Meet Dr. Andrew Rypel, our new fish squeezer

Andrew, 5 years old, with a bass.

This year, we have the pleasure of welcoming Dr. Andrew Rypel to UC Davis and the Center for Watershed Sciences to his appointment as the new Peter B. Moyle and California Trout Endowed Chair in Coldwater Fishes. Dr. Rypel shares some of this thoughts about fish, science, and his new position:

1. How does it feel to be the new Peter B. Moyle and California Trout Endowed Chair in Coldwater Fishes?

Incredible and unbelievable – a great stroke of fortune – the opportunity of lifetime! What else can one say? When I first started out in fish science, my primary goal was to just have a cool job where I got to work with fishes. Over time, that has evolved; for example, I have developed other aspirations and interests, like using science to move the needle on conservation issues that matter. However, to have reached a point and be honored like this…wow.

It feels especially surreal to follow in the footsteps of Peter Moyle. As I have gotten to know Peter over the last year, it’s clear we share much in common. We’re both Midwesterners! We also see eye-to-eye on many of the fish conservation issues of today and the type of thinking that will be required to come up with solutions that work for fishes – and people. I’m really looking forward to collaborating with Peter and his many former students in the coming years.

Another draw to this opportunity for me was the potential to partner with a dynamic and forward-thinking organization like CalTrout. Working with people and organizations that are passionate, organized, and driven by science – that is what has always been needed to do conservation science right, but increasingly so as global environmental change effects take further grip on our fishes and ecosystems. It is telling that the slogan for CalTrout is “Fish-Water-People,” which is similar to what you see in any Fisheries Management textbook describing a proper fisheries management system – the interaction of fish, habitat and people. CalTrout is full of dedicated folks that have staked much to make my position available in its current form. I recognize this and am energized and inspired by it.

Margaret Mead said, “Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it’s the only thing that ever has.” Collectively, we are poised to do some special things in the coming years, and I am thrilled to be a part of that science and the partnerships that will support that!

2. What are you looking forward to most in this new position?

A few things. Number one on the list is teaching and mentoring students. Over the past several years the importance of leaving a legacy for future generations has crystallized for me. That legacy can be physical, like healthy and resilient fish populations, but it can also be values-based. It is hard to conserve something if people don’t care about it.

Teaching and mentoring students on the diversity and mysteries of fishes is something I am already relishing – fish biology class here at UCD is already in full swing! The moments when a student first holds or touches a fish, perhaps one they might have never held or touched before, is special. I’ve seen it change people – I really have! And it doesn’t even have to be with fish, although I would prefer that. Connecting with salamanders, ducks, plants, even insects can be transformative for people. It’s a particularly special experience though when that experience (E.O. Wilson might refer to it as biophilia) dovetails together with the scientific method and the collection of data towards some larger question or public good.

Andrew Rypel, and the results of a day “sampling.”

There are nerdy fish things I am looking forward to working on in California. Places to study others have not, or not much. Interesting things to think about, new species to work with. California is like no other place I have been, and the fishes, freshwater fauna, and environmental issues are unlike every other place I have worked. It appears to be a place ripe for those with a creative approach to science and conservation, and I am excited to join the conversation and start conducting science. The Center for Watershed Sciences is emblematic of this type of interdisciplinary approach – a place where scientists of disparate interests and backgrounds can gather to collaborate collectively on problems that matter.

Finally, I am excited to work with various agency partners and CalTrout on applied conservation issues. What most people find surprising about successful conservation and natural resource management work is that it often involves a heavy dose of working with people. Perhaps unsurprisingly, most scientists are not trained to actually work with people. This is unfortunate because so many of the potential solutions to the environmental problems that plague us are fundamentally people problems as they are linked to policy and governance structures.

I am a firm believer that scientists do need to escape the “ivory tower.” There was a hashtag going around on Twitter recently (#actuallivingscientist) that I found to be a rather sad and ironic commentary. As in “nobody knows an actual living scientist.” And as much as I hate to admit this, this is probably our fault. As human beings, we naturally gravitate to and align ourselves with people similar to us, which only reinforces group-think and confirmation bias. Gathering, harvesting and adapting new and different ideas is what is most exciting to me. And these ideas can come from anywhere, including from people you might not agree with on every single issue. I of course have many ideas and experiences from my past work that I am excited to share. Yet I am also anxious to learn more about the ideas of others, perhaps especially those of non-scientists. It’s more fun to meet, interact and work with a diversity of people anyways!

3. What will this position allow you to do that you weren’t able to do before?

I’ll focus on one particularly important thing that came with this job for me. Tenure. Some people don’t realize, but tenure is under attack in the US. In some ways, this is understandable as in other job sectors, job security is not the norm. However, erosion in tenure protections is unfortunate for science. It is one of the basic protections for academics in pursuing truth, as we are mandated to do, e.g., via the scientific method. It also frees up scientists to pursue ideas that might challenge the status quo or otherwise be unprofitable.

I have the hard-won experience now to have worked in places where scientists were not afforded such protections, and it fundamentally changes the way scientists behave and work. Researchers quickly learn the consequences when they produce data or research that is at odds with those in power. The effect is large and chilling. I am grateful for having received tenure at UC Davis, and hope to use it. Not to intentionally “rock the boat” or go after controversial ideas, but to do science – real science that we think is important. That science can be risky, can have economic implications but not necessarily, and to do it with students within the support system or tenure – that is huge.

I am increasingly convinced tenure is an essential element to a free and democratic society. People might be surprised, but without tenure protections, ideas and data that challenge and diversify our thinking and that of our students are lost, and we can often behave like scared sheep.

3. What will you research and how will it benefit the world?

Honest answer: I don’t know. I have so many ideas and topics I am personally interested in, but I also want to do research that connects with people and has the potential to move the needle on priority conservation issues. So…I am all ears! Once I finish teaching this fall, I would like to get in a car and drive around the state – learn the people and what the priority and consensus science needs might be. It is a big state and there are so many people to meet, agencies and non-profits to engage, fishes to see! All this is to say – if you have an idea or would like to work with me, or have an idea, come find me, I would love to hear your ideas and find ways to align my research here with things people care about!

4. What sparked your interest in research or science in general?

Andrew and his father, after a good day.

Well, I am one of those people that grew up fishing. I got it from my Dad, who started taking us at a very young age. I was raised in Wisconsin and would spend summers exploring every inch of the lakes, rivers, streams and wetlands in Wisconsin (mostly northwestern WI). Anything me and my Dad could wedge a canoe or a pair of waders into. I knew from a very young age that I wanted to work with fishes, I just never thought it would be possible.

When I was in college, I majored in the closest thing I could find to something involving fishes – Environmental Science. However, I had never really “done” science. It wasn’t until I was 23 or so and finishing up my MS at Auburn University that I figured out I might have a talent at science. My MS project was related to studying sexual differences in PCB pollution in fishes from a reservoir. On the side though, I wound up getting interested in the ecology of freshwater drum (Aplodinotus grunniens).

Drum (or Sheepshead as they are sometimes called) are a curious and intriguing species – they have the largest latitudinal range of any freshwater species in North America. And individuals can be ultra long-lived (>70 years old!). They occur in both lakes and rivers, and in some of the larger rivers, can dominate fish biomass. Nobody was doing on work on them, and I found that odd.

I wound up writing a small grant to do a statewide survey of some of freshwater drum populations in Alabama, and I got the funding. It was exhilarating to get funding and really go after a science idea, travel all over the state to do the field work, do the lab science and stats and then write and publish a series of papers on it. That was it – I was hooked – and it was clear to me that I loved science (and fish) and had a talent at it. The rest is history!

5. What is an interesting fact about yourself or something you want people to know about you?

I play guitar and have played in several bands, and solo. I have a recorded version of Amazing Grace that is archived in the Library of Congress. Before the freshwater drum project hit, I was seriously considering moving from Auburn to Nashville to be a singer – songwriter. Good thing science worked out! I still love to play – only now mostly for our two young boys.

I do believe though that science has a creativity component. There is a good book called Thinking Fast and Slow that makes a solid brain science case for this – our minds are sharpened by using both the slow (science and reasoning are slow processes) and fast (creative) parts. There is also a case for the SciArt movement in there. People can’t do science all the time, the brain isn’t built like that. Art, music and other creative endeavors are a chance to use the other parts of our brain, and that probably enhances our overall ability to think. It’s also a chance to connect with our parallel scholars of the humanities with whom we rarely interact.

Andrew Rypel is a fish biologist and holds the Peter B. Moyle and California Trout Endowed Chair in Coldwater Fishes at the University of California, Davis. He is also an affiliate of the Center for Watershed Sciences.

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Accounting for groundwater movement between subbasins under SGMA

by Christina Buck, Jim Blanke, Reza Namvar, and Thomas Harter

The Sustainable Groundwater Management Act (SGMA) presents many new challenges and opportunities.  One challenge is accounting for ‘interbasin flow,’ or subsurface groundwater movement between subbasins, a piece of the overall water budget required in Groundwater Sustainability Plans (GSPs).

Interbasin flow as part of the groundwater budget.

The Department of Water Resources is tasked with evaluating whether groundwater management in one subbasin will undermine an adjacent subbasin’s ability to reach sustainability.  Recognizing that subbasins throughout the Central Valley are interconnected, it’s much better to address this technical and management challenge up front rather than have each subbasin individually submit their GSP and hope for the best.

To tackle this issue, the Water Foundation funded a project administered by Butte County Department of Water and Resource Conservation that gathered a group of Technical Collaborators (TC) to discuss and provide recommendations on quantification of interbasin flow in GSPs.  Since interbasin flows cannot be measured directly, the project reviewed available groundwater models to investigate how they may or may not be suitable in estimating interbasin flows within the northern Sacramento Valley.

Technical collaborators providing recommendations and report content.

Groundwater models will be a part of our future

The complexity of processes affecting interbasin groundwater flows make groundwater models effective and typically necessary tools for quantifying these flows. SGMA does not legally require the use of a groundwater model. Yet, successfully avoiding the six Undesirable Results defined by SGMA will require accounting for a complete surface water and groundwater budget. Models also enable GSAs to estimate the effects of groundwater management practices that affect the water budget (e.g., decreased pumping or increased recharge) on groundwater conditions over time. Models will be key to leveraging diverse local data sets and knowledge into a consistent science-based framework to guide groundwater management.  Models that can evolve with the Groundwater Sustainability Plan (GSP) process are key to efficient and informed adaptive management, to guide monitoring and to inform practice decisions, and as a learning tool for stakeholders.

Existing tools and model selection

The northern Sacramento Valley area is covered by three regional models including two Central Valley-wide models: 1) C2VSim developed by the Department of Water Resources (DWR) and 2) CVHM developed by the United States Geological Survey (USGS).  These models are both undergoing significant updates.  Another regional, Sacramento Valley-wide model is currently being developed by DWR called SVSim.  In addition, local groundwater models also exist (e.g., Butte Basin Groundwater Model).  None of the existing regional or local groundwater models were specifically developed for SGMA.

Although the regional models are a valuable starting point and are based on a shared physical understanding of groundwater flow, they differ in their representation of aquifer geology and in their approach to simulating hydrological processes (“boundary conditions”) that drive groundwater flow and storage.  They also contain inputs developed from different data sources. These differences partly stem from the diversity of objectives for which these models were originally created, but also from conceptual and data uncertainty about appropriately representing, for example, pumping, agricultural recharge, or stream-groundwater interaction, among others.  The three models therefore yield somewhat different water budgets and differing results in simulating groundwater level conditions.

Given these differences, agencies should consider the following question when considering which groundwater model to use for GSP development: How well does the model match my current understanding of the land surface layer and groundwater budgets in my area? This question can be answered by considering the quality and amount of data, supply and demand, boundary conditions, water budget results, and calibration.

The Technical Collaborators concluded there is not an obvious choice of one of the regional models for the northern Sacramento Valley.  Therefore, each subbasin should compare the model inputs and results to locally available historical data, if possible. An existing surface layer model or other water budget datasets should be used only to assist in selecting the appropriate groundwater model. It is not appropriate to mix output from the groundwater model with other local water budget sources. Groundwater model results should be presented in full to keep the results internally consistent. In addition, simulated groundwater elevations near the boundaries have the most effect on quantifying interbasin groundwater flows. Therefore, evaluating a model’s representation of groundwater levels in comparison to historical data is important, particularly in the areas along subbasin boundaries.

Cooperation and uncertainty

The most critical factor to address interbasin conditions will not come from a pure technical remedy, but rather from cooperation. Early cooperation with neighboring subbasins to compare interbasin flow estimates is important. Although the exact values may be different, the estimated interbasin flow magnitude and direction should be similar. Differences should  be expected and – if the models are well constructed – reflect our uncertainty in the modeled systems.  Differences in model outcomes need not disrupt progress on sustainable groundwater management and may help guide both, monitoring efforts, and management decisions.  Modeling the groundwater system and working towards sustainability is an iterative process and agencies should utilize adaptive management practices.  The uncertainty inherent in models needs to be anticipated and accounted for when making decisions based on their results.  Estimates and representation of the system in models will improve over time with a long term investment in these tools.

Final report available

The final report includes recommendations for the northern Sacramento Valley region, for GSAs statewide, and for DWR and USGS who are developing and maintaining the regional models.  For more background and details on the outcomes and recommendations of the Technical Collaborators, the final report is available from the project website:

The project was made possible through the generous support of the Water Foundation, an initiative of the Resources Legacy Fund.   

Christina Buck is the Water Resources Scientist for Butte County Department of Water and Resources Conservation.  Jim Blanke is a Senior Hydrogeologist at RMC, A Woodard & Curran Company.  Reza Namvar is a Senior Water Resources Engineer at RMC, A Woodard & Curran Company.  Thomas Harter is a groundwater expert at the University of California, Davis and an Associate Director of the UC Davis Center for Watershed Sciences.

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20 Years Ago a Pretty Good Idea: The UC Davis Center for Watershed Sciences

by Jeffrey Mount

Our beloved home.

The UC Davis Center for Watershed Sciences turns 20 years old this month.  I am the first Director of the Center.  The current Director — Jay Lund — asked me to write an  account of the origins of the Center, including some reflection on any key lessons.

The Center was and remains an academic start-up.  Although the administration at the time was supportive, the intellectual venture capital to get it going came from the faculty. And it was really a handful of faculty, staff and students that made this program work.

In the late 1990’s, institutions around the country were coming to grips with consequences of the traditional research university structure.  Built around narrowly-defined, discipline-based colleges and departments, the 20th century university had made great strides in research and education.  But increasing specialization, while important for advancing basic understanding, was not up to the task of addressing society’s big challenges.  Solutions to complex, large-scale problems lie at the boundaries of disciplines.  This is especially pertinent to the many economic, social and environmental dimensions of managing water.

From left: Jay Lund, Peter Moyle, and Jeffrey Mount.

The Center came about when Peter Moyle and I – a fish biologist and a geologist – began comparing ideas and understandings of the effects of seasonal inundation on a local floodplain.  From this early partnership, the concept of the Center was born.  It was to be an academic home for water management problem solving — not fundamental research — that relied on collaboration between faculty and students from diverse fields. It was to be a bridge between academic silos and, most important, it was to be useful to California.

From this effort — and a lot of trial and error — we learned a few key lessons.

Timing is everything.  We got this Center going in fall of 1998. In the previous year, California had the great Central Valley flood, which followed the 1987-92 drought, one of the most punishing in state history.  There was unprecedented attention to solving the problems of the Sacramento-San Joaquin Delta at all levels of government. The Packard Foundation, which was interested in fostering science in support of environmental decision-making, provided Center start-up funds.  The CALFED Bay-Delta Program provided early research funding, and helped to institutionalize the science/policy feedback loop that has become a hallmark of the Center.

Good ideas are of little value if they don’t have champions.  Inertia is a powerful force in institutions as large and complex as UC Davis.  The only way to overcome this—and to promote new approaches and ideas—is to have dedicated champions willing to take risks for you.  Beyond the faculty members involved in the enterprise, there were key individuals on and off campus who went to bat for us.  This included folks like Bob Floccini, Director of the John Muir Institute for the Environment, Bob Grey and Virginia Hinshaw, Provosts who saw the value of this work, and deans like Peter Rock who embraced the approach.  Off campus champions were people like Michael Mantell of Resources Legacy Fund who—representing the Packard Foundation—gave the Center its first large grant, and Mike Eaton of The Nature Conservancy who invited us down to the Cosumnes River Preserve to conduct experiments on their floodplain.

Leverage good ideas with good people.  No matter how good the idea, if it is not staffed by outstanding people, it will not succeed.  The Center, during its early start up years, attracted a lot of people to work in it.  But we discovered early on that multi-disciplinary centers are not a good fit for everyone.  Whether faculty, research staff or students, the five key ingredients for successful Center collaborators were:

  • the ability to play well with others (the most important!)
  • a genuine interest in learning from each other
  • commitment to spending resources on growing the common enterprise, rather than financing one’s own projects
  • a desire to make a tangible difference, rather than to just publish papers
  • a sense of humor, preferably self-deprecating

    The original Watershed Lab, Crab Louie, and our guru for the five traits of a successful collaborator.

Individuals with these five attributes prospered in the early years of the Center.  Indeed, one of the  most productive collaborations that I was involved in included Peter Moyle (fish biology), Jay Lund (engineering), Richard Howitt (agricultural economics) and eventually Ellen Hanak  (economics – from the Public Policy Institute of California).  This also applied to many of the early student founders, like Carson Jeffres, Wendy Trowbridge, Kaylene Keller, Josh Viers, and  staff people like Cheryl Smith, Ellen Mantalica and Diana Cummings, who wanted to see the Center thrive as much as any of the principals did.

Good ideas need a good home.   A physical home creates identity, both for those working in the Center and for those who work with the Center.  And identity—or branding as it is called today—is key to success.  A physical home also makes it easier for people to collaborate and to administer the enterprise.  Lucky for us, two off-campus champions—Senator Mike Machado and Jerry Meral (then of the Planning and Conservation League)—saw this need, and collaborated to place funding for the Watershed Sciences Building in a successful 2000 bond bill.

Building the Watershed Center from scratch involved taking a timely good idea, cultivating champions, attracting good colleagues and giving it a good home.  For all involved, it was a challenge to put it together, but it was also a lot of fun.  I am gratified to see that 20 years later, and under Jay Lund’s able stewardship, it is still going strong.  Happy 20th anniversary, UC Davis Center for Watershed Sciences.

Jeffrey Mount is a senior fellow at the PPIC Water Policy Center. He is an emeritus professor at UC Davis in the Department of Earth and Planetary Sciences and founding director of the Center for Watershed Sciences. 

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Evolutionary genomics informs salmon conservation

by Tasha Thompson, Michael Miller, Daniel Prince and Sean O’Rourke

Adult spring Chinook salmon, Salmon River, California (Photo credit: Peter Bohler)

Spring Chinook and summer steelhead (premature migrators) have been extirpated or are in decline across most of their range while fall Chinook and winter steelhead populations (mature migrators) remain relatively healthy. Because premature migrating fish are closely related to mature migrating fish within the same river, conservation policy typically lumps them into the same conservation unit. Thus, spring Chinook and summer steelhead, in most situations, don’t receive special conservation protections despite sharp declines.

In our recently published study, we show that incredibly important genetic adaptations can rely on rare evolutionary events in single genes, and that current conservation policies can fail to protect this type of adaptive variation. Most current policies protect genetic adaptations between distantly related population units, but they don’t necessarily protect adaptations within closely related population units, and the consequences of that can be substantial: in the case of Chinook and steelhead, the consequences could be the permanent loss of an economically, culturally, and ecologically important life history. To account for this type of adaptive variation, current conservation policies will likely need to be improved.

Chinook salmon ‘holding’ and circling before heading upstream to spawn (Photo credit: Jan Jaap Dekker)

Pacific salmon are born in freshwater streams, migrate to the ocean as juveniles, spend a few years there, then return to the stream they were born in to spawn. Some species of Pacific salmon, specifically steelhead (a legendary sport fish) and Chinook (a workhorse of the West Coast fishing industry), exhibit two strikingly distinct life history types within their species when it comes to spawning migration time. Mature migrators (a.k.a. fall Chinook and winter steelhead), return from the ocean in a sexually mature state. These fish migrate directly to their spawning grounds and spawn almost immediately. In contrast, premature migrators (a.k.a. spring Chinook and summer steelhead) return to freshwater months before sexual maturity. These fish migrate high into the watershed and hold in cold, deep pools over the summer while their gonads develop, then spawn at about the same time as mature migrators.

Premature migrators are special for a number of reasons: they play an important ecological role by carrying marine nutrients higher into watersheds than mature migrators, they are very significant to the cultures and traditions of the indigenous peoples of the Pacific Northwest and Northern California, they provide a larger window of fishing opportunity, and they have much higher fat content than mature migrators so taste much better.

Policies that lump together premature and mature populations have been justified by two  assumptions that our study shows are incorrect. The first assumption was that spring Chinook and summer steelhead had evolved from their mature migrating counterparts independently in each river; the second was that spawning migration time was controlled by many genes that each has a small effect. These led to the belief that premature migration had evolved many times and therefore could easily re-evolve in the future if lost.

Genomic data analysis (Photo credit: Gus Tolley)

To identify the genetic basis for migration timing, we used an inexpensive and efficient technology called RAD (restriction-site associated DNA) sequencing to test hundreds of thousands of points throughout the steelhead genome, and then compared the results of summer steelhead to the results of winter steelhead to see where their genomes differed. We did the same thing with spring and fall Chinook.

Strikingly, we found that the same genetic region differed between summer and winter steelhead as between spring and fall Chinook, and that variation in this single region (a gene called GREB1L) completely explains the difference between migration types in both species.

Next, we investigated if premature migration versions of GREB1L had arisen once or multiple times. We found that all summer steelhead versions had arisen from a single event and all spring Chinook versions had arisen from a single event. The evolutionary events were different between the species, so both evolutionary events occurred sometime in the past 15 million years since the two species diverged. Finding that the same gene is crucial for premature migration in two separate species and that all the premature migration versions of this gene we examined arose from a single evolutionary event within each species strongly suggests that the genetic mechanisms for evolving premature migration are limited and happen very rarely across evolutionary time.

For the Pacific Northwest and Northern California, our study indicates that we should be much more concerned about the decline of spring Chinook and summer steelhead than we previously were. The premature life history depends on a particular version of the GREB1L gene. However, the number of fish carrying that version has declined dramatically. If premature migrating fish are lost, that version will be lost and may take many thousands to millions of years to re-evolve.

Juvenile steelhead sampling on the Salmon River, California (Photo credit: Mikal Jakubal)

This study is also significant for many specific rivers and local communities, such as the Klamath Basin in Northern California, that have seen dramatic declines of spring Chinook and summer steelhead. In many of these locations, grass roots efforts are among the only things keeping these fish from totally disappearing. Premature migrators have been completely lost from many California rivers where they used to be abundant, and most populations that remain are severely depressed. For example, the Salmon River in Siskiyou County only had approximately 100 spring Chinook return this year, where it historically had tens of thousands. The same pattern is common throughout Oregon and Washington too.

Identifying the premature migration gene has also allowed us to develop genetic markers to easily test the migration type (premature or mature) of ambiguous samples such as juveniles or carcasses for which the migration type was not previously able to be determined. This will enable a better local scale understanding of the ecology of premature vs. mature migration, factors behind the decline of premature migrators, and steps that can be taken to bolster premature populations.

Now that genomic technologies allow us to determine the genetic basis and evolutionary history of important adaptations, we can use this information to improve conservation policies. More specifically, we can better protect adaptations that exist within closely related population units, are disproportionately impacted by human activities, and are unlikely to re-evolve in human timeframes.

Tasha Thompson and Daniel Prince are Ph.D. Candidates in the Integrative Genetics and Genomics Graduate Group at University of California, Davis. Michael Miller is an Assistant Professor of Population and Quantitative Genetics in the Department of Animal Science at University of California, Davis. Sean O’Rourke is an Assistant Project Scientist in the Department of Animal Science at University of California, Davis.

Further reading

D. J. Prince, S. M. O’Rourke, T. Q. Thompson, O. A. Ali, H. S. Lyman, I. K. Saglam,T. J. Hotaling, A. P. Spidle, M. R. Miller, The evolutionary basis of premature migration in Pacific salmon highlights the utility of genomics for informing conservation. Sci. Adv. 3, e1603198 (2017).


Posted in Biology, Conservation, Fish | Tagged , , , | 1 Comment

Groundwater Nitrate Sources and Contamination in the Central Valley

by Katherine Ransom and Thomas Harter

In California’s Central Valley, many communities depend significantly or entirely on groundwater as their drinking water supply. Studies estimate the number of private wells in the Central Valley to be on the order of 100,000 to 150,000 (Viers et al., 2012; Johnson and Belitz, 2015).

Elevated nitrate concentrations in groundwater can be a problem for private well owners, community service districts, and municipalities who rely on groundwater wells. Drinking water with a nitrate concentration greater than 10 mg/L NO3-N (the drinking water standard known as the maximum contaminant level, or MCL) has been linked to health effects such as low infant blood oxygen levels, miscarriage, and certain cancers.

We recently completed several studies that show the extent of nitrate contamination in shallow groundwater and the likely sources of the contamination in the Central Valley. The results show that, at the private well depth, a relatively small area is predicted to exceed the MCL, but a large portion of the valley is predicted to have elevated nitrate (at the 5 mg/L rate, a concentration considered to indicate elevated nitrate levels from human impacts). The public well depth is overall less at risk, but still has a decent amount of area predicted to exceed 5 mg/L.

The Central Valley is a highly productive agricultural region with approximately 7 million of California’s nearly 9 million acres of irrigated farmland (California Department of Water Resources, Agricultural Land and Water Use Estimates, 2010). In addition, over 80% of California’s 1.8 million adult cows live on dairies in the Central Valley.

Nitrate is a naturally occurring form of nitrogen, but is also created in areas with excess fertilizer, manure, urban and food processing waste effluent applications, or septic leach fields spaced at high density.  Much of the excess nitrogen (N) is converted to nitrate, which eventually makes its way into groundwater where it can persist for decades or even centuries – a process known as nitrogen leaching.

We estimate that 550 thousand tons of N fertilizer, 240 thousand tons of manure N, and 4 thousand tons of urban and food processing waste effluent N are annually applied to or recycled in Central Valley agricultural lands for food production. About 130 thousand tons of N are fixed from atmospheric nitrogen directly by leguminous crops (mostly alfalfa). While harvest removes about half of the nearly one million tons of N input to cropland,  and some nitrogen is lost to the atmosphere, about 360 thousand tons N per year is potentially leaching to groundwater from agricultural lands.

Other sources in the Central Valley are estimated to leach 20-25 thousand tons N to groundwater (urban areas: 10, municipal wastewater and food processing percolation basins: 4, dairy lagoons and animal holding areas: 6, and septic leach fields: 3). Manure production has increased exponentially since the middle of the 20th century through the mid-2000s, when dairy cow numbers levelled off. In contrast, fertilizer use increased predominantly in the decades after World War II and has largely levelled off since the late 1980s. Crop production has continued to increase steadily over the past 70 years (Harter et al., 2012; Tomich et al., 2016; Harter et al., 2017).

Estimated potential groundwater nitrate-nitrogen loading from cropland (not including alfalfa, left); and from alfalfa, urban areas, golf courses, dairy corrals, and wastewater/manure lagoons (right) in the Central Valley in the mid-2000s. Cropland leaching was estimated using a mass balance approach. Other leaching was based on reported nitrogen fluxes, measured leaching rates, or estimated from surveys. 1 kg N/ha/year = 0.9 lb N/acre/year (Harter et al., 2017).

Land use, nitrate leaching, and domestic groundwater

The amount of nitrate that leaches to groundwater (nitrogen loading rate) can be highly variable between different crop or land use types and among an individual crop or land use. This is due to differences in crop nutrient demands, soil and climate properties, and farm management techniques. Most measurements of nitrogen loading from crops are based on a few field studies performed over 30 years ago. The above estimates of potential nitrogen loading to groundwater are based on reports of N applications and N removal to harvest for nearly 60 different crops and on research about atmospheric N losses and other nitrogen pathways. But independent confirmation of estimates that are based on actually measured groundwater nitrate data has been lacking.

We performed a Central Valley analysis of domestic well nitrate data to relate groundwater nitrate to surrounding land uses and to estimate the amount of nitrogen loading from 15 crop and land use groups. This study focused exclusively on data from private domestic wells since they are typically more shallow and more likely to show impacts from more recent (5-30 years ago) surface activities on water quality. A database of recent nitrate measurements (past 15 years) from 2,149 private wells was assembled and the land use surrounding each well was determined (Ransom et al., 2017a). Using these data, we estimated a range of likely loading rates for each crop or land use type.

Results of the study indicate confined animal feeding operations (dairies), citrus & subtropical crops, and vegetable & berry crops to have the highest estimated nitrogen loading rates, while rice, water & natural land use, and alfalfa & pasture crops have the lowest. Many crop and land use groups have overlapping estimated ranges.

The groundwater nitrate-based estimates and the average potential leaching rates obtained from mass balance analysis are fairly consistent for Citrus & Subtropical, Vegetables & Berries, Field crops, Grapes, and the Water & Natural group. However, mass balance-based estimates are greater for Manured Forage crops, Nuts, Cotton, Tree Fruit, and Rice. Groundwater-nitrate-based estimates for urban areas and CAFOs appear largely consistent with reported data.  Lower estimates of nitrate leaching, when compared to estimates of nitrogen loading, are partially due to the (multi-)decadal travel time between the source of nitrogen leaching and the location of domestic  or other production wells where nitrate was sampled. But possibly also due to some natural attenuation of nitrate in groundwater (denitrification).

Land use from the CAML data set for the 15 crop and land use groups used in the study and the same crop and land use groups keyed to the median estimated nitrogen loading rate in kg N ha-1 yr-1 for the corresponding group (right side).

Identifying nitrate sources

Other sources besides manure and fertilizer may also contribute to groundwater nitrate concentration, including septic waste and natural sources (though natural sources typically contribute very minimal amounts.) Also, the amount of nitrate in an individual well is often the result of several nitrate sources. We quantified the amount of nitrate from each of four sources (manure, fertilizer, septic, and natural) in 56 private wells in the San Joaquin Valley (Ransom et al., 2016). Results of this “fingerprinting” study indicate that multiple nearby sources have likely contributed to an individual well’s nitrate concentration; it also shows some regional patterns in groundwater nitrate sources: manure sources are often more dominant in private wells located in dairy regions such as Hilmar, while fertilizer sources are more dominant in the citrus crop regions of Orosi and Woodlake. Septic system sources were shown to be a dominant source in some wells on the outskirts of urban centers where septic system density is high. The study also demonstrates that – without detailed site-specific investigations – significant uncertainty exists about a specific nitrate source’s contribution to the nitrate measured in a particular drinking water well.

Estimated amount of nitrate from each of the four sources, as percent of total, for each study well. Wells with overlapping pie charts were offset to prevent overlap.

Concentration of contamination

Finally, a joint effort between UC Davis and the USGS resulted in a high resolution estimation of nitrate concentrations across the Central Valley, at the average depth of a private domestic well and, separately, for the average depth of public supply wells (Ransom, et al. 2017b). These maps were developed by considering 146 mapped variables that potentially relate to the risk for groundwater nitrate contamination. These included soil and climatic variables, and recent estimates of groundwater age, nitrogen accounting, and groundwater chemistry.

The 146 maps were compared to nitrate measurements from over 5,000 private and public wells, taken during the past 15 years. Using a machine-learning algorithm to find patterns in the data, we created a ranking of which variables were the most likely to affect groundwater nitrate concentrations at the two depths. Among the 146 mapped variables, groundwater chemistry related to denitrification, historical nitrogen application amounts in agriculture, groundwater age, well distance to rivers, and amount of natural land use surrounding wells (among others) were rated as the most important to determine a location’s nitrate concentration.


Well locations of wells used in Ransom et al. (2017b) color coded by well nitrate concentration (3508 wells total) for shallow (1400 wells, mostly private) and deep (2108 wells, mostly public supply) zones.

Prediction of groundwater nitrate at median depths of private and public supply wells (54.86 m and 121.92 m, respectively). Unmapped (white) area within the Central Valley boundary was due to missing data.

Efforts are ongoing by agriculture and State of California agencies to better control sources of nitrate contamination through improved crop nitrogen management, while also developing programs to support affected communities with drinking water treatment and alternative supplies. These programs recognize that nonpoint source pollutants require an approach that is different from traditional groundwater pollution programs given the large number and broad distribution of nitrate sources, and the resulting wide-spread groundwater nitrate pollution. Our work supports the strategy taken by these efforts, which focus on regional source control and more support for drinking water treatment and alternative supplies. With this research, we hope to highlight areas where nitrate contamination is most likely to be elevated, provide further evidence for the regional scale contribution from various nitrate sources, and help focus nutrient management and educational efforts.

Katherine Ransom graduated in June 2017 with a PhD from the University of California Davis, Hydrologic Sciences Graduate Group. Her work has focused on statistical models of groundwater contamination. She is currently working as a postdoctoral researcher with the United States Geological Survey through UC Davis on predicting and mapping groundwater parameters in the Great Lakes region. Thomas Harter is a groundwater expert at the University of California, Davis.

Further Reading

Harter, T., K. Dzurella, G. Kourakos, A. Hollander, A. Bell, N. Santos, Q. Hart, A.King, J. Quinn, G. Lampinen, D. Liptzin, T. Rosenstock, M. Zhang, G.S. Pettygrove, and T. Tomich, 2017. Nitrogen Fertilizer Loading to Groundwater in the Central Valley. Final Report to the Fertilizer Research Education Program, Projects 11‐0301 and 15‐0454, California Department of Food and Agriculture and University of California Davis, 325p.,  and

Harter, T., J. R. Lund, J. Darby, G. E. Fogg, R. Howitt, K. K. Jessoe, G. S. Pettygrove, J. F. Quinn, J. H. Viers, D. B. Boyle, H. E. Canada, N. DeLaMora, K. N. Dzurella, A. Fryjoff-Hung, A. D. Hollander, K. L. Honeycutt, M. W. Jenkins, V. B. Jensen, A. M. King, G. Kourakos, D. Liptzin, E. M. Lopez, M. M. Mayzelle, A. McNally, J. Medellin-Azuara, and T. S. Rosenstock, 2012. Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis. 78 p.

Johnson, T. D., and K. Belitz, 2015. Identifying the location and population served by domestic wells in California, Journal of Hydrology: Regional Studies, 3, 31–86. Available at

Ransom, K. M., A. M. Bell, Q. E. Barber, G. Kourakos, and T. Harter, 2017a. A Bayesian approach to infer nitrogen loading rates from crop and landuse types surrounding private wells in the Central Valley, California, Hydrology and Earth System Sciences Discussions, 2017, 1–27. Available at

Ransom, K.M., B.T. Nolan, J. Traum, C.C. Faunt, A.M. Bell, J.M. Gronberg, D.C. Wheeler, C. Rosecrans, B. Jurgens, K. Belitz, S. Eberts, G. Kourakos, and T. Harter, 2017b. A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA. Science of the Total Environment, 601-602: 1160-1172. Available at

Ransom, K. M., M. N. Grote, A. Deinhart, G. Eppich, C. Kendall, M. E. Sanborn, A. K. Souders, Wimpenny, Q.-z. Yin, M. Young, and T. Harter, 2016. Bayesian nitrate source apportionment to individual groundwater wells in the Central Valley by use of elemental and isotopic tracers, Water Resources Research, 52(7), 5577–5597. Available at .

Tomich, T., S.B. Brodt., R.A. Dahlgren, and K.M. Scow (eds)., 2016. California Nitrogen Assessment.

Viers, J., D. Liptzin, T. Rosenstock, V. Jensen, A. Hollander, A. McNally, A. King, G. Kourakos, Lopez, N. D. L. Mora, A. Fryjoff-Hung, K. Dzurella, H. Canada, S. Laybourne, C. McKenney, Darby, J. Quinn, and T. Harter, 2012. Nitrogen sources and loading to groundwater, Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Technical Report 2, Center for Watershed Sciences, University of California, Davis. Available at

Posted in Agriculture, California Water, Groundwater, Nitrate, Water Supply and Wastewater | Tagged , | 4 Comments

Floodplains in California’s Future

by Peter Moyle, Jeff Opperman, Amber Manfree, Eric Larson, and Joan Florshiem

Sacramento River meander migration, from 1904 to the present. Image credit: Amber Manfree

The flooding in Houston is a reminder of the great damages that floods can cause when the defenses of an urban area are overwhelmed.  It is hard to imagine a flood system that could have effectively contained the historic amount of rain that fell on the region—several feet in just a few days.  However, these floods are a stark reminder of the increasing vulnerability of urban areas across the world and the need for comprehensive strategies to reduce risk.  The evidence is clear that green infrastructure, as defined below, can increase the resiliency of flood management systems and, when managed for multiple services, can reduce flood risk for many people while also promoting a range of other benefits.

Floodplains provides an overview of floodplains and their management in temperate regions.

California has a history of large floods, some almost as dramatic as those that have devastated Houston. They occur just infrequently enough that many forget they can be a problem and then complain about cost of flood insurance.  During this past winter of record precipitation, California did a remarkable job of containing and diverting the water. Damaging floods were not an issue.  Of course, the 200,000 citizens of Oroville who had to be evacuated because of the threat of flooding from a broken dam spillway may feel differently.

Unfortunately, climate change models tell us that big floods in California may become bigger and more frequent in the future because there will be more rain and less snow as the result of warmer air temperatures.  Fortunately, in Central California, part of the solution for dealing with big floods already exists: the Yolo and Sutter Bypasses.  These huge floodplains fill with flood waters from the Sacramento River and its tributaries that cannot be contained by dams.  The floodwater is passed rapidly to the Delta and San Francisco Estuary, and then out under the Golden Gate over weeks and months.

Illustrated river-ecosystem concepts from Floodplains. Image credit: Amber Manfree

While flooded, the bypasses provide productive habitat for fish and waterbirds.  When not flooded, they are farmed or managed as wildlife areas. They are examples of “green infrastructure,” soft, flexible flood protection that also benefits the environment.  There are other examples from all over the world, although hard infrastructurelike walls, levees and dams is much more common.  In California, the new Central Valley Flood Protection Plan 2017 Update emphasizes investment in green infrastructure (although it is not called that in the plan) as a long-term approach to flood management.

We think the world needs a lot more such green infrastructure to meet the forecasted challenges and to support floodplain ecosystems that can also function for farming and recreation. Engineered floodplains are a prime opportunity for multi-benefit outcomes. We have documented this trend, and reasons why green infrastructure works so well, in a new book: “Floodplains: Processes and Management for Ecosystem Services”, published by University of California Press.

Our focus is reconciliation ecology, the science of integrating habitat for wild plants and animals into landscapes dominated by people. The book is based on our many years of studying floodplains in California, which is a leader in using floodplains for flood management.  But we also venture to other regions, especially Europe, Australia, and Asia, for new insights.   Towards the end, we provide 15 maxims to guide flood management such as “A bigger flood is always possible than the biggest experienced so far.”

“Our time spent on rivers and floodplains has certainly shown us that much has changed and been lost over time. But we have seen more than just glimmers of hope in reconciled floodplains that are diverse and productive. We take heart from the huge flocks of migratory white geese and black ibis that congregate annually on California floodplains and from knowing that, beneath the floodwaters, juvenile salmon are swimming, feeding, and growing among cottonwoods and rice stalks, before heading out to sea. We can envision greatly expanded floodplains that are centerpieces of many regions, protecting people but also featuring wildlands, wildlife, and floodplain-friendly agriculture. Connectivity among floodplains, people and wild creatures is within reach, as is a future in which people work with natural processes rather than continually fighting them.” (p. 218).

Peter B. Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences. Jeffrey J. Opperman is a research associate at the Center for Watershed Sciences at the University of California, Davis and is the Global Freshwater Lead Scientist for World Wildlife Fund, working with teams across the world to develop and implement strategies to protect and restore rivers and floodplains. Amber Manfree is a postdoctoral researcher in Geography with the UC Davis Center for Watershed Sciences. Eric W. Larsen is a research scientist and fluvial geomorphologist in the Department of Human Ecology at the University of California, Davis. Joan L. Florsheim is a Researcher in fluvial geomorphology, hydrology, and earth surface processes at the Earth Research Institute, University of California, Santa Barbara.

Further reading

Opperman, J.J., et al. 2017. Floodplains: Processes and Management for Ecosystem Services.

Posted in Around the World, Climate Change, flood, Floodplains, reconciliation | Tagged , | 3 Comments

The Little Shasta River: A model for sustaining our national heritage

by Ann Willis, Rob Lusardi, Alex Hart, Susan Hart, Blair Hart, Andrew Braugh, Amy Campbell, Ada Fowler

Ranchers coexist with salmon streams in the Shasta Valley. Photo credit: Carson Jeffres.

Rancher: farms. Conservationist: fish. Researcher: science.

Too often, identity is used to divide us. Stereotypes are used to stake out conflicting positions. It’s a zero-sum approach that ignores the commonality of our natural – and national – heritage.

Most Californians – indeed, most of the country – have no idea who or where we are. Tucked up in the State of Jefferson, the Little Shasta Valley is a picturesque landscape not commonly associated with California: rolling hills and arid, wide rangeland, bounded by mountain ranges.

But within this landscape, we’re building a community of collaboration that reflects our values as landowners, conservationists, and scientists and stands as an example of what is possible when we put aside our preconceptions: a sustainable future for us all.

As landowners, stewardship is not just second nature, but a core value that ensures our livelihood, honors our heritage, and provides opportunity for future generations. Our family, the Harts, has ranched in the Little Shasta since 1852; the land is part of our legacy. We see our place as part of the ecosystem, not in spite of it. We know that when ecosystems falter, so has our stewardship. But we also know that working with partners who know as much about fish as we know about cattle, there’s a groundbreaking opportunity for wildlife and agriculture alike.

As conservationists, we see how people are integral in preserving our natural heritage. Worldwide, 80 percent of the places where animals live are under a high level of threat because of human presence. The new environmentalism recognizes that we’re not just visiting nature – we’re part of it. To be sure, there are places that require preservation. But as we look at the interconnected scale of our environmental challenges, we know that our conservation strategies must move beyond postage-stamp preserves and embrace the entire landscape, including people and their livelihoods.

As scientists, our mission goes beyond discovery to inspiration. Rather than simply gathering data to inform, we must listen to the vision stewards are trying to achieve and use science to understand whether and how it’s possible – or whether that vision may need to change. When landowners volunteer to keep water in a stream, it’s our duty to use science to know when, where, and how much of that water will do the most good. With science, we put people back into the landscape in a way that’s connected, not contrary, to the way the land works.

Just like an ecosystem includes many species that are vital to its success, we recognize that our community will only succeed when we work together.

That’s why our groups recognized the tremendous opportunity presented four years ago, when The Nature Conservancy and California Trout approached the Harts to talk about coho salmon. TNC and CalTrout had already developed strong conservation programs in the Shasta River watershed. With the help of the UC Davis Center for Watershed Sciences and other partners, conservation projects in the upper watershed like Big Springs Creek had already shifted the direction of coho salmon from degradation towards recovery. Those projects gave the Center an opportunity to develop a scientific approach to conservation that would sustain conditions for cold water species on a working ranch – an approach that could be used on working landscapes throughout the West.

Those projects also gave landowners in the valley an opportunity to see how our groups worked and what we produced, both in terms of guidance and results. So when we were approached, we knew we were talking with partners who used good science to find workable solutions.

Good stewardship preserved stream habitat for fish in the middle of a commercial-scale, working cattle ranch that’s been in production since 1852. Photo credit: Ann Willis.

The Harts’ stewardship had preserved an oasis of salmon habitat and a working ranch for the past 150 years. Trees provided stability to stream banks and shelter to aquatic life;  while also diverted, water flowed through the stream, keeping gravels clean and pools connected. The problem was too little water when young coho would migrate from their freshwater nurseries to the ocean.

Such problems seem obvious. But as we’ve found over a decade of collaboration, science helps us dismiss issues that at first glance might seem like “obvious” problems, but in fact are not. By doing so, we can direct our resources to places where they’ll have the biggest benefit, and avoid investing in projects that might look good, but produce little. And, our work provides a strong foundation from which we could show others in our community why were some actions were taken, but not others, and how those actions allowed both the rangeland and fish to endure.

This kind of community-driven, science-based conservation is critical, not just in the Little Shasta Valley, but across the American West. Rangelands, forests, and farms all overlap some of the most diverse ecosystems in the United States – landscapes we need to support generations of people, flora, and fauna to come.

Ann Willis is a research engineer who focuses on water management for working land conservation at the Center for Watershed Sciences. Robert Lusardi is the California Trout/UC Davis Wild and Coldwater Fish Lead Researcher. Susan, Blair, and Alexandra Hart are fifth and sixth generation ranchers in the Little Shasta Valley. Andrew Braugh is the Mt. Shasta/Klamath Regional Director for California Trout. Amy Campbell is the Mt. Shasta/Klamath Project Director for the Nature Conservancy. Ada Fowler is a Project Scientist with the Nature Conservancy.

Further reading

How Protecting Water Helps Industry and Nature. New York Times T Brand Studio.

Willis et al. 2013. Water resources management planning: conceptual framework and case study of the Shasta Basin.

Nichols et al. 2016. Little Shasta River Preliminary Assessment.

Nichols et al. 2017. Little Shasta River Aquatic Habitat Assessment 2016.

Posted in Agriculture, Conservation, Fish, reconciliation, Restoration, Sustainability | Tagged , , | 4 Comments

Preliminary Analysis of Hurricane Harvey Flooding in Harris County, Texas

by Nicholas Pinter, Nicholas Santos, and Rui Hui

Located in Harris County, Texas, Houston is the 4th most populous city in the US.  The flooding now unfolding in the Houston area is a human and economic disaster likely to rank with Hurricanes Katrina and Sandy among the worst in US history.  At the present moment, little quantitative information is available about the extent of flooding or economic damages.  The inundation is so widespread that detailed assessment has not yet been possible.  Even measurement of the flooding by visible-light based satellite has been impossible because the remnants of Hurricane Harvey have stalled over the Gulf Coast for the past week, dumping record precipitation and obscuring the skies from satellite view.

Our team in the Natural Hazards Research and Mitigation Group at the University of California, Davis conducted two sets of analyses to provide preliminary information on the pattern of flooding and to provide some context on historical flood damages in the Houston area.  Specifically, we:

(1) Processed radar data from the Sentinel-1A satellite from Aug. 29, at the peak of flooding in many areas.

(2) Analyzed data from the US National Flood Insurance Program (NFIP) to look at the nature and pattern of flood exposure in Harris County, including Houston.

Satellite Analysis

The Sentinel-1 system, which consists of two satellites, was launched by the European Space Agency.  The Sentinel-1 satellites carry radar sensors, which can scan the surface at night and through cloud cover.  In addition, this radar imagery is sensitive to standing water, making it an ideal tool for mapping the extent (but not depth) of flood water covering an area.

A Sentinel-1 satellite passed over Houston on August 29, which we used to create a map that highlights water and flood inundation on the surface.  We overlaid the resulting map on flood-zone boundaries from FEMA’s National Flood Hazard Layer and on other geographical data. Finally, we further compared the surface water extent with known pre-storm extents by flood-zone in order to determine flooding extent in each area in the portion of the county we assessed.

The resulting inundation map shows the striking extent of flooding in Houston and provides context for the on-the-ground photos coming out of the area.  Reservoirs are overflowing, streams and rivers surging high over the surrounding floodplains, and highways and roads are now themselves rivers.


An image of the flood inundation map in Harris County, Texas, showing the flooding extent of Hurricane Harvey. Click to open and explore.

Table 1 shows the extent of flooding mapped by flood zones, as defined by FEMA.  The flooded area in square miles is not an accurate measure of total area underwater because image pixels with vegetation or buildings will not be classified as standing water.   For example, designated floodways (river channels, mostly) were certainly 100% full of water throughout the study area on 8/29, but the radar signal categorized only 30% of those pixels as water.  However, the distribution of water-designated pixels correctly illustrates the pattern of flood inundation.  In the future, we plan to create a raster map that shows the boundary between flooded and not-flooded land in Harris County, from which accurate total inundation areas can be calculated.


Table 1. Distribution of flood inundation in Harris County, Texas in different mapped flood zones.

In Table 1, the percentages of total flooded area illustrate the great intensity of flooding resulting from Harvey.  About two-thirds of the inundation is outside of FEMA’s Special Flood Hazard Area, which is the so-called “100-year” floodplain, or area with a 1% or greater chance of flooding in any given year.  The 13.44% of inundation in the 500-year floodplain is very similar to the total portion of the study area in the mapped 500-year zone, suggesting that on average, flooding on Aug. 29 completely filled Harris County’s 500-year floodplain.  More than that; over 50% of estimated inundation occurred outside of any mapped flood zone.

History of Flood Damage and Exposure in Harris County

Texas has a long history of damaging flooding, and Houston has seen some of the worst of it, well before Harvey.  Since 1964, Harris County has had 27 federally declared disasters related to flooding and/or coastal storms.  We obtained databases of NFIP policies nationwide back to 1994 and insurance claims back to 1972.  For the analysis here, we identified current policies and past claims in the City of Houston, Harris County, and Texas as a whole.  We also examined repetitive flood losses.

As of June 30, 2017, Harris County policyholders held 249,212 NFIP flood insurance policies, covering $70.34 billion of assets, and generating $138.4 million in annual premiums. Over 40% of Texas NFIP policies are from Harris County.  Texas-wide, there are 593,115 policies in force, covering $161.2 billion, with $ 364.0 million in premiums.  Texas represents about 12% of NFIP policies nationwide and about 10% of annual premiums to NFIP.  Notably, and in contrast to the trend nationwide, the number of NFIP policies both in Harris County and in Texas has declined during the past several years (Figure 2).  Numbers of policies peaked in 2008 and have declined every year since that time.  This decline occurred despite several large floods in Texas during that time, which tend to sharply increase flood-insurance penetration in other areas of the country.  In addition, policy totals in Texas began declining well before Biggert-Waters 2012, federal legislation that raised NFIP premiums for some policyholders.

NFIP policies in force, by year, in Texas and in Harris County.

From 1975 to early 2015 (span of our NFIP claims data), NFIP policyholders in Texas experienced 194,029 paid flood losses, totaling over $9.2 billion (2015 dollars) in claims. The largest number of losses and NFIP claims occurred in 1979, 2001, and 2008 (Figure 3).  From 1975 to early 2015, Harris County had 77,697 paid flood losses, totaling about $3.6 billion (2015 dollars).

NFIP flood losses, by year, in Texas and in Harris County (in 2015 dollars).

Repetitive Flood Losses in Harris County

In 1998, the National Wildlife Federation report, Higher Ground, identified a major challenge to the NFIP – policyholder who made flood claims again and again, with some of them receiving cumulative payments many times the structure’s value.  In 1998, the worst case was one home that was flooded 16 times.  Today, the largest number of claims on a single structure has risen to 40.  And Texas has a disproportionately large share of repetitive loss structures and losses.

FEMA maintains a list of properties flagged as Severe Repetitive Loss Properties (SRLPs); defined as those that have had at least four claims (each ≥$5000) or total claims exceeding the value of the structure.  Of about 30,000 designated SRLP properties across the US, 4889 are in Texas, the second highest of any state (after Louisiana).  SRL properties in Texas have received $962 million in NFIP payments, the 2nd highest of any state (after Louisiana).  It seems likely that Harvey will push Texas to #1.

A total of 2794 of Texas’s SRL properties are located in Harris County, where 1925 of those are in the City of Houston. This number, summed together, is more SRLPs than any in other jurisdiction in the US. The total number of NFIP paid losses for SRL properties in Harris County is 15,685 (10,321 in Houston), the largest of any area in the US. The total of NFIP payments for SRL properties in Harris County is $596,025,224 ($195,971,067 in Houston), also the largest total of any area in the US.

We have also examined individual SRL properties, tabulating the worst of these in a variety of ways.  By counting the maximum number of paid claims, one property in Houston has been rebuilt at taxpayer expense 29 times.  We have also calculated total claims per property as a multiple of that structure’s value.  We tabulated the 30 largest of these ratios for single-family residential structures nationwide (structures valued <$10,000 excluded).  Harris County and Houston have 9 of these 30.  For example, one Houston-area home, valued at $116,335, has received NFIP payments totaling $1,848,916, or 15.9 times the structure’s value.  Other properties show even larger ratios.

There is room for some optimism in Texas.  FEMA provides funding to reduce long-term flood losses by mitigating individual properties, including acquiring and demolishing the most flood-prone structures.  In Harris County since 2000, 996 such properties have been acquired, at a cost of $63.5 million.  This optimism must be tempered, however, by the vastly greater pace of new construction in the Houston region.

The catastrophic flooding in the wake of Hurricane Harvey will certainly generate extensive discussion.  By some calculations, the current flooding represents the third “500-year” flood in the Houston area in the past three years.  Harris County flood managers have suggested that these extreme events represent rare, but plausible expressions of natural and stationary hydrology.  In contrast, credible counterarguments focus on climate-change tipping points as well as the rapid and extensive suburban development.  The catastrophic extent of current flooding in Texas points not only to a truly extreme event this year, but to a pervasive pattern of repetitive flooding. This pattern, in Texas and the Houston area in particular, points almost inescapably to local factors such as runaway development and lack of balanced hydrologic planning.  Recognition of these root causes is a vital first step in reshaping policies and guiding recovery in the wake of Harvey.

Nicholas Pinter is the Roy Shlemon Professor of Applied Geosciences in the Department of Earth and Planetary Sciences and an associate director of the UC Davis Center for Watershed Sciences. Nick Santos is a GIS developer and researcher at the Center for Watershed Sciences. Rui Hui is a postdoctoral researcher with the Center for Watershed Sciences.

Posted in Around the World, flood, Floodplains, Planning and Management, Tools | Tagged , , | 31 Comments

Trump Killed Obama’s Flood Protection Rule Two Weeks Ago

by Nicholas Pinter

This post was originally published as an op-ed in Fortune.

Jesus Rodriguez rescuing Gloria Garcia after rain from Hurricane Harvey flooded Pearland, in the outskirts of Houston, on Sunday. Image source: REUTERS/Adrees Latif via Business Insider

Whether or not you like President Donald Trump, the current administration has not been gifted with great timing. Just 10 days before Hurricane Harvey made landfall, the White House rescinded one of the most progressive flood-risk management tools on the books, an Obama-era executive order that added caution when building structures in flood-prone areas.

Obama’s order improved flood safety standards of the U.S. National Flood Insurance Program (NFIP). The NFIP was established in 1968 to provide federally underwritten flood insurance to residents of states and communities that agree to control development in land the government deems prone to flooding. The NFIP and its flood maps are imperfect, but they beat the pre-1968 alternative, which was basically uncontrolled development on U.S. floodplains. How much worse would things be without the NFIP? Much of U.S. floodplain land might look like Houston does today, and Houston’s floodplains would be even worse.

The biggest problem with flood maps in the U.S. is that they are drawn as “lines in the sand”—implying that there is a flood risk on one side and none on the other. That is a false and dangerous message. The best way to approach a line on a flood map is like seeing a poisonous snake: Don’t panic, but stay well clear.

This issue was handled deftly by the Obama administration. In January 2015, Obama issued Executive Order 13690, which established the new Federal Flood Risk Management Standard (FFRMS). In brief, this standard called for a more cautious approach to construction at the boundaries of flood hazard zones. The approach was flexible and didn’t even require an admission of climate change as being the cause—just more caution.

Within days, eight Republican senators sent a letter opposing the new standard as an impediment to land development and economic growth. Among the signatories was John Cornyn of Texas. Within three months of sending that letter, large areas of Cornyn’s district were underwater, including damage to new buildings that may not have been there had the FFRMS been in place earlier. Then severe flooding happened again in 2016 on the Brazos River. And now Harvey is wreaking havoc.

The new FFRMS would have limited the construction of new structures in Houston in the path of floods like the ones we’re seeing from Harvey, and the standard was an important step toward greater flood resiliency nationwide.

The senators who signed the letter opposing Obama’s Executive Order 13690 were from Texas, Louisiana, Mississippi, Arkansas, Georgia, and Missouri. These states include some of the largest net recipients of NFIP funds. From 1994–2014, Mississippi received $5.60 in NFIP disaster payouts for every dollar in premiums its residents paid, compared to three cents for Wyoming and four cents for Utah, for example.

Why such imbalances? Bad luck, in part—Louisiana’s $3.82 is sharply reduced if you subtract Katrina. But climate change seems to be ticking up the magnitude and frequency of storms, and uncontrolled development without a doubt puts more and more infrastructure at risk. Three 500-year floods in Houston in the past three years, as some suggest, is beyond random bad luck.

Federal flood insurance payouts and other disaster relief are not just another form of political pork sent home, like highway dollars fixing potholes. Every dollar is a tiny compensation for the misery endured by flood victims. The White House’s rationale for killing Executive Order 13690 was to establish “discipline and accountability in the environmental review and permitting process for infrastructure projects.” Score one point for partisan dogma.

Instead, our shared goal should be to find prudent measures to wind down flood losses, not convulsively labeling any limitation on developing flood-prone land as a “job killer.” The Federal Flood Risk Management Standard was just such a prudent measure, a reasonable precaution to limit damages from future Harveys.

Nicholas Pinter is the Shlemon professor of applied geosciences and associate director of the Center for Watershed Sciences at University of California, Davis.

Posted in Around the World, Climate Change, flood, Floodplains, Planning and Management | Tagged , , , | 9 Comments

We hold our convenient truths to be self-evident – Dangerous ideas in California water

by Jay Lund

View of strawberry fields, Elkhorn Sough Reserve, power plant, and the Monterey Bay.

Success in water management requires broad agreement and coalitions.  But people often seem to group themselves into communities of interests and ideology, which see complex water problems differently.  Each group tends to hold different truths to be self-evident, as outlined below.

These beliefs, when firmly held, do not stand up to scientific scrutiny, appear to other groups as self-serving nonsense, and hinder cooperative discussions on better solutions.  The counter-productive aspects of these ideas make them dangerous to policy discussions.  Since accomplishment in water policy requires a pretty broad consensus, these ideas ultimately become dangerous even to their advocates:

  1. There is a silver bullet solution. If only California [desalinated seawater, built more storage, used less water, recycled wastewater, imported water from Canada, captured more stormwater, …, invested in my project], its water problems would be solved.  The most effective water systems in California, such as those that were most successful during the drought, adopt a portfolio approach, with a variety of thoughtfully integrated water supply and demand reduction activities.  Strategic water management is more like good diversified financial investing, rather than betting on a winning horse.
  1. I win if you lose. It is often hard to know if you are winning in California’s water conflicts.  How much better off will the environment or farming be with more water?  Some, rather than answering this complicated question, find it easier to measure success by the amount of water denied to a competing interest.  Identifying villains is often convenient for politics and fund-raising, even as it distorts issues and solutions, and makes cooperation almost impossible.  The stereotypical Westlands vs. delta smelt conflict is an example where each “side” views their success in terms of how much water it prevented the other from receiving.  The strategy of opposing success by others only makes effective solutions more difficult to discuss and achieve.
  1. We can “solve” or “fix” water problems. Some problems can be solved permanently.  But California is a dry state with a huge, dynamic economy, massive irrigated agriculture, and a diversity of native ecosystems; it will never completely solve its water problems.  California will always have water problems and conflicts, which will change with time – as they always have.  Yet, California has managed to have tremendous economic prosperity and agricultural productivity while remaining a relatively good place for people to live despite its dry Mediterranean climate.   Even with water problems, we largely succeed anyway. But we can do better, especially in protecting our native ecosystems.  Discussions of solutions should be realistic about not solving all problems for all time.
  1. Someone else should pay. Finance is always easier if someone else pays.  We all want federal or state funds.  Water bonds pass costs on to the not-yet-voting future.  Alas, the water sector is one of the wealthiest parts of government.  State, federal, and bond funds are supported by general taxes or reductions in programs that serve poorer-than-average folks.  Reliance on state, federal, and bond funds often adds costs and skews programs away from being effective.  Getting money from others becomes a substitute for effective water management.   Water development in California should be set up more on a ‘pay as you go’ basis, with more stable funding for public and environmental purposes.
  1. Regulation will protect the environment. Regulations are good for preventing bad things, and environmental regulations have stopped many environmentally bad things since the 1970s.  But regulations alone have been ineffective at rebuilding the environment and protecting it in the face of many poorly anticipated changes – such as invasive species, non-point pollution, climate change, and population growth.  If we want good things to happen environmentally, we need to organize and fund ourselves so that good things happen.  Historically, we largely overcame massive public health problems only when we organized local, state, and federal agencies to solve these problems broadly and inspect and work with each other, with steady and substantial local and state funding.
  1. We were promised. Over the last 150 years, almost every water interest has been promised their ideal water delivery by some politician or law.  At some time, we (or our revered predecessors) accepted the promise in lieu of a less convenient but more realistic statement of what could be done. We all know that such promises can rarely be met.  This applies to water contractors, water right-holders, environmentalists, floodplain residents, and water users alike.  We all have unrequited aspirations.  Dwelling on these disappointments disrupts discussions and work towards better solutions.
  1. We need trust. No group can manage California’s water problems alone.  Trust makes working with others much easier.  But there is often little trust.  We all buy cars and houses from people we do not trust and vote for politicians that we should not trust.  If trust were a pre-requisite for business dealings, we would all be growing our own food, living in tents, and mostly dying young.  “Lack of trust” as a reason not to talk or advance is self-fulfilling and ultimately self-defeating – unless you are enamored with the status quo.  Earning each other’s trust is good, but finding ways to work together anyway is needed, in all walks of life.
  1. It will work as planned. California is a complex system that is always changing and has many uncertainties.  Planning is essential, but the idea that everything will go as planned is absurd.  Still, it is often politically convenient to represent plans as perfect.  We need to prepare plans and resources so that they can accommodate imperfections.  This is sometimes called adaptive management.

These dangerous ideas often have short-term benefits to particular groups – bringing public attention, raising money, establishing a firm negotiating position, and garnering and promoting internal cohesion within a community of interest.  But sticking to such ideas is ultimately self-defeating, impedes actual advancement for all interests, and demonstrates a lack of long-term seriousness of purpose and thought.

Success in water management in California will never be absolute, but we can do better if we avoid cynicism and work out how to more effectively discuss and better cooperate.  Doing so will require effort, creativity, trade-offs, working across diverse agencies and groups, and dispensing with some convenient but dangerous ideas that get in our way.

My own ideological affiliation?  “More research is needed.”  My ideological heresy? We don’t need all that much money for research if we work and communicate earnestly, and often collectively, to make research relevant and useful.

Further reading

Hanak, E., J. Lund, A. Dinar, B. Gray, R. Howitt, J. Mount, P. Moyle, and B. Thompson, Managing California’s Water:  From Conflict to Reconciliation, Public Policy Institute of California, San Francisco, CA, 500 pp., February 2011.

Hanak, E., J. Lund, A. Dinar, B. Gray, R. Howitt, J. Mount, P. Moyle, and B. Thompson. 2010. “Myths of California water: implications and reality.” West-Northwest 16(1): 3-73

Lund, J. (2017), Reflections on Cadillac Desert, J. Lund, July 9,

Lund, J. (2016) How bad is water management in California?, June 26,

Sabatier, P.A. and H.C. Jenkins-Smith (1993), Policy Change And Learning: An Advocacy Coalition Approach, Westview Press.

Wiens, J. , J. Zedler, V. Resh, T. Collier, S. Brandt, R. Norgaard, J. Lund, B. Atwater, E. Canuel, and H.J. Fernando (2017), “Facilitating Adaptive Management in the Sacramento-San Joaquin Delta,” San Francisco Estuary and Watershed Science, Vol. 15, No. 2, July.

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

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