetable, and tree nut crops in California do not receive federal subsidies.)

Hanak, E., J. Lund, A. Dinar, B. Gray, R. Howitt, J. Mount, P. Moyle, and B. Thompson (2011), Managing California’s Water:  From Conflict to Reconciliation, Public Policy Institute of California, San Francisco, CA.

Hanak, E., B. Gray, J. Lund, D. Mitchell, C. Chappelle, A. Fahlund, K. Jessoe, J. Medellín-Azuara, D.  Misczynski, and J. Nachbaur, Paying for Water in California, Public Policy Institute of California, San Francisco, CA, March 2014

 8. Would we save a lot of water if we stopped allowing water use for exported crops? Cumulative jobs

If crops were not allowed to be exported, farmers, as businesses, would be forced to grow less profitable crops that could be sold in the US or California.  Because most irrigated crops use similar amounts of water per acre, eliminating crop exports would not save much water.

Economically, a disproportionate amount of revenue and jobs in California’s agriculture comes from exported crops (almonds) and crop-derived products (wine).  Banning crop exports would reduce the price of almonds for Californians, while greatly reducing rural employment and revenues and increasing rural poverty.

Medellin-Azuara J., J. Lund, R. Howitt. 2015. Jobs per drop irrigating California crops, CaliforniaWaterBlog, April 28, 2015.

9. If everyone dried their lawns, wouldn’t that end our water problems?

Roughly, urban water use is about 20% of human water use in California and 10% of total water supplies in California.  Landscape irrigation is about 50% of urban water use, statewide.  So, drying up all urban landscaping in California (reducing urban water use by 50%), would only make 5% more water available in California.  This would easily be enough water to support expansion of many wetlands in California, supporting waterfowl and some fishes.  Or, if reallocated to farms, drying all urban landscaping might allow expansion of agriculture by about 12% or about enough to end groundwater overdraft in the Central Valley.  It would help, but is no panacea.

Drying all urban lawns and landscaping would not nearly be enough to end all water shortages among environmental, agricultural, and other urban water users.

Drying lawns every year would also eliminate the easiest drought response available to cities.

California Department of Water Resources (2014). California Water Plan Update 2013. Volume 3: Resource Management Strategies. Department of Water Resources, Sacramento, California.

10. Wouldn’t giving up on Delta smelt free enough water for agriculture and ending groundwater overdraft?

The restrictions on Delta water exports and operations that solely support Delta smelt have only a small effect on Delta exports, even during drought years.  (The restrictions reduce water exports more in wetter years.)  Uncaptured water, and Delta outflows needed to maintain in-Delta and water export water quality is generally much higher.  Two studies came this conclusion, independently.  Most water flowing into the Delta in wetter periods flows out because it is not captured from lack of infrastructure (which is costly to expand), rather than environmental regulations.

Lost water deliveries

Gartrell G, Mount J, Hanak E, Gray B. 2017. A new approach to accounting for environmental water: insights from the Sacramento–San Joaquin Delta. Public Policy Institute of California. San Francisco, CA

Reis, G. J, Howard, J. K, & Rosenfield, J. A. (2019). “Clarifying Effects of Environmental Protections on Freshwater Flows to—and Water Exports from—the San Francisco Bay Estuary”. San Francisco Estuary and Watershed Science, 17(1)

Some larger lessons

California is often a dry place with many water users and uses, and there will be disputes over who should get how much water when.  In such an environment it is easy and popular to call for others to conserve water.  Sometimes water conservation does not make more water available, but only shifts water from one user to another or away from groundwater recharge.  Still, careful and thoughtful water conservation in all water use categories is important and will likely be increasingly useful in the future, despite its costs.

Part I link, for questions 1-5: https://californiawaterblog.com/2019/05/12/some-innocent-questions-on-california-water-part-i/

Jay Lund is a Professor of Civil and Environmental Engineering at the University of California, Davis.  Josué Medellín-Azuara is an Acting Associate Professor of Civil and Environmental Engineering at the University of California, Merced.

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A water portfolio planning report card for California

by Jay Lund


Kern Water Bank conjunctive use with waterbird benefits

Governor Newsom recently called for a state portfolio of actions to manage water under rapidly changing climate and other conditions.  This post reviews the state of water portfolio planning in California today.

In this complex changing world, major problems are rarely solved with a single solution or a single problem-solver. Portfolio-based planning and management tries to do many things in an organized and coordinated way, often with friends to collectively improve water management, reduce costs, and improve environmental conditions overall.  This sounds idealistic, but with hard work this approach has been tremendously successful when earnestly applied.

The most common portfolio plans are financial.  We feel safer if retirement funds have a diverse portfolio of different stocks, bonds, real estate and other investments, as well as social security and pension payments and an ability to manage expenses.  Government finance similarly is more stable if supported by a range of taxes and fees and some discipline and ability to reduce expenses.  Energy systems also usually involve a diverse portfolio of power stations connected by a flexible transmission network, along with pricing and efforts to manage energy demands and rules for managing shortages and outages.  Good portfolios provide a foundation for flexibility and help hedge against uncertainties.

California’s most advanced water management portfolios are by local and regional urban water suppliers seeking to diversify supplies and manage demands, often in cooperation with neighbors.  The Sacramento Water Forum, and efforts of EBMUD, MWDSC, SCVWD, CCWD, SDWA, Orange County, the Inland Empire and other areas show local and regional water agencies adapting to changes in conditions in California with great success using portfolio management.  These efforts almost always involve cooperation with outside agencies.

The safety of drinking water systems relies on a portfolio approach known as “multiple barriers.” Regulating harmful substances, source water protection, water treatment, disinfection, and public health monitoring and responses provide multiple layers of actions and institutions to reduce drinking water contamination and waterborne disease outbreaks.

Local agricultural water suppliers also employ portfolio approaches.  These cases are less well-funded, but usually include effective efforts to conjunctively manage surface water and groundwater supplies, in cooperation with farmers and often in cooperation with outside agencies. YCWA, YCFCWCD, KCWA, and other agencies have been leaders.

For floods, portfolio approaches also have become common, led by federal policy, with a mix of “structural” and “non-structural” approaches advocated to reduce the frequency of flooding and reshape human activities to suffer less when flooding occurs.  California benefits from a mix of flood warning, evacuation, floodplain management, flood bypass, levee, and reservoir operation activities and preparations at federal, state, and local levels.

Even in ecosystem management, portfolio approaches have been developed to help restore and maintain waterfowl in California, and North America, involving a range of institutions and a diverse and substantially coordinated set of adaptable management actions.  In California this includes the  Central Valley Joint Venture, which has been a foundation for broader relative successes for waterfowl.

California’s recent droughts and floods show the success of portfolio approaches.  The extreme events from 2012-2017 were more easily managed and caused less damage when agencies had developed effective portfolio water management approaches.  The areas hardest hit lacked preparation based on portfolio planning.  These results are illustrated by the overall portfolio water management scorecard below.

Portfolio Report Card for Water Management California:

Problem Grade Explanation
Urban water A- Mostly great success, illustrated by recent drought.  Still room for further improvement and opportunities to benefit from expanded collaborations.  Prop. 218 might limit cooperation.
Agricultural water B- Good successes, but more difficult future. Opportunities to benefit from expanded collaborations with urban, flood, rural drinking water, and ecosystem interests.
Rural drinking water D+ Band-aid approaches to a more systemic problem. Problem is relatively cheap to address, but wickedly hard to effectively organize and fund.
Floods C+ Good history of portfolio development and use, but lacks steady funding and attention outside of emergency management.  Still room for improvement.  Small communities remain problematic.
Ecosystems D Generally absent or poor development or use of portfolio or other active management approaches.  Poor development and integration of science. Waterfowl management is the most advanced and successful.
Groundwater C Improving over time, but far to go, particularly for water quality.  Worsening water quality in agricultural areas is a major challenge. SGMA brings major opportunities.  State needs a common technical groundwater program.
Delta C Slow improvements.  Stewardship Council plan is a potential foundation, but efforts to integrate efforts across agencies are slow to develop; meanwhile ecosystems decline and water demands rise.
Regional integration C+ Steadily improving in urban regions, with room for improvement.  Rural regions will be challenged much more by SGMA, which also can help structure opportunities.
Interagency integration D+ Largely absent among state agencies, isolated to a few examples.  Some excellent isolated programs, poorly integrated into agency and interagency efforts.  Disintegration disrupts developing a common understanding of problems and potential solutions.

The Governor is right to call for more and better use of portfolio management in California water.  The general portfolio approach has shown great value and effectiveness, but also has several challenges.

Three barriers hinder development of effective portfolio management:

Intellectually, people who would be involved in portfolio approaches must sufficiently understand and be willing to deal with the greater complexity and flexibility of portfolio management.

Organizationally, portfolio management requires organizing more people in more complex ways.  Organizing people is never easy.  Organizational issues include a host of legal, funding, coordination, personnel, and sociology issues.

Politically, those involved must be sufficiently unafraid of a portfolio approach. Challenges arise because most portfolio approaches require more entanglements and risks with outsiders for cooperative activities, such as conjunctive use, water trading, or economies of scale from regional facilities and activities.

It is remarkable how successful and widespread portfolio water management has already become despite these barriers.  Not surprisingly, portfolio management often takes time to develop and requires some motivating need and pragmatism.

Portfolio management has still greater and growing potential.  Improving portfolio management will be motivated and challenged by a more rapidly changing climate, growing collapses of native ecosystems, ending groundwater overdraft under SGMA, changes in Delta and storage infrastructure and environmental management (new flow regulations and/or voluntary agreements), and the need for cooperation to sustain economic prosperity at reasonable costs for agricultural and urban water users.

Moreover, portfolio management has still greater importance in helping balance and integrate management for multiple benefits.  This is nicely hinted-at by the State’s co-equal goals for the Delta Plan’s elements.  As single-purpose management becomes more effective, it ultimately struggles with management for other objectives.  As such, California’s portfolio water management must grow beyond narrow objectives and into a greater and less adversarial balancing across objectives.  Organizing state, local, and regional activities to achieve such balancing and integration might be the biggest challenge.

Further Readings

Central Valley Joint Venture. http://www.centralvalleyjointventure.org/partnership/what-is-the-cvjv

Hanak, E., J. Lund, A. Dinar, B. Gray, R. Howitt, J. Mount, P. Moyle, and B. Thompson (2011), Managing California’s Water:  From Conflict to Reconciliation, Public Policy Institute of California, San Francisco, CA.

Lund, J. (2019), “Portfolio Solutions for Safe Drinking Water – Multiple Barriers,” 7 April, CaliforniaWaterBlog.com

Lund, J. (2019), “Portfolio Solutions for Water – Flood Management,” 3 March, CaliforniaWaterBlog.com

Lund, J. (2019), “Portfolio Solutions for Water Supply,” 10 March, CaliforniaWaterBlog.com

Lund, J. (2019), “Shared interest in universal safe drinking water,” January 13, CaliforniaWaterBlog.com

Lund, J.R., J. Medellin-Azuara, J. Durand, and K. Stone, “Lessons from California’s 2012-2016 Drought,” Journal of Water Resources Planning and Management, October 2018. (open access)

Pinter, N., J. Lund, and P. Moyle (2019), “The California water model: Resilience through failure,” Hydrologic Processes, March, and blog post.

White, Gilbert (1966), Alternatives in Water Management, Publication 1408, National Academy of Sciences – National Research Council, Washington, DC, 52pp.

Jay Lund is a Professor of Civil and Environmental Engineering at the University of California, Davis where he is also Director for the Center for Watershed Sciences. He has always liked the idea of optimizing portfolios (perhaps a little too much).

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Evaluating Landscape Effects of Turf Replacement

Erik Porse, Stephanie Pincetl, Diane Pataki, and Tom Gillespie

Outdoor landscapes in California use water for irrigation, especially during summer. Outdoor water use is the largest portion of residential water use, especially in hotter inland areas and cities with larger lots. While lawns have value for recreation and aesthetics, replacing existing turf lawns with well-designed low-water landscapes that incorporate native and climate-appropriate shrubs, grasses, and trees, along with mulch varieties that replenish soil and retail water, can have many benefits. These benefits include diversifying plant species, lowering irrigation needs, reducing stormwater runoff, and potentially reducing fire risk in fire-prone areas. Replacing turf, combined with homeowner education and proper irrigation, also makes yards more drought resistant. In contrast to urban water management policies that “fallow” lawns during drought to conserve water, low-water landscapes with native and other climate-appropriate plants can provide water savings in both dry and wet years.

Many water utilities in California actively fund turf replacement programs that provide rebates to home and business owners. Cities with municipal water utilities, as well as regional water providers and state programs, all fund rebates. Property owners voluntarily apply to replace turf. Programs require that applicants submit a landscape plan, along with before-and-after pictures to verify. Water agencies pay out rebates that subsidize some costs of replacing turf, which might otherwise be prohibitive for many property owners.

As with any public funding initiative, evaluative studies help assess the effectiveness of investments. For many years, evaluative studies of turf replacement were limited. More recent evaluations, based on well-designed experiments or statistical methods accounting for many factors that affect water use, generally show that turf replacement programs yield sustained water savings. A recent report from the Alliance for Water Efficiency compiled data across multiple turf replacement programs and found average water savings of 11-76 gallons/square foot annually after replacing turf.

While water savings is often studied for turf replacement, it is only one of several important objectives to evaluate. Post-program evaluations can study multiple outcomes, including:

  • Effects of turf removal on water use and conservation savings,
  • Changes in land cover and types of plant species after replacing turf,
  • Socio-demographic trends in program participation,
  • Preferences for post-replacement landscapes by both residents and professional landscapers,
  • Cost-effectiveness of such programs for water savings and associated cost drivers.

As part of efforts by Metropolitan Water District of Southern California (MWD) to assess its 2014-2016 turf replacement program during the California drought, we evaluated how yards changed after converting a lawn through a MWD rebate in LA County. We also evaluated trends in participation across cities.


The program boosted funding for turf replacement by $350 million. Residents received $2.00 of incentives per square foot of lawn removed, which was paid following documented evidence of replacement. This was sometimes supplemented by additional local incentives, such as in the cities of Los Angeles and Long Beach.

The vast majority of applications in LA County (80%) occurred within the City of Los Angeles, which offered an additional $1.75/sq-ft rebate from the local water retailer. Projects were clustered geographically, with areas of high and low project participation. Statistical analysis with landscape and sociodemographic factors identified that owner-occupied households were more likely to participate, and lower-income households were less likely to participate. Other variables such as property size did not significantly affect participation.

Pictures 2

After replacing turf, most parcels contained a diversity of plant types, including shrubs, succulents, perennial herbs, and grasses. Most locations had 6-10 species of plants. California native plants were identifiable on approximately 15% of properties. Landscapes also had a variety of ground cover, including wood chips (mulch), bare soil, gravel, and artificial turf. Notably, MWD no longer supports using artificial turf in subsidized turf replacement projects. We evaluated these land cover changes by examining pre- and post-images of 1,000 participating properties using Google Streetview.


Table 1: Land cover types identified as part of analysis of parcels with turf replacement

Land Cover Types Description
Artificial turf Synthetic turf, noticeable via imagery
Bare ground No vegetative ground cover visible
Woodchips Wood chips or mulch
Gravel Small to medium-sized stones
Plants Various plant types, which can be dispersed evenly or clustered. Includes low-lying or shrubby plants, but not turf
Lawn Grass or turf

Figure 4

Some “neighbor effects”, where one property owner’s lawn replacement spurs nearby properties to replace lawns, also appeared. Thirty-six percent of properties examined in Streetview had nearby properties with partial or no lawn cover. This suggests that water utility programs might act as “seed funding” to stimulate broader change to converted additional landscapes.

Water utilities can improve turf replacement programs in several ways. Although the MWD program boosted funding during drought, replacing lawns during normal or wet years is a better strategy. Almost all water-conserving plants take time to establish. Drought resilience in low-water use plants results from deep root structures. Water utilities should maintain or boost turf replacement programs during wet years.

Water utilities should also incorporate native and drought tolerant species into program requirements (many do) and work with non-profit groups to educate homeowners on proper irrigation, soil management, and care. Deep-rooted trees, shrubs, and bunchgrasses require different irrigation techniques than turfgrass lawns. Most residents do not understand the different needs.

Finally, to improve equity, water agencies should seek to increase participation in lower-income communities. Agencies are sometimes restricted in developing programs that target subsidies for particular socioeconomic groups. As an alternative, they can devise programs by working with non-profits, obtain grants to support work in lower-income communities by verified installation contractors, and improve outreach and communication. A key goal should be reducing up-front costs to increase uptake.

Residents gain personal satisfaction from their yards, but yards are not just private goods. Yards beautify neighborhoods, reduce local surface temperature, and improve urban habitat. Well-designed urban landscapes also can help infiltrate water and reduce stormwater runoff. Turf replacement can provide a broader set of ecological, social, and water conservation benefits in cities.

Erik Porse is a research engineer at the Office of Water Programs at Sacramento State and a Visiting Assistant Researcher at UCLA’s Institute of the Environment and Sustainability.

Stephanie Pincetl is Director of California Center for Sustainable Communities and a Professor-in-Residence in UCLA’s Institute of the Environment and Sustainability.

Diane Pataki is a Professor in the School of Biological Sciences at the University of Utah. She is a plant and ecosystems ecologist who studies the role of urban landscaping in local climate, air quality, greenhouse gas emissions, and water resources.

Tom Gillespie is a Professor in the School of Geography at UCLA.

Further Reading

Agthe DE, Garcia MW, Goodnough L (1986) Economic Evaluation of a Rebate Program for Saving Water: The Case of Mesa. Journal of Environmental Systems 16:81–86. doi: 10.2190/JPL5-FP13-K25C-F526

AWE (2019) Landscape Transformation: Assessment of Water Utility Programs and Market Readiness Evaluation. Alliance for Water Efficiency

Baum-Haley M (2013) Evaluation of Potential Best Management Practices: Turf Removal. California Urban Water Conservation Council, Sacramento, CA

Helfand GE, Sik Park J, Nassauer JI, Kosek S (2006) The economics of native plants in residential landscape designs. Landscape and Urban Planning 78:229–240. doi: 10.1016/j.landurbplan.2005.08.001

MWD (2014) California Friendly Turf Replacement Incentive Program Southern California Appendix E: Water Savings from Turf Replacement. Metropolitan Water District of Southern California, Los Angeles, CA. February 24, 2014.

Hooper VH, Endter-Wada J, Johnson CW (2008) Theory and Practice Related to Native Plants: A Case Study of Utah Landscape Professionals. Landscape Journal 27:127–141. doi: 10.3368/lj.27.1.127

Mayer P, Lander P, Glenn DT (2015) Outdoor Water Efficiency Offers Large Potential Savings, But Research on Effectiveness Remains Scarce. Journal of the American Water Works Association 2015:61–66

McCammon T, Marquart-Pyatt S, Kopp K (2009) Water-Conserving Landscapes: An Evaluation of Homeowner Preference. Journal of Extension 47: Article Number 2RIB5

Sovocool K, Morgan M (2005) Xeriscape Conversion Study Final Report. Southern Nevada Water Authority, Las |Vegas, NV

Sovocool K, Morgan M, Bennett D (2006) An In-Depth Investigation of Xeriscape as a Water Conservation Measure. Journal of the American Water Works Association 98:82–93

Sovocool K, Rosales JL (2004) A Five-Year Investigation Into the Potential Water and Monetary Savings of Residential Xeriscape in the Mojave Desert. Southern Nevada Water Authority, Las Vegas, NV

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Some common questions on California water (Part I)

by Jay Lund

California water infrastructure

California’s water network (by Josh Viers, UC Merced)

People are interested in California water problems, and they ask reasonable questions.  Here is a first installment of short science-based answers to some reasonable questions often heard at public and private discussions of water in California.  (Longer answers are possible, of course.)

  1. Why doesn’t California just build desalination plants to end water shortages and leave more water in streams for the environment?

Desalting ocean water is expensive, about $2,000-$3,000/acre-ft.  This cost is too high to be economical for almost any crop in California.  This cost is also over $1,000/acre-ft more than other sources available to California’s cities (including wastewater reuse, conservation, and buying water from farmers).  Providing only 20% of California’s urban water use by desalinating sea water (1.4 maf/year) would cost households at least $3.5 billion/year (about $300/household per year).  The environment would benefit more from other expenditures of such money.


  1. How much water do we lose from evaporation? Wouldn’t reducing evaporation from reservoirs be cheaper than building new reservoirs?

Evaporation is the second largest flow of water in California, following precipitation.  Average California precipitation is roughly 200 million acre-ft/year, with roughly 70 maf/year of river runoff, meaning that most precipitation (~130 maf/yr) evaporates quickly back to the atmosphere.  Additional evaporation of runoff occurs from agricultural fields, reservoirs, and urban landscapes (evapotranspiration is roughly 26 maf/yr from crops, 2 maf/yr from cities, and 2 maf/yr from reservoirs and canals).  Evaporation in all its forms is most of the water that falls on California.

Retaining and reducing evaporation is usually difficult, because it is so widely distributed and driven by the sun, which we all enjoy in California.  Farmers often manage irrigation to reduce unproductive evaporation from bare soil.  Water system operators sometimes shift water among reservoirs to reduce evaporation.  Since the 1950s, researchers have experimented with adding covers and thin layers of floating chemicals to reduce evaporation from reservoirs, but these are rarely economical or environmentally friendly.


  1. If we are short of water, why don’t we just build new reservoirs?

Just as a refrigerator stores food, but does not make it, reservoirs don’t make water, but only shift it in time.  For reservoirs to supply water, they must first fill with water from an earlier wetter time.  Even the largest reservoir cannot reliably supply more than its river’s average annual inflow.

Reservoirs are important and attractive because of California’s seasonally variable streamflows and wet and dry years.  They can reliably store water from California’s wet winters for the following dry summer, because modest amounts of storage can refill every year.  Larger reservoirs become less efficient for storing water from wetter years for dry years, when a reservoir might need several years (or longer) to refill.  Large reservoirs for over-year drought storage often refill infrequently, but re-paying for their construction occurs every year.

Increasingly large reservoirs become more expensive and refill less frequently, providing less water per unit of storage expansion and cost.  The additional water supplied from larger reservoirs can become very expensive.  In addition to these limitations of physics and economics, environmental objections and concerns often arise for new and expanded reservoirs.


  1. On California’s coast, why don’t we gather fog water?

California’s coast is often foggy and some of its coastal ecosystems receive a sizable share of their water from summer fog.  But for humans, the costs of gathering fog water will almost always greatly exceed the costs of alternative water sources or the value of the water use they would supply.


  1. Why doesn’t California import water from the Pacific Northwest, the Great Lakes, or the Mississippi River? They seem to have extra water. 

The Pacific Northwest, Great Lakes, and Mississippi River all have relatively abundant water supplies.  These water sources also are all far from California, with mountain ranges in between.  Constructing and operating aqueducts, tankers, or railcars to move water great distances is expensive, and moving water (which is heavy) over mountains is very energy-intensive.  The cost of moving water these great distances typically exceeds the value of the additional water uses in California (Perrier and Fuji water might be exceptions).  Environmental, political, and legal opposition also would likely be barriers to California importing large amounts of water.

Some Larger lessons

Some broader lessons arise from this first set of common questions on California water.  First, there are many ways to get water in California, which vary tremendously in cost, availability, environmental impact, and practicality.  Second, because so many potential water sources are available in California, it is sometimes said, “There is rarely a shortage of water, but more often a shortage of cheap water.”  California is often a dry place, and the relative costs and benefits of different water supplies and demands typically drive the use, rejection, and research for water management options.

Jay R. Lund is Director, Center for Watershed Sciences and a Professor of Civil and Environmental Engineering, University of California – Davis

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The California Water Model: Resilience through Failure

by Nicholas Pinter, Jay Lund, Peter Moyle

Sacramento 1862

Figure 1.  1861-62 flood in Sacramento.

A review of 170 years of water-related successes in California suggests that most successes can be traced directly to past mistakes.  California’s highly variable climate has made it a crucible for innovations in water technology and policy.  Similar water imperatives have led to advances in water management in other parts of the world.  A close look at California’s water model suggests that “far-sighted incrementalism” is a path to progress.  Given the complexity of water management systems, better scientific information and new policy tools must be developed coherently and collaboratively over time.  A history of learning from previous failures can guide progress towards stable, secure, and resilient water systems worldwide.  This includes learning from other regions and other “water models” – the one option clearly superior to innovating in response to your own mistakes is learning from the errors of others.

This post summarizes an article just published in Hydrological Processes, available from the publisher at http://www.authorsharing.onlinelibrary.wiley.com/share (specify Article DOI: 10.1002/hyp.13447) or https://onlinelibrary.wiley.com/doi/epdf/10.1002/hyp.13447

 Average runoff in California is about 100 km3/yr, but our ecosystems and parts of our economy have been water-limited for decades.  Part of the state’s challenge comes from the variability of its climate.  Average years are unusual, and instead long droughts are punctuated by years of heavy rain or snowmelt and flooding.  Nonetheless, the state has managed to thrive, with 40 million people, agricultural production exceeding $45 billion/year, and the world’s sixth largest economy.  California’s droughts and floods and tension between economic growth and environmental protection have pushed it to develop a diverse toolkit for managing water.

The toolkit consists of an integrated system of infrastructure, laws, institutions, and economic tools. This system, the ”California water model,” has evolved from the first Spanish settlement, through the gold mining era, the ascendancy of agriculture and major cities, to the recent broad mix of objectives that includes strong environmental protection. California has steadily adapted its water management by making mistakes and then learning from those mistakes. In 2017, for example, California avoided major flooding despite the winter being one of the wettest on record and major spillway failures. This was partly due to luck. Reservoirs began low from a drought and winter storms were widely spaced. And most flood infrastructure, particularly the flood bypasses, functioned well. California’s water model offers broad lessons for water managers, particularly in arid regions.

Water in California is framed by the state’s Mediterranean climate.  Summers are long and dry and most precipitation comes during the winter.  Historically, much of the water supply comes from mountain snowmelt (the state’s largest surface reservoir), reservoirs, and groundwater.  In addition to this seasonality, wet years often follow droughts, and vice versa, high variability accentuated by climate change. This near-perpetual alternating water crisis forces Californians to find innovative solutions.  Whereas other US states and other countries may have decades to settle into a false sense of security, California’s hydrologic extremes accelerate innovation.

In 2017, California emerged from a severe five-year drought.  The drought’s effects on agriculture were limited because past droughts had led to more flexible water markets, and farmers greatly expanding groundwater pumping.  Although the state lost about a third of its water supply, agricultural revenue losses were only 3%, and only about 6% of the land was fallowed.  This was in part because producers of lower-value crops sold or transferred their water to producers of higher value crops such as fruit, nuts, and vegetables and to urban water users.  The expanded groundwater pumping raised the visibility and impacts of long-term groundwater problems, which in turn led to passage of California’s Sustainable Groundwater Management Act, which will regulate groundwater in the future.

At the other extreme, California also has long history of damaging floods, and flood risk remains widespread today.  Winter storms of 1861-62, turned much of the Central Valley into an inland sea, and frequent levee breaches through the 19th and 20th centuries resulted in high costs to landowners and to the state. In less variable regions, the decades between major floods lead to a “hydro-illogical cycle” in meaningful steps avoid flood damage are forgotten in intervals between disasters.  Early on in California, repeated flooding led to construction of Yolo and Sutter Bypasses, which remain a world model for basin-scale flood management.  A costly 1986 levee failure (and national headlines from New Orleans in 2005) sparked new legislation and investment that has upgraded many California levees from some of the worst in the nation to some of the best.  Repeated flood disasters have kicked the state in the right direction, although much work always remains.  The near-disaster at Oroville Dam in February of 2017, where two spillway failures led to major evacuations, sparked scrutiny and investment at Oroville Dam and for aging water infrastructure across California.  Other regions with large dams, or contemplating new dams, should include Oroville’s lessons in their textbook.

sjv land subsidence

Figure 2.  Unchecked groundwater overdraft has brought ground-surface subsidence.  California’s San Joaquin Valley’s severe subsidence over the past century, continues locally today.  Photo courtesy of Michelle Sneed, US Geological Survey.

Despite successes, California’s water management faces continued challenges.  High on this list, protecting endemic aquatic species remains a vexing challenge.  Despite legal protections under federal and state regulations, California’s native fishes are in rapid decline, with 80% of species on paths towards extinction.  California will need to expand its toolkit – such as by accepting “reconciliation ecology” as a new model for maintaining natural diversity in the face of human pressures and a changing climate.

We suggest that a prerequisite for providing and maintaining healthy aquatic ecosystems and adequate supplies of clean water is “far-sighted incrementalism” among water managers and political leaders.  Incrementalism involves addressing seemingly intractable problems by small forward-looking steps.  “Far-sighted,” at least in California, has involved forward-thinking planning among scientists, managers, and leaders during and after each water-related crisis.  The common response after a damaging flood is reactive – repair the levee breach and rebuild floodplain neighborhoods.  Far-sighted leaders see opportunities in such a crisis to move the system forward, usually incrementally, in a longer-term strategic direction (usually too controversial or difficult to achieve in one step).  California must continue to support organized and independent learning from and adapting to disasters and extremes.

 Lessons for managing water in a thirsty world

By 2050, an additional 2.3 billion people worldwide will face severe water stress, especially in Africa and southern and central Asia.  Already, 2.1 billion people worldwide lack access to safe drinking water. Three out of four jobs worldwide depend upon access to water and water-related services.  Water-limited regions and populations must prepare for changes in water management, addressing existing and emerging weaknesses and learning from mistakes, if possible from other areas, without repeating those errors.

Water management successes often rest on past failures – failures from which scientists, managers, and leaders learn and adapt.  This is especially true for California, where hydrologic variability frequently tests water systems and water policy.  As the world, especially the arid to semiarid world, looks for water solutions, the failures and lessons from California’s turbulent history can provide guidance for future global water resilience.

Nicholas Pinter, Jay Lund, and Peter Moyle are faculty in the Departments of Earth and Planetary Sciences, Civil and Environmental Engineering, and Wildlife, Fish, and Conservation Biology (respectively) and work together at the Center for Watershed Sciences at the University of California, Davis.  Email: npinter@ucdavis.edu; jrlund@ucdavis.edu; pbmoyle@ucdavis.edu

Further Readings

Auerswald, K, P. Moyle, S.P.Seibert, and J. Geist. 2019. HESS Opinions: Socio-economic and ecological trade-offs of flood management – benefits of a transdisciplinary approach. Hydrology and Earth System Sciences 23: 1035-1044.  https://www.hydrol-earth-syst-sci.net/23/1035/2019/  Open access.

Dettinger MD, Ralph FM, Das T, Neiman PJ, & Cayan DR. 2011. Atmospheric rivers, floods and the water resources of California.  Water, 3: 445-478.

Faunt, C., and M. Sneed, 2015.  Water availability and subsidence in California’s Central Valley.  San Francisco Estuary & Watershed Science, vol. 3, available fromhttps://ca.water.usgs.gov/pubs/2015/FauntSneed2015.pdf

Grantham, T.E., R. Figueroa, and N. Prat, 2013.  Water management in mediterranean river basins: a comparison of management frameworks, physical impacts, and ecological responses.  Hydrobiologia, 719: 451–482.

Independent Forensic Team, 2018.  Independent Forensic Team Report, Oroville Dam Spillway Incident, Jan. 5, 2018, https://damsafety.org/article/oroville-investigation-team-update

James, L.A., and M.B. Singer, 2008. Development of the Lower Sacramento Valley Flood-Control System: Historical Perspective, Natural Hazards Review, 9(3): 125-135.

Kelley, R., 1989.  Battling the Inland Sea, University of California Press, Berkeley, CA.

Konar M, Evans TP, Levy M, Scott CA, Troy TJ, Vörösmarty CJ, Sivapalan M. 2016. Water resources sustainability in a globalizing world: who uses the water? Hydrological Processes, 30: 330-336.

Lund, J.R., J. Medellin-Azuara, J. Durand, and K. Stone, “Lessons from California’s 2012-2016 Drought,” J. of Water Resources Planning and Management, Vol 144, No. 10, October 2018. (free download)

Lund, J., 2016.  You can’t always get what you want – A Mick Jagger theory of drought management.  California Water Blog, https://californiawaterblog.com/2016/02/21/you-cant-always-get-what-you-want-a-mick-jagger-theory-of-drought-management/.

Moyle, P., R. Lusardi, P. Samuel, and J. Katz. 2017. State of the Salmonids: Status of California’s Emblematic Fishes 2017.  Center for Watershed Sciences, University of California, Davis and California Trout, San Francisco, CA. 579 pp. https://watershed.ucdavis.edu/files/content/news/SOS%20II_Final.pdf

Multi-Benefit Flood Protection Project, 2017.  Projects, http://http://www.multibenefitproject.org/projects/.

OECD Organisation for Economic Co-operation and Development, 2012.  OECD Environmental Outlook to 2050: The Consequences of Inaction.  OECD Publishing, Paris.  http://dx.doi.org/10.1787/9789264122246-en

Opperman, J.J, P.B. Moyle, E.W. Larsen, J.L. Florsheim, and A.D. Manfree. 2017 Floodplains: Processes, Ecosystems, and Services in Temperate Regions. Berkeley: University of California Press.

Pinter, N., A. Damptz, F. Huthoff, J.W.F. Remo, and J. Dierauer, 2016.  Modeling residual risk behind levees, Upper Mississippi River, USA.  Environmental Science & Policy, 58, 131-140.

Pisani, D., 1984. From the Family Farm to Agribusiness: The Irrigation Crusade in California, 1850–1931. Berkeley: University of California Press.

Soulsby, C, Dick J, Scheliga B, & Tetzlaff D. 2017. Taming the flood—How far can we go with trees? Hydrological Processes, 31: 3122–3126.

Vahedifard, F., A. AghaKouchak, E. Ragno, S. Shahrokhabadi, and I. Mallakpour, 2017.  Lessons from the Oroville dam.  Science, 355: 1139-1140.

Van Lanen HAJ, et al. 2016. Hydrology needed to manage droughts: the 2015 European case.  Hydrological Processes, 30 https://doi.org/10.1002/hyp.10838

WHO & UNICEF World Health Organization and the United Nations Children’s Fund, 2017.  Progress on drinking water, sanitation and hygiene: 2017 update and SDG baselines. Geneva: World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF).


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Fish are born free, but are everywhere in cages this spring

by Carson Jeffres, Eric Holmes, and Andrew RypelBluff cage

State, federal, and local governments, water users, and the public are all concerned with the survival of salmon.   Over decades, and especially recent years, most salmon runs have severely declined in California.

Part of sustaining salmon populations is improving the survival and fitness of young salmon as they grow for weeks to months before out-migrating to the Ocean.

Growth of these young salmon is particularly low in the river channels confined with levees on each side.  Without adequate food and cold water temperatures, young salmon grow slowly.  Along with slow growing conditions, as spring arrives and water temperatures become warm and clear, predators become more abundant and prey on young salmon.  These two punches of poor growth plus potential predation makes the river channels hostile environments for young salmon.

Historically, young salmon would spread with flows from winter rains and snowmelt and feast over the Central Valley’s vast seasonal floodplains, until levees and upstream dams made these floodplains largely inaccessible.  These floodplains had abundant food for the salmon, particularly insects and zooplankton.  Today, young salmon are confined mostly to river channels, which lack the greater availability of foods in potentially adjacent floodplains (see the video of food abundance on floodplain).

In the early 1900s, the Sacramento Valley’s Yolo and Sutter flood bypasses were built to restore some of the Valley’s natural flood conveyance capacity (a novel flood control idea at the time, and still so today) (Hundley 1989).   Increasingly, these bypasses provide multiple benefits.  They remove dangerous floods from cities (notably Sacramento), are farmed (e.g., for rice and other crops), and provide valuable ecological habitat.

In the 1980s, flood bypasses were modified to also serve migrating waterbirds, restoring some seasonal wetlands along the Pacific Flyway.  Winter riceland flooding was spurred originally by air quality regulations prohibiting burning of post-harvest rice stubble.  This single shift in farming practices effectively doubled available flooded habitat for wintering waterfowl in the Central Valley and the results were very successful (Garone 2011).

In recent years, several groups have been exploring further modifications to Sacramento Valley flood bypasses to restore some of this area’s natural seasonal fish habitat.  This exploration began from observations that salmon migrating through the Yolo Bypass in wet years grew larger than salmon migrating down the leveed Sacramento River channel (Sommer et al. 2001).  Subsequent studies found that young salmon grow much larger on floodplains and flooded bypass lands (Jeffres et al. 2008, Katz et al. 2017).


2019 Salmon Growth Cage Experiment Locations

This year, UC Davis Center for Watershed Sciences and California Trout have four different studies over approximately 100 miles using floating cages with baby salmon inside.  A total of 85 cages were deployed to study fish growth across a variety of habitats and the potential benefits of these habitats to outmigration survival (see map).  These widespread experiments are evaluating differences in water quality, food resources, growth rates and differences in survival between fish grown on floodplains and control fish.

These experiments place young salmon in cages at locations representing different habitat and flow conditions, protecting them from a variety of predators to help clarify effects of habitat, food density, water quality, food density, and location on fish growth.  Raising baby salmon in cages in not always easy.  Watching, tending, and probe instrumentation are especially challenging with so many cage sites in high flows (like this year), requiring special attention to safety.

The insights and information resulting from this year’s field experiments will help prioritize and guide management and restoration throughout the Central Valley.  Better understanding the ties of land and water management for salmon provides opportunities for more effective restoration efforts and the cooperation of land owners and other environmental interests.

This year’s extensive fish growth experiments are a major step forward building on over a decade of collaborative research, observations, and experiments involving a variety of fish and water management agencies and interests, as well as intense and crucial involvement from land owners and the local agriculture.  Such broad collaborations are needed to develop effective solutions and take the broad actions needed reverse recent declines in salmon populations.

little fish

Fish initially caged

successful fish

Fish at end of experiment

Carson Jeffres is a Professional Research Scientist, Eric Holmes is a staff scientist, and Andrew Rypel is an Associate Professor of Wildlife, Fish and Conservation Biology at UC Davis’ Center for Watershed Sciences.

Collaborators in these and earlier studies include: California Trout, California Department of Water Resources, US Bureau of Reclamation, US Fish and Wildlife Service, California Department of Fish and Wildlife, River Garden Farms, Cal Marsh & Farms, Conaway Ranch, California Rice Commission, US Department of Agriculture – Natural Resources Conservation Service, the Delta Science Program, Northern California Water Association, River Garden Farms, Reclamation District 108.

Further reading

Garone, P. (2011). The fall and rise of the wetlands of California’s Great Central Valley: Univ of California Press.

Sommer TR, Nobriga ML, Harrell WC, Batham W, Kimmerer WJ (2001) Floodplain rearing of juvenile Chinook salmon: evidence of enhanced growth and survival. Can J Fish Aquat Sci 58:325–333

Kelley, Robert (1989), Battling the Inland Sea: Floods, Public Policy, and the Sacramento Valley, University of California Press, Berkley, CA.

Jeffres, C., Opperman J.J.., & Moyle P. B. (2008).  Ephemeral floodplain habitats provide best growth conditions for juvenile Chinook salmon in a California river. Environmental Biology of Fishes. 83(4),

Katz, J., Jeffres C., Conrad L., Sommer T., Martinex J.., Brumbaugh S., et al. (2017).  Floodplain farm fields provide novel rearing habitat for Chinook salmon. PLoS ONE. 12(6),

Megan Nguyen (2017), Yolo Bypass: the inland sea of Sacramento, 20 February, CaliforniaWaterBlog.com.

One project web site: http://salmon.calrice.org/

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