Science Happens

By Andrew L. Rypel

Looking back…

The famous expression ‘Life Happens!’ has certainly been around awhile. It’s reserved as a sort of colloquialism, describing how someone’s life or life plans are completely upended by circumstances, usually because of seemingly random events. This summer, I’ve been reflecting on how these types of events also seem to occur in science. Science, much like life, seems to kinda happen.

In my experience, most scientists follow surprisingly non-linear pathways through their careers. I can’t recall any scientist that set out with a specific plan and then perfectly executed that plan over a career. I’m sure they exist, but it must be rare. Things happen – you meet people, read interesting new things, change the science, and are changed by the changing science and experiences around you. It can feel a bit like a ‘random walk’ as described in movement ecology. And if you study a ecosystem or population for a long time, something big is bound to happen, and it will usually be a surprise. This might come from a species invasion, a mega-disturbance such as from a flood or wildfire, a population collapse, development of land, or any number of other things. It’s one of the reasons long-term research is so vital to our understanding of how the environment works. Humans tend to be quite bad at predicting shocks and shifts in dynamic systems. In their ‘fat tails’ paper, Batt et al. 2017, show how extreme events are more likely to occur for biological variables. Thus ecologists studying aquatic organisms and ecosystems in particular should expect surprises.

In other cases, ideas somehow seem to find their cosmic time. Anecdotally, it seems common enough that scientists have an idea, wait, and then someone else publishes it. And this usually isn’t because another scientist takes their idea (aka ‘scoops them’), but because an idea’s time has somehow come. Perhaps because new tools emerge that enable pursuit of ideas previously intractable. In The Structure of Scientific Revolutions, Kuhn (1962) described a process of ‘normal science’, primarily as an articulation of prevalent and previously settled upon theories and frameworks. Sometimes this articulation by the science community happens in synchrony. 

Alternatively, in The Selfish Gene, Dawkins (1976) searched for an evolutionary explanation for seemingly harmful behaviors that persist. For example, what is the fitness benefit of martyrdom? Or devoting one’s life to unappreciated art or science? The proposed hypothesis – a surprising one to many, was the notion that ideas themselves might be in competition with one another. Interestingly, it was here where Dawkins originally coined the term ‘meme’ and is apparently still miffed at the internet highjacking of the word. Essentially, he suggested a selection process on ideas themselves, such that some ideas proliferate with success, while others die out. The ideas themselves, like viruses, owe nothing to the host. The meme concept or memetics apparently remains highly controversial throughout science.

Research on ‘panfish’ species like Pumpkinseed Sunfish was not something I thought I would ever do, or become so passionate about.

Good ideas are often timeless, but also frequently forgotten or ignored for a variety of biased reasons. In these cases, research does not happen – which is unfortunate for everyone (Rypel et al. 2021). For example, the confluence of climate change and biodiversity loss are fundamentally challenging science and society to find novel workable solutions. Indigenous knowledge successfully conserved ecosystems and biodiversity across the globe for long periods of time (Ogar et al. 2020). Unfortunately, western science too often emphasizes a single way of knowing, while ignoring other valid approaches (Dentzau 2019). Blending Indigenous knowledge with other science systems is an exciting step forward for many fields, but especially in the ecology and fisheries fields where I work and collaborate. Relatedly, transdisciplinary science strives for innovation in large part because of a willingness to search for useful ideas in other areas and/or fields – to get uncomfortable. This process seems to generate ideas that are fitter in both the scientific and sociopolitical realms. Yet for years, interdisciplinary science was actively discouraged. Working at the boundaries of the sciences and Indigenous frameworks is where much research will occur in the future. None of these science roads are, or will be, linear.

In my own science journey, conservation needs drive much of what I study. In graduate school I studied rivers, primarily because I grew up on some spectacular ones and was raised to love them, and also because I started to grasp their widespread degradation. Two studies in particular (Benke 1990 and Dynesius and Nilsson 1994) were important in understanding the scope of the problem. Work by Stanley and Doyle (2003) was motivating to help understand the complexities but importance of removing ‘deadbeat dams’. I later studied freshwater mussels, in part because I had always been fascinated by them, but also because I met several experts (seemingly randomly) who patiently taught me some identification, how endangered they were, and how new information could help save them. Amazingly, some of these folks even wanted to collaborate with me! When I worked for the Wisconsin DNR, I studied overfishing in bluegill and management options to remediate overfished ‘panfish’ populations #InDefenseOfPanfish. This topic was one of the top research priorities for fisheries biologists in that region at the time. I never dreamed I would move to California and study western fishes, water and drought. But life happens, and I got this amazing job at UC Davis and now work on all the crazy water and native fish issues in the West. Occasionally, I try and fail at explaining the subtleties of California water to friends and family that live in more hydrated regions.

Teaching exited young people about the beauty of fishes and joy of conservation is one of my favorite parts of the job.

It’s impossible to understand all the reasons behind the twists, turns, ups and downs in a science journey. And certainly going with the flow too much can be a bad thing too. Sometimes I wonder whether in California water science, we whipsaw too much in our priorities. Might we have better success if we set a more solid, albeit less trendy or weather-based course, and stuck to it? But surprises do happen that change the game – and we need to make room for them in the science enterprise. The fat tails paper tells us we should expect lots of surprises. And, it can be fun to think back about the serendipity of it all. Estes, another California scientist, reflected on the science magic of the twists and turns in this 2020 book – Serendipity

One thing is clear – scientists rarely work along a linear path and this certainly seems to be the case in California water. This is a topic I try to talk about openly with my own students. Some of my colleagues occasionally rib me for being a generalist, but conservation science has extraordinary depth of interest and overlap with so many fields and important issues. Water in particular connects all these things. We should be open to that which we haven’t planned. And so I thought this topic might make for an interesting blog post for you all too. 

If you feel comfortable, please share your own unpredictable (or not) science/water journey in the comments below! If you feel uncomfortable, perhaps this will help stimulate your thinking 🙂

Further Readings

Batt, R. D., S. R. Carpenter, and A. R. Ives. 2017. Extreme events in lake ecosystem time series. Limnology and Oceanography Letters 2:63-69.

Benke, A. C. 1990. A perspective on America’s vanishing streams. Journal of the North American Benthological Society 9:77-88.

Dawkins, R. 1976. The Selfish Gene. Best Books.

Dentzau, M. W. 2019. The tensions between indigenous knowledge and western science. Cultural Studies of Science Education 14:1031-1036.

Dynesius, M., and C. Nilsson. 1994. Fragmentation and flow regulation of river systems in the northern third of the world. Science 266:753-762.

Estes, J. A. 2020. Serendipity: An Ecologist’s Quest to Understand Nature. University of California Press.

Kuhn, T. S. 1962. The Structure of Scientific Revolutions. University of Chicago Press.

Ogar, E., G. Pecl, and T. Mustonen. 2020. Science must embrace traditional and indigenous knowledge to solve our biodiversity crisis. One Earth 3:162-165.

Rypel, A. L. 2015. Effects of a reduced daily bag limit on bluegill size structure in Wisconsin lakes. North American Journal of Fisheries Management 35:388-397.

Rypel, A. L., W. R. Haag, and R. H. Findlay. 2009. Pervasive hydrologic effects on freshwater mussels and riparian trees in southeastern floodplain ecosystems. Wetlands 29:497-504.

Rypel, A.L., P. Saffarinia, C.C. Vaughn, L. Nesper, K. O’Reilly, C.A. Parisek, M.L. Miller, P.B. Moyle, N.A. Fangue, M. Bell-Tilcock, D. Ayers, and S.R. David. 2021. Goodbye to “rough fish”: paradigm shift in the conservation of native fishes. Fisheries 46 605-616.

Rypel, A.L., C.A. Parisek, J. Lund, A. Willis, P.B. Moyle, Yarnell, S., and K. Börk. 2020. What’s the dam problem with deadbeat dams?

Stanley, E. H., and M. W. Doyle. 2003. Trading off: the ecological effects of dam removal. Frontiers in Ecology and the Environment 1:15-22.

Meet Dr. Andrew Rypel, our new fish squeezer.

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You Can’t Always Get What You Want – A Mick Jagger Theory of Drought Management


Graph of cumulative job and revenue data for California (Josue Medellín-Azuara, 2015)

by Jay Lund

[This is a reposting of a post from February 2016, near the end of the previous drought.  For human uses, conditions seem somewhat similar to this point in the previous drought, so this perspective might be useful. A couple of more recent readings are added to this post.]

“You can’t always get what you want
But if you try sometimes you just might find
You get what you need,” Rolling Stones (1969, Let It Bleed album)

The ongoing California drought has many lessons for water managers and policy-makers. Perhaps the greatest lesson is how unimportant a drought can be if we manage water well.

For the last two years, California lost about 33% of its normal water supply due to drought, but from a statewide perspective saw statistically undetectable losses of jobs and economic production, despite often severe local effects. Agricultural production, about 2% of California’s economy, was harder hit, fallowing about 6% of irrigated land, and reducing net revenues by 3% and employment by 10,000 jobs from what it would have been without drought. Yet, high commodity prices and continued shifts to higher valued crops (such as almonds, with more jobs per acre) raised statewide agricultural employment slightly and raised overall revenues for agriculture to record levels in 2014 (the latest year with state statistics).

Cities, responsible for the vast majority of California’s economy, were required to reduce water use by an average of 25% in 2015. These conservation targets were generally well achieved on quite short notice.   Most remarkably, there has been little discernible statewide economic impact from this 25% reduction in urban water use, although many local water districts are suffering financially.


More groundwater pumping greatly reduced drought impacts. Picture courtesy of DWR.

How could such a severe drought cause so little economic damage? Much of the lost water supply from drought was made up for by withdrawals of water from storage, particularly groundwater. But the substantial amount of water shortage that remained was largely well-allocated. Farmers of low-valued crops commonly sold water to farmers of higher-valued crops and to cities, greatly reducing economic losses. Within each sector, moreover, utilities, farmers, and individual water users allocated available water for higher-valued uses and shorted generally lower-valued uses and crops.

If shortages are well-allocated, California has tremendous potential to absorb drought-related shortages with relatively little economic impact. This economic robustness to drought arises from several characteristics of California’s economic structure and its uses of water.

First, the most water-intensive part of California’s economy, agriculture, accounts for about 80% of all human water use, but is about 2% of California’s economy. So long as water deliveries are preserved for the bulk of the economy, in cities, California’s economy can withstand considerable drought (Harou et al. 2010). And the large strong parts of the economy can aid those more affected by drought.


Gross annual revenue for California crops ($ millions). (using California Department of Water Resources irrigated crop acres and water use data)

Second, within agriculture, roughly 80-90% of employment and revenues are from higher-valued crops (such as vegetable and tree crops) which occupy about 50% of California’s irrigated land and are about 50% of California’s agricultural water use. If available water is allocated to these crops, a very large water shortage can be accommodated with a much smaller (but still substantial and unprecedented) economic loss.  Water markets have made these allocations flexibly, with some room for improvement.

Global food markets have fundamentally changed the nature of drought for humans. Throughout history, disruptions of regional food production due to drought would lead to famine and pestilence. This is no longer the case for California and other globally-connected economies, where food is readily available at more stable global prices. California continued to export high-valued fruits and nuts, even as corn and wheat production decreased, with almost no effects on local or global prices. Food insecurity due to drought is largely eliminated in globalized economies (poverty is another matter). Subsistence agriculture remains more vulnerable from drought.

Third, cities also concentrate much of their water use in lower-valued activities. Roughly half of California’s urban water use is for landscape irrigation. By concentrating water use reductions on such less-productive uses, utilities and individual water users greatly lowered the costs of drought. If cities had shut down 25% of businesses to implement 25% cuts in water use, the drought and California’s drought management would have been truly catastrophic.

Fourth, although California’s climate is very susceptible to drought, California’s geology provides abundant  drought water storage in the form of groundwater, if managed well.  The availability of groundwater allowed expanded pumping which made up for over 70% of agriculture’s loss of surface water during the drought and provided a buffer for many cities as well. If we replenish groundwater in wetter years, as envisioned in the 2014 groundwater legislation, California’s geologic advantage for withstanding drought should continue.

All of this leads to what we might call a Mick Jagger theory of drought management. Yes, droughts can be terrible in preventing us from getting all that we want, and will cause severe local impacts. But if we manage droughts and water well and responsibly, then we can usually get the water that the economy and society really needs. This overall economic strength also allows for aid to those more severely affected by drought. This is an optimistic and pragmatic lesson for dry drought-prone places with strong globalized economies, such as California.

California’s ecosystems should have similar robustness of ecosystem health with water use, and naturally persisted through substantial droughts long ago.  But today, California’s ecosystems entered this drought in an already severely depleted and disrupted state.   (The Mick Jagger characterization of California’s ecosystems might be “Gimme Shelter,” from the same album.)  If we can sufficiently improve our management of California’s ecosystems before and during droughts, perhaps they will be more robust to drought. Reconciling native ecosystems with land and water development is an important challenge.

“If I don’t get some shelter
Oh yeah, I’m gonna fade away” Rolling Stones (1969, Let It Bleed album)

The drought reminds us that California is a dry place where water will always cause controversy and some dissatisfaction.  However, despite the many apocalyptic statements on California’s drought, the state has done quite well economically, so far, overall. But, the drought has identified areas needing improvement, so that we can continue to get most of what we really need from water in California, even in future droughts.  We should neither panic, nor be complacent, but focus on the real challenges identified by the drought.

Jay Lund is Co-Director of the Center for Watershed Sciences and Professor of Civil and Environmental Engineering at the University of California – Davis.

Further reading

Lund, J.,  Follow the Water! Who uses how much water where?,, Posted on

Hanak, E., J. Mount, C. Chappelle, J. Lund, J. Medellín-Azuara, P. Moyle, and N. Seavy, What If California’s Drought Continues?, 20 pp., PPIC Water Policy Center, San Francisco, CA, August 2015.

Harou, J.J., J. Medellin-Azuara, T. Zhu, S.K. Tanaka, J.R. Lund, S. Stine, M.A. Olivares, and M.W. Jenkins, “Economic consequences of optimized water management for a prolonged, severe drought in California,” Water Resources Research, doi:10.1029/2008WR007681, Vol. 46, 2010

Howitt R, Medellín-Azuara J, MacEwan D, Lund J and Sumner D., “Economic Analysis of the 2015 Drought for California Agriculture.” Center for Watershed Sciences, UC Davis. 16 pp, August, 2015.

Medellín-Azuara J., R. Howitt, D. MacEwan, D. Sumner and J. Lund, “Drought killing farm jobs even as they grow,”, June 8, 2015.

Wikipedia, “You Can’t Always Get What You Want”,’t_Always_Get_What_You_Want

Wikipedia, “Gimme Shelter”,

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The vortex of executive activity

by Jay Lund

The graphic below seems to apply to any bureaucracy, with larger bureaucracies showing this tendency more strongly.  In this vortex conception of management, one can often make more progress from the periphery than from the center of power.

The center spins rapidly, always changing directions, but moving little in space.  Those in the periphery can go a greater distance.  Being in the center is more exciting and prestigious, but not necessarily more productive.

This analogy came to me while working in the Washington, DC area, where I encountered an abundance of very smart hard-working people, who seemed to accomplish little due to opposition from a high density of very smart hard-working people.

Almost all innovations in water and water management come from the periphery.

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Two-way thinking in natural resource management

By Andrew L. Rypel

“I have more confidence in the ability of institutions to improve their thinking than in the ability of individuals to improve their thinking” ~Daniel Kahneman

It is long recognized that there are two dominant modes of thinking (Glatzeder 2011). New research and empirical data support the elemental interplay between these modes in our behavior, summarized in the book Thinking, Fast and Slow by Nobel Prize winning economist Daniel Kahneman. These two modes or systems of thinking are dynamic and influence our behavior in a vast variety of subtle and less so ways. System 1 is ‘fast’ and intuitive, operating almost unconsciously, and relies on learned associations. It is tempting to rely on this mode for decisions that must be made quickly. The problem is that this mode is often wrong. System 2 by contrast uses reason, and the slow process of reasoning. Immanuel Kant wrote“All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.” Yet reason and System 2 require deliberate focused effort, and training to get better at. It is ‘slow’. The enlightenment was fueled largely by a growing appreciation for System 2. System 2 thinking is also endemic to science and the scientific method which developed as a way of using reason and rational thought. This is the system used to conduct what is now colloquially and increasingly referred to as ‘deep work’. Sadly many of us, while claiming to rely extensively on System 2, in fact spend most of our time in System 1. A prime example is our politics. How often are any of us swayed by excellent arguments from the other side, even following a rational debate?

The question for this blog is: Can Kahneman’s ideas be applied to group decisions, and thus to natural resource management? It’s a bit murky, but there are clues, and I have some thoughts. In Thinking, Fast and Slow  Kahneman was clearly writing about the combination of the two systems in each person – not groups of people. Yet it seems plausible that a well-managed team of people could avoid the excesses and extract the best elements of thinking from each system. But, different teams of people invariably have different mixes of System 1- or 2-leaning thought. Further, the appropriate mix of thinking needed for each environmental problem may differ, and change over time. 

Reflecting on the usefulness and practicality of both systems of thinking is probably universally helpful. This exercise is an example of ‘metacognition’, which can be defined generally as: thinking about how you think. Metacognition is a high order abstraction that might help us personally, but also collectively as team members or leaders in organizations. System 1 is needed to make timely decisions and prevent gridlock and lack of progress. It is the system in which we spend most of our time, and there is a reactive ease to its use. But this system has inherent flaws and is vulnerable to poor judgment. Humans generally avoid decisions perceived as risky because of loss aversion, which has evolutionary foundations. Thus, we often default towards safe and familiar decisions, even when a riskier choice might be better. System 2 can help reduce loss aversion (by better thinking through the pros and cons of a decision), provided there is enough time, and often the best available science. It is increasingly clear that Kahneman himself believes group decisions can be improved, primarily through slower processes and better decision making structures (see above opening quote to this blog found in this recent piece).

Fig. 1. Idealized natural resource management system adapted from Nielson 1999

Potential applications to natural resource management

Natural resource management, including water management, balances the needs of organisms, ecosystems and people (Fig. 1). Effective management occurs at the nexus of all three areas. Yet because many resource agencies are political, there are discrete time pressures on decisions. This could be because elected and appointed leaders hold power for only short periods, laws and regulations change alongside attitudes, political circumstances favor or preclude decision-making, or because an ecosystem or resource is collapsing in front of us. The time-sensitive nature of these decisions makes resource management agencies vulnerable to biases and issues associated with both thinking systems. Quality resource management might therefore hinge on a general ability to balance Systems 1 and 2 thinking.

It remains unclear how most extant water or conservation organizations lean disproportionately towards System 1 or 2 thinking. One might argue that, given their famously grinding speed, government organizations rely overly on System 2, perhaps to prepare for politically-opportune times or to avoid the controversy of actually making decisions. However, there are also abundant examples of government decisions being made rashly and without the time needed to fully appreciate key dynamics. The private sector ostensibly seems to favor System 1 for its faster decision-making and links to constantly changing financial markets. Yet it is also clear that most folks staking large sums of private capital on a venture extensively reason the issue from multiple angles before a risky decision. 

The value of two-way thinking

There is usefulness to both systems. Do we appreciate the value of both systems and find ways to organize and challenge ourselves and our organizations for the missing piece? For example, we need to organize our science and policy-makers to spend time on problems and solutions well in advance of short political windows of decision-making opportunity. This implies a need for greater organization of science syntheses to continually prepare policymakers for the types of decisions they will need to make over their tenure. Scheffer et al. 2013 articulates another undervalued benefit, specifically to slow decision making. That is, that many breakthroughs come outside the confines of the traditional workplace. By supplying enough time, stronger decisions might emerge through simple activities like dog walks, bowling adventures, or picnics where novel thoughts and conversations might take place. Can organizations and leaders deliberately generate the space for unstructured conversations and serendipity? Can this lead towards new compromises? New conservation and business successes? A recent survey of CEOs found that dealing with complexity was often identified as the greatest institutional challenge (Kleiman 2011). The CEOs then identified several directions for overcoming rising complexity; this included increasing creativity, increasing dexterity, and improving customer relationships. Yet budgeting time for developing these skills or encouraging person-to-person interactions are rarely prioritized in strategic plans or time planning exercises.

In many natural resource organizations, it probably helps to have people highly skilled in System 2 thinking. There are good reasons for System 1 thinking, but too often, it is simply wrong, and bad decisions can be avoided with a slower process. Perhaps there is not enough time to develop full blown science studies on a topic. Nonetheless, can we quickly summarize and synthesize previous scientific information from similar enough work to infuse elements of System 2 thinking into fast decision making? This is an advantage to having in-house science bureaus or R&D arms in organizations. And also a sad aspect to their (often hyperpolitical) demise. It is a challenge to have System 2 ecosystem management in a System 1 political world. 

Conversely, are there examples where we ‘research topics to death’? Clearly, the answer is yes. Perhaps what we really want is the ability to make decisions with System 2 thoroughness but with closer to System 1 speed. In California, we know the Sacramento-San Joaquin Delta is in a prolonged state of decline and the status quo is not working – at best. Time is increasingly limited before more species go extinct. More research along the lines of the last 40 years is unlikely to yield novel breakthrough information and abate the trajectory. More research is always needed, but more decisions are also needed – if they are the right decisions. However, it is challenging, especially given the ever-changing mix of system thinking needed for each problem and through time. This disorientation contributes to our bad intuition about probability, poor perception of time, and faulty decisions overall (Nowotny 2016). 

What can we do about all this?  Well, the adaptive cycle of natural resource management might be inevitable. We will need to experiment – a lot – and build on things that seem to work. Lund (2022) provides an overview for ‘rational water planning’, which is simply an in-depth look at one kind of System 2 approach. We can learn from prior experiments, even if they produced negative or null results. Large experiments, likely perceived to be ‘risky’, probably have a better chance at saving our California biodiversity, and to some extent us. To accomplish this, we will need well-trained scientists and managers skilled in System 2 to help design and monitor the great experiments of the future. We also need leaders unafraid and supported enough to pull the trigger on changing the status quo in a timely manner (i.e., those with an appreciation for the need to exercise System 1). Finally, we should expect the unexpected – and be prepared to try new experiments when the last great thing fails. 

Bog wetlands in the fall. Photo by Andrew Rypel

Andrew L. Rypel is a Professor and the Peter B. Moyle and California Trout Chair of coldwater fish ecology at the University of California, Davis. He is a faculty member in the Department of Wildlife, Fish & Conservation Biology and Co-Director of the Center for Watershed Sciences.

Acknowledgements: I thank Jay Lund and Steve Carpenter who provided thoughts and comments on earlier versions of this essay.

Further Reading:

Glatzeder, B. 2011. Two modes of thinking: evidence from cross-cultural psychology. pp 233-247 in S. Han and E. Poppel, eds Cultural and neural frames of cognition and communication: on thinking. Springer, Berlin, Germany.

Kahneman, D. 2013. Thinking Fast and Slow. Farrar, Straus and Giroux, New York, NY USA.

Kleiman, P. 2011. Learning at the edge of chaos. SISHE-J: The All Ireland Journal of TEaching and Learning in Higher Education 3: 62.1-62.11.

Lund, J. 2022. Approaches to water planning.

Newport, C. 2016. Deep Work: Rules for Focused Success in a Distracted World. Grand Central Publishing, New York, NY USA.

Nielson, L. A. 1999. History of inland fisheries management in North America. Pages 3-30 in C. C. Kohler, and W. A. Hubert, editors. Inland Fisheries Management in North America. American Fisheries Society, Bethesda, MD USA.

Nowotny, H. 2016. The Cunning of Uncertainty. Wiley, Hoboken, NJ USA.

Rypel, A.L., P.B. Moyle, and J. Lund. 2021. A swiss cheese model for fish conservation in California.

Scheffer, M., J. Bascompte, T.K. Bjordam, S.R. Carpenter, L.B. Clarke, C. Folke, P. Marquet, N. Mazzeo, M. Meerhoff, O. Sala, and F.R. Westley. 2013. Dual thinking for scientists. Ecology and Society 20: 3.

Understanding noise in human judgements

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Dissecting the use of water management plans in California

By Nicola Ulibarri

California uses plans as a primary tool for managing water throughout the state. Regulations like the Urban Water Management Planning Act of 1983, Regional Water Management Planning Act of 2002, Water Conservation Act of 2009, and Sustainable Groundwater Management Act of 2014 require local water agencies to write plans documenting their available water supplies and develop approaches to use water more sustainably and/or ensure a secure supply. This blog probes the goals California has in requiring local and regional water plans, and asks whether the plans are a good tool for achieving more sustainable water use.

California loves water plans, but without much justification

Since the 1980s, plans have been a go-to tool for the California state legislature and the Department of Water Resources (DWR). Plans are just one of many different policy tools the state could use to shape how Californians use and manage water. For instance, they could directly regulate how much different industries can use, they could implement a new tax to encourage conservation, or they could require the use of specific water saving technologies; each of these tools are used by state agencies in other policy domains. However, the state has been reluctant to regulate water use directly, instead setting broad goals (like achieving sustainability) and getting local actors to decide how they want to achieve those goals (individually or within a region) and codify those strategies within a plan.

If we examine the legislation that authorizes DWR to require water management plans, we find relatively little justification for why they chose a plan as opposed to any other tool (Escobedo Garcia and Ulibarri 2022a). In each statute, the legislature lays out detailed and explicit goals for achieving water security, encouraging conservation or regional coordination, or enhancing long-term sustainability – but then legislates the use of plans without discussion of their strengths or weaknesses. As an extreme example, in SB X7-7 (which authorizes DWR to require Agricultural Water Management Plans), the rationale for requiring irrigation districts to write plans is simply because other water agencies have to: “Urban water districts are required to adopt water management plans… [and] Agricultural water suppliers that receive water from the federal Central Valley Project [CVP] are required by federal law to prepare and implement water conservation plans… [Therefore] Agricultural water suppliers [including those who do not receive CVP water] shall be required to prepare water management plans to achieve conservation of water” (CWC §10,801). They assume that planning is good, and therefore require plans.

California water plans are good at managing for water quantity, but overlook environmental and social impacts

To understand what objectives water management plans are achieving, we can assess the written content of a plan, to see what dimensions of water management they discuss. As an example, a plan that focuses entirely on human uses of water, without discussing any environmental consequences of where that water was obtained from, is unlikely to intentionally improve environmental quality if implemented. Likewise, a plan that has a detailed evaluation of how climate change is likely to affect future water availability is more likely to develop management approaches that take that variability into account.

In reviewing plans written by water agencies in the Kings, Cosumnes, and American watersheds (Escobedo Garcia and Ulibarri 2022b), we found that across all plan types, they had a thorough discussion of water supply available in their jurisdiction, including an analysis of current and future conditions (Figure 1). Almost all plans discussed water quality, but less than half incorporated more than a brief discussion, suggesting a lack of attention to potential contamination issues. 

Figure 1. Level of detail in Central Valley water management plans. Bars show percent of plans discussing each category in detail, briefly, or not at all. (Source: Escobedo Garcia & Ulibarri 2022b)

Relative to water supply, plans had far less attention to environmental dimensions of water management (e.g., species or ecosystem health), the impact of climate change on the water cycle, or even human-environment dimensions like water for agriculture. However, the category that was least likely to be discussed was the social impacts of water supply, either socioeconomic impacts (e.g., a lack of water for disadvantaged communities) or health-related impacts from contamination – almost no plans discussed either topic in detail.

Finally, all plans detailed a variety of management tools to improve the sustainability and security of water supplies in their jurisdictions. Coordination activities (e.g., plans to hold annual stakeholder meetings) were the most commonly proposed tools, followed by monitoring. Less common, but still present in about half of the plans, were conservation activities or strategies to build new infrastructure or update existing infrastructure. 

Water agencies write plans because they have to, but don’t necessarily implement the plans

We can also look at the content of the plans to assess how useful that plan is as a tool to guide actual management of water. With the exception of quantifying their water supplies, most plans appeared to meet the minimum guidelines required by DWR, rather than adding detail that would render the information in the plan more useful. For instance, despite proposing a number of management tools, very few of the plans included details about how those tools would actually be implemented – who would implement them, on what timeline, or with what funding. Even the most thorough plans overall – Groundwater Sustainability Plans – suffered from this limitation, with most plans to implement managed aquifer recharge suffering from a lack of feasibility (Ulibarri et al. 2021). Other evidence that the plan contents weren’t implemented comes because updated versions of the plans (most of which are required on 5-year cycles) would explicitly say they hadn’t implemented prior proposed activities, often citing a lack of funding.

Interviews with the agencies that authored water management plans confirmed that the plans were written because they were legally required, but did not guide the agencies’ day to day actions. For instance, they told us, “We use the urban water management plans as a… planning tool just to comply with state law because we have to, but when a new development comes in, we’re not pulling that out and looking at okay, did we account for that?” and, “We do Urban Water Management Plans. Those are required every five years by law, so we have to do those.” The water agencies used other documents, such as Water Master Plans, for their day-to-day decisions, not those required by DWR.


California loves its resource management plans. And to comply with planning requirements, Californians spend large amounts of time and money: water utilities drafting or contracting out the plans, stakeholders crafting detailed comments on plan drafts, and state agencies writing guidance documents, conducting trainings, and reviewing submissions. However, in light of worsening droughts, ecological collapse, and unequal access to clean drinking water, it’s necessary to think critically about whether plans are the best tool, or are being best employed, to solve ongoing water challenges.

Nicola Ulibarri is an Associate Professor of Urban Planning and Public Policy at the University of California, Irvine.


Escobedo Garcia, N., & Ulibarri, N. (2022a). Plan writing as a policy tool: instrumental, conceptual, and tactical uses of water management plans in California. Journal of Environmental Studies and Sciences, 1-15. 

Escobedo Garcia, N., & Ulibarri, N. (2022b). Planning for effective water management: an evaluation of water management plans in California. Journal of Environmental Planning and Management, 1-21.

Ulibarri, N., Escobedo Garcia, N., Nelson, R. L., Cravens, A. E., & McCarty, R. J. (2021). Assessing the feasibility of managed aquifer recharge in California. Water Resources Research, 57(3), e2020WR029292.

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The Great Lakes and Invasive Species

This week’s CaliforniaWaterBlog post is an excerpt (Box 1) from a recent Delta Independent Science Board report on non-native species and the California Delta.  This excerpt summarizes the experience of the Great Lakes, and how its physical and ecological management has led to waves of profoundly disruptive species invasions, resulting in a sequence of “novel” ecosystems.  This sequence of invasions seems likely to continue to shape the Great Lakes.  This history is a wake-up and warning for policymakers and those working on California’s Delta.  Dan Eagan’s 2018 book is an excellent and readable history of these cyclic invasions and attempts to manage and cultivate them.

The Great Lakes are one of the most well-studied and invaded ecosystems in the world. Nearly every aspect of management is impacted by invaders (Egan 2018). The Great Lakes’ aquatic ecosystem developed following the last Ice Age by the recession of continental glaciers. Native species evolved from remnant populations in local and regional streams and a few that swam upstream. The Great Lakes’ topography, particularly Niagara Falls, limited species introductions to the upper Great Lakes until commercial navigation expanded in the early 1800s with the construction of New York’s Erie Canal and the Welland Canal that linked the lower Great Lakes to the upper Great Lakes.

Among these invasive species was the sea lamprey (Petromyzon marinus), which spread through the Great Lakes over several decades and depleted native predators particularly the lake trout (Salvelinus namaycush), which lacked any defenses. After years of scientific study, it was found that sea lamprey could be suppressed (but not eliminated) by treating specific stream reaches with a species-specific poison at specific times of the year when they were most vulnerable. Sea lamprey populations were reduced by about 90%, but control efforts continue, costing more than $20 million annually (Kinnunen 2018).

The herring-like alewife (Alosa pseudoharengus) also entered the Great Lakes, replacing intermediate species in the food web. With sea lamprey suppressing native predators, alewife boomed so high, they experienced massive annual die-offs that had to be removed from Chicago beaches by bulldozers. Commercial fishing began on alewife. To further help control the alewife population, several species of Pacific salmon (Oncorhynchus spp.) were introduced (Parsons 1973). Salmon survived well in the Great Lakes and triggered a massive sports fishery that bought billions of dollars annually to the Great Lakes. Annual stocking of (non-native) salmon raised in hatcheries became a major fisheries management priority and now stocking rates are tied to the production of its main prey, the non-native alewife.

The opening of the Saint Lawrence Seaway eventually brought larger, faster commercial ships and their ballast water to the Great Lakes, resulting in the new introduction of a wide range of species. Most notably, the introduction of zebra mussels (Dreissena polymorpha) to the Great Lakes in the late 1980s is considered the poster child of a successful invader. It has had profound impacts on the ecology and economy of the Great Lakes that range from clogging of water intakes for drinking and water-power operations (estimated costs into the billions) to loss of native clams to the decimation of primary production and disrupted food webs including the salmon recreational fishery. Interestingly, the invasion of the Great Lakes by zebra mussels was predicted more than a century before, based on shipping connections between the Great Lakes and areas where the mussel was well established (Carlton 1991). Quagga mussels (Dreissena rostriformis bugensis) invaded a few years later and have largely out-competed zebra mussels throughout the deeper portions of the Great Lakes. Both mussels have since spread throughout much of the Midwest and well into the west including California, Nevada, and Texas.

There is now concern about further invasions, including the movement of several Asian carp species (Cyprinus spp.) up the Mississippi River to the Great Lakes through the Chicago Sanitary and Ship Canal.

At each stage in this continuing history, local and regional interests and different state, provincial, national governments, and international bodies have acted, often out of necessity to manage these ecosystems or control major pathways such as ship ballast water. Management efforts to control invaders once established have been very limited. The entire Great Lakes ecosystem has been transformed by invasive species.


Carlton, J. (1991). Predictions of the arrival of the zebra mussel in North America. Dreissena Polymorpha Information Review, 2:1.

Delta Independent Science Board (2021), The Science of Non-native Species in a Dynamic Delta, Delta Independent Science Board, Sacramento, CA.

Egan, Dan (2018), The Death and Life of the Great Lakes, W. W. Norton & Company, 384 pp.

Kinnunen, R. (2018). Great Lakes sea lamprey control is critical. Michigan State University Extension, Michigan State Sea Grant.

Parsons, J.W. (1973). History of Salmon in the Great Lakes, 1850 – 1970. Technical Paper 68. U.S. Bureau of Sport Fisheries and Wildlife, Great Lakes Science Center.

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Follow the Water!

by Jay Lund

People often have strange ideas about how water works.  Even simple water systems can be confusing.  When water systems become large complex socio-physical-ecological systems serving many users and uses, opportunities for confusion become extreme, surpassing comprehension by our ancient Homo sapien brains.

When confused by conflicting rhetoric, using numbers to “follow the water” can be helpful.  The California Water Plan has developed some such numbers.  This essay presents their net water use numbers for 2018, by California’s agricultural, urban, and environmental uses by hydrologic region. 

Net water use is the amount by which a water use deprives water from other uses.  This differs from gross water use (a.k.a. applied water use) which includes both the net use plus any water returned after use which is available downstream for other uses.  The biggest net water uses, which deplete the most available water, are evapotranspiration from crops, urban landscapes, and wetlands, as well as required flows to the ocean.  Even large instream environmental or hydropower flows high in a watershed can have little net water use if reused downstream. 

The water accounting for agricultural and urban net water use is fairly strong here, but accounting for environmental flows remains primitive, and should probably be a lower bound.  Much past accounting conveniently (and sloppily) quantified “environmental water use” as all water not consumed by agriculture and cities, which inflated environmental water use.  The environmental water accounting here includes only evapotranspiration from interior environmental purposes (mostly wetlands) and outflows to the ocean required by law and regulation.

Here are the raw regional net water use numbers for 2018 by hydrologic region (arranged mostly north to south) by major purpose.  Details and data are available at

Table 1. Net water uses in 2018 by hydrologic region and use category

If the average water availability in California is about 75 million acre-ft per year, clearly there will be more “surplus” ocean outflows and some greater water use in wetter years, and less “surplus” outflow and water use in drought years.  In this large, diverse, and complex water system, it is hard to catch every drop before it reaches the ocean.  Even in very dry years, some water escapes the clutches of water managers and users.

Table 2. Percent of net water use in each hydrologic region by major water use

Table 2. Percent of net water use in each hydrologic region by major water use

California’s tremendous hydrologic and water use diversity jumps out from Table 2.  In the North Coast, net water use is 94% environmental (mostly outflow from wild and scenic rivers), with very little other uses (agricultural use here might be a bit more from illegal agriculture).  Most of California’s hydrologic regions have less than 10% of their water use being environmental, including the major urban regions and three of the largest the agricultural use regions.  All regions could be called unbalanced, individually, in different ways, which makes the state on average seem more balanced than it really is. 

When presented as percent of net water use, agriculture is the largest overall water use in California, and urban use is a distant third, as least in 2018.  Urban water conservation is good and merits some attention, but we clearly obsess with it disproportionately from a statewide perspective.  Agriculture is the big water use, and it is important how this use is managed (and largely reduced) for the future and for droughts.  Slash and burn approaches to water conservation hurt people and often ecosystems.

Other DWR data would show that total environmental use varies wildly from dry to wet years because much of it is for wild and scenic river flows. 

Table 3. Percent of net water use for each major use, by hydrologic region

96% of net environmental water use is in just two northern regions. Most regions in California have less than 1% of total state net water use for environment.  89% of agricultural water use is concentrated in just four regions.  73% of urban water use occurs in just two regions.  We often talk about how important or unimportant water uses are for California overall, while neglecting how even small uses statewide can dominate in some regions, and how some uses of large statewide concern are almost absent from many regions.

We should make more use of numbers in water policy. For example, Greg Gartrell et al. (2017 and 2022) have done insightful analyses of Delta inflows and outflows, which dispel several myths and put Delta water balance in perspective.  Grafton et al. (2018) show how water conservation based on gross water use is often ineffective and misleading for saving water.  A recent Delta Independent Science Board (2022) report reviews how we might make better water numbers and put them to better use for current and future challenges.  Implementing the Sustainable Groundwater Management Act will require far better and more available numbers for groundwater, surface water, and water demands than we have ever had.

We need insightful numbers to challenge and improve our current conceptions and prepare a more common basis for the difficult water discussions needed for a better future.  

Jay Lund is a Professor of Civil and Environmental Engineering and Co-Director of the Center for Watershed Sciences at the University of California – Davis. He is easily confused, so numbers help him think things through.

Further reading

Delta Independent Science Board. 2022. Review of Water Supply Reliability Estimation Related to the Sacramento-San Joaquin Delta. Report to the Delta Stewardship Council. Sacramento, California.

DWR, California Water Plan water use data

Gartrell, G., J. Mount, and E. Hanak (2022), “Tracking Where Water Goes in a Changing Sacramento–San Joaquin Delta, Technical Appendix: Methods and Detailed Results for 1980–2021,” PPIC, San Francisco, CA.

Grafton et al. (2018), “The Paradox of Irrigation Efficiency”, Science,

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Saving Clear Lake’s Endangered Chi

By Peter B. Moyle and Thomas L. Taylor

‘Tens of thousands of these fish once ascended streams in Spring. They are of major cultural importance to the Pomo people who harvested them as a valued food source.’ When you read statements like this, most likely it is salmon that come to mind. Yet this statement characterizes the Clear Lake Hitch or Chi, a non-salmonid fish, that ascends the tributaries to Clear Lake (Lake County) to spawn each spring (Thompson et al. 2013, Pfieffer 2022). Spawners are typically 10-14 inches long. They once moved up the streams in large numbers as soon as spring rains created sufficient stream flows to attract the fish (Moyle 2002, Moyle et al. 2015, Feyrer 2019).

We had the good fortune to be able to observe runs in the 1970s when we were studying Clear Lake’s unique fish fauna, following in the bootsteps of John Hopkirk. Hopkirk (1973) described the Clear Lake hitch and other Clear Lake fishes as unique forms adapted for life in this ancient (2.5 million years!) lake. Moyle was studying the lake’s fishes, while Taylor was documenting the distribution and ecology of the stream fishes (Taylor et al 1982.). Taylor also was (and still is) fascinated with photographing native fishes. The abundant hitch made good subjects. The photographs here show hitch spawning in streams in the 1970s and in 1990, when they were considerably more abundant than they are today, a reminder of what we are now missing.

Lure imitating a juvenile Clear Lake hitch. Lucky Craft Pointer 100-089.

In the same period, graduate student Eugene Geary conducted a life history study of hitch because of their abundance and predictability, perfect for a M.S. thesis study (Geary and Moyle 1980). We were concerned about their long-term persistence in the lake because they were thought of as ‘rough fish’(Rypel 2021) and knew that another stream spawner, the Clear Lake splittail, had already been extirpated (Moyle 2002, Moyle et al. 2015). When exploring the spawning streams, at times we would see dozens of fish that were dead for no apparent reason. We were told that local kids had a tradition of ‘hitching’, killing fish for the fun of it. There was also a commercial fishery in Clear Lake that, while focused on Sacramento blackfish, harvested hitch every year as well. Non-native predators also took their toll. Local largemouth bass anglers still use a lure made to look like a juvenile hitch (see photo above). Yet, in the 1970s, hitch were abundant enough so that they were labeled as a “persistent” native fish in the paper on their life history (Geary and Moyle 1980).

This optimistic view of their persistence was overshadowed by the fate of splittail and thicktail chub which had been extirpated from Clear Lake, and by Sacramento perch, which were rare (and are now extirpated from the lake). In 1989, the California Department of Fish and Wildlife listed Clear Lake hitch as a Fish Species of Special Concern. In 2014, the California Fish and Game Commission listed it as Threatened. This year, the USFWS has agreed to consider listing it as Threatened (see Taxonomic issues that might have prevented listing have now been resolved (Baumsteiger and Moyle 2019).

The causes of its rapid decline toward extinction are multiple and are tied to large-scale changes to Clear Lake and its watershed (Thompson et al. 2013, Moyle et al. 2015). However, the single biggest cause of the recent decline seems to be stream habitat degradation, including barriers, gravel mining, and loss of crucial spring flows for spawning and early development, as well as for transport of the larval fish back to Clear Lake. These problems are exacerbated by the current severe drought (e.g., Larson 2022). This spring, spawning hitch were found in only two tributaries (Kelsey, Adobe creeks) and many of those fish had to be rescued and returned to the lake, when streams stopped flowing (Pfeiffer 2022). Any eggs and larvae produced by these fish were stranded in the drying streams.

The fate of Clear Lake hitch is tied to restoring spring flows to spawning streams, along with barrier removal and other habitat restoration actions. Such restoration will take continued leadership by the Pomo people in the watershed, cooperation among the numerous agencies with authority in the region, citizen volunteer efforts (such as stream surveys), and lots of funding from state and federal sources.

Ideally, the actions to protect Clear Lake hitch would also stimulate interest in other remaining endemic lake-dwelling species such as Clear Lake tule perch, Clear Lake sculpin, and Sacramento blackfish. Saving the Clear Lake hitch could open a whole new chapter for fish conservation in Clear Lake and its tributary streams.

Peter B. Moyle is a Distinguished Professor Emeritus at the University of California, Davis and is Associate Director of the Center for Watershed Sciences.Thomas L. Taylor is a retired fish biologist with a long history of working on California fishes. He is a native fish enthusiast and has spent thousands of hours in streams photographing fish.

Further reading

Baumsteiger, J., M. Young, and P. B. Moyle. 2018. Using the Distinct Population Segment (DPS) concept to protect fishes with low levels of genomic differentiation: conservation of an endemic minnow (Hitch). Transactions of American Fisheries Society 148:406-416. 10.1002/tafs.10144.

Feyrer, F. 2019. Observations of the spawning ecology of the imperiled Clear Lake Hitch. California Fish and Game 105:225-23

Geary, R. E., and P. B. Moyle. 1980. Aspects of the ecology of the Hitch, Lavinia exilicauda (Cyprinidae), a persistent native cyprinid in Clear Lake, California. The Southwestern Naturalist 25: 385-390.

Hopkirk, J.D. 1973. Endemism in Fishes of the Clear Lake region in Central California. University of California Publications in Zoology 96.

Larson, E. 2022. State, local, and tribal officials partner to rescue stranded Clear Lake Hitch. Lake County News, April 30, 2022.,threatened.

Moyle, P.B. 2002. Inland Fishes of California, Revised and Expanded. Berkeley: University of California Press.

Moyle, P. B., R. M. Quiñones, J. V. E. Katz, and J. Weaver. 2015. Fish Species of Special Concern in California. 3rd edition. Sacramento: California Department of Fish and Wildlife.

Pfeiffer, J. 2022. Why I am fighting for a fish I have never seen. High Country News. May 25, 2022.

Rypel, A.L., P. Saffarinia, C.C. Vaughn, L. Nesper, K. O’Reilly, C.A. Parisek, M.L. Miller, P.B. Moyle, N.A. Fangue, M. Bell-Tilcock, D. Ayers, and S.R. David. 2021. Goodbye to “rough fish”: paradigm shift in the conservation of native fishes. Fisheries 46: 605-616 .

Rypel, A.L. 2021. Defending ‘Rough Fish.’ California Water Blog. University of California, Davis, Center for Watershed Sciences. December 19, 2021.

Taylor, T. L., P. B. Moyle, and D. G. Price. 1982. Fishes of the Clear Lake Basin. Pages 171-223 in P. B. Moyle, ed., Distribution and Ecology of Stream Fishes of the Sacramento-San Joaquin Drainage System, California. Publications in Zoology 115, University of California Press, Berkeley, California.

Thompson, L.C., G.A. Giusti, L.Weber, and R. F. Keiffer. 2013. The native and introduced fishes of Clear Lake: a review of the past to assist with decisions of the future. California Fish and Game 99(1):7-41.

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Unlocking how juvenile Chinook salmon swim in California rivers

By Rusty C. Holleman, Nann A. Fangue, Edward S. Gross, Michael J. Thomas, and Andrew L. Rypel

Despite years of study and thousands of research projects, some aspects of the biology of Chinook salmon remain altogether mysterious. One enduring question is how outmigrating salmon smolts behave and swim through our waterways to somehow find their way into the ocean. For example, it has long been noted that salmon ‘shoulder’ (hold on the river’s edge) at certain times along their oceanward journey, and that they tend to school and travel in packs alongside one another. Are they actively swimming through these habitats? Or merely drifting with the currents, akin to riding an innertube down the river. A better understanding of Chinook salmon swimming behavior could be helpful for managers. If salmon actively navigate, could we provide flows or otherwise manage water to promote salmon survival?

Fig. 1. (Top) Taggable-size spring-run Chinook salmon from the SCARF hatchery. Resting on top of the fish is a miniature acoustic transmitter ready to implant in the fish. (Bottom) Finishing JSAT implantation surgery on a juvenile spring-run Chinook salmon. Photos by Gabriel Singer.

Improved acoustic tagging technologies (such as juvenile salmon acoustic tags, “JSAT”) now allows researchers to study the movements of juvenile salmon as small as 65–75mm long along their entire journey (Fig. 1). The tags produce high frequency sounds detectable with hydrophones (underwater microphones) placed throughout waterways. With enough hydrophones in a small area, it then even becomes possible to track behaviors of salmon, including second-by-second motions inside critical areas of interest. In the Delta, areas of particular interest include areas near water pumping facilities and channel junctions (forks in the river), where the fate of salmon can be quite different if fish go one direction versus another.

Fig. 2. Map of study site including (a) Sacramento-San Joaquin Delta, including San Joaquin River and fish release locations. (b) Head of Old River study site, with computational grid and bathymetry, and the layout of the hydrophone array. White arrows show the downstream flow direction (noting that tidal flow reversal is possible on the downstream section of the San Joaquin River). (c) Location of gages relative to study site.

We studied swimming behavior of juvenile spring-run Chinook salmon in the San Joaquin River (Holleman et al. 2022). Spring-run are being reintroduced into the San Joaquin River, and a team at UC Davis has studied this population for the last 5 years, primarily using acoustic telemetry. One aspect of this work was an array of hydrophones at the Head of Old River to track salmon behavior at this critical junction (Fig. 2). These results build from related model development and analytical work published by this same interdisciplinary group (Gross et al. 2022). During typical flow conditions, most salmon ‘hang a left’ at this junction, meaning fish will arrive at the state or federal water facilities. Any fish salvaged at these facilities receive a truck ride to Chipps Island at the western boundary of the Delta where they are released back into the Estuary. In contrast, salmon that ‘go right’ at the junction traverse the engineered channels and predation exposure in the South Delta, including the deepwater Port of Stockton, before exiting the Delta at Chipps Island. Research with spring-run (Singer 2019, Hause et al. 2022) and fall-run (Buchanan et al. 2018) show fish that follow this route have very poor survivorship — sadly, even worse than those salvaged at the pumping facilities. Nonetheless, because the fate of fish hinges on this left/right route selection, it is an intriguing location to examine salmon swimming behavior.

Fig. 3. Location of water velocity measurements and model–data comparisons. Velocity vectors in the horizontal for
each transect showing modeled (green) and observed (black) velocities averaged over the top 2 m of the water column.

To complement data on fish movement we also studied hydrodynamics of the river at this same location. Using a boat-mounted acoustic doppler current profiler (ADCP), we mapped water velocity of the river at nine transects — six above the junction, one at the junction, and one below the junction on each branch. These data supported a three-dimensional hydrodynamic model of the study area (Fig. 3), which in turn provided estimates of water velocity along each observed smolt’s path. By comparing the water velocity and smolt’s movement we calculated a swimming speed and direction for each tagged fish. Such swim velocity vectors can identify longitudinal (upstream or downstream) and lateral (river right or river left) swimming components for each fish.

A key difference between this study and many previous swim speed studies is the focus on swimming behavior (what a fish chooses) rather than swimming capacity (what a fish is capable of). Over the 147,991 detections from tagged salmon, most swimming speeds were 0.15–0.20 m s-1 (Fig. 4), or 2–3 body lengths per second (BL s-1). These speeds are similar to, but slower than, previously observed swim capacity speeds for juvenile Chinook Salmon, often ~4 BL s-1. The observed long tail of high velocities is comparable to the result of Lehman et al. 2017 who measured maximum sustained swim speeds of ~7 BL s-1. While the smolts are capable of much faster movement, these data paint a picture of emigrating smolts cruising along at a relatively “comfortable” speed.

Fig. 4. Distributions of swimming speeds for juvenile Chinook salmon in the study.

In the absence of swimming or vertical movement, smolts would be passively transported with the flow, matching the velocity of the river. Our data show that smolts were almost always moving downstream, but slower than water velocities. This indicates that salmon smolts are actively navigating the river and not displaying passive behavior dominated by water flow. Positive rheotaxis (turning to face the current, see YouTube video above for a visual) was broadly observed. Further, this kind of behavior increased with water velocity, and was consistent with smolts moving through the area more slowly than the mean flow velocity. It’s unclear whether fish face into the flow for feeding, to observe and respond to predators, or if they just like to feel the wind in their face. Diurnal variations in swimming also indicated greater positive rheotaxis or downward vertical migration during daylight hours, along with greater lateral swimming. Understanding these behaviors is a fundamental component of answering important questions of route selection and transit time of emigrating Chinook Salmon smolts.

Overall, we learned that Chinook salmon smolts are far from simple passengers riding the flow of the rivers and tides to the sea. This study showed that smolts actively swim along the way, often pointed into the current or traversing the river side-to-side, and generally at a pace less than half of their top speed. It also showed how novel technologies such as acoustic telemetry can be leveraged to study very old questions in fisheries, natural resource management, and even behavioral ecology. More studies that combine these technologies will give increasing comparative information on how salmon smolts behave in different rivers and junctions. These results will help managers understand how salmon will react to various proposed water infrastructure and operating decisions.

Rusty Holleman is a Senior Researcher in Civil and Environmental Engineering at the Center for Watershed Sciences at University of California, Davis. Ed Gross is a research Engineer in the Department of Civil and Environmental Engineering at University of California Davis. Nann Fangue is a professor and Chair of the Department of Wildlife, Fish & Conservation Biology at University of California, Davis. Andrew Rypel is Co-Director of the Center for Watershed Sciences and a Professor and the Peter B. Moyle and California Trout Chair of coldwater fish ecology at the University of California, Davis.

Further Reading

Buchanan, R.A., Brandes, P.L., Skalski, J.R., 2018. Survival of Juvenile Fall-Run Chinook Salmon through the San Joaquin River Delta, California, 2010–2015. North American Journal of Fisheries Management 38: 663–679.

Gross, E.S., R.C. Holleman, M.J. Thomas, N.A. Fangue, and A.L. Rypel. 2021. Development and evaluation of a Chinook salmon smolt swimming behavior model. Water 13(20) 2904.

Hause, C.L., G.P. Singer, R.A. Buchanan, D.E. Cocherell, N.A. Fangue, and A.L. Rypel. 2022. Survival of a threatened salmon is linked to spatial variability in river conditions. Canadian Journal of Fisheries and Aquatic Sciences In Press. bioRxiv preprint available:

Holleman, R. C., E.S. Gross, M.J. Thomas, A.L. Rypel, and N.A. Fangue. 2022. Swimming behavior of emigrating Chinook salmon smolts. PLoS ONE 17(3): e0263972. 

Lehman B, D.D. Huff, S.A. Hayes, S.T. Lindley. 2017. Relationships between Chinook Salmon Swimming Performance and Water Quality in the San Joaquin River, California. Transactions of the American Fisheries Society 146: 349–358.

Rypel, A.L., G. Singer, and N.A. Fangue. 2020. Science of an underdog: the improbable comeback of spring-run Chinook salmon in the San Joaquin River,

Singer, G.P. 2019. Movement and survival of juvenile Chinook salmon in California’s Central Valley. Ph.D. Dissertation, University of California, Davis.

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Uncertainty in modeling, an Art Gallery

Water resource planners regularly rely on computer models to illuminate relationships between human- and natural-systems. Anyone who has tinkered with one of California water supply models knows this is a deeply left-brained exercise. During Winter 2021, as part of Jay Lund’s Art and Water class, water resource engineering students took a break from creating and analyzing mathematical models to exercise the right side of their brains and enjoy some art. Please enjoy this collection of art pieces curated by a group of graduate students who can’t quite figure out how to unplug…

“War (The First Discord)” (19th c.) – DeScott Evans

This piece illustrates the struggle and discord that can occur in hydrologic modeling practice. As these cherubs fight over the apple shown in the bottom left, we can imagine two experts fighting to model nuanced environmental processes to create a “more perfect” model. In the heat of battle, they fail to consider how the model informs effective policy and meaningful change. Is creating the most accurate model always worth the toil, resources, and effort? Instead, the cherubs could collaborate to share the apple and create a model that worked well enough to inform policy and promote meaningful change. – Abbey Hill

Composition II in Red Blue and Yellow” (1930) –  Piet Mondrian 

Uncertainty in modeling is inescapable. Instead of making the solution very complicated, why not make things easier? This painting by Mondrian consists only of straight lines and blocks of colors. We can’t predict the variability of precipitation and other key variables in the future, but simplified (Mondrian-esque) models can still be useful and inform water-saving policies. –  Zhendan Cao

Tree Cathedral (Cattedrale Vegetale) – Giuliano Mauri (2010)

This work of Earth art represents both the carefully planned infrastructure and unavoidable uncertainty inherent to modeling. Just as models build on known and existing systems, this work originates with the architectural history of Gothic cathedrals. However, models must also allow space for flexibility, which Wilby and Dessai (2010) describe as a “framework for robust adaptation.” The Tree Cathedral is built with rigid support structures to manipulate the tree growth pattern, but as time passes, the support cages rot and fall away, allowing the trees to stand on their own. The adaptable and flexible nature of the Tree Cathedral becomes apparent over the years as it continues to grow. Will the tree canopies form the roof of the Cathedral as planned? Will the trees continue to grow as intended? Uncertainty is central to the beauty of the Tree Cathedral and to the functioning of models. There is no way to control or plan for every possible eventuality. Will the Tree Cathedral stay standing, or will exposure to the elements cause it to fall? How will future climate outcomes compare to model predictions of increased drought or storms?  – Eleanor Fadely

“Bad Lemon (Creep)” (2019) Kathleen Ryan

Emerging artist Kathleen Ryan creates intricate mosaics of precious gemstones to create larger-than-life monuments to spoiled fruit. The artist’s process resembles that of a water resource planning model-builder. The modeler finds beauty when complex mathematical feedbacks and uncertainties nest neatly together and produce reasonable results. Stepping back and applying modeling to real-life scenarios (such as climate change and drought) reveals rotten dilemmas for water resource managers.  – Lindsay Murdoch

Dove (1949), The Flying Dove with a Raibow I and II (1952) and The Dove of Peace (1949) by Pablo Picaso; and The Birds by Georges Braque (1960)

This collection of Dove sketches by Pablo Picasso presents a parallelism between different models used in water planning, design and operation. If a real dove represents the watershed to water managers, the first painting illustrates the utopic model that perfectly simulates/forecasts existing hydrology, incorporating all heterogeneity and complexity. The second sketch would be physically-based, spatially distributed hydrologic models to predict hydrologic processes, accurate depiction of the dove, with some spatial heterogeneity at fine spatial resolutions, represented by the feather details. The next simple dove sketch would illustrate simpler physically based models with a few hydrologic processes, clearly depicting a dove but with less detail. The second to last sketch nicely relates to conceptual models in which each block represents a separate hydrologic process, for instance Tank Model (Sugawara 1972) for subsurface runoff and baseflow, that individually do not provide useful information, but when arranged meaningfully, can produce realistic watershed outputs (Klemes 1982). Thus, generating the dove shape. Finally, George Braque’s painting illustrates an empirical model in which the resemblance to a dove is exclusively due to its construction using watershed data. As such, if provided to other water managers, they might recognize them as a different bird or even E letters with humps, showing that empirical models are useful for the specific watershed they are developed for. – Francisco Bellido

Autumn Rhythm by Jackson Pollock (1950)

Despite the shocking global trend of rising temperature, its local implications can be obscure. As some pointed out, “There is a low level of agreement amongst climate models even about the sign of the seasonal rainfall” over large areas. Future climate projections do share some similarities with Jackson Pollock’s paintings. In this notable piece called “Autumn Rhythm”, the artist used a variety of dripping and pouring methods to create disordered lines and patches. This certainly reminds us about the numerous uncertainties embedded into climate predictions. Viewers often appreciate this painting for its randomness, abstractness, and the delivery of vitality and flow. As engineers, we also hope to uncover trends and beauty in the turmoil of the future.

Bridge Over a Pond of Water Lilies – Claude Monet (1993)

A low level of agreement amongst climate models on projected changes in key variables such as the magnitude of warming or the magnitude and sign of seasonal precipitation has led many to recommend dynamic adaptive management as an alternative to taking big actions now. There is undeniably some common sense to this “wait and see” approach. However, adaptive management merely supplants uncertainties in projecting climate with a myriad of other uncertainties such as the social, economic, and political environments around decisions planned to be made in the future, environments which may in fact be more conducive to decisions made today. Imagine Claude Monet’s universally admired painting, “Bridge Over a Pond of Water Lilies”, without the bridge – does the scene appear more untamed and wild? The notion of adaptive management is like the bridge: its elegant structure transforms the landscape into an orderly, calm and serene atmosphere. But it only appears that way. In reality, the chaotic unpredictability of the environment is more likely to undermine our adaptive plans, plans which are assuredly more embellished and highly dimensioned than Monet’s bridge. In sum, we cannot simply create a bridge over uncertainty, no matter how alluring it may be. – Wyatt Arnold

Further Reading

Klemes, V (1982), “Empirical and Causal Models in Hydrology,” Scientific basis of water resource management, National Academy Press, Washington, DC.

Wilby, R.L.  and S. Dessai (2010) “Robust adaptation to climate change,” Weather, Vol. 65, No. 7, July.

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