Habitat Preferences of various Delta species

Cartoon reprinted reprinted with permission from the Sacramento Bee. Originally published June 28, 2017.

Like fish, the different human professions involved in the Delta have different habitat preferences:

Lawyers: high turbidity and fear, complex egosystems, either high and cynical levels of expectation, abundant funds

Engineers: high clarity, data-rich nutrient sources, high expectation concentrations, abundant funds

Biologists: thrives on uncertainty and inconclusiveness, extreme biodiversity, highly dynamic ecosystems with complex structure, abundant funds

Spin-specialists: high turbidity, abundance of predators, corrosive water quality, data-free environment, abundant funds

Agency managers: seeks abundant refuge structure, low expectation concentrations, abundant funds

Academics: anywhere where more research is needed (everywhere with any funds).

None of these species is endangered.  They all thrive in the Delta, and seem to grow in population with declines in fish populations and Delta flows.

Posted in Wild and Wacky | 3 Comments

California WaterFix and Delta Smelt

by Peter Moyle and James Hobbs

Frank’s Tract, May 22, 2009. Large expanses of open water are likely to increase in the Delta, providing a justification for WaterFix. Photo by Peter Moyle

The delta smelt is on a trajectory towards extinction in the wild.  Heading into 2017, the spawning adult population was at an all-time low although this past wet winter has apparently seen a small resurgence.  However, increasingly warm summer temperatures in the Delta may dampen any upswing.  Given the long-term trajectory of the population and climate predictions for California, maintaining Delta smelt in the Delta for the next 20-30 years is not likely to happen without significant improvements to the habitat.

So, what happens to the remaining smelt when they encounter California WaterFix? This is the proposal centered around building two tunnels under the Delta to move Sacramento River water directly to the export pumps in the South Delta, benefiting Bay Area and southern California cities and southern Central Valley farms, as well as reducing the problem with reverse flows across the Delta.

In Hobbs et al. (2017) we gave cautious support to WaterFix. In this blog we discuss our reasoning for qualified support for such a controversial large-scale infrastructure project that will affect Delta fish and fisheries.  Our motivation comes from two facts:

(1) The status quo is not sustainable; managing the Delta to optimize freshwater exports for agricultural and urban use while minimizing entrainment of delta smelt in diversions has not been an effective policy for either water users or fish.

(2) Delta infrastructure (mostly levees) is old and increasingly vulnerable to catastrophic failure. Large-scale collapse of Delta levees will likely result in massive intrusion of salt water into Delta, shutting down water exports from the South Delta. Flushing this salty water will require large amounts of fresh water, further stressing water supplies.   The most likely fix will be construction of an emergency freshwater transfer system, which may actually make conditions worse than the status quo, from an ecosystem perspective.

So where do we see reasons to be optimistic about WaterFix from a fish perspective?

  • Entrainment of smelt into the export pumps in the south Delta should be reduced because intakes for the tunnels would be upstream current habitat for delta smelt and would be screened if smelt should occur there.
  • Flows should be managed to reduce the North-South cross-Delta movement of water to create a more East-West estuarine-like gradient of habitat, especially in the north Delta.
  • Large investments should be made in habitat restoration projects (EcoRestore) to benefit native fishes, including delta smelt.


There are huge uncertainties associated with WaterFix and EcoRestore, especially in terms of their effects on fishes.  Together, they are a giant experiment that may or may not work as promised, no matter what the models and experts say.  The giant fish screens for WaterFix, for example, will be pushing screening technology to the limit, having to protect weak swimmers like smelt and small sturgeon, as well as juvenile salmon.

WaterFix is supposed to operate using an adaptive management framework, to deal with uncertainty.  This means management activities can change as construction and operations proceed, as conditions change, and as new information becomes available. The framework for adaptive management is just being established by the Delta Stewardship Council for EcoRestore; it appears to involve many diverse agencies and it isn’t clear how consensus decisions will be achieved.  ‘True’ adaptive management treats each management action as an experiment with testable hypotheses and continuous monitoring that allows success or failure to be determined.  Large-scale experimentation with projects of this magnitude is difficult, even with adequate monitoring.  In short, adaptive management is a good idea but making it work at this scale would be unprecedented.

EcoRestore has many uncertainties as well.  Although restoration of tidal marshes should benefit salmon, water birds, and many other species, the potential for restored tidal wetlands to support delta smelt and other pelagic fishes is at best weakly supported with current scientific data.  Large-scale experimentation with EcoRestore projects will be challenging and will likely require 20+ years of data to make reasonable assessments

There are also trust issues with WaterFix. For it to work as promised, we have to accept that

  • Water will continue to be exported at roughly the same rates as it has been, with no increase in exports, but no decrease as well.
  • It will be operated without significant increases in water being diverted upstream of the Delta.
  • Full implementation of EcoRestore will occur and alleviate many of the endangered species issues.
  • Water for the environment will not be sacrificed every time there is a water emergency (the co-equal goals promise).

Trusting the operation of the project is a problem because under emergency conditions, such as another severe drought, environmental water could be re-allocated for other uses (e.g., through Temporary Urgency Change Petitions to the State Water Resources Control Board).  An additional worry is the current administration in Washington DC, which shows little concern for environmental issues and endangered species, could apply additional pressure or new regulations to change the water allocation system.

If you don’t trust that WaterFix will be operated as promised, what alternatives do you have? Here some general alternatives:

1. Status quo. This means continuing to rely on ad hoc responses to droughts and floods as well as delaying large-scale infrastructure improvements necessary to accommodate sea level rise, big storm surges, extended drought, and earthquakes. Under this scenario, invasive species will become even more dominant and native species, like smelt, will disappear.  There is room here, of course, for innovative programs that reverse island subsidence, control invasive species, and reverse declining trends in native fishes through large-scale habitat restoration and pulse flow releases from dams.  This will take a visionary effort, led by the Delta Stewardship Council, coordinating the actions of many agencies, a difficult task (See Lund and Moyle 2013 for suggestions on how to do this).

2. Build one tunnel, not two. The idea is to build a single tunnel that has just enough capacity to supply urban water needs or function as an emergency conveyance system when large levee failures or severe drought draws seawater into the Delta.  This could protect California’s urban water supply from catastrophic failure, but from a smelt’s perspective, this is just a step above the status quo, because ultimately the pumps in the South Delta will continue to be relied upon for most water exports (the dual conveyance solution). Cross-Delta movement of water will continue, if somewhat reduced, as will entrainment mortality of native fishes. Presumably, EcoRestore would be at least partially implemented, providing some relief for native fishes.

3. Roll back water delivery volumes to pre-1980 levels. The goal would be increased flows down the Sacramento and San Joaquin Rivers through the Delta and estuary. This would have many positive effects (Cloern et al. 2017) and would be especially beneficial to native fishes, like delta smelt, that require estuarine gradients of temperature, salinity, and water clarity. It would also allow for pulse flows to carry juvenile salmon out to sea and to flood parts of the Yolo Bypass for fish rearing on an annual basis.  Higher flows would also enhance the benefits of restoration projects under EcoRestore.  Unfortunately, given the politics and value of water in California, this option is very unlikely to happen, unless the environment is assigned an inviolable water right to make it truly ‘coequal’ with other water users.

4. Construct a North-South cross-Delta channel with reinforced levees, tidal gates, weirs, and barriers that would deliver Sacramento River water to the South Delta under most situations (see Lund et al. 2010). This version of dual conveyance would anticipate the need for emergency construction of such a facility should levees fail as the result of sea level rise, flooding, land subsidence, and earthquakes, or all four. However, this option would ignore most estuarine ecosystem needs of the Delta, especially if it was operated with little consideration for environmental water during drought conditions.  It could be partially mitigated through EcoRestore, provided the restoration efforts were tied to guaranteed flows down the Sacramento River and through the Delta, at key times.

Each of these four options face common challenges: they have to deal with major changes to the Delta wrought by sea level rise, subsidence of farmed islands in the south and central Delta, increased frequency of large storms/floods, and earthquakes.  While these projections, most featuring levee collapse, may seem alarmist, scientific studies predict large-scale change is going to happen; it’s merely a question of when. Thus, at some point, the south and central Delta will contain large expanses of salty water with reduced tidal influence, ending farming in this region. This new Delta will be a much more difficult place in which to move fresh water to the south Delta pumping plants.  Fish and invertebrates will continue to be abundant but the assemblages are likely to be made up of salt-tolerant forms, such as yellowfin goby, Mississippi silverside, starry flounder, striped bass, northern anchovy, Black Sea jellyfish, and overbite clam.  Lake-like regions might even be seasonally used by Delta smelt, although they will be too warm in summer. Fighting this magnitude of change to keep the status quo will require large investment in levees and barriers, as well as in EcoRestore, making the Delta even more artificial and highly managed than it is today.

So what happens to Delta smelt under these options?  Assuming partial recovery in response to the wet winter of 2016-17, assuming successful supplementation from a smelt conservation hatchery, and assuming EcoRestore and additional measures improve smelt habitat, guided by present Biological Opinions, the extinction of Delta smelt may be prevented.  If the tunnels survive lawsuits and political opposition, their operation is at least 10-20 years in the future. Thus, smelt recovery will have to be well on its way for the tunnels to have a detectable effect.  Meanwhile, the longer we delay, the more likely drastic large-scale emergency measures will be put in place, with little consideration for environmental or recreational needs.

So, the best option for smelt, and other native fishes, especially salmon, is #3, because it should result in a large increase in freshwater flows through smelt habitat (Moyle et al. 2012).  This conclusion is essentially the same as that of the much-ignored Recovery Plan for the Sacramento/San Joaquin Delta Native Fishes (USFWS 1996).  The realities of California water politics, however, dictate that one of the other three options is much more likely to happen. Of these options, the WaterFix + EcoRestore option deals best with future changes to the Delta and seems most likely to keep delta smelt, salmon, and other desirable fishes as part of the Delta ecosystem.  We are past the point where passive management and ad hoc responses to emergencies will keep delta smelt and most other native fishes as participants in the Delta’s ecosystem. Large scale changes require large scale, active management solutions, like WaterFix+EcoRestore.

Peter B. Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences. James Hobbs is a research scientist with the UC Davis Department of Wildlife, Fish and Conservation Biology.

 Further reading

Cloern, J. E., J. Kay, W. Kimmerer, J. Mount, P. B. Moyle, and A. Mueller-Solger. 2017. Water wasted to the sea? San Francisco Estuary and Watershed Science 15(2). jmie_sfews_35738. Retrieved from: http://escholarship.org/uc/item/2d10g5vp

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.  PPIC, San Francisco. 482 pp.

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.

Lund, J., E. Hanak, W. Fleenor, W., R. Howitt, J. Mount, and P. Moyle. 2007. Envisioning Futures for the Sacramento-San Joaquin Delta. San Francisco: Public Policy Institute of California. 284 pp http://www.ppic.org/main/publication.asp?i=671

Lund, J. R. and P.B. Moyle. 2013. Adaptive management and science for the Delta ecosystem. San Francisco Estuary and Watershed Science 11(3). http://www.escholarship.org/uc/item/1h57p2nb

Moyle, P.B. 2008. The future of fish in response to large-scale change in the San Francisco Estuary, California. Pages 357-374 In K.D. McLaughlin, editor.  Mitigating Impacts of Natural Hazards on Fishery Ecosystems.  American Fisheries Society, Symposium 64, Bethesda, Maryland.

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 pp.

Moyle, P. B., L. R. Brown, J.R. Durand, and J.A. Hobbs. 2016. Delta Smelt: life history and decline of a once-abundant species in the San Francisco Estuary. San Francisco Estuary and Watershed Science 14(2) http://escholarship.org/uc/item/09k9f76s

US Fish and Wildlife Service. 1996.  Recovery Plan for the Sacramento-San Joaquin Delta Native Fishes. US Fish and Wildlife Service, Portland, Oregon.  193 pp

Posted in California Water, Conservation, Delta, Fish, Planning and Management, Restoration, Sacramento-San Joaquin Delta, Sustainability | Tagged , | 16 Comments

Small, self-sufficient water systems continue to battle a hidden drought

by Amanda Fencl and Meghan Klasic

Workshop participants in Salinas in July 2017 discuss ways to build local and regional drought resilience. Photo by A. Fencl

California’s drought appears over, at least above ground. As of April 2017, reservoirs were around 2 million acre feet above normal with record breaking snowpack . This is great news for the 75% of Californians that get their drinking water from large, urban surface water suppliers. Groundwater, however, takes longer to recharge and replenish. What does this mean for the more than 2,000 small community water systems and hundreds of thousands of private well-reliant households that rely on groundwater?

Of the ~25% of Californians not served by large, surface water suppliers, this pie chart shows the breakdown of populations served by system size and water source.

Small water systems are defined in our study as those have fewer than 3,000 connections, i.e. those that are not required to file an Urban Water Management Plan (UWMP). A large proportion of small systems serve low-income communities in rural areas. These communities are burdened with high unemployment, crime, and pollution, and their water systems typically have lower technical, managerial, and financial capacity for operations. Of the approximately 13 million people living within disadvantaged communities (DAC), nearly 2 million get their drinking water from a small system. These low income communities are disproportionately exposed to contaminated drinking water, usually from small systems that struggle to comply with regulations.

These same small systems were hit hard by the drought, and in many cases are the least prepared. The state knew this headed into the drought: “California also has small, rural water companies or districts with virtually no capacity to respond to drought or other emergency [… a portion of the small systems]  in the state face running dry in the second or third year of a drought (p.56, emphasis added). In contrast, urban drinking water suppliers (larger systems) are required to have a water shortage contingency plans (Shortage Plan) since the passage of the Urban Water Management Act in 1983. Aside from lower reservoir levels and toxic algal blooms, the majority of large surface water suppliers weathered the recent drought (2012-2016) without supply disruptions or other negative impacts to their customers. A 2015 survey distributed by the UC Davis Policy Institute shows that more large systems (89%) have written drought contingency plans (Plan) than small systems (63%) (manuscript in prep). When asked whether their Plan was sufficient to mitigate the drought’s impacts on water supply, 22% of large and 28% of small system respondents said it was not sufficient or only somewhat sufficient, which begs the question of how can these be improved before the next drought?

A private, domestic well on rural property outside of Visalia in Tulare County where one of the authors lived during fieldwork. Photo by A. Fencl

Small, rural water systems and their frequently disadvantaged residents remain vulnerable to quality and supply concerns (see Water Deeply’s Toxic Taps series for a look at these concerns in the Central Valley). They usually only have one or two different water sources and have few permanent or emergency interties with neighboring systems; this limits their supply flexibility, which is critical during multiple dry years. Small systems account for 71% of systems that faced drought-related supply or quality emergencies and sought financial assistance from the State Water Resources Control Board (Water Board).

Furthermore, 2800+ households on private, domestic wells reported problems due to the drought. The severity of private well failures prompted the Water Board to create a one-time funding program to assist households and local/state small systems (those under 15 service connections): $5 million was available as low-interest loans or grants.

Recognizing the extra burden of small systems, the 2016 Executive Order Making Conservation a Way of Life directed DWR to “work with counties to facilitate improved drought planning for small suppliers and rural communities”. The explicit focus on these systems and communities highlights the state’s acknowledgement that, “The ongoing drought has brought attention to the reality that many small water suppliers and rural communities are struggling to meet demands with significantly reduced water supplies – or even running out of water altogether” (p.3-17, emphasis added).

DWR’s Draft Executive Order Framework gives counties two years to figure out how to ensure drought resilience for households and areas under their jurisdiction that are otherwise not covered by an existing drought contingency plan. Hopefully, this will ensure that during the next severe drought, we won’t see 2800+ households running out of water; they will have long-term solutions in place. The East Porterville project underway in Tulare County shows what’s possible when state financing and local political will align.

A meeting of community members in East Porterville. DWR explains its plan for connecting ~1000 households on private wells, without running water, to the nearby City of Porterville. June 2016. Photo by A. Fencl

A team of UC Davis researchers interviewed a subset of California’s small “self sufficient” water system operators, managers, and board members during Summer 2016 about drought impacts, responses, and barriers to and options for adaptation. Self-sufficient systems do not purchase or import water from the Central Valley Project nor the State Water Project. In Summer 2017, the team organized three regional drought resilience workshops to complement the interview-based findings: Clear Lake, Modesto and Salinas. These workshops served to underscore the ongoing challenges facing smaller systems, the added water supply and quality pressures during extreme dry years and multi-year droughts, and the important role of the state in supporting local drought resilience.

The final phase of the research project will be day-long Forum on Drought Resilience for Small Systems in Sacramento next month. The forum is jointly hosted by the UC Davis Policy Institute and the Environmental Justice Coalition for Water. It will provide a venue for small system managers, state agency staff, technical assistance providers, and other interested stakeholders to discuss how best to overcome barriers to drought resilience for small systems. For more information on the Drought Forum, contact Meghan Klasic (mrklasic@ucdavis.edu).

Amanda Fencl is a PhD Candidate in Geography at UC Davis.  Her dissertation is on California’s complex drinking water system and its adaptation to drought and climate change.  Meghan Klasic is a 3rd year PhD student in the UC Davis Geography Graduate Group studying transboundary water quality management and climate change adaptation. Many thanks to Dr. Julia Ekstrom and Dr. Mark Lubell for their review and edits. This research was made possible by funding from an NSF Graduate Research Fellowship, California’s 4th Climate Impact Assessment, and EPA STAR.

Further reading

Arnold, Brad, Alvar Escriva-Bou, Jay Lund (2017) San Joaquin Valley Water Supplies – Unavoidable Variability and Uncertainty. California WaterBlog.

Balazs, Carolina and Isha Ray (2014) The Drinking Water Disparities Framework: On the Origins and Persistence of Inequities in Exposure. Am J Public Health. 104(4): 603–611.

DWR (2017) Making Water Conservation a California Way of Life: Implementing Executive Order B-37-16.

Ekstrom, Julia, Louise Bedsworth, Amanda Fencl (2017). Gauging climate preparedness to inform adaptation needs: local level adaptation in drinking water quality in CA, USA. Climatic Change.  February, Vol. 140, Issue 3–4, pp 467–481.

Feinstein, Laura et al. (2017). Drought and Equity in California. Pacific Institute.

Harter, Thomas (2017). Post-drought groundwater in California: Like the economy after a deep “recession,” recovery will be slow. California WaterBlog.

Lohan, Tara (2017). Toxic Taps. Water Deeply.

Posted in California Water, Drought, Stressors, Sustainability, Water Supply and Wastewater | Tagged | 8 Comments

Fish, flows, and 5937 – legal challenges on the Santa Maria River

by Karrigan Bork, JD, PhD

Santa Maria River as seen from a bike trail on the Santa Barbara County side, with the 101 Freeway bridge visible. Image source: Wikipedia

Driving down the 101, you cross a half-mile long bridge over the Santa Maria River into the city of Santa Maria, California. It’s a large bridge, with big levees to constrain the river on either end. But the Santa Maria River, like many southern California rivers, is dry throughout much of the year and has been for at least of part of every year on record. On average, the wide, sandy channel is dry over 90% of the time. Some dry periods stretch up to three years.

So why the big bridge?

The Santa Maria River watershed supports one of four key populations of federally endangered southern California steelhead that, according to the National Marine Fisheries Service, is essential for their recovery. Although these fish often go unnoticed, they are at the center of a pending lawsuit that focuses on ensuring dam operations comply with California Fish and Game Code Section 5937, which requires dam operators to keep fish downstream of a dam in good condition. If the lawsuit succeeds, minor changes in dam operation may produce significant improvements in wild steelhead populations.

The Santa Maria River watershed. Image source: USGS

The Santa Maria watershed covers 1,880 square miles (1.2 million acres), making it one of the largest coastal watersheds in the state. The Santa Maria forms at the junction of two rivers, the Cuyama and the Sisquoc. The Twitchell Dam blocks the Cuyama River just a few miles upstream from the junction, while the Sisquoc River flows unimpeded from its headwaters in the Los Padres National Forest. The national forest dominates the watershed, and most of the mountainous higher reaches of the watershed do little to slow runoff during rare rain events.

Although the watershed averages only 15 inches of rain per year, when rain does fall, much of the rain reaches the Santa Maria River quickly, transforming the dry riverbed to a raging mix of muddy water. Prior to construction of the large levee system, these floodwaters regularly inundated the city of Santa Maria, transforming the city streets into the canals of Venice.

Flooding during a 1913 storm in the City of Santa Maria. Santa Maria flooded on a regular basis before the levee system was built. Image source: Santa Maria Historical Museum

This is an incredible river system: from year to year, it ranges from desert to flood, with little in between. Nevertheless, its groundwater supplies water to the city of Santa Maria and helps support annual agricultural production in Santa Barbara County of roughly $1.4 Billion. Incredibly, it also supports a vital population of the federally endangered southern California steelhead.

How do steelhead, which by definition require outmigration to the ocean followed by eventual return migration to their birth stream to spawn, survive in a river system that almost never flows to the ocean? Both the adult steelhead migration and the smolt outmigration depend on precise flow conditions, and these conditions are rarely met. Historically, 80% of monitored years failed to provide opportunities for adult steelhead to migrate upstream, and 75% of monitored years failed to provide opportunities for smolt outmigration. Still, in spite of these historical impediments to passage, the steelhead were once one of the most common fish in the Santa Maria system, and the Santa Maria run was the second largest in Southern California.

Southern California steelhead. Image source: Aquarium of the Pacific

The southern California steelhead exhibit several life history adaptions to the Santa Maria River’s extreme environment. First, the steelhead population spends as little time as possible in the Santa Maria River itself. The population spawns far upstream in the perennial headwaters of the Sisquoc River, where their offspring grow and wait for good conditions for outmigration. The adults and smolts move quickly through the Santa Maria as flood waters recede at the end of periodic high flow events. In the winter, adult steelhead in the ocean wait near the Santa Maria River lagoon, anticipating these high flow events, and adults may spend several years waiting for a single flow event that will allow them to migrate upstream.

Second, the steelhead population is intimately linked with the resident rainbow trout population in the Sisquoc River headwaters. The resident rainbow trout interbreed freely with the steelhead, and 14-42% of the resident fish possess genes associated with anadromy. When the steelhead population is unable to migrate for a prolonged period of time, the resident population sustains them, and when poor conditions wipe out part of the resident population, the returning steelhead repopulate the stream. These populations protect each other, and long-term stability of either population requires the other.

These adaptations, coupled with additional adaptations to higher temperatures and other local conditions, have enabled the historic persistence of this steelhead population. But the establishment of the Twitchell Dam on the Cuyama River in 1958 started the steelhead on a long decline, and now they hang on by a thread. The dam stores as much of the winter and spring flow of the Cuyama River as possible, then slowly releases the water during the summer months in an effort to ensure that all of the water from the Cuyama goes into groundwater and never makes it to the sea. Although the steelhead never made much use of the Cuyama River itself, the flow changes have altered the flow regime on the Santa Maria in several important ways, most notably by reducing the total number of up- or downstream migration opportunities and by increasing “false positives,” flows in the Sisquoc that induce migration without any chance of letting fish make it through the Santa Maria River alive. These changes have decimated the steelhead population.

Twitchell Dam on the Cuyama River, a tributary of the Santa Maria River. Image source: USBR

California law prohibits operation of a dam in this way. California Fish and Game Code Section 5937 requires “ The owner of any dam shall . . .  allow sufficient water to pass over, around or through the dam, to keep in good condition any fish that may be planted or exist below the dam.” Under California Fish and Game Code Section 5900, the term “Owner” includes the United States . . . , the State, a person, political subdivision, or district (other than a fish and game district) owning, controlling or operating a dam or pipe. The state of California has generally failed to enforce 5937, leaving enforcement to private nongovernmental organizations like California Trout or the Natural Resources Defense Council. In the most recent 5937 lawsuit, the Environmental Defense Center, representing Los Padres Forest Watch, and Lawyers for Clean Water, Inc., representing San Luis Obispo Coastkeeper, filed suit against the Santa Maria Valley Water Conservation District, which operates Twitchell Dam. The lawsuit seeks a court order requiring the water district to comply with Section 5937 by releasing water to support additional steelhead migration.

As in many water disputes, the issue is less the total amount of water and more the timing of releases. Both an independent report and the experts supporting Los Padres Forest Watch and San Luis Obispo Coastkeeper estimate that the steelhead need only 2-4% of the water stored annually by Twitchell Dam released strategically during flow events that would otherwise almost, but not quite, support steelhead runs. As required by 5937, smarter water management can save these steelhead. At this point, whether that happens is up to the Water District and the Court.

Karrigan Bork is a Visiting Assistant Professor with a joint appointment at the McGeorge School of Law and the Dept. of Geological & Environmental Sciences, both part of the University of the Pacific. His research interests include environmental law, natural resources law, international law, and administrative law, focusing on the interplay of science and law. He is currently serving as a consultant to Lawyers for Clean Water, Inc., in the lawsuit discussed here.

Further reading

Stillwater Sciences and Kear Groundwater. 2012. Santa Maria River Instream Flow Study: flow recommendations for steelhead passage. Prepared by Stillwater Sciences and Kear Groundwater, Santa Barbara, California for California Ocean Protection Council, Oakland, California and California Department of Fish and Game, Sacramento, California.

Karrigan Börk, Joe Krovoza, Jacob Katz & Peter Moyle. 2012. The Rebirth of Cal. Fish & Game Code 5937: Water for Fish, 45 U.C. Davis L. Rev. 809

Peter Moyle and Brian Gray. 2011. Dammed Fish? Call 5937.


Posted in California Water, Fish, Groundwater, Planning and Management, Sustainability | Tagged | 3 Comments

Water wasted to the sea?

by James E. Cloern, Jane Kay, Wim Kimmerer, Jeffrey Mount, Peter B. Moyle, and Anke Mueller-Solger

This article originally appeared in the journal San Francisco Estuary and Watershed Science.

Water flowing to the sea from the San Francisco Bay Delta. (Image source: Joey Lax-Salinas Photography)


If we farmed the Central Valley or managed water supplies for San Francisco, San Jose or Los Angeles, we might think that fresh water flowing from the Sacramento and San Joaquin rivers through the Delta to San Francisco Bay is “wasted” because it ends up in the Pacific Ocean as an unused resource. However, different perspectives emerge as we follow the downstream movement of river water through the Delta and into San Francisco Bay.

If we were Delta farmers or administered Contra Costa County’s water supply, we would value river water flowing through the Delta because it repels salt intrusion (Jassby et al. 1995) and protects water quality for drinking, growing crops and meeting other customer needs.

If we were responsible for protecting at-risk species, we would value river water flowing through the Delta to the Bay and ocean because it stimulates migration and spawning of native salmon, delta smelt, longfin smelt, and splittail while reducing the potential for colonization and spread of non-native fish (Brown et al. 2016). River flow reduces toxic selenium concentrations in clams eaten by sturgeon, splittail, and diving ducks (Stewart et al. 2013), and it delivers plankton and detritus to fuel production in downstream food webs (Sobczak et al. 2002).

If we managed a Bay Area storm water district or sewage treatment plant, we would value water flowing from the Delta into the Bay because it dilutes and flushes such urban contaminants as metals, microplastics, and nutrients (McCulloch et al. 1970).

If we directed restoration projects around the Bay, we would value water flowing from the Delta into the Bay because it brings sediments required to sustain marshes that otherwise would be lost to subsidence and sea level rise (Stralberg et al. 2011; Schoellhamer et al. 2016). Sediment input from rivers also sustains mudflats (Jaffe et al. 2007) used as habitat and probed for food by more than a million willets, sandpipers, dunlins and other shorebirds during spring migration (Stenzel et al. 2002).

If we fished the Pacific for a living, we would value river flow into the Bay because it carries cues used by adult salmon to find their home streams and spawn (Dittman and Quinn 1996), it brings young salmon to the sea where they grow and mature, and it creates bottom currents that carry young English sole, California halibut and Dungeness crabs into the Bay (Raimonet and Cloern 2016) where they feed and grow before returning to the ocean.

If we liked to romp along the shore or served on the California Coastal Commission we would value rivers flowing to sea because they supply the sand that keeps California’s beaches from eroding away (Barnard et al. 2017).

Finally, if we were among those who want to conserve California’s landscape and biological diversity, we would value river water flowing to the sea because it creates one of the nation’s iconic estuaries and sustains plant and animal communities found only where seawater and fresh water mix (Cloern et al. 2016).

Is the fresh river water that naturally flows through the Delta to San Francisco Bay and on to the Pacific Ocean “wasted”? No. The seaward flow of fresh water is essential to farmers, fishers, conservationists, seashore lovers, and government agencies that manage drinking water supplies, restore wetlands, protect coastlines, and clean up sewage and storm pollution. Wasted water to some is essential water to others.

James Cloern is a senior research scientist with the U.S. Geological Survey. Jane Kay is an independent science writer. Wim Kimmerer is a research professor with the Romberg Tiburon Center for Environmental Studies. Jeffery Mount is a senior fellow with the Public Policy Institute of California. Peter B. Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences. Anke Mueller-Solger is the Associate Director for Projects at the U.S. Geological Survey.

Further reading

Barnard PL, Hoover D, Hubbard DM, Snyder A, Ludka BC, Allan J, Kaminsky GM, Ruggiero P, Gallien TW, Gabel L, McCandless D, Weiner HM, Cohn N, Anderson DL, Serafin KA. 2017.   Extreme oceanographic forcing and coastal response due to the 2015-2016 El Niño. Nat Commun 8:14365. doi: 10.1038/ncomms14365.

Brown LR, Kimmerer W, Conrad JL, Lesmeister S, Mueller–Solger A. 2016. Food webs of the Delta, Suisun Bay, and Suisun Marsh: an update on current understanding and possibilities for management. San Francisco Estuary and Watershed Science 14(3). doi: http://dx.doi.org/10.15447/sfews.2016v14iss3art4.

Cloern JE, Barnard PL, Beller E, Callaway JC, Grenier JL, Grosholz ED, Grossinger R, Hieb K, Hollibaugh JT, Knowles N, Sutula M, Veloz S, Wasson K, Whipple A. Life on the edge – California’s estuaries. In: Mooney H, Zavaleta E, editors. 2016.  Ecosystems of California: a source book. Oakland (CA): University of California Press. p 359-387.

Dittman A, Quinn T. Homing in Pacific salmon: mechanisms and ecological basis. Journal of Experimental Biology. 1996 Jan 1;199(1):83-91.

Healey M, Goodwin P, Dettinger M, Norgaard R. 2016. The state of Bay–Delta science 2016: an introduction. San Francisco Estuary and Watershed Science 14(2). doi: http://dx.doi.org/10.15447/sfews.2016v14iss2art5.

Jaffe BE, Smith RE, Foxgrover AC. 2007 Anthropogenic influence on sedimentation and intertidal mudflat change in San Pablo Bay, California: 1856-1983. Estuarine Coastal and Shelf Science 73:175-187. doi:10.1016/j.ecss.2007.02.017.

Jassby AD, Kimmerer WJ, Monismith SG, Armor C, Cloern JE, Powell TM, Schubel JR, Vendlinski TJ. 1995 Isohaline position as a habitat indicator for estuarine populations. Ecological Applications 5(1): 272-289. doi:10.2307/1942069

McCulloch, DS, Peterson DH, Carlson PR, Conomos TJ. 1970. Some effects of fresh-water inflow on the flushing of South San Francisco Bay – a preliminary report: U.S. Geological Survey Circular 637A, 27 p.

Raimonet M, Cloern JE. 2016. Estuary-ocean connectivity: fast physics and slow biology. Global Change Biology (Internet]. [cited 2017 March 18]. Available from: http://onlinelibrary.wiley.com/doi/10.1111/gcb.13546/full

Schoellhamer DH, Wright SA, Monismith SG, Bergamaschi BA. 2016. Recent advances in understanding flow dynamics and transport of water-quality constituents in the Sacramento–San Joaquin River Delta. San Francisco Estuary and Watershed Science 14(4):1-25. doi: https://doi.org/10.15447/sfews.2016v14iss4art1.

Sobczak W, Cloern J, Jassby A, Muller-Solger A. 2002. Bioavailability of organic matter in a highly disturbed estuary: the role of detrital and algal resources. Proceedings of the National Academy of Sciences of the United States of America 99(12): 8101-8105. doi: 10.1073/pnas.122614399.

Stenzel LE, Hickey CM, Kjelmyr JE, Page GW. 2002. Abundance and distribution of shorebirds in the San Francisco Bay area. Western Birds 33: 69-98.

Stewart AR, Luoma SN, Elrick KA, Carter JL, van der Wegen M. 2013. Influence of estuarine processes on spatiotemporal variation in bioavailable selenium. Marine Ecology Progress Series 492: 41-56. doi:10.3354/meps10503.

Stralberg D, Brennan M, Callaway JC, Wood JK, Schile LM, Jongsomjit D, Kelly M, Parker VT, Crooks S. 2011. Evaluating tidal marsh sustainability in the face of sea-level rise: a hybrid modeling approach applied to San Francisco Bay. PloS one 6(11): e27388. doi: http://dx.doi.org/10.1371/journal.pone.0027388.

Posted in Uncategorized | Tagged | 9 Comments

A simplified method to classify streams and improve California’s water management

by Belize Lane, Sam Sandoval, and Sarah Yarnell

Alterations to the natural flow regime for human water management activities have degraded river ecosystems worldwide. Such alterations are particularly destructive in regions with highly variable climates like California, where native riverine species are highly adapted to natural flooding and drought disturbances. In California, less than 2% of the total streamflow remains unaltered, while over 80% of the native fish species are now imperiled or extinct .

Determining the natural flow regime for altered stream reaches is difficult as unimpaired streamflow records are unavailable for many locations of interest. Where data is available, previous methods distinguished such specific stream types that their application was limited and unhelpful for regional management. To improve California’s water management, particularly around determining environmental flows for our diverse ecosystems, we needed a better method that addressed the diversity and scale of California’s streams.

Hydrologic Classification

Hydrologic classification is a strategy for distinguishing groups of stream reaches with similar streamflow characteristics for regional water management efforts. UC Davis researchers recently developed a hydrologic classification for California that is specific enough to make critical distinctions between natural streamflow patterns (also called natural flow regimes), but general enough to support the development of environmental flow targets in altered stream reaches across the state.

The California hydrologic classification is based on available hydrologic and geospatial data. First, key hydrologic metrics (e.g., measures of streamflow magnitude, duration, timing, frequency, and rate of change) pertinent to river ecosystems were calculated for all available reference streamflow gauge stations with long-term (>20 years) unimpaired or naturalized discharge data. These metrics were input to an initial streamflow gage classification model that distinguished statistically distinct natural stream classes; each reference streamflow gage was classified into a stream class based on its specific hydrologic metric values.

Then, a predictive linear regression model was developed based on relationships between the initial streamflow gauge classification and upstream catchment attributes (e.g., climate, topography, soils, and geology). The model was highly accurate at predicting the stream classes of reference gauges and performed well compared to regional hydrologic studies. This second model (Figure 1) was then used to predict the stream classes of all the reaches in California.

Predictive model of stream classes based on upstream catchment attributes, from Lane et al. (2017a).

The resulting hydrologic classification (Lane et al. 2017b) identified nine natural stream classes (Figure 2) with distinct streamflow patterns that are the result of several characteristics of rainfall-runoff response, including: dominant water source (snowmelt, rain, groundwater), hydrologic attributes (mean annual flow, extreme low flow duration and timing, etc), climate setting (mean annual precipitation, mean August and January precipitation, etc.) and topographic and geologic setting (slope, catchment area, dominant rock type, soils compositions, etc.).

Hydrologic classification of California, combing results of Lane et al. (2017a) and Pyne et al. (2017).

California’s Natural Stream Classes

Snowmelt (SM): SM streams exhibit highly seasonal flow regimes with spring snowmelt peak flows, predictable recession curves, very low summer flows, and minimal winter rain influence. These sites exist along the crest of the Sierra Nevada with most sites in the southern, higher elevation portion of the mountain range.

High elevation, Low Precipitation (HLP): HLP streams are distinguished from SM streams by their higher base flow (due to porous geology) and lower peak flows (due to less snow) but exhibit a similar seasonal signature and predictability.

High- and Low-volume Snowmelt and Rain (HSR and LSR): The transition from a SM to a LSR to a HSR regime closely tracks the elevation gradient from the peaks of the Sierra Nevada to the floor of the Central Valley. LSR and HSR streams exhibit similar bimodal snow-rain patterns but illustrate a transition toward earlier snowmelt peak and increasing winter rain contributions along the elevation gradient.

Rain and seasonal Groundwater (RGW): Generally at lower elevations, RGW streams exhibit higher minimum flows and earlier summer peak flows than LSR streams, as well as the distinctive influence of winter rain storms in high and unpredictable winter flows.

Winter Storms (WS): WS streams, driven by winter rain storms, exhibit distinct duration, timing and magnitude of high flows during the rainy season. They are characterized by high interannual flow variance, due to the variability of winter storm patterns, and very low base flows during summer. WS streams generally follow the spatial distribution of strong orographic precipitation in the north coast region.

Groundwater (GW): GW streams are distinguished by significantly higher and more stable flows year-round, mostly located along volcanic geologic settings.

Perennial Groundwater and Rain (PGR): PGR streams combine the stable, base flow-driven conditions of GW streams during summer with the high magnitude winter peak flows of WS streams in catchments with low annual streamflow.

Flashy Ephemeral Rain (FER): Prevalent in arid southeastern California, FER streams are characterized by the highest interannual flow variance, extended extreme low flows and large floods, and the lowest average daily flow of any class.

The following figure (Fig. 3) illustrates the extreme seasonal and interannual hydrologic variability between stream classes. For example, the SM flow regime exhibits a highly predictable spring snowmelt pattern with low interannual variability (<6) while the WS flow regime exhibits highly variable winter storm flows (<18) and very low summer flows.

Reference dimensionless hydrographs illustrate seasonal and interannual flow regime variability between natural stream classes for four of the nine classes (Lane et al. 2017b). Reference streamflow gauge time-series were aggregated for each stream class and daily streamflow was non-dimensionalized based on average annual streamflow to highlight pattern variability.

Environmental Water Management Implications

This hydrologic classification provides the fundamentals for understanding the diversity of natural streamflow patterns and their spatial arrangement across the state. It also supports the need for broad-scale environmental management of California’s many impaired rivers. The spatial extent and reach scale of the classification are expected to substantially improve the overlap of biological and hydrologic datasets statewide. The hydrologic classification provides a footprint of the locations of distinct natural stream classes which, combined with ecological and geomorphic information, can be used to design environmental flow targets. Future comparisons of ecological patterns between natural and hydrologically altered streams within each stream class are expected to yield flow-ecology relationships that can provide the basis for rapid statewide environmental flow standards.

Belize Lane recently received her PhD in Hydrologic Sciences from UC Davis and is now an Assistant Professor in Civil and Environmental Engineering at Utah State University. Samuel Sandoval is an Associate Professor in the Dept. of Land, Air and Water Resources and UC Agricultural and Natural Resources Cooperative Extension Specialist. Sarah Yarnell is a senior researcher at the Center for Watershed Sciences.

Further reading

Lane BA, Dahlke HE, Pasternack GB and Sandoval-Solis S (2017a). Revealing the Diversity of Natural Hydrologic Regimes in California with Relevance for Environmental Flows Applications.

Lane BA, Sandoval-Solis S, Yarnell SM, Stein ED (2017b) Characterizing diverse river landscapes using hydrologic classification and dimensionless hydrographs. In Preparation.

Magilligan FJ and Nislow KH (2005). Changes in hydrologic regime by dams. Geomorphology.

Pyne MI, Carlisle, DM, Konrad CP and Stein ED (2017). Classification of California streams using combined deductive and inductive approaches: Setting the foundation for analysis of hydrologic alteration.

Quiñones RM, Moyle PB (2015) California’s freshwater fishes: status and management. FISHMED

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

Reflections on Cadillac Desert

William Mulholland, pointing. (Image source: LA Times)

by Jay Lund

In 1986, when Mark Reisner published his book Cadillac Desert, I had just begun professing on water management. The book went “viral,” before the word viral had its present-day internet-intoxicated meaning.  The book offered a compelling revisionist history and understanding of water development in the American West, based on economic self-interest, ideology, and Floyd Dominy’s personal drives.  Since then, Cadillac Desert has been a “must read” book for Western water wonks.

Cadillac Desert, by Marc Reisner

Cadillac Desert fell in the tradition of Muddy Waters (1951), Dams and other Disasters (1971), Rivers of Empire (1985), and Water and Power (1983), all written by giants in the field critical of Western water development, but was much better written and marketed (though less scholarly) and the time was ripe for publication of such a thoughtful, popular work.  The era of large dam and water projects in the US had clearly ended, and needed a punctuation mark.  Mark Reisner provided an exclamation mark.

Main lessons at the time

The main lessons from the book (for me) were:

  • The 50-year era of building large regional and multi-state water projects was largely over (by 1987).
  • Why do we expect anything as important as water to not be political? The individuals, sociology, economics, and politics behind the era of large water infrastructure construction were fascinating and important. In fact, they proved to be more important than traditional engineering (my field) in shaping water management.  But contemporary and likely future politics and economics can no longer support continued traditional water project development.
  • The public institutions responsible for the successes and failures of the big infrastructure era were incapable of adapting to new conditions. The large federal and state agencies have largely lacked political and financial support needed to develop new talented and ambitious people to effectively lead these institutions in better adapted directions.
  • The West’s large water infrastructure systems have profoundly transformed and damaged the natural environment and pre-existing rural communities, particularly Native American communities.
  • In many ways, the water infrastructure of the Western US was over-developed, or at least mal-developed for contemporary society’s water management objectives.

Becoming conventional wisdom

Marc Reisner’s themes are now conventional wisdom.  Although these ideas were not new to well-read scholars, they were timely, well-written, and influential.  Almost all books and scholarship following Cadillac Desert have adopted or been underlain by these themes (such as The Great Thirst, 1992, The King of California, 2005, and Managing California’s Water, 2011).

But much has changed since Cadillac Desert was written (and revised in 1992).

Federal and State agencies no longer drive major water project construction.  The additional water deliveries from new major dam or canal projects are typically small and expensive.  The cheapest sites with the most capacity to deliver water already have water projects.  Remaining potential reservoir sites are usually much less cost-effective.

The economic and political drivers of Western water also have changed in fundamental ways.  The West is wealthier and much less agricultural.  Agriculture’s diminishing role in the West’s economy (now less than 5% of GDP and employment) and the steady urban water conservation efforts have made regional economic prosperity much less dependent on cheap and abundant water supplies.

Environmental laws and regulations now greatly hinder the development of new projects, and impinge on the operation of existing projects.  There is now great uncertainty and concern for the ability to preserve native aquatic species.

Federal and state budgets no longer have substantial funds available for large water infrastructure projects anyway.  There remains little political appetite to fund large federal and state water projects.

Floyd Dominy (Image source: LA Times)

Federal and State water agencies have become financially and intellectually impoverished and, tragically, have substantially lost most of their sense of mission.  Without a strong sense of mission, they often become mired in internal procedures and policies – and suffer greatly reduced effectiveness.  A Floyd Dominy would be completely hamstrung in today’s large agencies.

So where is Western Water going?  And where should we as professionals and interests work to make it go?  What should we teach students, the public, and policy-makers about Western water as it moves well beyond Cadillac Desert?

Emerging from the Desert

Cadillac Desert is now a bit dated in its lessons for the present and future water management and policy in the American West.  What should we be preparing for?

Water in the west will continue to be important and controversial.  But the structure of the West’s economy will continue to make it less dependent on abundant water supplies.  Modern urban economies need relatively little water to produce vast amounts of economic wealth.  Per capita urban water use continues to fall substantially, and can probably continue to do so for several decades.  Agricultural shifts to higher valued permanent crops, particularly vines and orchards, make farmers more interested in water reliability than total quantity.

Climate change will become more important, bringing more attention to variability and likely contraction of supplies and shifts in demands.  It will be hard to know how to change major water infrastructure for a warmer, more variable, and perhaps drier climate.  Larger reservoirs, while useful, might not be the most cost-effective solutions.

Local and regional water agencies have become increasingly important, and have been more successful at escaping the calcification of state and federal bureaucracies.  Cost-effective contemporary water innovations are largely in water conservation, water markets, conjunctive use of ground and surface waters, wastewater reuse, and other actions which are more appropriately and effectively led and financed at local levels.

Most modern water systems are built around carefully crafted portfolios of water supply and demand management activities involving local, regional, and larger actions, users, and management agencies.  State and federal agencies are most important in establishing legal and regulatory frameworks for local agencies and users to cooperate, as well as federal and state agencies continuing to run Dominy-era water supply projects.

Although individuals remain important, the success of adaptive water management portfolios over local, regional, statewide, and inter-state scales relies increasingly on networks of people.  It is hard and slow to organize a group of people distributed among many agencies and interests, but an effective convergence of ideas across such a network can be effective and powerful.  Water management has always relied substantially on the development of informal networks of experts across agencies, interests, and academia to lead progress and support the development of effective legal and institutional frameworks.

Implications for California and the West

Water problems and solutions for the American West continue to change.  The region is a dry place, with a highly variable (and probably increasingly variable) climate, that supports a growing population and economy.

Three more recent books give some options and optimism for improving water management in the West (Lund et al. 2010; Hanak et al. 2011; Fleck 2016; Mulroy 2017).  These all point to the importance of moving beyond the large projects of the Dominy era and the pessimism of Cadillac Desert.  They all point out that despite the inevitability of water problems in the dry Western US, substantial prosperity and relative ecological success can occur with thoughtful and cooperative management.  Excessive focus on conflict, and not the benefits of cooperation, is the surest recipe for failure.

Further reading

Arax, Mark and Rick Wartzman (2005), The King of California: J.G. Boswell and the Making of A Secret American Empire, PublicAffairs.

Fleck, John (2016), Water is for Fighting Over: and Other Myths about Water in the West, Island Press.

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, 500 pp.

Hundley, N. (1992), The Great Thirst: Californians and Water-A History, University of California Press, Berkeley, CA, revised 2001.

Kahn, Debra (2017), “Wry Jeremiah saw folly in dam construction’s ‘go-go years’,” E&E News, April 3, 2017

Kahrl, William (1983), Water and Power: The Conflict over Los Angeles Water Supply in the Owens Valley, University of California Press, Berkeley, CA.

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

Maass, A. (1951), Muddy waters; the Army Engineers and the Nation’s rivers, Harvard U. Press, Cambridge, MA.

Mulroy, Pat (ed) (2017), The Water Problem – Climate Change and Water Policy in the United States, Brookings Institution, Washington, DC., especially Chapter 4 on the Colorado River.

Morgan, Arthur E. (1971), Dams and Other Disasters: A Century of the Army Corps of Engineers in Civil Works, Porter Sargent Publisher.

Reisner, Marc (1986), Cadillac Desert: The American West and Its Disappearing Water, Revised in 1992, Penguin Books.

Worster, Donald (1985), Rivers of Empire: Water, Aridity, and the Growth of the American West, Pantheon Books.

Jay Lund is a Professor of Civil and Environmental Engineering at the University of California – Davis, where he is also Director of the UC Davis Center for Watershed Sciences.

Posted in California Water, Climate Change, education, Planning and Management, Stressors, Sustainability, Water Supply and Wastewater | Tagged | 12 Comments

San Joaquin Valley Water Supplies – Unavoidable Variability and Uncertainty

Dry fields and bare trees at Panoche Road, looking west, on Wednesday February 5, 2014, near San Joaquin, CA. Photo by Gregory Urquiaga/UC Davis 2014

by Brad Arnold1, Alvar Escriva-Bou2, and Jay Lund1

1 UC Davis Center for Watershed Sciences

2 Public Policy Institute of California

Passage of the Sustainable Groundwater Management Act (SGMA) and the recent drought have brought attention to chronic shortages of water in the San Joaquin Valley. Although the portfolio of water flows available to the Valley is diverse, several major inflows – including groundwater use, Delta imports, and local streamflows – are unsustainable or threatened by climate change and environmental demands. Here we examine long-term balances for San Joaquin Valley’s water supplies and demands that we discussed in a prior blog post.

In addition to the San Joaquin Valley’s substantial long-term water imbalance, many of its individual water supplies are highly variable and involve substantial operational, regulatory, and planning uncertainties. Not only is there growing concern for water scarcity for the San Joaquin Valley, the character and causes of this scarcity are highly and unavoidably variable and uncertain. We look at how major flows into and from the Valley vary and the uncertainty in such water balance estimates, with some policy and management implications.  

Large Variations in Valley Water Supplies and Use

The San Joaquin Valley’s water supply portfolio varies each year. Precipitation and river runoff from the central and southern Sierra Nevada and Coastal Range all vary greatly each year. Changing water conditions, such as those in recent droughts and wet years, provide a stark reminder of their immense variability.

The San Joaquin Valley. Map prepared by USGS.

A typical year’s ‘natural availability’ of river inflows averages about 10.1 MAF/year, roughly 56% of all Valley inflows from 1986 to 2015. These total river flows vary substantially each year, from 3.0 MAF in a dry year (2015, minimum) to 21.9 MAF in a wet year (1998, maximum); typical variation of approximately 5.6 MAF from the average in any given year. Other Valley inflows also vary annually – specifically SWP and CVP Delta Imports – and this erraticism of inflows can cause major impacts to the water balance in any single year (especially affecting San Joaquin River flows and groundwater pumping).This variability brings planning and management challenges and uncertainties for the Valley’s water resources.

When surface water inflows, outflows, and uses are “out of balance,” the difference typically comes from drawdown or refill from groundwater or surface reservoirs. Reservoir storage generally follows a seasonal refill and draw-down pattern – with additional refilling in wetter years balancing drawdowns in drier years. Groundwater storage shows a seasonal drawdown-refill cycle, and much larger imbalanced drawdowns in drier years (averaging about 1.8 MAF/year of San Joaquin Valley overdraft). The plot below compares annual natural availability data to other annual outflow and inflow for the San Joaquin Valley.

Natural nvailability data plotted with outflows and uses for 30-year period.

From linear regression lines for these scatter plots, an average annual decrease of 500 thousand acre-feet in Valley-wide natural availability (decreased Sierra Nevada, Coastal Range, and precipitation flows) generally coincides with the changes presented here:

Approximate changes to San Joaquin Valley outflows and uses
resulting from changes in natural availability (for the period 1986-2015).

These statistical regression slopes – constrained so slopes close the water balance – illustrate the relative trends and magnitudes of water flows and management responses to wet and dry years in the San Joaquin Valley. In drier years the major response is much greater groundwater pumping, reduced San Joaquin River outflows, somewhat decreased agricultural and urban net water use, and more withdrawals from surface reservoirs. In wetter years, many of these responses reverse.

Balanced water management in California must prepare to operate across diverse wet and dry year conditions. Large outflow and water use changes, and long-term groundwater overdraft, are clearly seen, including recent droughts – where natural availability averaged 2.3 MAF/year less for 2007 to 2015 than its 30-year average. If natural availability becomes more variable, as predicted with climate change, the result will likely be larger fluctuations in the Valley’s water balance. Valley inflows, outflows, and uses vary greatly, and vary together.

Large Statistical Uncertainty in Major Inflows

Estimates of individual inflows or outflows are more straightforward, but always include some error from measurement inaccuracy, modeling uncertainty, and hydrologic variability. The “standard deviation of the average” is an index of uncertainty in average flows based on statistical chance the “actualaverage flow differs from the historical sample average. Long-term averages are statistically better-behaved than estimates for a single year. However, if climate and underlying hydrologic processes are changing, errors may become less well-behaved.

Average flow estimates, such as those for the San Joaquin Valley water balance, are the basis for many water policy, planning, management, and regulation decisions. Averages are central for implementing the water budgets required by SGMA, estimating impacts for an environmental flow policy, and decisions to invest in water infrastructure or to trade water. But such averages often mask great variability and uncertainty. Given the economic value of this water, and how economic valuations ($/acre-ft) change from dry to wet periods, errors and variability from averages are important.  

Here we look at uncertainty in annual inflows from the Central and Southern Sierra Nevada – the origins of most natural availability for the San Joaquin Valley. Confidence in these flows is important to analyzing water demands and uses (especially for calculating groundwater overdraft as a water balance “closure term”). Technical Appendix A of the recent PPIC report details the river/inflow selection process and data sources.

Uncertainty range of flows for major San Joaquin Valley surface inflows. Average plus and minus standard deviation of annual flows and (smaller) standard deviation of average annual flows.
Second columns do not include recent drought years 2007 to 2015 data.

These data show important results: total standard deviation in average central Sierra Nevada inflows is about 1.74 MAF/yr, and southern Sierra average inflows have a standard deviation of 600 TAF/yr. This means there is a 33% chance the ‘actual’ average flows may deviate more than these amounts from the historical averages, either more or less. Neglecting recent drought years from 2007 to 2015 doesn’t necessarily reduce this uncertainty. There is substantial uncertainty in published “Full Natural Flow” estimates, both in single year and long term average values. If climate model projections are correct, climate change could make this long-term uncertainty even greater than uncertainty estimates based only on historical statistics alone.

Regional water balances have large uncertainties and intricate internal variabilities. Planning around water balances often overlooks these uncertainties. Three important implications from these unavoidable uncertainties and variability are:

  1. Given California’s natural hydrologic variability, and the inherent uncertainty of our models, water and groundwater plans need to be prepared for simple long-term water balances to be substantially wrong. Plans must support adjustments and adaptations into the future. This is especially relevant for SGMA-required local Groundwater Sustainability Plans.
  2. Water plans and operations also need to prepare for substantial variability in sources of water available across years. Source and sustainability planning should also account for uncertainty estimates and try to reduce them over time to improve the accuracy of their water budgets estimations.
  3. To reduce and better understand water uncertainties and variability, and improve collaboration among local and state interests, more solid regional water accounting and measurement is needed.

Further Reading:

Arnold, Brad, Alvar Escriva-Bou, Jay Lund, and Ellen Hanak (2017). Accounting Water for the San Joaquin Valley. California WaterBlog.

Arnold, Brad, and Alvar Escriva-Bou (2017). Water Stress and a Changing San Joaquin Valley. Technical Appendix A: The San Joaquin Valley’s Water Balance. 13 pp. Public Policy Institute of California, San Francisco, CA.

Escriva-Bou, Alvar, Henry McCann, Ellen Hanak, Jay Lund, Brian Gray. 2016. Accounting for California’s Water. Public Policy Institute of California.

Hanak, Ellen, Jay Lund, Brad Arnold, Alvar Escriva-Bou, Brian Gray, Sarge Green, Thomas Harter, Richard Howitt, Duncan MacEwan, Josue Medellin-Azuara, Peter Moyle, and Nathaniel Seavy (2017). Water Stress and a Changing San Joaquin Valley. 48 pp. Public Policy Institute of California, San Francisco, CA.

Posted in California Water, Planning and Management, San Joaquin River, Water Supply and Wastewater, Water System Modeling | Tagged | 7 Comments

Can Sacramento Valley reservoirs adapt to flooding with a warmer climate?

Englebright Spillway during the 1997 flood

Clementime Dam on the North Fork American River overtopping in 1997. Photo by Rand Schaal.

by Jay Lund and Ann Willis

Much has been written on potential effects and adaptations for California’s water supply from climate warming, particularly from changes in snowpack accumulation and melting, sea level rise, and possible overall drying or wetting trends.   But what about floods?

In a paper in the journal San Francisco Estuary and Watershed Science, we along with co-authors from the US Army Corps of Engineers review much of the literature to date and examine how Shasta, Oroville, and New Bullards Bar reservoirs might adapt to floods in a warmer climate, including a climate that is either wetter or drier.

Oroville Spillway during the 1997 flood

A torrent of water flowing from the Oroville Spillway during the 1997 flood

Since no one knows exactly what future floods will look like, the nine largest floods from the historical record were hydrologically modified to be warmer and either wetter or drier, using the National Weather Service hydrologic model used for flood forecasting.  These many modifications to past major floods were then run through a US Army Corps of Engineers’ model for flood operation of these reservoirs to evaluate what might happen, given the way we currently operate these reservoirs.  The results were both reassuring and disturbing.

1. Warming generally worsened flood inflows into reservoirs.  Even with less precipitation, warmer conditions often increased flood inflows to reservoirs.  When more precipitation fell as rain, rather than snow, and more existing snowpack melted, flood volumes increased.  This was particularly true for historical storms that were “cold”, where much of the precipitation was held as snowpack.  Warm storms, which historically produced less snow, were less affected by warming.

2. Reservoirs with flood operating rules that respond to the wetness of their watersheds seemed to adapt well to changes in climate, even fairly severe changes in temperature and precipitation.  This was true for Shasta and Oroville Reservoirs, whose existing flood operation rules vary with moisture conditions upstream.  This shows that existing reservoirs may have considerable ability to accommodate flooding effects of climate warming.

3. Reservoirs with flood operating rules that do not respond to upstream conditions may perform poorly with climate warming.  For example, New Bullards Bar’s flood rules do not change with upstream snowpack and wetness conditions.  For many plausible climate changes, modifications of past floods overtopped this dam, a potentially catastrophic flood risk for downstream residents.

Large uncertainties are common when dealing with both the future and the weather.  Nevertheless, some things can be known, or at least strongly suspected and supported, from reasoning that is organized, refined, and tested using computer modeling.

Accommodating changes in climate with changes in operating rules can often require changes in reservoir outlets (which can be costly) and changes in federal operating policies and authorizing legislation (which can be protracted and difficult).  Nevertheless, it is comforting to know that existing policies for some reservoirs seem to do well with changes in climate, and that making other reservoirs more reactive to upstream wetness conditions might make them more resilient to changes in climate, even before we know what the changes are.  Such changes in policies, while politically awkward and requiring some expense, appeared likely to be less expensive than major reservoir expansions or the costs of a major flood.

In terms of floods, climate warming need not mean that the sky is falling.  We are likely to have considerable ability to respond effectively, but in some cases, we will likely to need to make major changes.  Appropriate preparations will not be easy, but they should be possible with capable institutions at the federal (US Army Corps of Engineers), state (DWR, Central Valley Flood Protection Board), and local (counties, cities, and levee districts) levels.

Jay Lund is the director of the Center for Watershed Sciences. Ann Willis is a staff researcher at the Center for Watershed Sciences.

Further reading:

Willis, Ann D; Lund, Jay R.; Townsley, Edwin S.; Faber, Beth A (2011), “Climate Change and Flood Operations in the Sacramento Basin, California,” San Francisco Estuary and Watershed Science, July, Vol. 9, No. 2, 18 pages.

Posted in California Water, Climate Change, Floodplains | Tagged , , , , , , , | 2 Comments

Irrigation Management in the Western States, seen from overseas

by Fandi P. Nurzaman

The transformation of the western United States by irrigation offers hope for developing countries looking for models to improve their irrigation system for food security or agricultural prosperity.

The transformation of the American West from barren desert and low value grazing into one of the largest agriculture areas in the United States would be impossible without irrigation. Water supply infrastructure currently delivers waters for about 40 million acres of irrigated land (74% nationwide) across arid regions in the Western.

Replicating the same irrigation systems from the Western States would be impossible, but how irrigation institutions and financing mechanisms were developed to adapt some challenges in the past could still be useful practices.

Irrigation has been employed in the 17 western states for several centuries. At least since the 7th century, vast networks of canals were used by the Hohokam people in central Arizona for agricultural irrigation for the highest population density in the prehistoric of American Southwest. The Hohokam irrigation system was simple, but applied hydraulic engineering design features still used today and also became the precursor to modern-day Arizona’s major canal system.

During Spanish colonization in the American Southwest, irrigation was used to support agriculture and ensure political control in these areas by the Spanish Government. Settlers were granted access to irrigation water to secure and defend the colonized areas. The construction of complex and expansive irrigation systems, along with the introduction of water governance in those systems, became one of the most significant accomplishments of the Spanish Colonial period in the American Southwest.

Early in the 19th century, irrigation-based communities became more common and widespread in the western states as . The Mormons established the first irrigation-based economy and basic principles of water law. These principles became an important legal precedent for Western water law when they abandoned riparian water rights and adopted the doctrine of “prior appropriations for beneficial use.

After acquisition of the West by the United States, irrigation systems were rapidly developed to promote economic development and speed privatization of newly acquired arid and semiarid public land. Hundreds of irrigation projects and major dams were constructed as part of the Reclamation Projects, which currently irrigate about .

Expansion of irrigation in the western states also was supported by the transformation of institutions that deliver water and operate irrigation infrastructures. Neighbor-farmers created coownership in joint irrigation networks. These institutions ranged from unofficial organizations (unincorporated mutual systems) to legally constituted cooperative corporations under state law (incorporated mutual systems) or special local political subdivisions of state government (irrigation districts). Large irrigation projects with larger economies of scale and capital expenditures were not feasible by simple cost sharing among farmers. Institutional breakthroughs were developed to tackle financial barriers and to adapt regulatory challenges.

More recently, new problems pose challenges for water supply that developing countries should consider. As the population and concern for environment and sustainability grow, managing irrigation systems in the Western States becomes more challenging. Some water must be dedicated to ecological benefits, but environmental water uses were rarely counted as major water uses in the past. These , either for recreation or the environment, will increase competition for water and make irrigation water more vulnerable to water shortage, a perennial risk in the American West.

California’s recent Sustainable Groundwater Management Act (and similar regulations in other states) also will affect farmers and ranchers who use groundwater to supplement or replace shortages of surface water. These regulations will increasingly shape how groundwater is managed.

Western US farmers also have faced increasing discontinuance of irrigation due to inability to get irrigation water or economic driven factors such as rising costs for irrigation water. Decreasing irrigated acres in the long term could lead to economic losses for rural areas in the Western States. Farmers are likely to increase use of precision irrigation and to increase on-farm irrigation efficiencies. When severe drought happens again and water restrictions and curtailments occur, farmers might prefer to fallow some fields (to support other higher value crops) or sell their water during the drought. These irrigated areas significantly contribute to the United States’ economy and the Western States’ economies. Without irrigation, many agriculture products, especially wheat, vegetables, fruits, tree nuts, and berries, along with cattle farming and dairying products would be imported from other parts of the United States or other countries.

Irrigation has a foundational role in the development of the Western US. Developing countries could benefit by understanding the challenges encountered by the Western US and adjusting their irrigation system based on the Western US practices in order to address local issues they are facing.

Fandi P. Nurzaman is a graduate student at Department of Civil and Environmental Engineering, UC Davis and National Planner for Water Resources and Irrigation at the Indonesian Ministry of National Development Planning.

Further reading

Bretsen, S. N., Hill, P. J. (2007). “Irrigation Institution in American West.”  UCLA Journal of Environmental Law and Policy Vol. 25:283.

Howard, J. B. (1992). “Desert Canals: Hohokam Legacy.“ Pueblo Grande Museum Profiles No. 12. https://www.phoenix.gov/parkssite/Documents/d_048513.pdf.

Hutchins, W. A. (1931). “Summary of Irrigation-District Statutes.” United States Department of Agriculture, Miscellaneous Publication No. 103, January 1931.

Mays, W. M., (2016). “Irrigation Systems, Ancient.” Water Encyclopedia: Science and Issues. http://www.waterencyclopedia.com/Hy-La/Irrigation-Systems-Ancient.html. (November 29, 2016).

Nurzaman, F.P. (2017) Irrigation Management in the Western States, MS project Report, Department of Civil and Environmental Engineering, University of California – Davis.

Rivera, J. A., Glick, T. F. (2002). Iberian Origins of New Mexico’s Community Acequias.” The XIII Economic History Congress, Buenos Aires, Argentina, July 2002.

Zarr, G. (2016). “How the Middle Eastern Irrigation Ditch Called Acequia Changed the American Southwest.” AramcoWorld Vol. 67, No. 5, September/October, 2016.

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