Better Information Can Help the Environment

by Henry McCann and Alvar Escriva-Bou

This blog was originally posted on the Public Policy Institute’s Viewpoints blog.

Salmon swimming near Lake Tahoe. Image courtesy of PPIC.

We know that California’s aquatic species are at risk from a host of stressors and that drought pushes them closer to the brink. Yet there are significant gaps in our understanding of key factors affecting ecosystem health that make it difficult to effectively manage water for the natural environment. Good practices from other dry places offer lessons for protecting our struggling species and improving conditions in troubled ecosystems.

Water accounting―tracking how much is there, who has claims to it, and what is actually being “spent”―can provide a clearer picture of how and when to allocate water for the environment. Other states have improved their water information systems and reduced environmental problems.

For example, the Colorado Water Conservation Board has a network of high-tech stream gages to monitor freshwater ecosystems. These gages send text or email alerts to state environmental water managers within minutes of approaching low-flow conditions. Staff can respond quickly by requesting an evaluation of priority water needs among local water users and, where possible, shifting water to meet environmental needs.

By comparison, California lacks stream gages on half of the rivers and streams that support critical habitats. This makes active management of environmental water during droughts very difficult, if not impossible, in many parts of the state.

Better accounting can also help us prepare for drought, rather than just respond to it. Making better use of water during average and wet years can stabilize or enhance at-risk ecosystems. This increases their resilience to drought.

For example, drought-prone Victoria, Australia, uses sophisticated water accounting tools to coordinate environmental flows for all types of water years. Victoria also collects and organizes information on a number of critical ecological indicators for thousands of miles of streams and wetlands. This inventory informs Victoria’s short- and long-term decision making about where and when water will be most beneficial to ecosystems and thus helps build drought resilience.

California has a significant body of research on freshwater ecological indicators, but the information isn’t organized in ways that make it readily useful to environmental water managers.

Managing water for the environment is more than a technical challenge. It’s a social process that relies on complex decisions made by water users, regulators, and other stakeholders. Examples from other arid regions suggest that this social process is improved by having access to accurate and timely information. Strengthening water accounting in California is key to improving our ability to manage water for the environment and building the social license necessary to act. Before the next drought pushes more freshwater species to the brink, we would be wise to follow the lead of other semi-arid regions and invest in accounting systems that improve our understanding and management of our rivers and streams.


Henry H. McCann is a research associate at the PPIC Water Policy Center, where he works on data collection, analysis, mapping, and legislative tracking. Alvar Escriva-Bou is a research fellow at the PPIC Water Policy Center.

Further reading

Read the report Accounting for California’s Water (July 2016)
Read “Three Lessons on Water Accounting for California” (PPIC Blog, August 8, 2016)

Posted in California Water, Conservation, Planning and Management, Sustainability | Leave a comment

The Future of California’s Unique Salmon and Trout: Good News, Bad News

Rainbow Trout. Photo taken by Mike Wier. Courtesy of CalTrout.

by Robert Lusardi, Peter Moyle, Patrick Samuel, and Jacob Katz

California is a hot spot for endemic species, those found nowhere else in the world.  Among these species are 20 kinds of salmon and trout. That is an astonishing number considering California is also literally a hot-spot in terms of summer temperatures and that these salmonids are cold-water adapted. These 20 endemic are joined by 12 other species with broader distributions, north along the Pacific Coast.  In California, native salmon and trout are at the southern end of the range.  They survive here because mountains intercept rain and snow in the cooler months of the year and the powerful California Current keeps the ocean and coast cool year-round.  The big question is: can California’s diverse salmon and trout continue to persist in the face of a warming climate and declining coldwater resources?

We think the answer to this question is yes. But first, the bad news.  A new report issued by the Center for Watershed Sciences and California Trout has found that nearly 75% of the state’s salmon and trout (salmonids) could be extinct within the next 100 years.  Nearly 45% could meet the same fate in just 50 years if present trends continue. The good news is that the report shows that most of these fishes can continue to persist if appropriate actions are taken.

Chinook Salmon jumping out of the water. Photo taken by Mike Wier. Courtesy of CalTrout.


The report, State of the Salmonids II: Fish in Hot Water, was officially released on May 16th.  Originally conceived as an update on a report published in 2008, this report contains new information on how to maintain resilient populations. The report explores three important questions: 1) what is the status of all California salmonids, both individually and collectively, 2) what are the major factors responsible for their present status, and 3) how can California’s salmonids be saved from extinction?  To answer these questions, we conducted a thorough literature review and interviewed more than 70 species experts from fishery management agencies over a 14-month period.  Based on this research and interviews, the authors generated a full scientific account for each species. Each account was then peer reviewed by at least one, and often two or more, species experts.

We evaluated the status and future of each species using a standard set of seven criteria: (a) area occupied, (b) estimated adult abundance, (c) degree of dependence on human intervention to keep the species going, (d) physiological tolerance to changing conditions, (e) genetic risks, (f) vulnerability to climate change, and (g) threats from other factors, such as dams and diversions (each factor was evaluated separately to produce a composite score).  Each of the seven criteria was scored on a scale of 1 to 5, with 1 indicating the most extreme threat.  The scores were then averaged to produce an overall score, rating the ‘level of concern’ for each species (Table 1).  The scoring indicated 14 species were of critical concern, with a high risk of extinction in the wild, nine were of high concern, seven of moderate concern, and one of low concern (Figure 1).  One species, bull trout, is already extinct in California.

Table 1. Status categories, score ranges, and definitions for California salmonids.

Figure 1. Respective listings by state and federal management agencies, status scores, and Levels of Concern for California’s native salmonids.

Looking at this another way, 71% of anadromous salmon and trout and 74% of inland trout in California scored as critical or high concern, indicating a high likelihood of extinction in the next 100 years.  Further, 25 taxa are worse off than they were in 2008.  Downward changes in status were attributed to a continued decline from multiple factors, an improved scoring system, and the recent historic drought.  Species most likely to disappear from California included coho salmon, chum salmon, pink salmon, Sacramento winter-run Chinook salmon, two distinct populations of spring-run Chinook salmon, two distinct populations of summer steelhead, steelhead of the south coast, California golden trout, Kern River rainbow trout, and McCloud River redband trout.

Chinook Salmon. Photo taken by Mike Wier. Courtesy of CalTrout.

The good news is that 31 of 32 salmonids are still present in California.  This speaks to their ability to persist during difficult periods.  In fact, salmonids have been able to persevere for more than 50 million years despite volcanic eruptions, earthquakes, mega-droughts, and other climatic extremes.  Their ability to make it through these events is a reflection of the evolutionary enriched behavioral and life history diversity among populations and species.  Behavioral and life history diversity contribute to population and species resiliency under changing conditions.  When times are challenging, some populations die off while others hang on, ensuring long-term species persistence.

Over the last century, however, the ability of most of these salmonids to adapt to changing conditions has been greatly reduced due to rapid and extreme habitat degradation and interactions of hatchery salmonids with wild salmonids.  As a result, salmonids are more vulnerable to changing conditions today than ever before. This is particularly alarming considering that our analysis found that climate change was a critical or high threat for 84% of all salmonids in California, making it the single largest threat.  Climate change is affecting streamflow and temperature, reducing habitat, shifting food webs, and changing interactions between native and nonnative fishes.

The State of the Salmonids II report makes it clear that many native salmonids in California are on a trajectory towards extinction, if present trends continue.  The report outlines a set of solutions, termed “return to resilience,” the central tenet of which is improving behavioral and life history diversity of salmonid species.  The general strategy can be broken into two sets of actions:  managing places and conceptual strategies.  Within “places,” we recommend focusing on protecting and/or restoring four important types of habitats throughout California.  These include the following, which are not mutually exclusive:

1) Stronghold Watersheds, or the remaining fully functioning aquatic ecosystems in California such as the Smith River, Blue Creek, and the Eel River, so that they may continue to protect and enhance salmonid diversity,

2) Source Waters such as mountain meadows, springs, and groundwater, which will be vitally important in buffering the effects of climate change and providing cold water during the late summer and drought, and

3) Productive and Diverse Habitats including floodplains, lagoons, coastal estuaries, and spring-fed rivers—these are some of the most productive aquatic systems in California which have been shown to increase salmonid growth rates, alter migration timing and life history diversity, and improve adult returns.

4) Endemic Trout Waters. These are the isolated waters scattered around the state that are important for species like Eagle Lake Trout, California golden trout, and McCloud River redband trout. If the waters are altered significantly, the factors that make the endemic species unique will be lost.  Good examples, in progress, include restoring streams that support Goose Lake redband trout, restoring Pine Creek (the principal spawning stream for Eagle Lake rainbow trout), or enhancing flows in streams that support southern steelhead.

The report also discusses three important, conceptually based strategies to enhance salmonid diversity and production.

The first strategy is to embrace reconciliation ecology as a management tool.  Most ecosystems in California are altered by human actions with people continuing to be a key part of the ecosystem.  If the mechanisms supporting enhanced salmon and steelhead growth and diversity can be replicated in working landscapes, then this concept should be embraced.  A good example of this is the Yolo Bypass in the Central Valley where rice fields are being used as surrogate floodplain habitat and have been shown to greatly enhance growth in juvenile salmonids.

Southern Steelhead. Photo taken by Mike Wier. Courtesy of CalTrout.

We also recommend improving habitat connectivity and passage to historical spawning and rearing habitat. In general, improving connectivity among habitats used by different life stages of salmon and trout is desirable, as is renewed connectivity to historical spawning and rearing habitats.  Restoring connectivity of main rivers to their floodplains is one example of this. This also includes providing volitional passage over dams or removing dams that are no longer economically viable.  Access to historical spawning and rearing habitat may enhance population diversity and resilience to change.

The final concept for managing coldwater fishes is genetic management. The genetic effects of hatchery salmonids on wild fish are numerous and well documented.  Broad changes in genetic management and a reduction in interactions between hatchery and wild fish is required and is of fundamental importance.  At a minimum, such changes include the need to reduce gene flow between hatchery and wild salmonids, minimize straying of hatchery fish into adjacent watersheds, and marking all hatchery fish so that they can be distinguished from wild fish.

These “return to resilience” strategies are not limited by geography or taxonomic boundaries.  Rather, the actions should to be applied broadly throughout California if we want to have these iconic fish around for future generations of Californians.  The challenges in improving salmonid behavioral and life history diversity are not easy and require collective will.  We are optimistic that positive change is imminent and that if the solutions are fully implemented, many of the species reviewed in the State of the Salmonids II report will thrive in the future.

Robert A. Lusardi is a researcher at the Center for Watershed Sciences and is the California Trout-UC Davis Coldwater Fish Scientist.  Peter Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences.  Patrick Samuel is the Conservation Program Coordinator for California Trout. Jacob Katz is a Senior Scientist at California Trout.

Further reading

State of the Salmonids: Fish in Hot Water

Posted in Biology, California Water, Climate Change, Conservation, Fish, reconciliation, Salmon, Stressors, Uncategorized | Tagged , , , | 6 Comments

Facing Extinction II: Making hard decisions

Sacramento perch is an example of ‘gray’ extinction because it has been extirpated from its native habitats in the Central Valley. It exists only in a diminishing number of places where it has been transplanted. Photo is by Chris Miller of the Contra Costa Vector Control Agency and is from the CalFish website.

by Jason Baumsteiger and Peter Moyle

In part I of our blog, we projected a bleak future for many freshwater fishes, especially in California. Some difficult decisions will need to be made to prevent extinctions or to verify them.  However these decisions will rely on answers to one sweeping question: When is a species, in fact, extinct?

Some may argue this is a simple black/white or presence/absence question. But is it really? What if the species’ existence depends completely on humans? What if it no longer exists in its natural habitat or in the wild? What if it has been hybridized or genetically engineered? In such cases, is it fair to say this species is still the same as its wild predecessor?

In our recent paper, we attempted to tackle these questions and provide an honest, although imperfect, way to assess extinction. The first involves accepting that “grey extinction” exists. This is an area between formal threatened/endangered status and global extinction, where a species is in limbo – it is partially extinct. We know this sounds weird because under traditional usage extinction is an all or nothing proposition. However, there are in fact grey areas; they fall into five categories. Each represents ways a species may be partially extinct. These categories are by no means exhaustive, but do represent a reasonable framework where partial extinction can be examined closely. We look at these categories through the eyes of biologists trying to conserve species through either a single-species or a multi-species approach. We then weave these ideas into a decision tree to help managers recognize fishes (or any organism for that manner) which have reached “grey extinction” limbo.

Categorizing “grey extinction”

Mitigated extinction- This category represents the many ways that a species can become dependent on humans for its existence. The formal term is conservation-reliant but it just means that if we are not there to provide support, the species will quickly become globally extinct. Actions might include protection from predators, protection of habitat or even finding mating partners. Winter-run Chinook are a good example: they depend on humans for spawning habitat and early life-history protection (food, predator and disease avoidance). Without human intervention, winter-run Chinook (thanks to Shasta Dam) would quickly cease to exist.

Regional extinction – Here we are talking about what happens when a significant portion of a species’ range has been lost. Now you might say, isn’t that just extirpation? To which we would say, not necessarily. Regional extinction applies when a very distinct portion of that range is lost, such as a region occupied by a distinct population segment (DPS) or an evolutionarily significant unit (ESU). In California, a good example is the isolated population of bull trout that once existed in the McCloud River, which became extinct in the 1970s. The species is still widely distributed and a threatened species in much of its range, but it is now absent from California.

Native-range extinction – As the name implies, this is a species which no longer exists in its natural range but may exist elsewhere (say a reservoir somewhere). So while there are “wild” fish swimming about, they are not in the area in which they originally evolved. In California, Sacramento perch have disappeared from their native habitats in Central California. However, they were planted around the West as a gamefish that could live in alkaline waters, developing large populations in places such as Crowley Reservoir in the Owens Valley or Pyramid Lake in Nevada.

Fish were caught in Abbott’s Lagoon Pt Reyes. Photo by Peter Moyle.

Wild extinction – This category is one step further than native-range extinction. Now the species only exists as a captive population (think hatchery or zoo). Delta smelt are dangerously close to falling into this category.

Apparent extinction – This category is the final “holding pattern” category when we think the species is globally extinct because we cannot find it anywhere. However, we want to wait to be sure. We talked briefly about this in part I of the blog. Right now the International Union for Conservation of Nature (IUCN) tells us to wait 50 years before declaring extinction, but there is a big difference between species with 1 year vs. 25 year generation times. Therefore we propose a waiting period based on generation time: 1-5 years = 10 generations; 5+ years = 5 generations.

Single-species vs. Multi-species approaches

We have determined it is time to act. But how best to do so?  The current agency approach is based on single species (per the Endangered Species Act). As a species becomes endangered, we start doing everything we can to conserve that species, one species at a time. But as we mentioned, the endangered list is growing quickly.  These approaches will become cost-prohibitive as the list gets too big. And by law, work must continue until that species is “recovered”, which could essentially mean forever for many species. Instead we argue for taking a multi-species approach to conservation. Go in and restore the original habitat (or at least a reasonable portion of it). This saves both the species in peril AND all the species that naturally coexists with it. This might incur a huge cost initially, but if done right would be a one-time cost that returns native fishes to their native habitat in abundance. In other words, restore the system not just the numbers.

It is very important to note that we are NOT against human involvement in the saving of species. By no means! We are all for it. Some action is better than doing nothing. We simply want to stress the need to engage in conservation strategies that keep natural species in their natural habitats, where they can undergo natural selection for as long as possible. Administering artificial selection to save them, putting the species into “grey extinction,” should be a last resort. And we felt it is important to distinguish between those species which have been subject to such methods (artificial selection) from those which have not. The latter would seem to have a greater chance of survival in the wild. More information improves decision-making.

When we put these ideas together, we generated a decision tree to help navigate the many categories and approaches that one might take in assessing extinction (Fig. 1). This tree starts with the basic, but big, assumption that our society really wants to prevent more extinctions. Again our purpose is to show the pathways from traditional threatened/endangered listings to global extinction – or as the case may be, to  conservation successes. Our decision tree has checkpoints throughout which would be a great place for biologists and stakeholders to sit down and assess progress and future approaches. We recognize that this is not an all-inclusive look at all things extinction, but we do see it as a starting point to better management of species at every level.

Fig 1. Decision tree assessing extinction progression. Checkpoints are decision nodes and boxes are extinction categories. After checkpoint #2, two trajectories are indicated, one reflecting decreasing habitat availability (left) and the second reflecting increasing conservation-reliance and decreasing habitat availability (right). From Baumsteiger and Moyle (2017).

In an era where the integrity of science is being questioned, we can no longer afford to hide these facts and avoid these difficult questions. Transparency is paramount. People need to know how complex the issues are and what we are facing. Our paper is an attempt to meet this growing need, to lay our cards on the table to show what managers are up against when it comes to assessing extinction. Regardless of politics, we are all part of and depend on the same global ecosystem. How long should we allow species to drop out of that system before we become concerned? Extinction is very real, very permanent and the numbers in the gray area are increasing. The time is now to focus on these species before the slide accelerates. After all, decisions to save species from now on will only become increasingly harder.

Jason Baumsteiger is a Center for Watershed Sciences post-doctoral research fellow with Drs. Peter Moyle and Mike Miller. Peter Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences. 

Further reading

Baumsteiger, J. and P.B. Moyle 2017. Assessing extinction. Bioscience 67: 357-366.

Posted in Biology, Conservation, Fish, Planning and Management | Tagged , | 3 Comments

Facing extinction: California fishes

Thicktail chub. Preserved specimen from the California Academy of Sciences. Photo by P Moyle

by Peter Moyle and Jason Baumsteiger

At least two species of California fishes appear to be facing imminent extinction in the wild: delta smelt and winter-run Chinook salmon.  These species could join about 57 other North American fishes declared extinct. If we are fortunate, these species will continue to scrape by with small populations, maintained through considerable human effort.  But if we are unfortunate, these fishes, and likely other species, will disappear in the near future.   This likelihood suggests we need answers to the following questions:

  1. How do we know when a species is extinct? How long do we have to wait from the time the apparent last individual is captured to declaration of extinction?
  2. Who makes the official determination that a species is extinct?
  3. What role do captive populations play in the extinction process?
  4. Why is there a need to have an extinction policy in place?

Second to last known bull trout caught in California ,1975. Photo by P. Moyle

Rather than answering these questions, we start by answering another question: What do previous fish extinctions tell us about preparing for future extinctions?  Seven species of fish have gone extinct in California (Moyle 2002), eight if the eulachon (an anadromous smelt that has largely disappeared over the last 2 decades in CA) is counted. The Tecopa pupfish disappeared in 1970, after Tecopa Hot Springs was converted to a resort.  The High Rock Spring tui chub disappeared in 1989 when the spring was turned into a fish farm.  Two Colorado River fishes, Colorado pikeminnow and bonytail, are extirpated from the highly altered and polluted portion of the river in California but are present in habitats upstream, maintained largely by hatchery production. The last bull trout in California was caught in 1975 by UC Davis graduate student Jamie Sturgess after two fruitless summers spent searching for them in the McCloud River.  Attempts to reintroduce bull trout into the river in the 1980s failed. The Clear Lake splittail was not described as a species until 1973, by which time it was probably already extinct. Finally, the last recorded thicktail chub was caught in Steamboat Slough in the Delta in 1957.

Second to last known bull trout caught in California ,1975. Photo by P. Moyle

As far as we know, none of these fish were ever officially declared extinct for the first time by state or federal agencies. Extinction was usually recorded in an academic publication (Moyle 2002) and thereafter largely ignored. An exception may be the thicktail chub, which was declared extinct by Mills and Mamika in an administrative report by the California Department of Fish and Game, 23 years after the last fish was caught.  Part of the delay to declare extinction stems from fact that the seven species became extinct before the Endangered Species Act (ESA) was written or widely used; there was no endangered status declared to warn of potential extinction. Let us now address the questions posed at the beginning of this article.

1. How do we know when a species is extinct?  How long do we have to wait from the time the last individual is captured to declaration of extinction?

It would be easier to declare a species extinct if the last individual had a name, like Martha, the last passenger pigeon.  Or if all of a species habitat was destroyed, like the Tecopa pupfish and High Rock Spring tui chub, although even pupfishes thought be extinct have been re-discovered (Miller et al. 1989).

Extinction of fishes in big waters, such as the Delta or Clear Lake, is especially hard to pin down. There always seems to be the potential for a small population to be hidden somewhere, missed by sampling efforts, as happened with the Miller Lake lamprey in Oregon, once declared extinct.  Delta smelt has been unexpectedly discovered spending their entire life in fresh water in places like the Sacramento Deepwater Ship Channel.  And the small numbers caught by sampling programs in recent years probably still represent a population of several hundred or thousand. So hope springs eternal.

But when regular sampling programs cease catching any smelt and targeted efforts to capture them fail, then extinction is a likely conclusion.  When/if that happens to delta smelt, we recommend that targeted sampling cease (to avoid killing the last fish by sampling) and for biologists to wait for individuals to reappear or not in the regular sampling programs for 10 generations (20 years, assuming some smelt live 2 years).  The same general protocol would apply to other species as well, with sampling efforts based on generation time, not years.

2. Who makes the official determination that a species is extinct?

This is not clear.  State and federal Endangered Species Acts are designed to prevent extinction, not to assess it. For species like delta smelt and winter-run Chinook salmon, there will be considerable pressure to declare them extinct because maintaining even small populations requires releases of water from dams.  One possibility would be to have the agency responsible for listing a species convene a panel of 5-10 individuals representing all regional fisheries agencies and/or possessing real expertise on the species to make the determination. Another possibility is to convene a panel of fish biologists from outside the state to review the data and make a recommendation to the heads of CDFW, USFWS, and NMFS, who would make the actual determination of extinction.

3. What role do captive populations play in the extinction process?

Both winter-run Chinook salmon and delta smelt have populations in captivity, under careful genetic management to maintain genetic diversity.  If wild fish disappear, then a successful release of hatchery fish into the wild to re-establish wild populations depends on (a) the presence of natural conditions that will allow introduced individuals to thrive and reproduce, (b) hatchery fish not having become highly domesticated through ‘natural’ selection for survival in a hatchery environment, and (c) whether fish reared in artificial conditions are able to avoid predators, find food, and engage in reproductive activities once released.

The first condition is problematic for delta smelt because it would presumably require large increases in Delta outflow and control of several invasive species that compete with or prey on smelt.  This condition is the reason why trap and haul of winter-run Chinook adults to, and juveniles from, the McCloud River is being proposed by NMFS as a way to save the species, a controversial proposition (Lusardi and Moyle, in press).

The second condition is being handled by genetic management that allows controlled mating of individuals, with preference given to mating fish taken from the wild. How well that will work if wild fish are gone is not clear. Assuming the first two conditions are met, meeting the third condition will require creative rearing and reintroduction strategies where fish learn how to survive in a natural environment.

4. Why is there a need to have an extinction policy in place?

Extinction is increasingly becoming a reality for many species. Burkhead indicates that 57 fish taxa were driven to extinction in North America between 1898 and 2006, a rate 877 times greater than the natural background rate.  They estimated that, conservatively, 53-86 more fish taxa will be extinct by 2050 worldwide.  This fits with the projections of Moyle et al. that climate change will accelerate extinctions of California fishes. Ricciardi and Rasmussen modeled the extinction trajectories for all the aquatic fauna in North America and estimated extinction rates of 4% per decade “which suggests that North American freshwater ecosystems are being depleted of species as rapidly as tropical forests (p. 1220).”

Further studies by Howard et al. for the aquatic fauna of California support this conclusion as does the study of Grantham et al., which shows a disconnect  between fishes needing protection and protected areas.  Thus the evidence is growing that extinctions in freshwater ecosystems of California will become commonplace unless systematic action is taken to prevent them.  No doubt there are similar trends in terrestrial organisms.

In conclusion, the best strategy is not to let any fish species go extinct. If a fish species does go extinct, despite our best efforts, then funds and water used to keep the species going should be redirected towards keeping other species from following the same extinction trajectory. But to avoid spending scarce conservation dollars on species that have already gone extinct, we need a policy in place that provides a pathway for declaring a species officially extinct. We address this in part II of our blog.

Peter Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences. Jason Baumsteiger is a Center for Watershed Sciences post-doctoral research fellow with Drs. Peter Moyle and Mike Miller.

Further Reading

Baumsteiger, J. and P.B. Moyle 2017. Assessing extinction.  Bioscience 67: 357-366.

Burkhead, N. 2012. Extinction rates in North American freshwater fishes, 1900-2010. Bioscience 62: 799-808.

Grantham, T. E., K.A. Fesenmyer, R. Peek, E. Holmes, R. M. Quiñones, A. Bell, N. Santos, J.K. Howard, J.H. Viers, and P.B. Moyle.  2016.   Missing the boat on freshwater fish conservation in California. Conservation Letters. DOI: 10.1111/conl.12249.

Howard J.K., K.R. Klausmeyer K.A., Fesenmyer, J. Furnish, J. Gardali, T. Grantham, J.V.E. Katz, S. Kupferberg, P. McIntyre, P.B. Moyle, P.R. Ode, R. Peek, R. M. Quiñones,  A.C. Rehn, N. Santos, S. Schoenig, L Serpa, J.D. Shedd, J. Slusark, J.A. Viers, A. Wright, and S.A. Morrison. 2015. Patterns of freshwater species richness, endemism, and vulnerability in California. PLoS ONE 10(7): e0130710. doi:10.1371/journal.pone.0130710

Lusardi, R. and P. B. Moyle.  In  press. Two-way trap and haul as a conservation strategy for anadromous salmonids.  Fisheries.

Mills, T.J. and Mamika, K.A., 1980. The thicktail chub, Gila crassicauda, an extinct California fish. California  Department of Fish and Game, Inland Fisheries Endangered Species Program Special Report 80(2): 1-20.

Miller, R.R., J.D. Williams, and J.E. Williams 1989. Extinctions of North American fishes in the past century.  Fisheries 14(6):22- 38

Moyle, P.B., J. D. Kiernan, P. K. Crain, and R. M. Quiñones. 2013. Climate change vulnerability of native and alien freshwater fishes of California: a systematic assessment approach. PLoS One.

Ricciardi ,A. and J. B. Rasmussen. 1999. Extinction rates of North American freshwater fauna. Conservation Biology 13: 1220–1222.

Harrison I.J. and M.L.J. Stiassny. 1999. The quiet crisis: a preliminary listing of the freshwater fishes of the World that are extinct or “missing in action”. In R.D.E. MacPhee (ed.), Extinctions in Near Time: Causes, Contexts, and Consequences,pp.271-332. Kluwer Academic/Plenum Publishers, New York.

Posted in Biology, Conservation, Fish, Planning and Management | Tagged , | 5 Comments

GRA’s Contemporary Groundwater Issues Council weighs in on BMPs for Groundwater Sustainability Plans

Source: California Department of Water Resources

by Thomas Harter, Vicki Kretsinger Grabert, Reid Bryson, and Tim Parker

On May 26, 2016, eight days after the California Water Commission voted to approve emergency regulations for Groundwater Sustainability Plans, the Groundwater Resources Association (GRA) held the sixth annual workshop of the Contemporary Groundwater Issues Council (CGIC) to address a closely related component of Sustainable Groundwater

Cover for the Ground Water Sustainability Plan (GSP) Annotated Outline. Source: California Department of Water Resources

Management Act (SGMA) implementation: best management practices (BMPs).  With input from CGIC and other groups, the Department of Water Resources (DWR) has since
published its first round of BMPs and Guidelines on some core activities within Groundwater Sustainability Plans (GSPs): monitoring protocols, monitoring networks, development of hydrogeologic conceptual models, water budgets, and modeling. Additional BMPs and guidelines as well as statewide data support will be forthcoming as Groundwater Sustainability Agencies (GSAs) prepare their GSPs. Guidance on establishing sustainable management criteria, on engaging with tribal governments, and on communication and stakeholder engagements are next on DWR’s list.

The CGIC brainstormed around several areas related to BMPs and key actions by GSAs. The workshop results identified some key short-term and long-term GSA activities that would need support by the state. Short-term actions included the need for organization and communication at the local level to create or strengthen the foundation for future groundwater management decision-making.

Suggestions for short-term actions included:

  • building trust amongst local agencies, stakeholders, and the public through clear communication about the goals of sustainable groundwater management and governance options;
  • targeted capacity-building to encourage participation by all stakeholders; and
  • coordination of current monitoring and modeling efforts within a basin or subbasin.

Suggestions for long-term actions included:

  • investing in monitoring programs to fill data gaps,
  • developing projects to enhance recharge (particularly in areas subject to overdraft and areas where hardpans or other physical constraints limit natural recharge), and
  • developing a systematic approach to the evaluation and revision of water budgets to improve their accuracy.

Source: California Department of Water Resources

The BMPs since developed by DWR provide support for some of these important GSA
activities. Some ideas, considerations, and stated challenges around BMPs remain open and will continue to be discussed as GSAs, DWR, and the State Water Board move toward developing their GSPs. BMPs that the CGIC had also considered critical (but that did not make DWR’s initial round of publications) included governance, financing (both short-term and long-term), and (local) data-management systems.

Other, perhaps less urgent but important, state guidelines that the CGIC suggested that the state develop, included:

  • BMPs or guidances on water markets, groundwater-recharge rebates, and water-management approaches ranging from centralized decision-making to market-based allocations;
  • understanding and responding to uncertainty in water budgets,
  • process guidance for avoiding minimum thresholds and triggers, and
  • developing recharge programs (particularly those that encourage distributed recharge where a GSA or local agency may not be able to meter the amount of recharge, but which can nonetheless be significant on a regional scale).

Source: California Department of Water Resources

One area of particular concern included activities around the management of groundwater dependent ecosystems (GDEs) and surface water flows impacted by groundwater management. Many GSAs and local agencies will face challenges managing this important aspect of sustainability.  Some of those challenges stem from a lack of clarity in SGMA regarding the responsibility to manage groundwater basins to avoid impacts on GDEs, as compared to significant and unreasonable depletions of surface water.

Several participants noted that GSAs will need clear communication from DWR and the State Water Board as to the various datasets that the state will provide to GSAs versus those datasets that GSAs should anticipate developing at the local level.  Participants also noted that local agencies will need guidance from the state regarding its interpretation of requirements under SGMA for local agencies to:  (1) identify and map GDEs, and (2) avoid impacts to GDEs, relative to efforts associated with other interactions of surface water and groundwater, including non-ecosystem-related beneficial uses.  Urgency was placed at finding funding for additional surface water and groundwater monitoring to assess interconnected resources that may be implemented by the state and/or local agencies.

The CGIC suggested that DWR consider developing BMPs and guidance around several topics related to groundwater-surface water interaction:

  • monitoring surface-water/groundwater interactions at spatial and temporal scales relevant to basin management;
  • methods for modeling or otherwise quantitatively evaluating surface-water/groundwater interactions, including accounting for impacts that may result from groundwater pumpage that occurred after January 1, 2015, but that will not result in immediate impacts to groundwater-connected surface waters;
  • reservoir-management strategies for basins where reservoir releases have a significant impact on surface-water flow regimes; and
  • adaptive-management approaches suited to avoiding significant impacts to surface waters.

Thomas Harter is a groundwater expert at the University of California, Davis. Vicki Kretsinger Grabert (President and Senior Principal Hydrologist) and Reid Bryson are with Luhdhorff & Scalmanini, Consulting Engineers. Tim Parker is a consultant.

Further Reading

Sustainable Groundwater Management Act. CA Department of Water Resources

Groundwater Sustainability Plan Emergency Regulations (GSP Regulations). CA Department of Water Resources

BMP Framework Document. CA Department of Water Resources

BMP 1: Monitoring Protocols, Standards, and Sites. CA Department of Water Resources

BMP 2: Monitoring Networks and Identification of Data Gaps. CA Department of Water Resources

BMP 3: Hydrogeologic Conceptual Model. CA Department of Water Resources

BMP 4: Water Budget. CA Department of Water Resources

BMP 5: Modeling. CA Department of Water Resources

Preparation Checklist for GSP Submittal. CA Department of Water Resources

GSP Annotated Outline. CA Department of Water Resources

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

Accounting for Water in the San Joaquin Valley

SJV ave balance

Water Balance Inflow/Outflow Diagram (from Excel File). Parameter and source calculation details are explained in Appendix A of “Water Stress and a Changing San Joaquin Valley (PPIC, 2017)

by Brad Arnold1, Alvar Escriva-Bou1,2, Jay Lund1, and Ellen Hanak2

  1. University of California – Davis, Center for Watershed Sciences
  2. Public Policy Institute of California

Accounting for water supplies and uses is fundamental to good water management, but it is often difficult and controversial to implement. As with other types of accounting, this task is harder and costlier when information is not well organized.

Here we present a 30-year set of water balances for the San Joaquin Valley, California’s largest agricultural region and home to more than half of the state’s irrigated acreage. The valley has multiple sources of surface water and is the largest user of groundwater in California. Of particular interest in this region is understanding the extent of long-term depletion of water stored in aquifers (overdraft). This practice will need to be curbed as water users implement the Sustainable Groundwater Management Act (SGMA). Ending overdraft can be achieved by augmenting other water supplies and reducing net water use.

Annual estimates for water use and availability are available from California’s Department of Water Resources (DWR) and the U.S. Bureau of Reclamation (USBR). However, this information is often difficult to navigate and piece together, and has some important gaps. State water balances (e.g., DWR Bulletin 160 – California Water Plan Updates) are sometimes hindered by missing or inadequate data. They also are produced with significant lags; the state’s last published water balances are for 2010, and do not include any of the latest drought years.

To develop a high-level, up-to-date picture of water supplies and uses in the valley, we combined available public data to develop estimates of annual regional water balances for the years 1986 to 2015. Similar exercises should be done at the sub-basin and hydrologic region scales to enable local water users to develop and implement plans for bringing their basins into long-term balance under SGMA, using these balance data and information as planning tools.

The downloadable Excel file contains annual data, calculations, and sources (a detailed description of data and methods is provided in Technical Appendix A of PPIC, 2017). Changes in groundwater storage are calculated as the residual in the water balance—the difference between other water supplies and net water use. Total net water supply— from local and imported inflows, precipitation, and changes in storage (including groundwater overdraft or recharge)—must equal the sum of net water used or stored within the valley (in surface reservoirs and aquifers) plus exports and outflows.

These annual data show:

  • Local inflows from Sierra Nevada watersheds vary wildly between years, and drive regional groundwater pumping;
  • Net or “consumptive” water use—the water consumed by people or plants, evaporated into the air, or discharged into saline water bodies or groundwater basins—is fairly constant across these years. In drier years, stored surface water and groundwater pumping supplement annual inflows;
  • Variance in Delta imports from the State Water Project (SWP) and the Central Valley Project (CVP) is largely independent of other valley conditions. These imports are affected by water conditions in the Sacramento Valley, Delta pumping regulations, and water demand in other importing regions (especially Southern California);
  • San Joaquin River outflows also vary significantly, reflecting variable inflows from the Sierra Nevada watershed, as well as changes over time in environmental and water quality regulations on valley outflows.
  • Differences between annual water supplies and net water use result in changes in surface and groundwater storage. Wet years tend to increase storage and dry years tend to draw more water from reservoirs and aquifers.
Annual SJV balances

Annual Valley Inflow/Outflow Data.  Slight differences in totals are from changes in surface reservoir storage (not shown).

In most years, consumptive water use exceeds local surface and groundwater inflows, leading to overdraft of groundwater and concerns for long-term water use sustainability.  Valley-wide, just a few wet years saw net groundwater recharge. The 30-year average annual groundwater overdraft is roughly 1.8 million acre-feet per year (MAF/yr). It averaged 2.2 MAF/yr from 2001-2015—the driest 15-year period since the 1920s. Local watershed inflows average about 55 percent of total inflow; Bay-Delta inflows from SWP and CVP imports average about 25 percent of supplies, and direct diversions from the Delta by north-valley water users about 6 percent. Average shares of water sources in the San Joaquin Valley are in the charts below.

SJV water supply mix

San Joaquin Valley Annual Water Supply Breakdown (Periodic Averages). 
“Local supplies” indicates inflows from the Central and Southern Sierra Nevada and precipitation on the valley floor.

Our recent report, Water Stress and a Changing San Joaquin Valley, describes a range of approaches for bringing the valley’s water accounts into long-term balance. A variety of factors, including SGMA, water market opportunities, water rights, and other regulatory and management decisions, will lead water managers to rely increasingly on water accounting at the basin and sub-basin levels.

The valley’s overall dryness and the high variability between drought and wet years require better long-term water planning and more robust water accounting. Better water data collection and management—that is both more timely and transparent—is an important government role that will require stakeholders’ support. Improved accounting methods and data analysis across state and local agencies—as is common in several other western states—can facilitate better water management in this important region.

Excel File Notes:

  • Remember to ‘Enable Macros’ if prompted.
  • Sheets and workbook are protected to avoid accidental changes. As such, source data sheets are shown but formulas cannot be edited.

Further Reading:

Alvar Escriva-Bou, Henry McCann, Ellen Hanak, Jay Lund, Brian Gray (2016). Accounting for California’s Water. 28 pp. Public Policy Institute of California, San Francisco, CA.

Alvar Escriva-Bou, Henry McCann, Elisa Blanco, Brian Gray, Ellen Hanak, Jay Lund, Bonnie Magnuson-Skeels, and Andrew Tweet (2016). Accounting for Water in Dry Regions: A Comparative Review. 177 pp. Public Policy Institute of California, San Francisco, CA.

Ellen Hanak, Jay Lund, Brad Arnold, Alvar Escriva-Bou, Brian Gray, Sarge Green, Thomas Harter, Richard Howitt, Duncan MacEwan, Josué Medellín-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.

Jay Lund (2016). “Better Accounting Begets Better Water Management.” California WaterBlog.

Jay Lund (2016). “How Much Water was Pumped from the Delta’s Banks Pumping Plant? A Mystery.” California WaterBlog.

California Department of Water Resources (2013). Bulletin 160: California Water Plan Update 2013, Volume 2: Regional Reports – San Joaquin River Hydrologic Region. Division of Statewide Integrated Water Management: Strategic Water Planning.

California Department of Water Resources (2013). Bulletin 160: California Water Plan Update 2013, Volume 2: Regional Reports – Tulare Lake Hydrologic Region. Division of Statewide Integrated Water Management: Strategic Water Planning.

Posted in Uncategorized | 8 Comments

California’s drought and floods are over and just beginning

California is weird

California’s weather is weird and wild.  California has more extreme precipitation years (dry and wet) per average year that any other state.  Coefficient of variation for annual precipitation at weather stations for 1951-2008.  Larger values have greater year-to-year variability. SOURCE: M. Dettinger, et al. 2011. “Atmospheric Rivers, Floods and the Water Resources of California.” Water 3(2), 445-478.

By Jay Lund 

California is a land of extremes – where preparing for extremes must be constant and eternal.

The last six years demonstrated California’s precipitation extremes. From 2012-2015, California endured one of its driest years of record.  2016 was an additional near-average year, classified into drought because water storage levels were so low.

2017 will likely be the wettest year on record in northern California and one of the wettest years ever in most of California.  Most of California has over 160% of average precipitation, with over 150% of average snowpack. Reservoirs today are about 2 million acre feet above their long-term average for this date (having been about 8 million acre ft below average 2 years ago).

After wondering for years if the drought would end, the drought is definitively over, even as some impacts to forests, fish populations, and groundwater levels will persist for decades.  Last Friday, Governor Brown lifted his drought emergency declaration for the state, with a few exceptions.  But to keep drought lessons alive, this lifting also stressed a need to reduce wasteful water use and was accompanied by a state plan to make “conservation as a way of life.”

What should we have learned (or re-learned) from this decade’s dance with extremes?

  • California is a land of water extremes. California is a dry place, that is sometimes much drier than usual for long periods of time – we call these droughts.  California also can become very wet – which can cause floods if inadequately managed and prepared for.
  • California must manage for both extremes. Wet years allow gathering water into aquifers and reservoirs, but we can never economically capture all water in wet years. Even in dry years, we need to prepare for floods, in preparing infrastructure and emergency management. In all years we need to improve capabilities and coordination among water agencies (local, state, and federal).
  • Conditions can change quickly. The drought took two years to develop and two years to end (although some effects will last for decades).  Floods move faster and more violently, as Oroville’s spillways tore themselves apart in mere hours.
  • Groundwater is key to sustainability and prosperity for California’s human water uses. Increased groundwater pumping replaced about 70% of the drought’s agricultural water shortage. Groundwater provides by far the most water storage in California, and is the predominant storage for longer droughts.  The 2014 Sustainable Groundwater Management Act shows that this lesson was learned, but implementation remains a challenge.
  • The southern Central Valley will see large reductions in net water use. This uncomfortable truth is now widely accepted following the drought. About 15 percent of the southern Central Valley’s agricultural land depends on groundwater overdraft. Problems in the Delta and increased outflows for the San Joaquin River threaten perhaps another 15 percent of supplies.  Soil salinization, urbanization of agricultural land, technology, and climate change will also mostly push to reduce irrigated acreage.
  • Preparation is key to managing extremes – for both droughts and floods. Most cities and farmers did well in the recent drought and floods. A roughly 30% loss of water supply reduced statewide agricultural revenue by about 2-3% and urban losses were financially inconvenient but economically negligible.  Local impacts were sometimes much worse, especially for some rural communities. The biggest losses were in areas least prepared. Ecosystems were unprepared for this drought, with often devastating effects.  This wet year saw widespread minor flooding, but little major flooding, and identified some areas needing more attention and funding.
  • Future droughts and floods will be a bit different. This drought was worsened by higher temperatures, hit an agricultural economy with many more permanent (and more profitable) crops, and hit a system with more effective water supply agency cooperation, and a different composition of species in the Delta ecosystem.  We need to prepare for future droughts (and floods).
  • We need to do better. The extreme drought and wet year served to identify weaknesses in California’s water management. We must learn from these tests, and improve local, regional, and statewide water management.  Learning from past droughts and floods has make California’s water management as successful as it has been, and remains vital for sustaining a major dynamic civilization in such a dry and increasingly variable climate.

The last few years have shown some major problems:

  • Groundwater. Implementing the Sustainable Groundwater Management Act remains one of California’s greatest water challenges.
  • The Sacramento-San Joaquin Delta is a second key to sustainability and prosperity for California’s water system. We are still struggling with this one.
  • Rural water supplies. California still has 1-2% of its population with substandard drinking water quality. The drought highlighted the problems of these mostly small rural water systems. Some progress is occurring, but will require stronger county responsibility, oversight, and capability, aided by others.
  • Ecosystem management. The drought showed the weakness of remaining native ecosystems and pretty dreadful drought capability and preparation by agencies for their environmental responsibilities. State and federal agencies are neither organized nor funded to succeed here.
  • Investments in flood infrastructure. While most of California’s flood infrastructure did pretty well, the floods showed a need to invest in maintenance and updating of major flood infrastructure – and Californians will need to pay for this.
  • California lacks a coherent state water technical and scientific program, integrated across agencies. Lack of a common effective water balance, inadequately organized, transparent and expeditious data and modeling, fragmented science, and incoherent fragmentation of technical efforts add confusion, delays, costs, and hassles.  The state’s major drought, flood, groundwater, water right, rural drinking water, and environmental management problems mostly span agency responsibilities, requiring a common coherent technical program.  State effectiveness is hobbled without this.

As a mostly dry place with a highly variable climate, California’s water problems are eternal and will always be punctuated by floods, droughts, and other emergencies.  These are tests which invite, focus attention, and can help guide improvements.

If we want to continue to move forward, we cannot go back.

Jay Lund is a professor of civil and environmental engineering and director of the Center for Watershed Sciences at UC Davis. @jrlund113

Further reading

Alvar Escriva-Bou, Henry McCann, Ellen Hanak, Jay Lund, and Brian Gray (2016), Improving California’s Water Accounting, 28 pp. Public Policy Institute of California, San Francisco, CA.

Hanak, Lund, Dinar, Gray, Howitt, Mount, Moyle, and Thompson. 2011, Managing California’s Water: From Conflict to Reconciliation, Public Policy Institute of California, San Francisco, CA.

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

Lund, J., “The banality of California’s ‘1,200-year’ drought,”, 23 September 2015.

Lund, J. “You Can’t Always Get What You Want – A Mick Jagger Theory of Drought Management”, 21 February 2016.

Lund, J. and E. Hanak, “Resistance is futile: Inevitable changes to water management in California”, 7 January 2014

Posted in Uncategorized | 6 Comments

Down the DRAIN: California gets a jump on Delta tunnels

The intake structure for the first Delta tunnel was completed and began to transport water this winter to the central Delta. Photo source: Gus Tolley

by Nan W. and Dunlay J. Frobish

California took a step towards replumbing its archaic Delta water infrastructure by completing the first part of a contentious project. An intake for the first Delta tunnel was completed this fall, and with the return of wet weather, began transporting flows that will eventually bypass the Delta entirely.

Officially named the “Diversion Restoring Almonds Intake,” or DRAIN, the diversion intake conveys water into the central Delta to improve water quality and combat damage to water supplies and Delta ecosystems done by salt-water intrusion during the recent drought.

“The writing was on the wall for California’s big infrastructure projects,” said Rowe Foote, a legislative aide in the governor’s office. “The tunnels and the bullet train are our biggest goals. We need to get them done. We took a page from recent national election rhetoric: build now, get buy-in and pay later.”

Map of proposed Bay Delta Conservation Plan Dual Conveyance tunnel project. One of multiple potential intake locations was selected for the DRAIN. Source: California Natural Resources Agency

Since Californians have yet to approve full project funding, the first tunnel could only be partially completed using existing discretionary funds and a loan from Proposition 1 funds to improve access to south-of-Delta storage. Fiscal hawks in the governor’s office demanded that construction be limited to structures within the available budget, and that would provide on-going benefit regardless of whether future phases were ultimately approved.

The open bell-mouth DRAIN is unique for intake designs, and was selected because it physically limits diversions to surplus flows and can passively operate until future bonds and plans are approved. The passive structure means that intake flows will mimic the hydrograph, peaking when flows are high and receding as flows are low. Studies have shown that this kind of direct “functional flow” strategy helps preserve complex stream processes without overly complex interventions.

Record low reservoirs following the 2011-2016 drought gave California ample opportunity to complete construction of the bell-mouth intake for the first Delta tunnel. Photo credit: Dagon Jones.

The impetus behind fast-tracking the DRAIN’s construction came when poor water quality for local Delta intakes coincided with increasing reports of marine animals in streams and canals. Sea lions have been reported in Knights Landing, Dixon, and Vacaville, and several reports of whales in the Sacramento River.

Spectators watch as one of two humpback whales partially surfaces near the Port of Sacramento. Image source: U.S. Coast Guard via EPA.

“Our environmental flow policy is barely enough to keep fish the size of Delta smelt in the right place,” said Chuck Laird, a spokesperson for the state’s Natural Resources Agency. “It’s really no surprise that with the amount of salt-water intrusion, we’re starting to see marine mammals in places that used to be reliably fresh water habitat.”

“While California’s drought may be easing, the environment has essentially been in a drought for decades,” said the Center for Watershed Sciences LeRoy Tempe. “Combine the salt-water intrusion with flow reversals from the Delta pumps, and you’ve got whales swimming into our rivers while [Delta] smelt and juvenile salmon don’t know which way to go.”

Delta flows are notoriously convoluted. It is the hub of California’s critical infrastructure, conveying fresh water from the wetter northern part of the state to farms and cities in the drier south. But tidal “sloshing” greatly exceeds Delta outflows: as a result, inland channels like the dredged Sacramento Deep Water Ship channel has extended tidal mixing, bringing salty, tidal water up the channel. Experts have long warned that fresh water to the environment has been under-allocated in the Delta, and that its ecosystem won’t recover until those flows are restored.

The DRAIN’s use will be limited until Phase 2 can be implemented: the construction of a device to Prevent/Limit Unnecessary Gushing (the PLUG) can be fitted to improve the reliability of water deliveries.

Nan W. Frobish is an occasional contributor to the California Waterblog and director of life enrichment for the UC Davis Center for Watershed Sciences. Dunlay J. Frobish performs multiphase fluid flow experiments throughout the Delta.

Further reading

Bay Delta Conservation Plan. 2013 Public Review Draft BDCP.

Yarnell et al. 2015. Functional flows in modified riverscapes: hydrographs, habitats and opportunities. Bioscience.

Fleenor et al. 2017. Episode 1: “Unraveling the Knot” Water movement in the Sacramento-San Joaquin Delta. California WaterBlog.

Fleenor et al. 2017. Episode 2: “Unraveling the Knot” Water movement in the Sacramento-San Joaquin Delta. California WaterBlog.

California WaterBlog. 2015. Q & A on survival of California’s Delta smelt.


Posted in April Fools' Day, California Water, Delta | 13 Comments

Pumping out the Inland Sea – Delta exports in a time of plenty


Cumulative exports March 2017

Cumulative total SWP + CVP Delta water exports for recent years, Data source: CDEC

By Jay Lund

This is northern California’s wettest year of record, so far.  The Yolo Bypass has been flooded for most of this wet season, and is still flowing.  Are Delta water exports going to exceed the previous record exports from 2011 (6.5 maf)?  The figure above compares this year’s Delta water exports compare with other years before and after the 2007 Wanger Decision, and the drought years (2012-2016).

So far, the State Water Project and Central Valley Project together have pumped a little less than in 2011, 2006 (another wet year), or 2007. They are all pretty close (with most of these highest-export water years falling after CVPIA and Endangered species restrictions on Delta pumping).

Compared to the drought years, the first two years of drought were less dry and exports were supplemented by water drawn from California’s large northern-of-Delta surface reservoirs. By 2014 and 2015, surface storage for drought exports was substantially depleted. This surface storage depletion partially refilled in 2016 and is now fully filled.

The State Water Project pumped at record daily rates in January, in the figure below.  Daily maximum pumping was 10,426 cfs on February 2, exceeding the 8,500 cfs daily maximum from 2006-2016 and even Banks Pumping Plant’s listed capacity of 10,300 cfs.  This compares to several hundred thousand cfs of Delta outflow during January.

Harvey O. Banks Pumping Plant. SF Chronicle Graphic by John Blanchard.

State Water Project pumping began to plummet as San Luis Reservoir filled and damage was found at the intake to the pumping plant’s Clifton Court Forebay.  State Water Project pumping will be curtailed or stopped until this is repaired, with deliveries made good from San Luis Reservoir.  Spring is likely to remain wet, with substantial additional pumping later in the season.

Finding places to store pumped water south of the Delta is becoming difficult. MWD of Southern California has reduced its use of Colorado River water to employ and store this Northern California abundance.  About half of recent pumping has gone to filling San Luis Reservoir, which is essentially full.  The San Joaquin and Tulare basins are also wet, filling reservoirs locally and likely helping refill some of the region’s drought-depleted groundwater.

It may be worthwhile to invest in additional groundwater or surface storage, water infiltration capacity, and conveyance to places with more infiltration capacity.  But justifying such expensive decisions requires more economic calculations. For now, water managers throughout California are trying to avoid flooding, while maximizing the capture of flows for surface and groundwater storage.

Damage to the Clifton Court Forebay and lack of south-of-Delta storage (or conveyance to storage) are likely to keep this record-wet year from becoming a record Delta export year.  Recent SWP and CVP water allocations are not yet at 100% for all contractors, but will likely increase, and seem limited mostly by conveyance and storage infrastructure this year.  But for water users statewide, it is a welcome very wet year nonetheless.

This year is testing California’s water system in wet extreme conditions – for floods and capture of “surplus” flows, following five years of drought testing.  For California water, every year is a test.  Every year’s tests identify problems and opportunities.  Hopefully learn from these tests.

Maximum SWP exports

Data from DWR’s wondrous CDEC:

Jay Lund is the Director of the Center for Watershed Sciences and a Professor of Civil and Environmental Engineering at the University of California – Davis. He is grateful that the people of California pay him.

Further reading

Episode 3: “Unraveling the Knot” Water Movement in the Sacramento-San Joaquin Delta – Managing Flows, CaliforniaWaterBlog, 29 January 2017

Harter, Thomas. Post-drought groundwater in California: Like the economy after a deep “recession,” recovery will be slow,, 19 March 2017

Nguyen, Megan, Yolo Bypass: the inland sea of Sacramento,, 20 February 2017


Posted in Delta | 7 Comments

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

by Thomas Harter

The 2012-2016 drought has made many of us keenly aware of how “empty” our groundwater “reservoirs” have become. As the recent series of atmospheric rivers have left us with a massive snowpack, full surface water reservoirs (with some exceptions in southern California), and soggy soils, some questions are frequently asked:

Is the drought over, even for groundwater – if not, when will well owners see full recovery of their water table?  And could the massive amounts of runoff be captured to accelerate replenishment of our depleted groundwater aquifers?

The short answers: while the surface water drought is over, the groundwater drought is not. How much longer may it last? As a rule of thumb, in many areas it will take as many above average to wet years to recover our groundwater storage, as it has taken to draw it down. And while excess runoff can be used for recharge, California currently lacks the infrastructure and capacity to divert and hold flows like those released over the Oroville spillways for infiltration and groundwater storage.

Why does groundwater storage recovery take so much time? Groundwater is by far our largest of the four water reservoir systems in California, where agriculture and urban users consume about 40 million acre-feet (MAF) each year, mostly from spring to fall:

  • Mountain snowpack, in an average winter and spring, holds about 15 MAF
  • Surface water storage reservoirs have a total capacity of 40 MAF
  • Soils store many 10s of MAF of our winter precipitation for use by natural vegetation, crops, and urban landscaping
  • Groundwater reservoirs are endowed with well over 1,000 MAF of freshwater

With this endowment, groundwater storage works like a large bank account. We run deficits in dry times, taking out more than we deposit (more pumping than recharge); and we run savings in wet times, depositing more into the account than what we withdraw (more recharge than pumping). Ideally, over the longer term, the savings match the withdrawals – groundwater recharge matches groundwater pumping.

Dynamics of groundwater storage and water level change – a history lesson

Groundwater levels are the indicators that show how this bank account is performing. Rising groundwater levels mean increasing storage – more savings. Falling groundwater levels mean decreasing storage – running a deficit.

How much and when groundwater levels rise and fall varies greatly around the state. But there are some common patterns. Seasonal variations occur due to California winters being wet and cold while summers are dry and hot. Water levels rise during winter and spring due to recharge from precipitation and recharge from streams that carry winter runoff (plenty of bank deposits), while groundwater pumping is limited (small account withdrawals). On the other hand, groundwater levels decline during the summer and fall, when pumping exceeds local recharge.

Groundwater levels (and storage) also change over the longer term, in response to drought or wet years. In dry years, it is common to see water levels recover less during the (dry) winter. With the early onset of irrigation in the spring and lack of surface water leading to replacement with groundwater pumping, water levels drop quickly in the summer following a dry winter.  In wet years, the opposite occurs: water levels recover more strongly after a wet winter and groundwater levels are not drawn down as much in the summer, resulting in a net year-over-year rise in water levels.

In some regions, such as the Borrego Valley basin, the depletion has been a steady decline: each summer, water levels are drawn down more than they recover in the following winter, regardless of how wet the winter may be. In other places, the decline in groundwater levels may be less obvious:  year-over-year water levels fall during drought, but recover during wet years. But the recovery during a series of wet years doesn’t make up for the depletion during dry years, resulting in long-term overdraft.

Over the past 100 years, overdraft has drained groundwater resources by 150-200 MAF, with most of that depletion occurring in the middle and southern Central Valley, and in southern California. The overall decline in groundwater storage, time and again, has led to costly replacement of wells that have become too shallow to dip into a falling water table, land subsidence, seawater intrusion in coastal basins, water quality degradation in other basins, and depletion of streams that depend on groundwater for base flow during California’s long dry season.

The decline has also created groundwater storage space to replenish with extra water in wet years. For the past half century, Orange, LA, and Santa Clara counties have been busy building a diversity of water projects to take advantage of that additional groundwater storage space. During wet years, they refill it with excess water from local streams, the state and federal water supply system, urban runoff, and recycled urban water:

Figure 1: Average depth to groundwater in Santa Clara Valley, where overdraft began in the 1920s and continued for 40 years. It has taken another 40 years to recover from that overdraft. From: Santa Clara Valley Water District.

Notably, it has taken those basins two to four decades to recover from their deep overdraft accumulated during the early groundwater exploration in the 1920s through 1960s – a recovery often interrupted by droughts (1977, 1988-92).

Recharge as the driver for groundwater recovery after drought.

Recharge drives the amount of groundwater level recovery. Let’s take a closer look: Some of the recharge comes from precipitation that infiltrates into the soil, in excess of the soil water holding capacity. During dry years, that may be less than an inch in southern California and a few inches in central California. In a soggy, wet winter, some areas (especially on sandy soils) may see over a foot of recharge from precipitation. For the 10+ million acre Central Valley aquifer, this accounts for a significant portion of natural recharge. Streams and irrigation water returns provide the other significant portion of recharge. Intentional recharge through groundwater banking, aquifer storage and recovery, and intentional flooding of natural depressions can further enhance that recharge.

In the Central Valley, recharge in a critically dry year may be well below 10 MAF while pumping may far exceed 15 MAF – thus groundwater storage in a critically dry year may decrease by 3-7 MAF. The opposite occurs in a wet year like 2017 – groundwater pumping may be as little as 10 MAF, while recharge is well over 12 MAF, leading to storage gains of 2-5 MAF (see Figure 2 below). Hence a wet year’s gain is roughly of the same magnitude as a dry year’s loss.

The important point about this: the amount of recharge in a single wet year cannot wipe out three or four or five years of drought losses.

Figure 2: Annual (bars) and cumulative (lines) change in groundwater storage in the Central Valley aquifer between 2005 and 2010. Upper and lower best limits for a best estimate are obtained by assuming aquifer specific yields of 7% (blue) to 17% (green). From: DWR Water Plan 2013

How will a wet winter help drought-affected well owners?

Back to our wet winter of 2017. What will drought recovery be like for domestic, irrigation, and public water supply wells? For well owners that have kept water level records over the past 30 years, a good estimate of the time needed for recovery is to look at their records during the years after the 1988-1992 drought. Alternatively, the annual recovery rates during the wet winters of 2005-2006 and 2010-2011 may provide some good indication for recovery rates this year.

Where those records are not available, a look at DWR’s Water Data Library, with its easy-to-use map interface, may be helpful: clicking on a few wells in the area of interest will quickly reveal some examples of water level hydrographs and recovery rates, especially during the mid- to late 1990s (a series of rather wet years). Figure 3 shows some good examples from the Sacramento Valley (Yolo County) and the southern Central Valley (Tulare County):

Figure 3: Water level hydrographs for wells in Yolo and Tulare County, 1950 – current. Wells are identified by their DWR well identification number. Notice the decline in water levels during drought periods. Year-to-year recovery rates during the wetter periods of the 1980s and late 1990s mirror the rates of year-to-year decline in drought years. Data were obtained from DWR’s Water Data Library.

If neither of these resources are at hand, consider the rate at which water levels have fallen over the past five years: recovery may likely happen at about the same rate as water levels have fallen. For example, if water levels have fallen about 15 feet each year (spring to spring), this year may yield a water level increase of about 10 – 20 feet (spring to spring).

Additional recharge to accelerate groundwater recovery?

Could we not accelerate the process by recharging, for example, much of the over 2 MAF released from the Oroville dam during the three weeks of emergency releases in February (not counting Lake Shasta and other releases)?

Some of that water has in fact become recharge, directly from the Yuba River into the Central Valley aquifer system, from Marysvville and along the Sacramento River, as well as along the flooded Yolo Bypass to the Delta. But the Bypass contains fine-grained floodplain soils with very low infiltration capacity – about one-tenth of a foot per month (one of the reasons the  Bypass is ideal for rice fields). The Yolo Bypass is 60,000 acres – recharge from there may add about 0.01 MAF to the Central Valley aquifer system, a tiny fraction of the reservoir releases. Letting the floodwaters fill more of its original floodplains can increase that fraction, which is important to local groundwater.

If we dedicate some of the lighter soils with higher infiltration rates for use as intentional recharge basins, a likely recharge rate would be on the order of one or perhaps even a few feet of recharge in one month.  We would need 1-2 million acres of these lands just to put away the surplus Oroville outflow in February!

Another option is to systematically use agricultural land for winter irrigation while taking advantage of some of these flood flows.  Intentional winter recharge in the agricultural landscape could be coupled with smart reoperation of surface storage reservoirs to better match the slower groundwater infiltration rates with the intensive but short availability of flood waters.  Irrigating suitable agricultural land with surplus winter water may allow recharge of one-half to two feet of water between December and March – allowing for additional intentional recharge in wet years of perhaps 2-6 MAF across the Central Valley, if and where water rights, infrastructure, and agricultural chemicals could also be managed appropriately (Water Foundation, 2015). Considering that the Central Valley is irrigated with about 20 MAF between April and October each year, intentional agricultural winter recharge of 2-6 MAF during wet winters is not an unreasonable proposal. This type of recharge could indeed make a significant difference to the typical wet year groundwater storage gains of 2-5 MAF – theoretically doubling the current water level recovery rate during a post-drought winter like 2017 (Harter and Dahlke, 2014; DWR, 2017).

Figure 4: Soil Agricultural Groundwater Banking Index showing recharge suitability of soils in California’s agricultural regions. Potential recharge rates on “excellent” soils may exceed several tens of feet per year, where subsurface “storage space” exists; in contrast, “very poor” soils may allow for recharge of as little as 1 foot per year, even under ponding conditions.

Thomas Harter is a groundwater specialist with the UC Davis Center for Watershed Sciences.

Additional Resources:

Santa Clara County Water District. Groundwater: Where does our water come from?

California Department of Water Resources. California Water Plan 2013.

California Department of Water Resources. Water Data Library.

Water Foundation. 2015. Creating an opportunity on farm recharge.

Harter, T. and Dahlke, H.E. 2014. Out of sight but not out of mind: California refocuses on groundwater.

California Department of Water Resources. 2017. Sustainable Groundwater Management: Water available for replenishment.

Soil Agricultural Groundwater Banking Index.

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