Habitat Restoration for Chinook Salmon in Putah Creek: A Success Story

by Eric Chapman, Emily Jacinto, and Peter Moyle

2017 was another good year for Chinook salmon in Putah Creek.

Putah Creek is just a small stream flowing through Yolo and Solano counties, fed by releases of water from Lake Berryessa. For decades, Chinook salmon were rare in the creek.

Yet, now, with salmon populations struggling throughout the Central Valley, Putah Creek numbers are on the rise. Over the past five years the estimated number of adult spawners has increased from eight in 2013 to over 500 in each of the past three years (200-500 in 2014, 500-700 in 2015, 1500-1700 in 2016, and 700 in 2017).

When much of California was in the historic drought of 2012-2016, hatcheries resorted to trucking juvenile Chinook salmon far downstream to the Delta. The intent was to increase the number of juveniles reaching the ocean because survival is poor in the rivers during low water years (Michel et al. 2013, Michel et al. 2015). While trucking can sustain adult populations, it increases the rate of adult straying into other watersheds upon return from the ocean, rather than homing to their natal watershed (Johnson 1990, Lasko 2012).

However, ongoing restoration and management efforts in Putah Creek have made conditions favorable for attracting salmon. Flashboards blocking access to the creek at the Los Rios Check Dam in the Yolo Bypass are removed every year in November and salmon attraction flows are released for five consecutive days from the Putah Diversion Dam in Winters, CA.

Map of Putah Creek from the Putah Diversion Dam (PDD) to the Toe Drain (yellow star). Salmon migrate through the yellow area to and from the spawning grounds in red. Number of adult carcasses sampled (blue circles and numbers) in different sections (black circles) of the spawning grounds. The location of the rotary screw trap is above Winters, CA (yellow star).

Minimum flows were established to enhance rearing habitat for juvenile salmon and to facilitate outmigration (Kiernan et al. 2012). During summer and fall, the Solano County Water Agency has also been using heavy equipment to scarify (turn over) the bottom of selected reaches of the creek; this process exposes spawning gravel that has been buried by years of siltation and compaction.

Over the past two years, salmon spawning has been observed on nearly every patch of gravel from the Putah Diversion Dam to Davis, a distance of ~25 kilometers. Fish were observed spawning on the newly exposed areas and on sites from previous scarification efforts. Use by salmon seems to keep the sites from becoming cemented in again.

In Winters, people watched salmon spawning below the pedestrian bridge. This reach was site of a major restoration project that removed a concrete dam and recreated a meandering stream, greatly improving salmon habitat.

Where did these fish come from and are they spawning successfully? Are juveniles making it out of Putah Creek to the ocean and are any of them returning as adults to spawn? UC Davis and the Solano County Water Agency set out to answer these questions by sampling both adult and juvenile life stages.

Adult Sampling

In 2016, researchers from the UC Davis Department of Wildlife Fish and Conservation Biology began conducting carcass surveys throughout the creek. Surveys did not begin until December in 2016, but in 2017 they coincided with the arrival of adults in the creek. The researchers poled canoes from the Putah Diversion Dam to Davis at least once during every week of the run. This allowed them to estimate the number of fish throughout the creek from week to week.

Colby Hause, a researcher at UC Davis, poles a canoe during carcass surveys. (photo: Eric Chapman)

The 2017 estimate of 700 fish is likely within ± 20%.  In the future, we hope to employ other methods as well to estimate abundance, such as use of special cameras to record passing fish.

During the two years of carcass surveys, otoliths (ear bones) were collected in order to determine the origin and age of salmon spawning in Putah Creek. Genetic samples were also collected, and tiny, coded wire tags (CWTs) were extracted from fish missing their adipose fin. The missing fin indicates they were of hatchery origin.

Results from 23 CWT fish from 2016 found that 20 were from the Mokelumne River Hatchery, two were from the Nimbus Hatchery on the American River, and one from the Feather River Hatchery. All of the tagged fish were fall-run Chinook salmon that had been trucked downstream to be released closer to the ocean during the drought.

Two otoliths collected from a carcass and location of coded wire tags (CWT). Note that the head of this fish is pointing upwards (photo: Eric Chapman)

These 23 fish were a subsample of the 126 carcasses recovered on the creek. Otolith microchemistry from the 91 fish with an intact adipose fin was determined at the University of California Davis Interdisciplinary Center for Plasma Mass Spectrometry, focusing on Strontium (Sr) isotope ratios (87Sr/86Sr). These isotope ratios vary among rivers in the Central Valley of California. The strontium isotopes are incorporated into each otolith on a daily basis, allowing for assignment of natal origin of individual fish by measuring the isotope ratios at the core of the otolith.

The microchemistry of the otolith center reflects where the fish was hatched and reared. Unfortunately, considerable overlap exists among the strontium signatures of possible natal sources, including between rivers and hatcheries, making some results difficult to interpret. For example, the strontium signature of Chinook salmon from Putah Creek overlaps with that of the wild Feather River fish but not with those in fish produced in the Feather River Hatchery.

Gabriel Singer with a large male sampled during carcass surveys. (photo: Eric Chapman)

The otolith microchemistry showed that there were at least five stocks of fish in Putah Creek in 2016. One fish was sampled that could have been of Putah Creek origin but it could have also been a naturally produced Feather River fish. To determine the difference between Putah Creek and the Feather River, it will be necessary to incorporate other trace elements or isotope systems in the future.

Juvenile Sampling

In the spring of 2017, a rotary screw trap (RST) was deployed to determine spawning success and to describe emigration timing of the juveniles. This was an extremely high water year, with Lake Berryessa overflowing during much of late winter. Because of the hazards of running a trap at high flows, the trap wasn’t operated until May 1st when the water subsided. On May 2nd there were nine juvenile fall run Chinook salmon in the trap; juveniles were captured daily until May 20th,with a peak of over 30 fish on May 10th.

The screw trap used to sample juvenile Chinook in Putah Creek. Photo credit: Ken Davis

The 215 juvenile salmon sampled into June 2017 were large, averaging 97 millimeters in length and 11.4 grams in weight. This indicates that high flows did not push them out of Putah Creek, rather it provided rearing conditions that enabled them to thrive prior to migration. These conditions were likely found on the edges of the creek and outside of the banks where floodplain conditions exist.

Daily catch summary of juveniles sampled in Putah Creek during 2017.

The jury is still out on successful spawning and rearing in 2018. The RST has been deployed again in 2018, and hundreds of small outmigrating  juveniles were captured as of January-March.  One hundred of the largest fish will receive an acoustic transmitter that will be surgically implanted to track their survival and migratory behavior. Receivers that detect the transmitters will be situated at the base of the creek, enabling the researchers to determine emigration survival from Putah Creek. An array of receivers collaboratively deployed by UCD and fisheries agencies outside the creek will enable modelling of survival through the Delta and San Francisco Estuary all the way to the Golden Gate, which has the last line of receivers prior to the Pacific Ocean.

Typical juvenile salmon caught in the RST during 2017 spring sampling (photo: Eric Chapman)

Putah Creek is a success story for salmon because water releases from a dam and habitat restoration projects have worked together to attract salmon and to allow them to spawn and rear successfully. It is likely that at least some adult salmon that returned to spawn were themselves spawned in Putah Creek. It seems possible that in the future a run could develop that is not dependent on hatchery strays, but is made up of natal fish from the creek.

Otoliths and genetics help us understand what happens when a creek is reborn and made available to fish. Spawner surveys and juveniles caught in the rotary screw trap confirm that restoration actions are working and that Putah Creek offers habitat that is suitable for producing fall-run Chinook salmon on an annual basis. Putah Creek is already regarded as model for restoration of habitat for native fishes and other plants and animals. To add wild salmon to this trajectory of success requires continued management of the creek to benefit salmon, including expansion of habitat restoration projects.


We thank the Solano County Water Agency for funding this project and for all of their help throughout the project. We would also thank Malte Willmes and James Hobbs for processing the otoliths in the mass spectrometer. Finally we thank all of the members of the UCD Biotelemetry Laboratory (Gabriel Singer, Colby Hause, Tommy Agosta, Christopher Bolte, and Patrick Doughty), volunteers, and students for their help during field work.

Eric Chapman, the lead researcher, works in Peter Moyle’s fisheries laboratory in the Center for Watershed Sciences. Emily Jacinto is a lab assistant at UC Davis. Peter Moyle is professor emeritus at the University of California, Davis, and Associate Director of the Center for Watershed Sciences. 

Further reading

Johnson, S.L., Solazzi, M.F. and Nickelson, T.E., 1990. Effects on survival and homing of trucking hatchery yearling coho salmon to release sitesNorth American Journal of Fisheries Management10(4), pp.427-433.

Kiernan, J.D., P. B. Moyle, and P. K. Crain. 2012. Restoring native fish assemblages to a regulated California stream using the natural flow regime concept.  Ecological Applications  22:1472-1482.

Lasko, G.R. 2012. Straying of late-Fall-run Chinook salmon from the Coleman National Fish Hatchery into the lower American River, California. Masters thesis, California State University, Sacramento.

Michel, C.J., Ammann, A.J., Chapman, E.D., Sandstrom, P.T., Fish, H.E., Thomas, M.J., Singer, G.P., Lindley, S.T., Klimley, A.P. and MacFarlane, R.B., 2013. The effects of environmental factors on the migratory movement patterns of Sacramento River yearling late-fall run Chinook salmon (Oncorhynchus tshawytscha). Environmental biology of fishes96(2-3), pp.257-271.

Michel, C.J., Ammann, A.J., Lindley, S.T., Sandstrom, P.T., Chapman, E.D., Thomas, M.J., Singer, G.P., Klimley, A.P. and MacFarlane, R.B., 2015. Chinook salmon outmigration survival in wet and dry years in California’s Sacramento River. Canadian Journal of Fisheries and Aquatic Sciences72(11), pp.1749-1759.

Posted in Biology, Fish, Restoration, Salmon | Tagged , , , | 1 Comment

Improving Urban Water Conservation in California

by Erik Porse

The relatively dry 2017-18 winter in California resurfaced recent memories of drought conservation mandates. From 2013-16, urban water utilities complied with voluntary, then mandatory, water use limits as part of Executive Order B-37-16. Urban water utilities met a statewide 25% conservation target (24.9%), helping the state weather severe drought. Winter rains in 2016-17 led to a reprieve from mandatory conservation. Freed from statewide requirements, urban water agencies ended mandatory cutbacks by meeting “stress tests” that included several years of secured water supplies.

A useful outcome of the 2013-17 drought period was long-needed reporting data on monthly urban water use and conservation. This reporting has continued, creating a growing repository for measuring trends. The data helps understand how much water California cities actually use, including trends over time, across geography, and seasonal differences.

But, importantly, can it help understand how much water California cities should use? Some analysis of the water conservation reporting data, coupled with recent research, lends a few clues to this more complex question.

Seasonal and Geographic Differences in Water Use

Recent water use totals through the end of 2017 show that cities in many parts of the state continue to use less water compared to 2013, but not as efficiently as during drought. There were a few exceptions, including the South Coast where 59% of utilities reported increases compared to the similar period in 2013.

But examining trends over time and space is instructive. Some localities continued high, even ostentatious, rates of water use. In addition, seasonal differences are evident. Drier months see much higher per capita water use due to outdoor irrigation, as shown in graphics via the Pacific Institute’s water use webmap. But winter irrigation can be just as important. Moving towards urban landscapes with no winter irrigation requirements can be as effective as limiting summer irrigation.

Summer and winter water use across Los Angeles urban retailers (source: Pacific Institute, downloaded November 2017)

Benchmarking Per Capita Consumption

Many cities in California have higher rates of water use than counterparts in other countries. But what does a target of 100 gallons per person per day (total use) actually mean for urban life?

The 2016 Executive Order sought to address this question in part by requiring state agencies to develop water use budgets based on specified targets of indoor use, commercial and industrial needs, and outdoor irrigation. This effort is continuing. But water use budgets themselves do not reveal the implications of various per capita targets, especially for outdoor needs.

Could a city in coastal Southern California, for instance, exist with 80 gallons per capita per day of total use? What would this mean for its plants, trees, and landscapes? How would the effects change in the San Francisco Bay Area or the Central Valley? Urban ecology research demonstrates that plants and trees often show distinct and varying physiological characteristics and water use trends in cities, owing to irrigation habits, climate, and other factors. Such emerging knowledge must help inform practice.

In Los Angeles, for example, research used experimental data for species-specific tree and lawn water use to estimate outdoor water use budgets and associated effects of conservation on trees and plants. Across metropolitan LA, an estimated target of 80-100 gallons per capita per day could support trees and low water landscapes, along with current residential and commercial needs, while also allowing for significant cutbacks in imported water. More aggressive conservation at the lower end of that range would require long-term conversion of the existing tree canopy to low-water and drought tolerant species.

Urban Yards as a Resource

Well-designed urban yards can support important plant and animal species, but residents need better tools, information, and guidelines on soil and irrigation practices. Outdoor landscapes constitute 50% of total urban water use in many areas. Water utilities increasingly fund replacement of lawns as a way to promote long-term conservation. But most programs do not require resultant landscapes with ecological diversity and native plants.

Research from Los Angeles indicates that, even in the absence of such requirements, turf replacement can yield more diverse landscapes. Urban utilities with ecologists on staff can better ensure turf replacement that supports biodiversity, native vegetation, and trees. Some examples, such as the City of Long Beach’s turf replacement program, offer useful guidance for residents. Resources such as the Calflora database of native California plants and Cal-Poly’s Urban Forest Ecosystem Institute tree selection guide are excellent statewide resources. But improving native and drought-tolerant plant selections in California’s urban nurseries would allow residents to translate such information into practice.

Water Use in an Era of Big Data

Urban water use trends are usefully understood when consumption data is linked with other data sets, including US Census data, county property tax records, and climate trends. This allows for high-resolution analysis that informs investments and rate-setting procedures. Some examples of innovative data initiatives exist, including the California Data Collaborative. Such tools have cascading benefits for planning.

Statewide efforts around water data are ramping up, but the state’s fragmented system of water governance inhibits broader analysis. Moreover, high-detail water use data is difficult to obtain. More accessible data across residential, commercial, industrial, and institutional properties is essential for improving management. Linking and publishing this data is an important step for promoting 21st Century, data-driven urban water polices in California.

Responsibility at Many Levels

Both water utilities and residents are essential participants in continued conservation. Utilities must retool finances to stabilize revenues given long-term conservation. Additionally, they must better engage residents and community organizations in promoting culture change. But residents also have responsibilities. Building social capital is key. Community-based organizations help engage residents in this task. For example, The River Project with its Water LA program engages residents in remaking landscapes for dual goals drought-tolerance and stormwater management. The Sacramento Tree Foundation and TreePeople are additional examples of community-based groups effectively bridging gaps between residents and utilities. Water agencies that meaningfully engage community groups will be better positioned to promote long-term conservation.

Given the popularity and continued growth of California’s cities, along with the inevitability of drought, urban water conservation will need to continue. Implementing policies to promote equitable conservation, which also supports cities where we want to live, is a challenge that an innovative California is capable of tackling.

Erik Porse is a Research Engineer in the Office of Water Programs at
CSU-Sacramento and a Visiting Assistant Researcher at UCLA.

Further Reading

Cahill, R., & Lund, J. (2012). Residential water conservation in Australia and CaliforniaJournal of Water Resources Planning and Management139(1), 117-121.

Gleick, P. H., et al. (2003). Waste not, want not: The potential for urban water conservation in California. Oakland, CA: Pacific Institute for Studies in Development, Environment, and Security.

Hanak, E., & Davis, M. (2006). Lawns and water demand in CaliforniaPPIC Research Reports.

Litvak, E., Bijoor, N. S., & Pataki, D. E. (2013). Adding trees to irrigated turfgrass lawns may be a water‐saving measure in semi‐arid environmentsEcohydrology7(5), 1314-1330.

Litvak, E., Manago, K. F., Hogue, T. S., & Pataki, D. E. (2017). Evapotranspiration of urban landscapes in Los Angeles, California at the municipal scaleWater Resources Research53(5), 4236-4252.

Mini, C., Hogue, T. S., & Pincetl, S. (2014). Estimation of residential outdoor water use in Los Angeles, CaliforniaLandscape and Urban Planning127, 124-135.

Mitchell, D., Hanak, E., Baerenklau, K., Escriva-Bou, A., McCann, H., Pérez-Urdiales, M., & Schwabe, K. (2017). Building Drought Resilience in California’s Cities and SuburbsPublic Policy Institute of California.

Pataki, D. E., McCarthy, H. R., Litvak, E., & Pincetl, S. (2011). Transpiration of urban forests in the Los Angeles metropolitan areaEcological Applications21(3), 661-677.

Pincetl, Stephanie, Thomas W. Gillespie, Diane Pataki, Erik Porse, Shenyue Jia, Erika Kidera, Nick Nobles, Janet Rodriguez, and Dong-ha Choi. (2017) “Evaluating the Effects of Turf-Replacement Programs in Los Angeles County.”

Porse, Erik, Kathryn B. Mika, Elizaveta Litvak, Kimberly F. Manago, Kartiki Naik, Madelyn Glickfeld, Terri S. Hogue, Mark Gold, Diane E. Pataki, and Stephanie Pincetl. “Systems Analysis and Optimization of Local Water Supplies in Los Angeles.” Journal of Water Resources Planning and Management 143, no. 9 (2017): 04017049.

Posted in California Water, Conservation, Drought, urban water | Tagged | 3 Comments

Resurrecting the Delta for Desirable Fishes

by Peter Moyle, Carson Jeffres, John Durand

Cache Slough sunrise. Photo by Matt Young

The Delta is described in many ways.  When extolling the Delta as a tourist destination, it is described as a place of bucolic beauty; islands of productive farmland are threaded by meandering channels of sparkling water, a place to boat, fish, view wildlife, and grow cherries and pears.

But when its future is discussed, especially in relation to big water projects, this heavenly place is often portrayed as being on its way to an aquatic Hellscape.

The Sacramento Bee recently (April 8, 2008) published a reasonable editorial advocating a holistic approach to solving Delta problems.  But the editors chose language to describe the Delta such as:  it is “dying as the planet warms” and it is on the verge of “ecosystem collapse.” This language tracks that of groups that want to “save the Delta,” especially from proposed changes to its human-dominated plumbing system.

At the risk being labeled heretics, we say the Delta is not dying, and its ecosystem is not on the verge of collapse, but that it is changing.

The last time California faced real collapse of aquatic ecosystems was before the passage of the state and federal clean water acts in the 1970s, which eliminated or greatly reduced the dumping of huge volumes of toxic material into the estuary.  The present Delta, as measured by total fish populations, species diversity, navigability, migratory waterfowl abundance, and other measures, even water quality, is a ‘healthy’ ecosystem in many ways.

The most likely future Delta, even after widespread levee failure, will not feature a collapsed ecosystem (whatever that may be) or even a particularly unhealthy Delta ecosystem.  No matter what happens, there will still be fish and fisheries in the Delta, as well as boating, abundant wildlife, complex food webs and prosperous farms. But the future ecosystem may not have many of the species we find desirable today, especially endangered species such as delta smelt and winter-run Chinook salmon. Current land use patterns are also likely to change, away from urbanization and low-value agriculture.

If present trends continue, native fishes in the Delta will be replaced largely by alien species such as wakasagi smelt, Mississippi silversides, and largemouth bass. Deeply  subsided islands will be transformed via levee collapses to large open areas of tidal brackish water. These habitats will favor salt-tolerant species such as striped bass, starry flounder, crangon shrimp, splittail and various species of Japanese gobies.  In short, at least in the water, the fishes tell us that, no matter what happens, there will be thriving novel ecosystems that will support many of the same functions as today. The present ecosystem is already quite different from earlier manifestations of the ecosystem, especially the original historic ecosystem. Native species disappear while non-native species increase.

But we don’t have to accept whatever Delta ecosystem comes our way. To some extent, we can choose the species making up the future Delta ecosystem as well as many of its physical features, if we make some tough management decisions and accept that ecosystem changes will continue, some beyond our control.  Today’s somewhat foggy general vision of the Delta’s future seems to be that it will remain in its present configuration forever, with levees and channels maintained despite continual land subsidence, bigger storms, higher tides, and changing habitats and economies.  This Delta is assumed to continue as a freshwater system, thanks to large pulses of water from dams.  Despite these pulses, native fishes will gradually disappear, although fall-run Chinook salmon runs may continue due to hatcheries and trucking operations.  Delta smelt and longfin smelt will likely be extinct; they will no longer drive water decisions unless maintained by artificial propagation, like salmon. Fisheries for largemouth bass and other warm-water fishes will expand, dominating the system even more than today.

This vision does not have to prevail in all of the Delta.  We recently wrote a report that provides an alternative vision (Moyle et al. 2018, Making the Delta a Better Place for Native Fishes (https://www.coastkeeper.org/wp-content/uploads/2018/03/Delta-White-Paper_completed-3.6.pdf).   The vision we present is a modified version of some earlier thoughts (Moyle et al. 2013, and other references listed below).  The key to this vision is that management for native species and related values focuses on the North Delta Arc, a string of habitats connected by the Sacramento River.  The  Arc starts in the Yolo Bypass, continues through the Cache Slough region, then down the river past Rio Vista and into Suisun Marsh.  It also includes the Cosumnes-Mokelumne river corridor, to the Sacramento River.

Under this vision, the central and south Delta are treated as habitat that is, in fact, inhospitable for native fishes.  Indeed, native fishes may need to be excluded from these parts of the Delta, especially in summer.  The main issue for the central and south Delta is creation of a corridor for safe passage of adult and juvenile salmon and steelhead between San Francisco Bay and the San Joaquin, Tuolumne, Merced, and Stanislaus rivers.  This division of the Delta into two ecosystems is tacitly recognized already by most restoration projects (e.g., EcoRestore) as being located in the Arc.  This area provides the best opportunities because of habitat diversity and the fact that the Sacramento River connects these diverse habitats. The river also serves as the major migration corridor for fishes.

Our paper recommends 17 actions, listed below. Collectively, these actions could significantly improve habitat for native fishes, either directly or indirectly through stressor reduction and through development of new approaches via research. They at least will slow the ecosystem shift now occurring in favor of native species, floodplains, and wetlands.


  1. Four Easy Fixes (Fremont Weir, McCormick –Williams Tract, Delta smelt beaches, Putah Creek restoration).
  2. Expand Monitoring for Estuarine Health
  3. Provide a Water Right for the Environment
  4. Develop a Functional Flow Regime for the Delta
  5. Expedite Permitting and Implementation of Habitat Restoration Projects


  1. Expand EcoRestore and Learn from First 30,000 Acres
  2. Expand Restoration Projects in the North Delta Habitat Arc
  3. Establish Suisun Marsh as a Horizontal Levee
  4. Eliminate Predation Problems at Clifton Court Forebay
  5. Improve Delta Passage for Juvenile Salmon from the San Joaquin River and Tributaries.


  1. Reversing Subsidence in the Delta
  2. Accommodating Climate Change
  3. Reducing Impacts of Invasive species
  4. Reducing Impacts of Pesticides, Micro-contaminants, and Other Toxic Materials


  1. Experimenting with Island Flooding
  2. Evaluating Restoration Projects
  3. Developing a Stable Source of Innovative Research Funding.

As the report states: “The alternative to taking these and other actions is to continue on our present path, which is leading to the extinction of native fishes and the loss of significant fisheries for Chinook salmon, steelhead, striped bass and other fishes. It is important to remember that the Delta will always support a complex ecosystem. But whether that ecosystem is one that is desirable and consistent with our needs is up to us.”

The vision expressed by our report accepts that changes to the Delta ecosystem are inevitable but that, optimistically, we can collectively direct some of the change towards a more desirable state than will exist without high levels of additional activity. This vision can encompass actions favored by those who want to “save” the Delta, as well as those who envision a managed ecosystem that includes most of the remaining native fish fauna, as well as many other desirable elements, native and non-native.  It is not a vision that supports the rhetoric of a dying Delta or the Delta as a collapsed ecosystem, a rhetoric which does not lead to plausible actions to improve reality.

Peter B. Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences. John Durand is a researcher specializing in estuarine ecology and restoration at the Center for Watershed Sciences.  Carson Jeffres is a researcher specializing in fish ecology at the Center for Watershed Sciences.

Further reading

Durand, J., P. Moyle, and A. Manfree. 2017. Reconciling conservation and human use in the Delta. UCD California Water Blog, February 12, 2017.

Hanak, E., J. Lund, J. Durand, W. Fleenor, B. Gray, J. Medellín-Azuara, J. Mount, P. Moyle, C. Phillips, and B. Thompson. 2013. Stress Relief: Prescriptions for a Healthier Delta Ecosystem. San Francisco: Public Policy Institute of California. Available at www.ppic.org/main/publication.asp?i=1051

Hobbs, J.A, P.B. Moyle, N. Fangue and R. E. Connon. 2017. Is extinction inevitable for Delta Smelt and Longfin Smelt? An opinion and recommendations for recovery.  San Francisco Estuary and Watershed Science 15 (2):  San Francisco Estuary and Watershed Science 15(2). jmie_sfews_35759. Retrieved from: http://escholarship.org/uc/item/2k06n13x

Lund, J., E. Hanak, W. Fleenor, W. Bennett, R. Howitt, J. Mount, and P. B. Moyle.  2010. Comparing futures for the Sacramento-San Joaquin Delta. Berkeley University of California Press. 230 pp.

Moyle. P.B. W. Bennett, J. Durand, W. Fleenor, J. Lund, J. Mount, E. Hanak, and B. Gray. 2012. Reconciling wild things with tamed species- a future for native fish species in the Delta. California Water Blog. Center for Watershed Sciences, June 15, 2012. http://californiawaterblog.com

Moyle, P. B., W. Bennett, J. Durand, W. Fleenor, B. Gray, E. Hanak, J. Lund, J. Mount. 2012. Where the wild things aren’t: making the Delta a better place for native species. San Francisco: Public Policy Institute of California. 53 pages.

Moyle, P. B., W. A. Bennett, W. E. Fleenor, and Jay R. Lund. 2010. Habitat variability and complexity in the upper San Francisco Estuary. San Francisco Estuary and Watershed Science  8(3): 1-24. http://repositories.cdlib.org/jmie/sfews/vol8/iss3

 Moyle, P., J. Durand, A. Manfree. 2016. The North Delta habitat arc: an ecosystem strategy for saving fish. UCD Center for Watershed Sciences California WaterBlog. November 6. 2016.

Moyle, P.B., J. A. Hobbs, and J. R. Durand. 2018.  Delta smelt and the politics of water in California.  Fisheries 43:42-51.

Moyle, P.B., A. D.  Manfree, and P. L. Fiedler. 2014. Suisun Marsh: Ecological History and Possible Futures.  Berkeley: University of California Press.

Moyle, P.B., C. Jeffres, and J. Durand. 2018, Making the Delta a Better Place for Native Fishes (https://www.coastkeeper.org/wp-content/uploads/2018/03/Delta-White-Paper_completed-3.6.pdf)

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.


Posted in Delta, Fish, Restoration, Sacramento-San Joaquin Delta, Uncategorized | Tagged , , | 10 Comments

Modeling, Measuring, and Comparing Crop Evapotranspiration in the Delta

by Jesse Jankowski

Crop evapotranspiration (ET) is the biggest managed loss of water in California, accounting for roughly 80% of human net water use, and includes crop water applications transpired from plants and evaporated from soil. Methods to estimate ET have been developed based on a robust scientific understanding of its physics and data collected in the field or remotely by aircraft or satellites. Irrigation decisions often incorporate approximations of ET to help meet crop water demands, aided by field data from a state-supported network of weather stations.

For water managers, accurate ET estimation is important in large-scale accounting to calculate water available for multiple uses. In the Sacramento-San Joaquin Delta, consumptive water use informs project operations and affects the availability of environmental flows for fish habitat and salinity management. Water rights transfers and impacts of land fallowing also can be quantified by comparing ET from specific crops and bare soil. States like Idaho, with simpler agricultural systems, rely on ET models with remotely-sensed data to administer water rights.

As local parties work to implement the Sustainable Groundwater Management Act (SGMA) in California, ET measurements and estimates will be particularly important in modeling surface and groundwater availability and interactions.

At the request of the State Water Resources Control Board Office of the Delta Watermaster, UC Davis’ Center for Watershed Sciences convened seven modeling teams and one field team from the UC Davis Department of Land, Air and Water Resources to measure and estimate ET from agricultural lands in the Delta during the 2015 and 2016 water years (October 2014 through September 2016). Participating modeling teams included the Department of Water Resources (CalSIMETAW and DETAW models), the USDA Agricultural Research Service (DisALEXI model), the Irrigation Training & Research Center at Cal Poly (ITRC-METRIC model), NASA’s Ames Research Center (SIMS model), and UC Davis (UCD-METRIC and UCD-PT models).

Field stations were deployed to five fallow fields in 2015 and 14 fields of the dominant land uses, alfalfa, corn, and pasture, in 2016. These sites provided ground-based data for comparison to the modeled ET estimates. Land use surveys for each year were used to analyze ET estimates and gauge trends for specific land uses; 26 crop categories were selected to compute total agricultural ET within the Delta.

The estimates vary but give a sense of the total annual ET in the Delta, show trends for major crops in the area, and help quantify uncertainties for different land covers and times of year. The comparative study also provided policy insights for the use of model and field data in water resource management and to help improve estimation of ET in California.

Delta Service Area, ET model estimates, and field stations deployed for this study.

A 2016 Interim Report included a “blind comparison” of the models for the 2015 water year only. The Final Report contains results which benefited from group learning, standardized input datasets, and access to the UC Davis field data for the 2015 and 2016 water years. The seven models estimated about 1.4 million acre-feet of annual consumptive water use in the Delta; each model was within 11% of this average. Most ET occurs during the summer growing season (March through September) from five major land uses: alfalfa, corn, fallow lands, pasture, tomatoes, and vineyards.

Estimated annual ET, in thousand acre-feet, from crops in the Delta in 2015 and 2016.      *Information about specific models is provided in technical appendices to the Final Report.

The most common crops in the Delta in both years were alfalfa, corn, and pasture, which made up about 40% of Delta agricultural land and nearly 60% of its annual crop ET. Fallow lands increased to about 17% of the Delta’s agricultural lands and crop ET in 2016, though the 20 days of field measurements over bare soil in 2015 suggested that evaporation could be lower than predicted by the models. The largest differences between models occurred late in the growing season for almonds, corn, and potatoes, and relative variations between estimates were larger in the non-growing season when lands are typically fallow and ET is low due to colder temperatures and cloudy skies.

Detailed comparisons between models suggest that model assumptions, alternate input datasets, and interpolation between satellite images contributed to most differences and uncertainties among ET estimates. Although estimates could be improved with further calibration, ET models will also differ due to their human components: even when automated with computers, the expertise of a modeler is required to develop, run, and use them.

Estimated total monthly ET, in thousand acre-feet, from major crops in the Delta in 2016.

Several policy insights and recommendations arise from this work:

  • Land use surveys such as the ones done for 2015 and 2016 in this study are valuable for water planning. Years of data shows trends in land use, like the increased fallowing in the Delta in 2016 which might show preparation for permanent tree or vine crops. When combined with other input data from satellites, field stations, or models, land use surveys also can help estimate ET from specific locations and areas. Support for land use surveys and additional information on irrigation methods, winter crops, and native versus invasive vegetation will be important for a variety of water management and policy decisions.
  • Remote sensing-based water use estimates are less labor-intensive, offer better coverage, and provide more standardized estimation than diversion reports from individual water users. Even if such estimates are sometimes less accurate, they are more consistent through space and time. The results of the seven different models in this study help quantify when and where these uncertainties might be larger, as even small errors represent water with potentially high economic value, particularly during droughts.
  • More accurate and understandable evapotranspiration data can support better water planning at regional scales with full-coverage information. Farm-scale irrigation management can be improved with high-resolution estimates, and water trading is aided by quantifying the water saved from crop shifts or land fallowing. Better ET estimates also improve the accuracy of water balances, for Delta water operations and for groundwater balances in critical basins across California implementing the Sustainable Groundwater Management Act.
  • Meteorology data collected in the field can be used to estimate ET on much finer scales. Microclimates like the “Delta Breeze” and other temperature and humidity variations may cause ET to be lower than expected by models, and specific irrigation and crop maintenance practices will have their own impacts. Additional field data is needed for ET from fallow lands, particularly on Delta islands below sea level. A new field study is underway for the 2018 growing season. More comparisons and cooperation across field measurements and model estimates will be especially useful for unique regions like the Delta.
  • Although this study focused on crop ET, about 12% of the Delta is natural vegetation such as woodlands, riparian zones, and floating plants. Another 18% is open water or urban areas. Some non-agricultural lands may have higher ET than crops, so habitat restoration efforts could increase regional consumptive water use. Because most estimation methods are tailored towards agricultural ET, further model refinements and more field data from both upland and riparian vegetation are needed.
  • Having the State of California establish a collaborative group of agencies, research centers, academic institutions, and consultants to continue the study of evapotranspiration in the Delta and elsewhere would help improve ET estimates and increase the effectiveness of state and local investments in ET estimation. The exchange of common datasets and standards enhances transparency, access to technical information, public knowledge, and reduces overall costs. The large amounts of data made publicly available through this project alone are a great opportunity for further research.

The Final Report for the project and full model and field datasets can be viewed at the project website.

Jesse Jankowski (jjankowski@ucdavis.edu) is a graduate student in Civil Engineering at UC Davis and a research assistant at the Center for Watershed Sciences.

Further Reading

Allen, R.G., Pereira, L.S., Raes, D. and Smith, M. Crop evapotranspiration- Guidelines for computing crop water requirements. Food and Agriculture Organization of the United Nations irrigation and drainage paper 56, 1998.

California Department of Water Resources. California Irrigation Management Information System- Resources. 2018.

California Department of Water Resources. Land Use Viewer. 2018.

Idaho Department of Water Resources. Mapping Evapotranspiration. 2018.

Medellín-Azuara, J., Paw U, K.T., Jin, Y. Jankowski, J., Bell, A.M., Kent, E., Clay, J., Wong, A., Alexander, N., Santos, N., Badillo, J., Hart, Q., Leinfelder-Miles, M., Merz, J., Lund, J.R., Anderson, A., Anderson, M., Chen, Y., Edgar, D., Eching, S., Freiberg, S., Gong, R., Guzmán, A., Howes, D., Johnson, L., Kadir, T., Lambert, J.J., Liang, L., Little, C., Melton, F., Metz, M., Morandé, J.A., Orang, M., Pyles, R.D., Post, K., Roosevelt, C., Sarreshteh, S., Snyder, R.L., Trezza, R., Temegsen, B., Viers, J.H. A Comparative Study for Estimating Crop Evapotranspiration in the Sacramento-San Joaquin Delta- Final Report, Appendix set, and project datasets. Center for Watershed Sciences, University of California Davis, 2018.

Mount, J., Chappelle, C., Gray, B., Hanak, E., Lund, J., Cloern, J., Fleenor, W., Kimmerer, W., and Moyle, P. California’s Water: The Sacramento-San Joaquin Delta. Public Policy Institute of California, 2016.

Posted in Agriculture, California Water, Delta, Planning and Management, Tools | Tagged , | 1 Comment

Reality Check of California Water Fix Model results in a Critical Flow Year

by William Fleenor

The San Joaquin (left) and Sacramento (right) rivers meet near Antioch, an important location for X2 management during dry years. (Image credit: Carson Jeffres)

In 2008 a group from the Center for Watershed Sciences (including this author), joined by an economist from the Public Policy Institute, published findings that suggested that an alternative conveyance for Sacramento River water might improve ecological conditions in the Delta and improve reliability for Delta water exports [1, 2].

The original 2013 draft of the Bay Delta Conservation Plan (BDCP) (DEIR/EIS) included several alternatives using tunnels for Delta conveyance [3].  Long-term planning of this nature requires greatly simplified hydrodynamic models to simulate decades of data to estimate performance under a range of variable conditions.  These models also require manipulation to account for physical effects they don’t simulate (e.g., changes in habitat and sea-level rise conditions for which future management is unknown).

The manipulation involves simulating habitat changes and sea-level rise with other models that have far more physically accurate numerical computations, but which run too slowly to simulate details over many decades.  With results from the more accurate detailed models, a simple model can be calibrated to simulate a fuller range of conditions.

For the BDCP, the results of slow, more detailed 2- and 3-dimensional models (already imperfect) are incorporated into DWR DSM2, a faster 1-dimensional model, and run for a longer period, producing additional errors.  Results from DSM2 are then used to create an artificial neural network (ANN) for salinity intrusion used in the still-faster DWR CalSim II model to simulate the decades of planning for the DEIR/DEIS (more potential errors).  CalSim II is a monthly model that cannot resolve issues occurring on a shorter time scale (e.g., spring/neap tidal cycles, real-time flow changes, 14-day average compliance requirements, etc.).  Nearly all decisions made in the DEIR/DEIS were made using long-term averages of monthly averages of CalSim II results.

An earlier review of the DEIR/DEIS [4] pointed out this potential cascade of errors and recommended that the higher dimensional models be simulated for shorter periods of stressful conditions (e.g., drought) to corroborate the results.  The corroboration would help ensure that decisions made from the results were reasonable.

The final EIR/EIS [5] of the California Water Fix (FEIR/EIS) was released December, 2016 and still lacks such efforts to corroborate the results of the long-term simulations.

Here, I applied the 2-dimensional model, RMA2, to simulate Delta flows and salinity with and without the CWF for conditions of water year 2008, a dry year.  It is the same software used in CWF to provide input to modify DSM2 for habitat restoration.  It is the last year for which Clifton Court Forebay intake data have been made publicly available. (It would be easy to argue that not releasing Clifton Court Forebay operations data is a violation of California law (SB54).  These data are vital for detailed modeling of Delta flows and water quality.)

Figure 5-53 (Fig 1 below) in the FEIR/EIS summarizes results with a long-term average of ~3.5 MAF of water exported in dry and critical years with ~1 MAF of that through north Delta diversions (NDD).  Actual exports for water year 2008 were 3.43 MAF, which was similar to the long-term average and used for simulation with ~1 MAF taken from the new NDD intakes.

Figure 1 Figure 5-53 from the FEIR/EIS demonstrating exports in dry and critical water years

In the initial effort, I could not apply every operational restriction identified in the FERI/EIS, lacking time and money to re-write internal model code.  I honored first pulse constraints and sweeping velocity constraints past the NDD locations.  Beyond those, I applied the maximum volume of intake at the NDD locations to produce the maximum change throughout the Delta.  Using these criteria, the NDD volumes exceed 60% of total exports during the highest Sacramento River flows (6,000 of 11,000 cfs), but less than 30% during lower flow periods (Fig 2).

Figure 2. Modeled exports from NDD and south Delta pumps.

This modeling effort demonstrates that the work of the FEIR/EIS should hold true during low-flow drought periods, and I commend those involved with the modeling.  But I remain critical of their lack of providing detailed model corroboration.

One of the most watched Delta regulations is X2, the distance in kilometers from the Golden Gate Bridge of 2 psu (practical salinity unit) near the bottom along the path of the Sacramento River.  Since X2 is usually downstream of the confluence of the two rivers, and my analysis made no changes in net outflow, the only differences occur in fall and winter (Fig 3).  NDD exports only produced minor changes in X2 that could be easily managed.

Figure 3. Changes in X2 during water year 2008 by CWF and Base case

The key to salinity in Delta and export water is salinity in Franks Tract (FT).  Once salt gets into FT it is pulled to the pumps.  A graph of salinity changes in eastern FT helps explain when NDD affects Delta salinity (Fig 4), which includes the ratio of Total Exports to NDD.

Figure 4. Eastern Franks Tract EC changes along with Total Exports/NDD ratio.

Interestingly, salinity in Franks Tract falls during lower flow periods with CWF.  Only during the highest Sacramento River flows with NDD exports exceeding 50% of Total Exports does salinity in Franks Tract increase during CWF simulation.  The improvements during the lower flow periods result from a lower proportion of inflow into FT from False River and Dutch Slough, and a higher percentage of inflow from the Old River connection at the San Joaquin River (SJR) (supplied by water from the San Joaquin River and Sacramento River via the Delta cross channel).

The greater salinity near the end of January correlates with abrupt increases in the ratio of Total/NDD exports and the lack of Sacramento River water through the closed cross-channel gates.  However, for Total/NDD export ratios approaching 50% in May-June, salinity still falls with CWF.  A follow-up simulation capping the Total/NDD ratio to 50% shows that any increases in salinity can be managed.  Not shown is the simultaneous pulse of salinity up the San Joaquin River contributing to the January increase.  All these effects are manageable with proper insight and monitoring of the Delta.

For any given total export rate, any NDD export should reduce the negative net Old & Middle River flows (OMR) from through-delta pumping, and create more natural flow patterns through the Delta.  With proper monitoring and management, the negative OMR flows could likely be eliminated during critical times.  Creating a more natural flow pattern while reducing fish ‘salvage’ at the south Delta pumps and producing a system with improved reliability while maintaining Delta water quality goals would seem to benefit  all interests.

William Fleenor is an affiliate of the U.C. Davis Center for Watershed Sciences. His research focuses on the development and application of numerical hydrodynamic models for water management.

Further reading

[1] Lund, J., E. Hanak, Wm. E. Fleenor, R. Howitt, J. Mount, and P. Moyle, Comparing Futures for the Sacramento-San Joaquin Delta, Public Policy Institute of California, 2008, 241 pg

[2] Fleenor, W., E. Hanak, J. Lund, and J. Mount, “Delta Hydrodynamics and Water Quality with Future Conditions,” Appendix C to Comparing Futures for the Sacramento-San Joaquin Delta, Public Policy Institute of California, San Francisco, CA, July 2008.

[3] ICF International, 2013, Administrative Draft Environmental Impact Report/Environmental Impact Statement for the Bay Delta Conservation Plan, prepared for Califronia Department of Water Resources, U.S. Bureau of Reclamation, U.S. Fish and Wildlife Service, and National Marine Fisheries Service

[4] Mount, J., Wm. Fleenor, B. Gray, B. Herbold, and W. Kimmerer, 2013, Panel Review of the Draft Bay Delta Conservation Plan, prepared for The Nature Conservancy and American Rivers

[5] ICF International, 2016, Final Environmental Impact Report/Environmental Impact Statement for the Bay Delta Conservation Plan/California WaterFix, prepared for Califronia Department of Water Resources and U.S. Bureau of Reclamation

Posted in California Water, Delta | Tagged , | 3 Comments

Groundwater Recovery in California – Still Behind the Curve

by Thomas Harter and Bill Brewster

California has a unique and highly variable climate in which drought reoccurs periodically. California began this century in a dry period from 1999 to 2005, and experienced droughts from 2007 to 2009, and 2012 to 2016.  Such wet-dry cycles can be seen in Figure 1, which shows total rainfall amounts per water year (water years run from October 1 to September 30). These dry cycles greatly affect the state’s groundwater basins.

Figure 1: California statewide annual precipitation. Source: DWR 2017

Despite the current storms, the 2018 water year is well below average, and that pattern may continue. But from a groundwater perspective, it’s clear that dry is the new norm.

Why do groundwater basins continue to suffer the impacts of drought long after the rains have returned?  As explained last spring, a single wet winter after a dry period can replenish snowpack, soil moisture, and surface water reservoirs, but groundwater basins may take many years or even decades to recover.

An average or wet winter may make up for water level losses of one dry year, but often not much more.  Also, the amount and location of groundwater level recovery varies with other factors such as the local reliance on groundwater or chronic overdraft.

At the end of the most recent drought, the near average 2016 precipitation in Northern California helped stabilize groundwater levels, and some areas saw groundwater level recovery. The extremely wet winter in 2017 expanded groundwater recovery to most of California (Figure 2).

Throughout California, the wet winter of 2017 refilled groundwater storage leading to higher water levels in spring of 2017, when compared to spring 2016. Source: DWR 2017

In many areas with significant groundwater pumping, therefore, two average to wet years are not enough for groundwater to recover from several dry or drought years.  For example, the change in groundwater levels over the last 5 years (Figure 3) or the past 10 or 17 years (Figure 4) shows that groundwater aquifer conditions can have a long memory.

Figure 3: In most of California’s groundwater basins, the wet winter of 2017 did not refill groundwater storage to where it was before the 2012-2016 drought, in the spring of 2012. Source: DWR 2017

Figure 4: For most of California, 12 of the past 18 winters (and 7-8 of the past 11 winters) were below average or dry. As groundwater levels in most basins need one average or wet winter to recover from one below average or dry year, many areas are several average to wet years short of reaching water levels observed in spring 2000. Source: DWR.

The lack of groundwater level recovery is partly from persistent below-average precipitation in the past 20 years. This can be seen by comparing the long-term change in groundwater levels with the cumulative deviation from average (CDFM) statewide rainfall (Figure 5). The recent twenty-year sequence of more below-average years than average or wet years appears as a decline in the orange line in Figure 5. For comparison, DWR’s groundwater data and tools website includes groundwater level change maps of the difference in groundwater elevations over various time periods, with pie charts indicating the regional and statewide percent of wells increasing, decreasing, or staying relatively neutral (e.g., Figures 2 and 3). We can construct a groundwater level change index, for example, by subtracting the statewide percent of wells with increasing water levels from the statewide percent of wells with decreasing water levels over a period of time.  A positive number indicates more wells had increased water levels than decreased water levels, while a negative number means more wells have lower water levels than higher water levels.  For example, for Figure 2, the statewide groundwater level change index for 2016-2017 is computed as (30.7%+5.4%-1.0%-6.3%) = +28.8%.

The cumulative deviation from mean statewide precipitation (CDFM) since 1896 (blue line) shows that we reached peak surplus in 1983, 1998 and 2006. But by 2016, after a nearly steady ten-year decline, the deficit reached levels similar to the early 1990s. Note that the CDFM is, by definition, zero at the beginning and end of the averaging period.
Average and wet years can make up for groundwater decline in below-average years: The orange line indicates the difference between the total number of average to wet years to date and the number of below average to dry years to date. If an “average year” includes any year with at least 97% of average precipitation, then an equal number of years have been “average or above” years and “below average or dry” years since 1896 (difference = 0). For 1998 to 2017, five more years were “below average or dry” than “average or above”.

Figure 6 shows this groundwater level change index for 1, 3, 5, and 10 year periods preceding each year from 2012 through 2017. The long-term trends of all four indices – perhaps most so for the 10-year index – are similar to the precipitation trends– as precipitation deficit increases, the groundwater level change index becomes more negative (more and more wells with decreasing water levels). However, as the deficit decreases, fewer wells have decreasing water levels, and more wells have increasing water levels.  This very simple analysis doesn’t account for other factors that can affect long-term changes in groundwater levels, but shows the strong effect of the continued precipitation deficit, relative to 1998.

Figure 6: Comparison of the CDFM (blue) shown in the previous figure with a groundwater level change index that captures relative groundwater level change over the last 1 year, 3 years, 5 years, and 10 years prior to the year indicated at the bottom axis. The 10 year index most closely follows the precipitation CDFM.

What should well owners and operators expect for summer and fall of 2018 if it remains a below average to dry year? This would be like 2007 and 2012.  Both 2007 and 2012 followed wet years with surface reservoirs in good condition, like 2018.  Additionally, 2007 and 2012 had below average precipitation and a thin snowpack.

So, with a below average to dry 2018, groundwater levels would likely decline similarly to 2007 and 2012, but not as drastically as in 2014 or 2015 when additional groundwater pumping occurred from lack of available surface water for irrigation (Figure 7).

Figure 7: Unless April is exceptionally wet, expected water level changes between last fall and this coming fall will be of similar magnitude as between fall of 2011 (following a wet winter) and fall of 2012 (following a relatively dry winter, but with surface water storage carry-over from 2011 to support cities and agricultural irrigation). Source: DWR.

One thing is certain – California’s climate will continue to be variable.  And if the past 20 years are a guide, groundwater levels may have a difficult time recovering.  This reinforces the importance of drought contingency planning, especially for overdrafted groundwater basins and in basins with issues related to declining groundwater levels.

Thomas Harter is a Professor and Associate Director at the Center for Watershed Sciences. Bill Brewster is a Senior Engineering Geologist with the California Department of Water Resources.

 Further reading

CaliforniaWaterblog. Post-drought groundwater in California: Like the economy after a deep “recession,” recovery will be slow.

DWR Drought Page

Spring 2017 Groundwater Level Data Summary

USGS Runoff Estimates for California

DWR Groundwater Information Center Interactive Map Application

DWR Data and Tools Page

Posted in California Water, Groundwater | Tagged , | 2 Comments

Brown is the new gold: Water strategy is starting to pay dividends

by Nan Frobish

Planting orchards in deserts is part of California’s long-term vision for sustainable water management.

Governor Brown has unveiled a sweeping new strategy, “Brown is the New Gold,” to simultaneously make California more robust to drought, secure private water rights, buffer California’s growers against disastrous losses from a looming national trade war, and facilitate a market for environmental water.

“Leadership has not been clever enough, or strong enough, or perhaps visionary enough,” Brown said in a “Meet the Press” interview in 2017. “It takes a certain vision, how the hell do we get out of this? And it takes some political skill at the same time.”

And his vision proved prescient: with a potential trade war threatened between the Trump administration and China, California’s wine, nut, and fruit industries stood to lose billions.

“What’s the next most valuable thing our ag industry has besides the food it provides?” asked Brown. “Water. And someone always needs it.”

And now, Brown’s vision and a quirk in California’s water law have combined to form a system that secures farmer’s water, increases water for fish, and solves the problem using a market strategy – without one penny of government funds.

Brown began quietly laying the groundwork through the end of the recent drought. Reductions in urban water use, largely from the browning of outdoor landscapes, greatly reduced urban water use with minimal economic impact.  This promises to make more water available for agricultural and environmental uses into the future.

During the drought, farmers also faced large cutbacks, and in some cases farmers sold some of their water by browning their fields to that other farms could continue to prosper.

But most may remember the exemption to agriculture during the recent drought – while mandatory reductions were require for cities, farmers were largely left alone. While public outcry railed against what seemed to be a lopsided victory for farmers at the expense of cities and streams, the Brown administration was playing the long game.

Difference in idle Central Valley cropland between 2014 and 2011, relative to the total agricultural land in each region. Prepared by UC Davis Center for Watershed Sciences using information from the Satellite Mapping consortium project of DWR, NASA Ames Research, CSU-Monterrey Bay, USGS and the USDA. 

The key lies in California’s requirement that water right holders can temporarily transfer their right for another purpose or to another user without losing it – but only the portion of their water right that would have been used by the crop they are growing. Some of their water right is used to transport water from the stream to their fields, and the some is used by the crop; only the water used by the crop can be transferred.

So while fruit and nut growers have often been criticized for their profitable, water-demanding crops, their conversion of millions of acres to orchards has reclaimed millions of gallons of water as consumptive use – and thus provided a huge reservoir of tradable water in the event that these commodities take a hit from a global trade war.

Water markets have long been in place in California – the Central Valley Project water users have bought and sold water with each other for decades in ag-to-ag transfers. Ag-to-fish transfers are a newer market, but follow the same principle: a buyer needs water for the environment, a seller has water that might be more profitable as fish flow rather than orchard production, and they agree on a price.

Agricultural water is transferred back to the stream as part of California’s ag-to-fish water market.

“Fruit, nuts, fish,” says San Joaquin grower Lin Stuart. “It’s going to be what it’s going to be. We’ll still make money.”

“You can’t be a superpower and wallow in dysfunctionality,” said Brown. “As the world’s sixth largest economy, California is practically a superpower unto itself. We are going to show the nation what leadership truly looks like, rather than goofing off and averting our gaze.”

Under one provision of the new plan, the State would be able to sell farmers  environmental water if crop prices are high.  During the drought, environmental flow change orders allowed over one million acre feet of Delta outflows to be reduced.  Had this water been sold on the market, it would raise more money for the Delta environment than most water bonds have.

Professor Harold Hotelling of UC Atwater commented, “This scheme will bring market business solutions to all of California’s water problems.”

The State Water Board is considering introducing a WetCoin currency to ease water market transactions.

Nan Frobrish is the Director for Expedition Education at the Center for Watershed Sciences. She recommends first-hand interactions with stream hydraulics.

Further Readings

Hanak, E. and Jezdimirovic, J. Just the Facts: California’s Water Market. Public Policy Institute of California.

UC Davis Center for Watershed Sciences. Drought’s Economic Impact on Agriculture.

Arax, M. A Kingdom from Dust. California Sunday Magazine.

Mitric, J. If China Strikes Back On Tariffs, California Tree Nut Exports Could Take A Hit. Capitol Public Radio.


Posted in April Fools' Day | 7 Comments

California’s Water Data Problems are Symptoms of Inchoate Science and Technical Activities


“The truth is lost when there is too much contention about it.” – Publius Syrus (43 BC)

by Jay Lund

In 2016, California’s legislature passed AB 1755, the Open and Transparent Water Data Act, requiring that State agencies provide water data online, including existing datasets, with open-data protocols for data sharing, transparency, documentation and quality control.  That any legislative body, composed mostly of lawyers, would show interest in the wonkish topic of data and pass legislation on data management, is a testament to the failures of state agencies on the subject.  (Imagine state engineers suggesting changes in legislative rules.)

Efforts are now underway in diverse government agencies and other organizations to make water data available, accessible, and perhaps even organized and better explained.  Alas, if experience is a guide, most improvements from these efforts will be marginal, as they do not address the cause of California’s water data malaise.

Disorganized data is a symptom of disorganized technical work.  California has many agencies and programs involved in water management and regulation, particularly its Department of Water Resources, State Water Resource Control Boards, and Department of Fish and Wildlife.  Each agency has some excellent employees and the state supports some exemplary data and technical resources, particularly regarding floods, often in collaboration with other agencies.  But most of the state’s overall water-related scientific and technical activities are notoriously splintered across programs with independent legal mandates, funding sources, and lines of management, and overall leadership to serve the common good.  Addressing the root disorganization of the state’s technical efforts on water management and regulation is needed for long-term data success.

Fragmentation of the State’s technical activities also has other problems.  The many water accounting systems now hinder development of the common water accounting needed for groundwater recharge and management, water rights enforcement, environmental water management, and water markets.  The splintering of water quality and quantity data collection obscures insights needed for more effective management and hinders quality control within and across agencies.

Water data problems will likely worsen, particularly if unaddressed.  More data are being collected.  As prices for collecting data decrease, we collect much more.  Without organization, more data can add confusion.  The cost and controversies of making sense and developing insights from data is increasing.  Without synthesis, each side chooses the data and interpretations it wishes for.

Data will always be frustrating, even if we manage it well.  Good management and use of data will reveal sometimes unwanted insights and unrealized gaps and needs.  Good data management also raises demands for new analysis and quality control.  The more we know, the more we want to know and make sure of.  This is a price of progress.

California’s water challenges are leading to a more integrated water management, which needs to be supported by more integrated technical programs across the many state agencies and programs.  Implementing the Sustainable Groundwater Management Act will be excruciating for water users and all agencies without a common water accounting framework and common technical information (including recognized models and data).  The effectiveness of environmental flows will continue to be clouded and undermined without coordinated data collection, management, and analysis.  And water rights will be less secure, less marketable, and often unenforceable without more solid water accounting.

The problem is not lack of legislation or even (mostly) lack of money.  Local and regional water agencies already collect and manage immense amounts of water data, which can better contribute to a common understanding of California’s water.  State agencies need a more common scientific and technical program for water management and regulation, providing common support across agency boundaries.

The progress report on California Department of Water Resources’ (DWR’s) implementation of Assembly Bill 1755 contains many good things and is a step in the right direction.  However, these steps will not progress far or fast without a broader and more profound vision for more effective state technical water work, across agencies, extending well beyond DWR.  Integrated water management requires integrated scientific and technical work across the many state, local, and federal water data and technical efforts.

A few specific thoughts on the document:

  1. Funding for data management is as fundamental as funding personnel and personnel records, and should be part of every agency’s financial plan. That the report seeks separate funding for data management misses how fundamental data management is for the success of the state’s water management enterprise.
  2. A test bed and use cases are important, but it is also important not to stake too much on the success of the details of this narrow effort. Technology development often outstrips state software development.  Technological progress in this field can be both an opportunity (if we are prepared for it) and a problem (if we are not).  This is a rapidly-changing field.
  3. A “federated” approach to water data is needed.  The state’s most successful data and technical efforts are usually joint efforts across state and federal agencies, such as CNRFC, or joint efforts across state, federal, and local agencies for data collection. To be effective and not bog down in bureaucracy, a federated approach will need consistent accountability, motivation, and resources.  The most effective water data management efforts (CDEC and CNRFC) are motivated by flood problems, which must respond quickly to serve a wide range of users or create violent consequences.
  4. An improved institutional setting for data management might support improved technical information and coordination overall. Each state agency might develop a routine data management policy for its major functions, so that these data and functions might be more transparent and more easily coordinated across agencies.
  5. In data management, the best can be the enemy of the good. Trying to address too many issues too soon usually leads to collapse. Success will be frustratingly slow.
  6. One activity that would provide immediate and lasting service to all state and local agencies, as well as the public, would be on-line archiving of all reports done by or for state agencies. Maven’s water library is a prototype of such a system. The University of California library system is another suitable steward for such a system.  Any state project or decision process could archive analyses and reports with an automated system where agency staff and consultants could enter, catalog, upload, and archive documents into the library.  State agencies and programs often place documents on the web, but these can quickly become a dystopia of broken links.

The Department of Water Resources is accepting comments on its Progress Report – Implementing the Open and Transparent Water Data Act with Initial Draft Strategic Plan and Preliminary Protocols until March 30, 2018.

Jay Lund is a Professor of Civil and Environmental Engineering at the University of California – Davis, where he is also Director for its Center for Watershed Sciences. He enjoys data, and hungers for mostly better.

Further reading

California Legislative Information (2016), AB-1755 The Open and Transparent Water Data Act, https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=201520160AB1755

California Department of Water Resources, California Data Exchange Center (CDEC), http://cdec.water.ca.gov/

James, K. (2016), “California’s New Water Data Law Will Have Far-Reaching Benefits,” Water Deeply, 11 October.

Lund, J. (2016), How much water was pumped from the Delta’s Banks Pumping Plant? A mystery, CaliforniaWaterBlog.com, Posted on

Maven’s Notebook, California Water Library, https://cawaterlibrary.net/

Mount, J. (2018), Advice on Voluntary Settlements for California’s Bay-Delta Water Quality Control Plan Part 3: Science for Ecosystem Management, CaliofrniaWaterBlog.com, Posted on February 27, 2018.

National Oceanographic and Atmospheric Administration (NOAA), California-Nevada River Forecast Center (CNRFC), http://www.cnrfc.noaa.gov/

UC Davis Center for Water-Energy Efficiency, work on data analytics




Posted in California Water, Planning and Management, Tools | Tagged | 2 Comments

How engineers see the water glass in California


Engineering a water glass at 50 percent. Source: xkcd.com

It looks like 2018 will be a dry year, with snowpack about 50%.  How do engineers see the water glass in California?  Mostly the same as they did six years ago in the original version of this post, but we’ve added a few more perspectives.

By Jay R. Lund

Depending on your outlook, the proverbial glass of water is either half full or half empty. Not so for engineers in California.

Civil engineer: The glass is too big.

Flood control engineer: The glass should be 50 percent bigger.

Army Corps levee engineer: The glass should be 50 percent thicker.

Mexicali Valley water engineer: Your leaky glass is my water supply.

Delta levee engineer: Why is water rising on the outside of my glass?

Dutch levee engineer: This water should be kept in a pitcher.

Southern California water engineer: Can we get another pitcher?

Northern California water engineer: Who took half my water?

California Water Commission engineer: Would a bigger glass provide public benefits?

Tulare Basin water engineer: I’m saving that storage to capture floods for recharge.

USBR CVP or NOAA engineer: Is that water cold?

Consulting engineer: How much water would you like?

Environmental engineer: I wouldn’t drink that.

Water reuse engineer: Someone else drank from this glass.

Groundwater engineer: Can I get a longer straw?

Academic engineer: I don’t have a glass or any water, but I’ll tell you what to do with yours.

Lawyers, NGOs, managers, regulators, and elected officials also seem to have different views of glasses at 50% of their capacity.  We can start a collection of these perspectives.

Jay Lund is a professor of civil and environmental engineering and director of the Center for Watershed Sciences at UC Davis.

Further reading

Munroe, Randall. Glass Half Empty. xkcd.com

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Is Ecosystem-Based Management Legal for the Sacramento-San Joaquin Delta?

by Brian Gray (PPIC Water Policy Center), William Stelle (former NOAA Fisheries West Coast Administrator), and Leon Szeptycki (Stanford University, Water in the West)*

The Sacramento-San Joaquin Delta. (Photo credit: Carson Jeffres)


In a recent three-part series posted on this website, a group of independent experts (including one of the authors here) proposed new ways to manage the Sacramento-San Joaquin Delta ecosystem. The purpose of the recommendations is to inform negotiations on the revised Bay-Delta Water Quality Control Plan, which will set new water quality and flow requirements for the Delta and its tributaries.

These experts urged the State Water Board and negotiating parties to: (1) take an integrated approach to the Delta to improve food web productivity and habitat, while reducing harmful algal blooms; (2) coordinate management of freshwater flows, tidal energy, and landscape changes in the North Delta and Suisun Marsh to improve ecosystem function; and (3) develop a robust, well-funded independent science program to guide implementation and assessment of the water quality plan.

The experts note that populations of native fish species listed under the state and federal endangered species acts are so low that they are no longer reliable indicators of Delta conditions. They recommend shifting away from an emphasis on managing the Delta for these listed species. And they outline an ecosystem-based approach that would improve conditions for a wide range of terrestrial, wetland, and aquatic plants and animals—including listed fish species—as well as for human uses of the Delta’s water and lands.

These recommendations are intriguing, especially in light of growing consensus that the current approach to water quality and species protection in the Delta is failing to meet legal and policy objectives. But would management based on the proposed policies be legal?

Ecosystem-Based Management

An ecosystem-based approach to the Delta would differ in several important respects from the existing regulatory regime. Current regulations rely heavily on minimum flow and water quality standards, which are often met by releases from upstream reservoirs. These regulations also impose a variety of constraints on Central Valley Project (CVP) and State Water Project (SWP) operations—including seasonal restrictions on water exports from the south Delta—to minimize reverse flows and prevent dislocation and entrainment of fish.

The proposed approach calls for more flexible deployment of releases from upstream reservoirs to improve aquatic habitat, along with landscape changes to enhance habitat benefits from managed freshwater and tidal flows. The proposal also advocates focusing conservation and recovery actions on an arc of habitat from the Yolo Bypass through the North Delta and into Suisun Marsh (the “North Delta Arc”), which has been less altered by human interventions and is linked by the Sacramento River.  This area has a greater likelihood of producing significant, near-term ecological improvements compared with conservation actions elsewhere in the Delta. The proposal also would alter the current strategy of using large volumes of freshwater outflow to manage salinity in the Delta and Suisun Bay, choosing instead a geographically targeted approach to the application of freshwater flows.

Although it would represent a marked change from existing regulatory policy, an ecosystem-based strategy would be consistent with the water quality laws and the endangered species acts.

The Water Quality Laws

California’s Porter-Cologne Act implements the federal Clean Water Act and establishes independent state standards for water quality. It requires the State Water Board to set water quality standards that provide “reasonable protection” for an array of beneficial uses of the waters of the Delta ecosystem, including fish and wildlife and water supply. The courts have held that the Board has broad authority to determine what water quality criteria are reasonable and appropriate in light of competing demands on the resource, as long as its decision is supported by substantial evidence in the administrative record.

The Porter-Cologne Act thus grants the Board significant discretion to choose how best to deploy the freshwater available in the Delta. For example, if the Board concludes that the North Delta Arc is the most productive habitat for conserving and recovering protected species, then it would have authority to set water quality standards (including targeted flow requirements) that make this a priority region. If the Board is also persuaded that the central and south Delta are now unproductive and inhospitable habitat for native fish species, it could adjust salinity and flow standards accordingly.

In short, because of the multifaceted and flexible authority vested in it by the water quality laws, there is no significant legal impediment for the State Water Board to follow an ecosystem-based approach in revising its water quality standards for today’s Delta.

The Endangered Species Acts

The federal and state endangered species acts pose more difficult questions because they contain more rigid directives than do the water quality laws. Rather than setting standards to accommodate a variety of beneficial uses, these laws categorically prohibit the unauthorized “taking” of any protected fish. The federal statute also requires all federal agencies to ensure that their actions are not likely to jeopardize the continued existence of any listed species or adversely modify their critical habitat. Takings that are “incidental” to otherwise lawful activities—including water diversions and other water project operations—may be authorized by incidental take statements in biological opinions or by incidental take permits for non-federal activities. Both laws require the impacts of authorized takings to be “minimized,” and the state statute requires that they also be “fully mitigated.”

These laws govern water management in the Delta ecosystem principally as applied to the coordinated operations of the CVP and SWP, which must comply with a series of conditions set forth in biological opinions issued by the U.S. Fish and Wildlife Service (USFWS) for Delta smelt and by the National Marine Fisheries Service (NMFS) for anadromous species (salmonids and green sturgeon). The California Department of Fish and Wildlife (CDFW) plays a complementary role. Its principal regulatory authority in the Delta is through the longfin smelt incidental take permit issued to the SWP.

Legal Questions

The proposed ecosystem management approach raises several key legal questions to which we provide brief answers:

  • Is an ecosystem-based approach to water quality and species protection consistent with the federal and state endangered species acts?

Yes. Although the focus of the endangered species acts is on individual species and their critical habitat, there is nothing in the statutes that would preclude the fish agencies from adopting a more holistic and integrated approach—if the best scientific evidence supports the decision that the ecosystem objectives would be an effective means of fulfilling the no jeopardy/adverse habitat modification standards, as well as the mitigation requirements associated with the incidental take of each listed species.

Indeed, this legal question can be framed in a relatively simple way: What are good scientific metrics for predicting and assessing ecosystem functions (e.g., food web productivity) on which each species relies for its survival and recovery, and are these better expressed as ecological system metrics, rather than through the salinity, flow, and temperature metrics that are currently employed? If the ecosystem approach would be a better way to protect and enhance the biological requirements of each listed species, the fish agencies could approve it under the conventional consultation and incidental take regulatory processes.

  • Could the federal fish agencies revise the biological opinions for CVP/SWP operations to recognize the proposed focus on a North Delta Arc of critical habitat?

Yes. If the agencies conclude that creation of a North Delta Arc of habitat would promote the applicable conservation standards for each of the federally listed species, they would have authority to incorporate this strategy into the biological opinions. As noted above, these could include changes in upstream storage and release requirements to provide targeted flows into the Sutter and Yolo Bypasses, as well as other tidal sloughs and channels, to improve food webs and aquatic habitat.

  • Could the federal agencies revise the biological opinions to recognize a geographically specialized Delta ecosystem that reduces the emphasis on the central and south Delta as critical habitat for some species?

Yes. The federal endangered species act does not require conservation and recovery of listed species throughout their entire range of existing or potential habitat. It also affords the fish agencies considerable flexibility in setting priorities for habitat types and locations—if these conservation strategies would satisfy the no jeopardy/critical habitat directives for each listed species.

Therefore, if the best scientific evidence supports the conclusion that the central and south portions of the Delta are irreparably degraded and that the North Delta Arc is now the most promising habitat for the Delta smelt, the USFWS could adopt geographic specialization as a conservation strategy. This would be accompanied by changes in the critical habitat designation for the smelt, as well as adjustments in the incidental take limitations for the CVP and SWP south Delta pumps to account for this change in focus.

Similarly, NMFS could conclude (also based on the best available science) that the most promising habitat for Sacramento River salmonids is the North Delta Arc. Based on this determination, it too could shift the focus of its conservation and recovery directives to that region. The salmonid biological opinion also would have to include measures to promote passage of salmon and steelhead in the central and south Delta and lower San Joaquin River. As there is no scientific consensus on this subject, we recommend that NMFS—in cooperation with CDFW and the State Water Board—convene a small independent panel of creative scientists and engineers to evaluate the options.

  • Could the California Department of Fish and Wildlife revise the State Water Project’s incidental take permit for longfin smelt to recognize a specialized Delta ecosystem?

Yes. Although the longfin smelt once inhabited much of the Delta, its current population exists primarily in San Francisco Bay. As with federal law, the California Endangered Species Act does not require conservation and recovery of listed species throughout the full extent of their habitat, and it grants CDFW discretion to create priority habitat characteristics and locations. The department therefore would have authority to make the North Delta Arc (which once was important spawning habitat for the smelt) the focus of its conservation and recovery efforts.

Longfin smelt are anadromous and depend on freshwater and tidal flows in the Delta and Carquinez Strait. CDFW would have to ensure that the North Delta Arc conservation and recovery strategy would provide conditions that enable the fish to migrate between their freshwater and more saline habitats.

In addition, in revising the SWP’s incidental take permit, the department must determine that the North Delta habitat improvements would “fully mitigate” any adverse effects of the change in policy. Restoration and long-term enhancement of intertidal and sub-tidal wetlands in the North Delta is already part of the mitigation requirements of the SWP’s incidental take permit. If necessary to offset any risks posed to the smelt from the new habitat strategy, CDFW could require the acquisition and management of additional mitigation acreage.

Concluding Thoughts

Ecosystem-based management in the Delta may be a more efficient and effective means of implementing the water quality laws and endangered species acts than the current regulatory regime. Whether this is true will depend on the responses of the ecosystem and the fishes that inhabit it to the combination of targeted freshwater flows, tidal energy management, and landscape changes that would be concentrated along the North Delta Arc.

To test this new strategy, regulators, water managers, and environmental advocates must be willing to assume the risk of moving away from entrenched policies that have largely failed to achieve their objectives. The judgment whether the new approach is the “best available science”—and therefore may serve as the foundation for a revised water quality control plan and new biological opinions—rests with the regulators. We can simply say that there is nothing in state or federal law that would preclude such a decision.

More importantly, the strategy proposed in the earlier blog posts illustrates a foundational—but often neglected—principle of aquatic ecosystem management: Protection of water quality and conservation of species are one in the same, and neither can be achieved without the other. Perhaps the greatest contribution of the new Delta science will be to encourage the State Water Board and the fish agencies to work together to devise truly integrated standards for today’s novel Delta ecosystem.

* With contributions and insights on the intersections between law and science from Peter Moyle and Jay Lund (UC Davis) and Jeff Mount and Ellen Hanak (PPIC Water Policy Center).

 Further Reading

Gartrell, Greg, and Brian Gray. 2017. A Brief Review of Regulatory Assignment of Water in the Sacramento–San Joaquin Delta. Public Policy Institute of California.

Gore, James, Brian Kennedy, Ronald Kneib, Nancy Monsen, John Van Sickle, Desiree Tullos. 2018Independent Review Panel (IRP) Report for the 2017 Long-term Operations Biological Opinions (LOBO) Biennial Science Review: Report to the Delta Science Program. Delta Stewardship Council and Delta Independent Science Program.

Mount, Jeffrey. 2018a. “Advice on Voluntary Settlements for California’s Bay-Delta Water Quality Control Plan Part 1: Addressing a Manageable Suite of Ecosystem Problems.California WaterBlog, Feb. 13.

Mount, Jeffrey. 2018b. “Advice on Voluntary Settlements for California’s Bay-Delta Water Quality Control Plan Part 2: Recommended Actions to Improve Ecological Function in the Delta.” California WaterBlog, Feb. 21.

Mount, Jeffrey. 2018c. “Advice on Voluntary Settlements for California’s Bay-Delta Water Quality Control Plan Part 3: Science for Ecosystem Management.” California WaterBlog, Feb. 27.

Moyle, Peter, William Bennett, John Durand, William Fleenor, Brian Gray, Ellen Hanak, Jay Lund, and Jeffrey Mount. 2012. Where the Wild Things Aren’t: Making the Delta a Better Place for Native Species. Public Policy Institute of California.

Wondolleck, Julia, and Steven Yaffe. 2017. Marine Ecosystem-Based Management in Practice: Different Pathways, Common Lessons. Island Press.

Posted in California Water, Delta, Sacramento-San Joaquin Delta | Tagged , | 5 Comments