Evaluating California’s Adjudicated Groundwater Basins in the SGMA Era


A groundwater well. Photo taken by DWR.

By Ruth Langridge, University of California – Santa Cruz [i]

Groundwater is a critical resource in California. While the 2014 Sustainable Groundwater Management Act (SGMA) established new requirements and increased state oversight for many overdrafted basins,[ii] groundwater basins adjudicated before the passage of SGMA are exempt from the statute’s requirements[iii].

Groundwater adjudication is where water users turn to the courts to resolve a dispute about water in a basin[iv]. Theoretically, the court defines and quantifies water rights for all groundwater users in the basin, and appoints a Watermaster to ensure that the basin is managed in accordance with the court’s adjudication decree. Prior to adjudication, a “physical solution,” often involving allocating a “safe yield” quantity among users and importing water, may be negotiated, and the court can accept it in whole or in part, or reject it and craft a different solution to manage the basin.

Adjudicated basins underlie major areas in the state, including much of the Los Angeles and Inland Empire region along with desert and coastal areas[v]. Most are in Southern California, with little precipitation and heavy dependence on imported water.  Many basins were adjudicated to reduce overdraft and support additional growth through the importation of water, and consequently establish responsibility for paying for the imported water.

While adjudication is often promoted as the most efficient institutional approach to manage groundwater in the state[vi] there was limited analysis of the recent condition of adjudicated basins. The State Water Resources Control Board contracted with our research team to evaluate how adjudicated basin performance aligned with SGMA’s goals for sustainable groundwater management[vii]. We reviewed judgments, technical literature and other archival sources and conducted telephone interviews with key managers and participants in the adjudication process. The Watermaster, a technical expert, or a lawyer who participated in the adjudication process, reviewed and commented on each basin summary. Some conclusions from this examination are summarized below.

Groundwater adjudication is fundamentally not about the sustainable management of a groundwater basin.

Rather, adjudication is about the court resolving a controversy between parties about a problem in the basin and designating who is responsible for providing a solution. Controversies can include whether the basin is in overdraft, who has a right to water, how much water can be withdrawn individually and collectively, who is responsible for providing or paying for sufficient water for future growth, and how overdraft and safe yield should be defined and calculated. Adjudication is rarely about the full spectrum of requirements for sustainable management addressed in the SGMA. This is a central issue with adjudications if the goal is the sustainable management of a groundwater basin. Moreover, although the court in principle resolves the initial questions posed in adjudication, parties frequently return to court.

Water rights are the central focus of adjudication

The legislature noted this narrow reach of adjudication in its definition of “comprehensive adjudication” as “an action filed in superior court to comprehensively determine rights to extract groundwater in a basin.”[viii] The court may approve a physical solution to remedy the problem in the basin, and the physical solution can overlap with some goals of the SGMA. However, the sustainable management of a groundwater basin is not the underlying purpose of the adjudication or the role of the court.

In practice, individual water rights often are not quantified in adjudications. Although California’s water laws usually dictate the priority of water rights, other factors, including the needs of the individual parties, are often negotiated and incorporated into final judgments. We found that allowable withdrawals often became concentrated in a small number of users in the years after adjudication. Small groundwater users and disadvantaged communities are rarely included in the physical solution.

Established water rights are difficult to alter, but the conditions placed on water rights in a basin can be quite flexible and vary considerably. Requirements to reduce demand, to pay for replenishment water if a water right is exceeded, carryover credits, and whether a water right can be transferred vary by basin. Each condition can affect both the sustainable management of the basin and the communities that rely on the basin for water supply.

With the exception of basins under mutual prescription, requirements to reduce demand did not necessarily apply equally to all pumpers. Aligning with California water rights priorities, overlyers were often allowed to pump with  limited restrictions, generally did not have to reduce pumping until appropriators reduced their withdrawals, and sometimes did not have to reduce pumping at all, or only in an extreme drought. With respect to carry-over credits, no expiration date resulted in a large accumulation of stored water credits in some basins that if used could result in significant basin overdraft.

Transfers are widely promoted to facilitate the market-based exchange of water rights. Most transfers in adjudicated basins are from overlyers, usually agricultural users, to appropriators, who are municipalities or water purveyors. Transfers affected land use and had both positive and negative changes. In the Mojave Basin adjudication, a desert area with little precipitation, some farmers sold their production rights, usually to municipal producers. This generally occurred in the Alto Subarea, and the transfers supported significant municipal growth[ix].  It is difficult to temporarily “fallow” a large municipal area during an extreme drought.

Approaches to determining safe yield,[x] overdraft, and groundwater trends are variable with no standards to determine these quantities.

The court is theoretically tasked with calculating the “safe yield” of a basin in determining water rights[xi]. SGMA defines sustainable yield as “The maximum quantity of water, calculated over a base period representative of long-term conditions in the basin and including any temporary surplus, that can be withdrawn annually from a groundwater supply without causing an undesirable result.” Undesirable results include permanently lowered groundwater levels, subsidence, degradation of water quality in the aquifer, or decreased stream flows[xii]. These terms are defined in multiple ways among adjudicated basins and in some basins are not calculated or used[xiii]. Additionally, specific metrics in many basin are often calculated relative to a previous base period of pumping[xiv] and frequently do not account for future climate change impacts.

Overdraft definitions also varied and most basins do not address accumulated overdraft. Additionally, controlled overdraft, sometimes called temporary surplus, is a strategy in several basins. This is where the amount is withdrawn exceeds the safe yield of the basin to create storage space to capture water in wet years. An issue is whether water will be available to the basin in wet years and if it will be used to recharge groundwater.

Most adjudicated basins rely on imported water to manage overdraft and/or to provide for future water needs. With climate change, more emphasis on net water use reduction is essential.

The heavy reliance on imported water is currently problematic for many basins as the cost of imported water has increased and it has become less available, and some basins anticipate that cost and scarcity will continue to be problems in the future.

A positive feature of adjudication is that a management structure is usually put in place.

The Watermaster is supposed to monitor the basin and provide annual reports to the court, which has continuing jurisdiction. Watermasters in many basins did provide strong oversight, but the appointment of a Watermaster did not always occur or did not occur in a timely manner, and reporting was not always required or was limited in scope.

The key challenge will be to resolve conflicts between strategies to move towards sustainable groundwater management and the priorities of individual water rights holders.

We recommend that adjudications always include a groundwater management plan, and annual reports that are accessible with a clear standardized format and conclusions. Projections for future climate changes and demographic shifts should be incorporated into water supplies and demands, and definitions of safe yield should incorporate consideration of interconnections between surface and groundwater and pumping impacts on relevant ecosystems.

To bring adjudication outcomes into line with SGMA, in 2015 the Legislature enacted two bills that primarily focus on reducing the costs and extended time period of the adjudication process[xv]. They also create processes to help ensure that adjudication is fair, comprehensive and aligned with SGMA goals for sustainable groundwater management. While the legislation does not force an adjudication to comply with the substantive terms of SGMA, the court needs to first consider any existing SGMA plan when adopting a physical solution[xvi].

The literature emphasizes that enforceable rules regarding access and use of common pool resources are essential for ensuring sustainable management.  Our research points to the challenges and opportunities for adjudication in attempting to reach sustainable management.

The Reports:

Ruth Langridge, Abigail Brown, Kirsten Rudestam and Esther Conrad, 2016, An Evaluation of California’s Adjudicated Groundwater Basins, Report for the State Water Resources Control Board, http://www.waterboards.ca.gov/water_issues/programs/gmp/resources.shtml

Ruth Langridge, Stephen Sepaniak and Esther Conrad, 2016, An Evaluation of California’s Special Act Groundwater Districts, Report for the State Water Resources Control Board, http://www.waterboards.ca.gov/water_issues/programs/gmp/resources.shtml

Other Relevant Work of Interest:

Enion, Rhead, (2013) “Allocating Under Water: Reforming California’s Groundwater Adjudications,” Emmitt Center on climate Change and the Environment, UCLA School of Law, Policy Brief #4;

Blomquist, William (1992) Dividing the Waters: Governing Groundwater in Southern California. ICS Press, San Francisco, CA;

Lipson, Walter (1978) Efficient Water Use in California: The Evolution of Groundwater Management in Southern California, Rand Corp: Santa Monica, http://www.rand.org/pubs/reports/2009/R2387.2.pdf

Relevant legislation

Links to the relevant legislation can be found at:http://www.water.ca.gov/groundwater/groundwater_management/legislation.cfm; 2014 Sustainable Groundwater Management Act: AB 1739 (Dickinson), SB 1168 (Pavley), and SB 1319 (Pavley). Additional bills signed by the Governor in 2015 to amend the California Water Code: SB 226 (Pavley) – addressing groundwater adjudications, SB 13 (Pavley), AB 939 (Salas), and AB 617 (Perea)

[i] This research was funded by the State Water Resources Control Board, The John Randolph Haynes and Flora Haynes Foundation and UC Water Security and Sustainability

[ii] SGMA covered 127 high or medium priority basins that were designated as high or medium priority under the California Statewide Groundwater Elevation Monitoring (CASGEM)

[iii] The SGMA was followed by the passage of Assembly Bill 1390 (AB 1390) and Senate Bill 226 (SB 226) in 2015 that provide some procedures for groundwater adjudications.

[iv] Adjudication can be a civil action filed in a county superior court or it can be a process initiated by the State Water Resources Control Board, although the latter is rare.

[v] The West Coast and Central Basins alone are two of the most utilized urban basins in California with a service area that is home to over ten percent of California’s population residing in 43 cities in southern Los Angeles County (http://www.prnewswire.com/news-releases/wrd-board-approves-landmark-master-plan-to-expand-groundwater-supplies-300341313.html).

[vi] While problems include the cost and the extended period of litigation, the benefits are considered to be the assignment of property rights with a transferable water entitlement, and the ability of the Watermaster to regulate groundwater production while also allowing water users flexibility in water planning. See Enion, Rhead, (2013) “Allocating Under Water: Reforming California’s Groundwater Adjudications,” Emmitt Center on climate Change and the Environment, UCLA School of Law, Policy Brief #4; Blomquist, William (1992) DIVIDING THE WATERS: GOVERNING GROUNDWATER IN SOUTHERN CALIFORNIA. ICS Press, San Francisco, CA; and Lipson, Walter (1978) Efficient Water Use in California: The Evolution of Groundwater Management in Southern California, Rand Corp: Santa Monica, http://www.rand.org/pubs/reports/2009/R2387.2.pdf

[vii] The SWRCB provided the list of all the basins adjudicated prior to the passage of SGMA. Basins with pending adjudications were not included.

[viii] Senate Bill 226 and Assembly Bill 1390 passed by the California Legislature in the 2015–2016 Regular Session.

[ix] Comment from David Seielstad, Senior Watermaster Technician, Mojave Water Agency, 8/2-15.

[x] While the term “sustainable yield” is invariably implied in court decisions, most groundwater adjudications utilize the term “safe yield.”

[xi] A distinction is made between safe yield as a purely physical metric defined by hydrologists and “sustainable yield,” which accounts for both physical and social conditions in determining appropriate withdrawals to minimize declining levels and ensure the long-term resilience of groundwater systems.

[xii] http://www.water.ca.gov/groundwater/sgm/definitions.cfm

[xiii] Safe yield sometimes refers just to local precipitation, but can also include artificial water such as imported water or recycled water, as well as return from imported flows.

[xiv] This is the case even with basins that did not use the Doctrine of Mutual Prescription (initially defined by the court in the Raymond Basin adjudication) to determine both water rights and water allocations.

[xv] SB 226 (Pavley) and AB 1390 (Alejo)

[xvi] Code of Civ. P., § 849

Posted in Groundwater | Tagged | 1 Comment

Water is for fighting over? – a review of John Fleck’s recent book

waterisforfightingforBy Jay Lund

Most expressions on Western water issues are reflex or studied advocacy favoring a single viewpoint or opposing other viewpoints.  A minority provide thoughtful and reasonably balanced insights.  John Fleck’s new book, “Water is for fighting over” is at the 1% extreme of thoughtful readable pieces on western water.  The book is one of the most insightful and helpful works on Western water since Cadillac Desert.

Although the work focuses on the Colorado River, its lessons and observations are likely to resonate throughout the American West, dry parts of the world, and for those managing natural resources more generally.  His observations represent a new and more useful view of how to manage the wicked problems of western water.

The main lessons I gleaned from the book are:

  • Water problems will not lead to the broad collapse of civilization in the American West. The West’s overall economy is now largely uncoupled from needing abundant quantities of water.  The urban economies that produce more than 90% of Western wealth have found that they can continue to grow with relatively little water use.  Conservation happens, despite its costs.
  • Only the West’s agricultural sector, which uses 70-80% of developed water supplies for a few percent of the region’s economy, is water-intensive. Fortunately, the most valuable agricultural production is about half of agricultural water use.  Even agriculture has flexibility.
  • Water is better managed when local, state, and federal interests cooperate that if they feud. The costs to all from non-cooperation should weigh heavily on advocates and stakeholders.
  • Cooperation is not easy, and is based fundamentally on individual relationships and institutional settings. Despite the existence of hundreds and sometimes thousands of local, state, federal water agencies, no one is fully in charge of Western water systems.
  • Regional, state, and federal agencies often need to carefully foster a broad network of individual relationships and establish incentives for local agencies and interests to cooperate. Without such external help (often resented in public), it is difficult for local interests to break free of the chicken games common among local water interests for their own long-term good.  (Alas, risk-averse state and federal agencies often fail to undertake these network-fostering roles thoughtfully or proactively.)
  • Shared scientific and technical understanding, developed and disseminated by these broad informal networks, is needed to support agreements. (Here again, one struggles to see state, federal, and local agencies crafting such common understanding.)
  • Some fundamental dilemmas remain for western water management. How can difficult discussions of changes in water management among often conflicting interests be small enough to make progress, since they rely on a network of informal discussions, but inclusive enough to not leave out important interests? How can less organized environmental and impoverished interests be represented?
  • Progress is often incremental, incomplete, and opportunistic. Droughts, earthquakes, and lawsuits are both problems and opportunities to make progress.  Persistence across generations is probably needed, as progress on some problems allows work on imperfections.

One quibble.  Mr. Fleck is fond of saying that the saying “Water flows uphill towards money” is a myth.  Perhaps this is true in the strictest sense that “Water does not necessarily flow uphill towards the most money”, but it is also clear that “Water does not flow uphill without money.”  Almost all Western water management is based on economic motivations, even if imperfectly in terms of economic theory.

Much like Cadillac Desert, “Water is for fighting over” is a readable and compelling overview of Western water problems, but with a refreshingly new and more positive perspective.  The book’s lack of a chapter on the sex life of a major public figure will diminish its relative readership, but I hope this oversight will not reduce the book’s public policy impact.

Real progress is possible in Western water.  Although there will be pain, we are not doomed. Progress and sustained success can come from persistent informal dedication from individuals and organizations who do not hide behind easy rhetorical myths and work towards their long term interests.  Fighting over water is a losing battle.

Further reading

John Fleck (2016), Water is for Fighting Over: and Other Myths about Water in the West, Island Press, Washington, DC, 264 pp.  Amazon

John Fleck’s blog: http://www.inkstain.net/fleck/

Jay Lund is Director of the UC Davis Center for Watershed Sciences and a Professor of Civil and Environmental EngineeringHe did a little summer reading.

Posted in education, Uncategorized | Tagged , | 6 Comments

Comparing Delta Consumptive Use: Preliminary Results from a Blind Model Comparison

By Josué Medellín-Azuara, Kyaw Tha Paw U, Yufang Jin, Quinn Hart, Eric Kent, Jenae’ Clay, Andy Wong, Andrew Bell, Martha Anderson, Daniel Howes, Forrest Melton, Tariq Kadir, Morteza Orang, Michelle M. Leinfelder-Miles, J. Andres Morande, William Li, and Jay R. Lund

As California works to improve its official accounting of water for a range of purposes, one major area lacking widely accepted quantification is the consumptive use of water for agriculture, particularly evapotranspiration (ET) from crops.  In the Sacramento-San Joaquin Delta, such estimates are important, along with other hydrologic flows, for a variety of water rights, operational, and regulatory purposes.

Consumptive use is the proportion of water removed that cannot be reused elsewhere in a basin. For crops in the Sacramento-San Joaquin Delta, this is mostly evapotranspiration. In a region’s water balance, consumptive use can become a keystone for estimating groundwater recharge, outflows from a basin, and the availability of water for water exchanges or market transactions. In places like the Sacramento-San Joaquin Delta (the Delta), crop consumptive use estimation may have the additional challenges of adjusting for a collection of localized factors such as fog, canal seepage, evaporation from canals, and widely varying wind conditions.


Figure 1. 2015 Land use in the Sacramento-San Joaquin Delta, by LandIQ.

Models for calculating consumptive use have been researched for many years and have the potential for improved accuracy in estimating Delta outflows and informing water management and diversion in this complex and fragile estuarine system.  Yet, given the many agencies, stakeholders, and institutions relying on this water system hub, self-reporting of water diversions and estimates of consumptive use are often a challenge.

In an effort to reduce the information gap and converge efforts on consumptive use research, estimation and measurement, the State Water Resources Control Board’s Office of the Delta Watermaster convened funding from several state, regional, and local Delta water agencies to do a comparative study on consumptive use for the Delta. Researchers from the Center for Watershed Sciences and the Department of Land, Air and Water Resources at UC Davis partnered with researchers from UC Cooperative Extension, DWR, NASA-Ames Research Center, USDA-Agricultural Research Service, and CalPoly’s Irrigation Training and Research Center to conduct this study. The two-season study covers the 2014-2015 and 2015-2016 water years and includes completion of land use surveys for each year, deployment of field measurement equipment (thanks to the cooperation of farmers and organizations within the Delta), and estimation of consumptive use using seven methods and models such as CalSIMETAW, DETAW, METRIC, Priestley-Taylor and SIMS.

The study includes an initial report on measurement of evapotranspiration in bare soil, and a blind comparison of evapotranspiration estimates using seven different methods, applied independently. The interim report is posted on the project website at: https://watershed.ucdavis.edu/project/delta-et

Preliminary findings show that bare soil evapotranspiration at the end of the irrigation season was close to zero in four locations selected for field measurements during September-October of 2015 (Figure 2).


Figure 2. Daily actual ET (ETa) measured from bare soil stations (surface renewal and eddy covariance) along with daily reference ET (ETo) from the nearby CIMIS stations. Lines are mean values across stations and gray shading represents one standard deviation from the mean.

A more extensive field campaign during 2016 includes more than a dozen measurement stations over corn, pasture and alfalfa fields, and covers more of the growing season. This will greatly improve measurement and enhance future comparisons of ET estimation methods.

Preliminary findings are that the average annual crop evapotranspiration estimated by the ensemble of the models tested in the Delta Service Area is about 1,550 thousand acre feet (TAF) (Figure 3). That ensemble estimate is roughly consistent with the annual estimates used in DWR’s California Water Plan Update 2013. Crops with the highest variation in ET estimates across estimation methods under comparison are are tomatoes, vineyards and potatoes.  All estimates are within about 20% of the median estimate with the higher discrepancies during December and January, months with lower crop evapotranspiration, and September, in which some crops are being harvested.

The fact that all estimation methods do not closely agree is not surprising, and would be highly unusual in comparisons of ET estimation. However, further work should be able to increase the agreement among these estimates. In addition, it should improve understanding of why and how much different estimation methods are likely to differ, and how modeling and remote sensing estimates are likely to differ from field estimates of crop ET.


Figure 3. Total evapotranspiration estimates for selected crops in the Legal Delta and the Delta Service Area (October 2014-September 2015). Estimates are derived from monthly average estimates of daily evapotranspiration for each method. CalSIMETAW and DETAW coverage is limited to the Delta Service Area.

Discrepancies in model estimates are driven by several factors including variation in input datasets and processes, inherent methodological differences, and other varying meteorological conditions. Refined estimates produced by all of the methods during the second year of study will use common input datasets and protocols to enhance the value of comparisons.  In addition, improved algorithm calibration based on analysis of 2015 data is likely to reduce the range of variation in ET estimates across methods and improve the accuracy and credibility of all methods.

A final report on this two-year study will include final estimates of consumptive use from all methods for the 2014-2015 and 2015-2016 water years. The final report will benefit from a longer field measurement campaign and improved common protocols and input datasets. It is expected to be available during late spring 2017.

Improving estimation of consumptive use is a step toward improving the reliability and transparency of data and analysis for water management, with potential for reducing reporting and accounting expenses for farmers and the state.

Josué Medellín-Azuara, Jay R. Lund, and Andrew Bell are affiliated with the Center for Watershed Sciences, UC Davis. Kyaw Tha Paw U, Yufang Jin,  Quinn Hart, Eric Kent, Jenae’ Clay, and Andy Wong are afiilliated with Land Air and Water Resources, UC Davis. Martha Anderson is affiliated with USDA-ARS. Daniel Howes is affiliated with CalPoly Irrigation Training and Research Center. Forrest Melton is affiliated with NASA-Ames, Monterrey. Tariq Kadir and Morteza Orang are afilliated with the Department of Water Resources. Michelle M Leinfelder-Miles is affiliated with UC Cooperative Extension.

Further Reading

Medellín-Azuara, J., Paw U, K.T., Jin, Y., Hart, Q., Kent, E., Clay, J.,Wong, A., Bell, A., Anderson, M., Howes, D., Melton, F., Kadir, T., Orang, M., Leinfelder-Miles, M., and J.R. Lund. (2016). Estimation of Crop Evapotranspiration in the Sacramento San Joaquin Delta for the 2014-2015 Water Year. An Interim Report for the Office of the Delta Watermaster, State Water Resources Control Board. Center for Watershed Sciences, University of California, Davis. Last Access September 28, 2016

Medellin-Azuara, J. and Howitt, R. (2013) Comparing Consumptive Agricultural Water Use in the Sacramento-San Joaquin Delta: A Proof of Concept Using Remote Sensing, Center for Watershed Sciences University of California, Davis. Last Access September 28, 2016.

Siegfried, Lucas J.; Fleenor, William E.; & Lund, Jay R.(2014). Physically Based Modeling of Delta Island Consumptive Use: Fabian Tract and Staten Island, California. San Francisco Estuary and Watershed Science, 12(4). Jmie_sfews_20875. Last access September 28, 2016


The authors are thankful for funding and research support provided by the State Water Resources Control Board, California Department of Water Resources, the Delta Protection Commission, the Delta Stewardship Council, the North Delta Water Agency, the Central Delta Water Agency, and the South Delta Water Agency.  The authors also appreciate the assistance provided in various capacities by Nadya Alexander, J. Andrés Morandé, William Li, Cathryn Lawrence and Barbara Bellieu, who made this report possible.

Posted in California Water, Delta, Uncategorized, Water System Modeling | Tagged | 8 Comments

Drought Prospects in California for the New 2017 Water Year – October 1, 2016

By Jay Lund

Happy New Water Year 2017!

Hopefully everyone has recovered from their celebrations.

The 2016 drought year is over.  It was milder year than the four previous drought years.  The great wet hope of the “Godzilla” El Nino did not end the drought, but brought only near average precipitation.

Going into the new water year, California remains in a drought.

Here are some highlights of current conditions, with links from the California Department of Water Resources’ California Data Exchange Center (CDEC) at http://cdec.water.ca.gov.

Reservoir and Groundwater Storage Conditions

Major reservoirs in California begin this new water year about 3.3 maf lower than long-term average surface storage on September 30.  Groundwater is likely to be recovering in the northern parts of California, but is probably continuing to drop in large parts of the southern Central Valley which are still receiving less water than expected, and are subject to overdraft even in non-drought years.  Cumulative drought groundwater overdraft probably now exceeds 12 maf. (Alas, California does not maintain estimates on long-term groundwater balances, but this will come someday.)

Total water storage is probably depleted 15-20 maf from pre-drought conditions.  Soil moisture in much of the Sierras and Central California remains in drought conditions (due to both unusually high temperatures and lower precipitation).  Like groundwater, conditions of forests and native fishes are severely depressed and are likely to see substantial drought impacts for years after hydrologic conditions improve.

But this seemingly bad situation is substantially better than in October 2015.

Many reservoirs are in pretty good shape in terms of overall storage, certainly compared with October 2015.  Shasta, Oroville, New Don Pedro, and many other sizable reservoirs are entering the new water year with near-average storage levels.  Shasta levels must now be viewed more cautiously, however, because of heightened concerns for operational disruptions due to depressed populations of endangered winter run salmon.  Most surface storage depletions (current storage relative to their historical average) remain in reservoirs at New Melones (tributary to the San Joaquin River, 800 taf depletion), Trinity (in the north, 700 taf depletion), San Luis (which relies on Delta exports to fill, 450 taf depletion), and Oroville (550 taf) and Folsom (250 taf depletion), which were depleted somewhat to make up for reduced releases from Shasta due to temperature concerns.   Lake Cachuma, which serves the Santa Barbara region is also nearly exhausted with only 14 taf remaining and a drought depletion of 135 taf.


Figure 1. Major reservoir storage in California at end of 2016 water year

Ecosystem Conditions

Fish – Native fish populations in California are largely down during the drought, with some down by frightening percentages, such as winter run salmon.  These populations effects will likely require years of effort to recover and make management of future drought years more important.

Waterfowl – Duck populations improved considerably in 2016 from 2015, which were about 25% below the long term average.

Forests – The accumulated effects of drought and warmer temperatures are likely to leave forests susceptible to diseases, pests, and further drought conditions.  There is little that water managers can do to affect drought impacts to forests, although this might be one of the drought’s biggest and most long-lasting effects.

Native ecosystems in good shape should allow more flexibility for agricultural and urban water supply operations.  Alas, this is not the case.  Ecosystem storage, so to speak, is severely depleted.

Will the 2017 Water Year Be Dry?

Statistics from about 100 years of historical records show not a lot of correlation of unimpaired runoff between years.


Figure 2. Scatter plot of Water Year runoff for Sacramento River since 1921

When digested by quintiles, Table 1, only slightly more insight is gained.  Very dry years seem more likely to beget another very dry year and not a very wet year.  And both very dry and middling years have a slight, and probably not statistically significant, chance of producing another drier runoff year. Some of these effects might be residual due to the new water year beginning with drier soil moisture and groundwater conditions than average. (Note, this quintile (20%) water year classification differs from the DWR water year classification which includes a weighting of the previous year’s runoff, and so has a built in higher correlation.)


Table 1. Probabilities of wet and dry conditions from historical data

Thoughts for the coming drought year

Welcome to California water, where anything can happen.

It is best to be prepare for another drought year (and prepare for floods as well).

Even if precipitation is average, there will still be residual storage depletion and ecosystem effects from the previous dry years.  These effects will be harder to manage if the coming year continues to be much warmer than average.  Except for some ecosystem and rural community conditions, which remain quite serious, there is no reason for panic. (Panic is often counterproductive – urgency would be appropriate.)

Many farmers in the southern Central Valley will still feel the effects of water scarcity, even if the hydrologic drought ends, as ending overdraft and greater environmental demands and restrictions for the Delta and San Joaquin River impinge on historical water delivery expectations.  They have a long-term problem worsened by the drought.  Farmers in the Sacramento Valley face some years of disruptions in the timing of water deliveries due to temperature problems for winter run salmon.

In any event, and especially if 2016-2017 is dry, there is urgency to make progress on state, federal, regional, and local water management.  Groundwater, water conservation, water markets, and the Delta remain urgent management concerns, which will interact and require a common state water accounting system sooner rather than later.

And El Nino? The great wet hope will continue, but one should probably consider the historical correlation of El Nino with northern California runoff, below, and dissipate less time with speculative predictions and invest more time on moving California forward with its difficult water problems.


Figure 3. El Nino index versus Sacramento Valley runoff (maf) for the last 50 years.

2016 Water Year Precipitation

Precipitation totals for the ending water year were average-ish historically, and great compared with the previous two years, but made worse due to continued high temperatures.  Below are the final cumulative plots for the 2015-2016 water year, with some comparative companionship.

sanjoaquin2016 northsierra2016 tulare2016

Here are some web sites to watch in the coming water year.

Reservoir levels:








http://cdec.water.ca.gov/cgi-progs/products/PLOT_ESI.pdf – Sacramento Valley

http://cdec.water.ca.gov/cgi-progs/products/PLOT_FSI.pdf – San Joaquin Valley

http://cdec.water.ca.gov/cgi-progs/products/PLOT_TSI.pdf – Tulare Basin

Jay Lund is Director of the UC Davis Center for Watershed Sciences and Professor of Civil and Environmental Engineering at UC Davis. 

Further reading

LOIS HENRY: The backstory of a water scare you never knew about, Bakersfield.com, April 13, 2016.

Posted in California Water, Drought, Uncategorized | Tagged | 5 Comments

How much water was pumped from the Delta’s Banks Pumping Plant? A mystery.

By Jay Lund

As the old saying goes, “Someone with one watch knows what time it is, someone with two watches is never sure.”

Water accounting is fundamental to water management, but is not easy.  But any accounting is more difficult and expensive if it is less organized.  To illustrate this point, let’s look at estimates of one of the largest, most important, and “easiest” to measure flows in California: the annual pumped quantity of California’s State Water Project (SWP) Banks Pumping Plant (Banks) in the Delta for the years 2006 through 2010.

Public sources for annual quantity of Banks delivery includes DWR and USBR sources and documentation.  Pumped water quantity estimates from these sources are shown in the table and chart below, with hyperlinks to sources.


Notes and Sources:

  1. DWR State Water Project Annual Report of Operations, Table 1: Project Pumping by Plant, Calendar Year
  2. USBR Central Valley Operations: Delta Operations Water Accounting Reports, (monthly sum, calendar year); Delta Pumping Plant: State/Fed Banks
  3. DWR, DAYFLOW Program, Environmental Planning and Information Branch, water entering pumping plant’s Clifton Court Forebay, originally water year, here converted to calendar year
  4. DWR Bulletin 132: Management of the California State Water Project (2014 Report) Table B-6: Annual Water Quantities Conveyed through Each Pumping Plant, pg. B-67, Calendar year
  5. DWR State Water Project Final Delivery Capability Report (2014 Report) Tables 7-2 through 7-11: Historical SWP Deliveries, Calendar Year
  6. DWR Bulletin 160: California Water Plan, Update 2013 Volume 5. Technical Guides, Water Portfolios. Data Summary 1998-2010, State Water Project Deliveries, by Water Year^ – Calendar year, unless otherwise specified
    # – Water Years represent the annual water cycle and run from October 1 through September 30 and are named for the calendar year in which they end.
    * DWR SWP Operations Control Office also releases weekly Summary of SWP Water Operations with year-to-date, month-to-date, and weekly pumping quantities. These data are not included as data are updated weekly with prior weeks’ data removed from site (e.g., ‘Water Pumped’ for Banks CDWR, Total).


DWR SWP Annual Reports of Operations, Bulletin 132 series, and, USBR CVO Water Accounting Reports all explicitly state quantities as pumped through Banks. DWR SWP Capability Reports and Bulletin 160 Water Plan Updates provide values as total SWP deliveries, so subtracting North Bay Aqueduct and Feather River deliveries should be volumes pumped through Banks. DAYFLOW estimates are inflows into Clifton Court Forebay to Banks Pumping Plant.

Why are the values different? Specifically, why do these values match closely in 2006 and differ so much by 2010?  Inquiries and data references were unable to answer those questions. Perhaps some water transfers are not counted as SWP deliveries (including, CVP-related transfers through Banks).  Perhaps some pumping from Banks is counted as deliveries for other projects.  Some small differences occur for DAYFLOW between water entering Clifton Court Forebay and water pumped through Banks.

Although there are technical challenges to water accounting, the challenge of water accounting is more organizational than financial or technical.  California’s current water accounting systems have difficulty presenting a transparent, well documented, and consistent accounting of water availability and use.  This seems to apply even to some of the largest, most centrally controlled, and technically easiest flows in the system, such as Banks Pumping Plant.

Poor organization makes water management in California unnecessarily more difficult, controversial, opaque, and expensive. Propagation of volume differences from the many pumping plants, canals, and other water infrastructure in California only exacerbates this situation. We are paying several costs for many watches.

Further Reading

Alvar Escriva-Bou, Henry McCann, Ellen Hanak, Jay Lund, Brian Gray (2016), Accounting for California’s Water, Public Policy Institute of California, San Francisco, CA.  (The technical appendix is especially useful for showing how other states and countries organize their water accounting.)

Posted in California Water, Planning and Management, Tools, Uncategorized | Tagged | 8 Comments

How ecogeomorphology changed my life

by Tyler Goodearly


Goodearly pictured above with Dr. Peter Moyle, preparing to do a fish survey using a seine. Photo credit: Carson Jeffres

For as long as I can remember, I’ve wanted to study fish. Like my idols, Jacques Cousteau, or Steve Irwin, or Jeff Corwin, I too had the “fish itch,” and I knew I must follow this passion.

By the time I was in the seventh grade I had devised a 10-year plan to make this dream come true:  I would excel academically in high school, then go to UC Davis where I would study Wildlife, Fish, and Conservation Biology under the renowned Dr. Peter Moyle (whose name was a common one around our dinner table). Yes, this was an ambitious goal, but I was as determined as a Chinook salmon returning to spawn – nothing could get in my way.

Little did I know, being only 12 years old at the time, that this plan, once put into action, would not actually do much to propel me into ichthyologisthood. Instead, one person, with a single proposition to take a single class, would change my life and give me all the tools I needed to become a fish biologist. It’s only upon reflection that I realize the significance of that pivotal class: Ecogeomorphology.

It was senior year, early 2015, and there was one question that was simultaneously running through all of my fellow students’ minds: “What am I going to do after graduation?” I’d tell the meddlesome snoopers who were constantly nagging me with this question that I wasn’t sure yet, that maybe I’d go to grad school, or maybe I would travel, or really any awkwardly ambiguous excuse that would lead to the demise of these irksome conversations. I couldn’t bear to tell them that 12-year-old Tyler’s plan had failed. I was terrified to graduate because, for the first time in my life, I would not know my next move.

Conducting a snorkel survey in the Tuolumne River

Goodearly pictured above conducting a snorkel survey in the Tuolumne River during Ecogeomorphology 2015

It was in this state of existential doubt that my friend asked me this seemingly benign question: “Will you take Ecogeomorphology with me?” She knew I was in the mindset of saving the world and emphasized that this class would have a field excursion that would help hone my planet-saving skills. Regardless, I was reluctant to join. It was not part of my plan, and I was fearful of that octosyllabic word. To date, I had little field experience, and coming from indoors-only family, I had little camping experience. I was afraid that I wouldn’t be able to compete with my peers who all seemed to know where they were going post-college. I struggled with this fear until the very last day of open registration, and in a whirlwind of temporary bravery and oh-my-goodness-what-am-I-getting-myself-into I submitted my application (just a few questions about how I would be a good fit for the class, which can only accommodate 14 students).

This class was like no other class I had taken. Unlike other classes, this one took the “big picture” approach to learning. Each week, we had two, one-hour lectures that focused on biological (eco) and physical (geo) properties converging to shape (morph) our rivers. We learned about the connection between pizza toppings and our beloved Sierra Mountains, how salmon are well-adapted for California’s Mediterranean climate, and how rivers move across landscapes in predictable patterns. In addition, the supplemental weekly labs taught us methods on how to collect data in the field; these included drawing reach sketches, taking flow measurements, processing benthic macroinvertebrates, seining, and identifying fish. By integrating this array of disciplines, I learned how to look at a river and understand it on a whole new level:  I learned how to read the physical environment in order to reveal histories of the river and how to predict where in the river fish could take refuge. I was able to understand the conflicting needs of natural resources and where to allocate them, and I began to appreciate the complexity of conservation.

Goodearly holding a Sacramento Sucker. Check out those fleshy papillose lips! PC: Denise DeCarion

Goodearly holding a Sacramento Sucker. Check out those fleshy papillose lips! PC: Denise DeCarion

What really set this class apart from any other was that once feared but now eagerly anticipated, nine-day camping trip, during which we put the field methods and theories we learned into practice for our own research. Our trip revolved around the Tuolumne River watershed. We started at the headwaters in Tuolumne Meadows, Yosemite and throughout the nine days made our way down to the end of the river where it joins the San Joaquin River in the Central Valley. At each stop along the way we put our conceptual and practical tools to use, and our professors took every opportunity to test our knowledge by asking us questions about the river that was right in front of us.

Unlike laboratory settings, fieldwork is unpredictable and requires resiliency and educated improvisation. For example, I had intended to do my research project on Yellow-Legged Frogs. Specifically, I wanted to make a map of where they occur with the physical conditions of the water they were; however, we never found any frogs! Instead, I wrote my paper on where they should have been and why we didn’t find any.

Goodearly wearing a backpack electrofisher preparing to head into the field to perform a community survey for one of Peter Moyle's projects (PC: Diana Heppe)

Goodearly wearing a backpack electrofisher preparing to head into the field to perform a community survey for one of Peter Moyle’s projects. Photo credit: Diana Heppe

Being able to tell employers that I, a recent graduate desperate for a job, had worked in the field and conducted my own research, gave me an edge over my competition. I easily found a job immediately after college (meddlesome snoopers, I hope this finally lays your inquisitions to rest) working for… PETER MOYLE! Though temporary, that job was by far the best summer of my life.

With the help of that experience, I earned a job with the California Department of Fish and Wildlife. It was another seasonal job, this time working with salmon carcasses. As gloriously disgusting that may sound, I was very happy. Through that project, I met the people of Cramer Fish Sciences (a firm I had been applying to for years). They were able to see me put to use the skills I learned from my Ecogeomorphology class, and asked me to apply for an open position (oh, how the tables had turned).

Today I am still with CFS as a field biologist and I know 12-year-old Tyler would be proud. I cannot emphasize enough how paramount the Ecogeomorphology class has been in my success. It is my profound hope that future students will be granted the same gifts that the professors and staff of the Ecogeomorphology class have given me.

Tyler Goodearly is a Fish Biologist working for Cramer Fish Sciences located in West Sacramento, CA. He graduated in June 2015 with a B.S. in Wildlife Fish and Conservation Biology from UC Davis.

Further reading

Support Ecogeomorphology

It takes a river. Amy Quinton for Capitol Public Radio

UC Davis Grand Canyon: Ecogeomorphology 2016

Posted in education, Uncategorized | Tagged , , | 1 Comment

Ecogeomorphology: A Transformative Expedition Education

This week, the Center for Watershed Sciences is proud to feature our flagship education course, Ecogeomorphology. What began as a collaboration between then-Professors Jeffrey Mount and Peter Moyle to introduce students to cross-discipline thinking in expedition settings has developed into a transformative opportunity for the select graduate and undergraduate students to experience a range of settings throughout California and the West, led by professors throughout the campus.

Why are classes like this worthy of the California WaterBlog? Because they are how we develop water leaders who can collaborate across disciplines, understand the complexity of water issues, and translate their educational experiences into visionary strategies for water management.

We’ll be posting media features about this expedition course throughout the week, including:

We’ll update this post with links to these media features as they go live.

We kick of this media series with a video blog by Ecogeo alumna Megan Nguyen about the expedition course developed for undergraduates. Ms. Nguyen’s Ecogeo experience included not just interdisciplinary research, but also communications training that aimed to improve students’ abilities to deliver clear messages on multi-media platforms. We hope you enjoy seeing the myriad ways people have been inspired by these trips as much as we have enjoyed developing them.

Megan Nguyen is a junior specialist at the Center for Watershed Sciences and alumna of the undergraduate Ecogeomorphology course. Her work specializes in using multimedia platforms to communicate complex water policy and technical concepts with easy-to-understand and engaging infographics.

Further reading

UC Davis Grand Canyon 2016 interactive website

Ecogeomorphology class archives

Support Ecogeomorphology

Posted in California Water, education, Uncategorized | Tagged , , , , , , , | 1 Comment

California WaterBlog survey and recommended reads

by Ann Willis

Editor’s note: The survey link is now closed. Thank you to all who participated! If you have feedback, feel free to comment directly on this post. A. Willis 9/22/2016

As the water year comes to an end, we are curious about what topics California Waterblog readers would like to see addressed. Were there water issues you wish we’d written more (or less) about? Take our 5-minute survey to help us understand how we might improve the California Waterblog.

In the meantime, here are some recommended reads for everyone from water wonks to people who simply love the West.

California Rivers and Streams by Jeffrey Mount – Perfect for water wonks who want to improve their understanding of basic stream processes with a book that doesn’t require an advanced degree to engage them. Mount, a senior fellow at the PPIC Water Policy Center, emeritus professor at UC Davis in the Department of Earth and Planetary Sciences, and founding director of the Center for Watershed Sciences, writes a seminal book that helps readers make the connection between physical and biological stream processes and how land use practices affect them.

Cadillac Desert by Marc Reisner – A must-read for those looking to put current water policy into context of the development of the West. Arguably the quintessential book on the American West and its transformation through the “reclamation” of its water. The formidable personalities of William Mulholland and Floyd Dominy, who dominated this era of development, will leave an impression long after the last page of this book. Reading this book will transform any experience throughout California, including Owen’s Valley to Yosemite and its submerged sister, Hetch Hetchy, and give fuller insights to its current water conflicts.

The Secret Knowledge of Water by Craig Childs – “There are two ways to die in the desert: thirst and drowning.” Adventurers at heart and Ecogeomorphology alums will appreciate the inspiration of Childs’ explorations to find water in its natural, elusive desert habitat and its power for extremes. People who love the extreme remoteness of the West will also appreciate Childs’ description of its landscapes. Perhaps his most haunting passages are his descriptions of the midnight shuffle of feet as border crossers make the dangerous trek north, guided by water more than general direction.

All the Wild That Remains by David Gessner – This parallel biography of Edward Abbey and Wallace Stegner is recommended for those who are water wonks by day, but moonlight as readers, writers, and people whose souls are nourished by the landscape and human experience of the West. Gessner considers the contrasting philosophies of each iconic figure in the context of the current drought, as well as provides insightful histories of how each man developed into his ultimate archetypal personality. Also recommended, of course, is anything by these two authors, who grappled with the soul of the West through their writing. Desert Solitaire by Abbey and Angle of Repose by Stegner are great places to start for those who are unfamiliar with the iconic place each author holds in Western literature.

Ann Willis is a staff research associate at the Center for Watershed Sciences and editor of the California WaterBlog. Her conversion from an East Coast elitist to Western water scientist began with Wallace Stegner’s Angle of Repose.

Posted in education, Uncategorized | Tagged | 4 Comments

New Baton Rouge flood map show limits of current risk and planning methods

This aerial image shows flooded areas of North Baton Rouge, La., Saturday, Aug. 13, 2016. Louisiana Gov. John Bel Edwards says more than 1,000 people in south Louisiana have been rescued from homes, vehicles and even clinging to trees as a slow-moving storm hammers the state with flooding. (Patrick Dennis/The Advocate via AP)

This aerial image shows flooded areas of North Baton Rouge, La., Saturday, Aug. 13, 2016. (Patrick Dennis/The Advocate via AP)

by Nicholas Pinter, Nicholas Santos, Rui Hui, Kathleen Schaefer

The flooding in Baton Rouge and surrounding areas of Louisiana is a major disaster, claiming an estimated 13 lives and displacing more than 100,000 people from their homes. The National Weather Service reported that rainfall in Louisiana this past week reached up to a 1000-year event (0.1% chance of occurring each year). The American Red Cross has called this the worst US disaster since Hurricane Sandy.

Our team of researchers in the Natural Hazards Research and Mitigation Group at the University of California, Davis undertook a preliminary analysis to determine extent of flood inundation during this recent event and its relationship with Louisiana’s history of major floods and development behind levees.

Louisiana has a long history
BatonRougefloodfactsof disastrous flooding. In 1998, the National Wildlife Federation report Higher Ground ranked two of the parishes hard-hit by this week’s flooding, East Baton Rouge and St. Tammany Parish, 7th and 22nd among communities nationwide with the highest damages for repetitive-loss properties.  In 1998, there were 1,107 repetitive loss properties in these two parishes, resulting in claims to the NFIP totaling $47,534,736.  As of November 30, 2015, these two parishes were still in the top 25 severe repetitive loss properties (22nd and 5th respectively for payments received); NFIP claims total $117,131,310.

The National Flood Insurance Program (NFIP) was established in 1968 to curtail flood damages through nationwide mapping of flood hazard to guide sound floodplain management.  NFIP maps (“FIRMs”) are used to inform residents of potentially flood-prone land, guide development and construction ordinances, and to set insurance rates and requirements.  We analyzed the distribution of flood inundation around Baton Rouge in order to assess how well NFIP and FEMA maps provided guidance to avoid damages during the extreme and, arguably, unusual precipitation and flooding this past week.

One-third of the flooding we mapped was outside of FEMA’s designated 100-year flood zone, which is the “line in the sand” for floodplain management in the US.  Many floodplain residents and political leaders falsely believe that flooding cannot occur beyond the mapped 100-year line.  But nationwide, roughly 25% of NFIP flood-damage claims occur outside of 100-year zones.  This can result from drainage problems (as opposed to rivers going over their banks), because of levee failures, where local FEMA map panels are out of date, because climate change or basin development have worsened flooding, or simply because an area gets hit by an event larger the so-called 100-year storm (1% annual probability).  For all of these reasons, flood insurance can be a great deal and is highly recommended in many areas outside of FEMA mapped hazard areas, as events in Louisiana show.

Analysis of NFIP Policies and Past Claims in the Flooded Area

We obtained databases of NFIP policies back to 1994 and insurance claims nationwide back to 1972.  For the analysis here, we identified current policies and past claims for 19 communities in the flooded area near Baton Rouge that are part of the current Louisiana Presidential Disaster Declaration, e.g. communities in East Baton Rouge Parish and Livingston Parish. As of June 30, 2016, these communities have 54,644 NFIP policies-in-force covering around $12 billion in property, with those policy-holders paying about $40 million in annual premiums. The number of NFIP policies in these communities increased regularly from 1994 to 2014 (Figure 1), with a sharp increase following Hurricane Katrina in 2005.  The largest portion of this increase was for properties outside the mapped 100-year floodplain – property owners who bet wisely and are now facing a much more secure future than most of their neighbors.


Figure 1. Annual number of policies in force from 1974 to 2014, by flood zones

Like all of Louisiana, the area hit by last week’s storm has a long history of flooding. From 1972 to early 2015, the communities we studied as part of our analysis had 16,403 paid NFIP claims. Of these, 10,961 claims (67%) were for properties located in 100-yr floodplain, 2,811 (17%) for properties out of 100-yr floodplain, 74 (0.5%) in coastal hazard area, and the remaining 2,577 claims (16%) were in undefined areas (Figure 2). The total building and content damages for these claims are about $422 million in 2016 dollars, which includes $293 million for properties located in 100-yr floodplain, $76 million outside of 100-yr floodplains, about $3 million in coastal hazard areas, and $49 million for properties located in undefined areas (Figure 3).


Figure 2. Annual number of NFIP claims paid from 1972 to 2014, by flood zones


Figure 3. Annual building and content claim payment in 2016 dollars, by flood zone

Satellite-Based Flood Inundation Analysis

Using imagery from the European Space Agency’s Sentinel-2A satellite in the vicinity of Baton Rouge, Louisiana, we mapped flooding from the recent storm event (Figure 4).  While much of the area was still obscured by clouds on Aug. 14, East Baton Rouge and nearby communities were mostly clear.  About 30 square miles of flooded surface were mapped in the Baton Rouge area, which does not include additional flooding inside of buildings or in cloud-obscured locations. This flood inundation was overlain on FEMA’s National Flood Hazard Layer, which shows floodplains as identified on Flood Insurance Rate Maps, as well as the National Levee Database (NLD).

About two-thirds (66 percent) of the flooding detected from satellite imagery in the study area occurred inside of FEMA’s Special Flood Hazard Area (SFHA; Zones A and AE in Table 1), which is the regulatory standard in the US.  The SFHA aims to identify areas that would be inundated by the so-called 100-year flood event, meaning the flood that has a 1% chance or less of occurring in any given year.  Some FEMA maps also identify areas subject to larger 500-year floods (0.2% chance in any given year), and these areas around Baton Rouge also experienced extensive flood damages.  This is expected during such an extreme storm event, and serves as a reminder to residents and local leaders to remember flood hazard during the many years and even decades where mapped floodplain land may remain dry.  Even more importantly, flooding above the 100-year level is a harsh reminder to all of us – a rebuke to the US system in which development and construction can in many cases occur mere inches outside of the 100-year line.   


Table 1. Distribution of flood inundation in the study area around Baton Rouge, LA in different mapped flood zones

The US Army Corps of Engineers National Levee Database (NLD) provides levee protection information for about 14% of the estimated 100,000 miles of levees in the United States.  We identified 147 mi2 of levee-protected area in our study area around Baton Rouge, but the majority of that area is west of the Mississippi River. Most of the studied area east of the Mississippi River lacked levees or else has levees that are not included in the NLD.

News reports from Louisiana include reports of breaches or overtopping of several levees by flood waters and in our analysis, we identified 11.5 square miles of flooding within levee-protected areas, mostly in East Baton Rouge. A well-known limitation in US flood-risk policy is that land behind levees certified and accredited as able to withstand 100-year or larger floods is written out of flood-hazard maps, but levees do not reduce flood risk completely. Residents and business owners behind any levee should look to Louisiana and remember that every levee carries a “residual risk” of failure or overtopping during an extreme event.  In some cases, levees even create their own flood risk, when drainage systems and pumps are overwhelmed by locally intense rainfall.  FEMA does not map for such “drainage flood”, and early reports indicate that this type of flooding was prevalent during this event in Baton Rouge.


There are numerous lessons to be learned from the recent flooding in Louisiana.  As evacuations and rescues turn towards flood recovery, careful research should target the distribution of flooding and flood damages.  In particular, the extent of inundation outside of mapped hazard zones should be studied in order to guide both recovery and future planning efforts.  Inundation outside of FEMA’s SFHA, or 100-year floodplains, may be attributed to the extreme intensity of this weather event.  But every 100-year or larger flood is an extreme event, and such “Act of God” explanations are too often used as an easy out that can serve to dodge systematic assessment of past planning and flood-risk enforcement and development.  Widespread flooding outside of mapped hazard zones can also reflect climate-driven shifts, land-surface changes that generate larger storm runoff, stream-channel modifications, overreliance on levees, or outdated maps (sometimes willfully delayed by local development interests).

In addition, our experience working with flood-impacted communities across the US and worldwide highlights that decisions made in Louisiana during the next few weeks can determine the region’s long-term future.  Key decisions will be made on whether to clean out the mud and rebuild in place or, instead, whether to mitigate – invest now in reducing future flood losses.  Homes can be elevated or flood-proofed, and the most flood-prone properties can be relocated to safer locations.  Research shows that each $1 invested in flood mitigation in the US returns an average of $4-5 in long-term savings.  And our experience is that the first weeks following a major flood disaster are a window of opportunity that soon closes.  Louisiana residents, disaster managers, and political leaders need to take a step back and look at the regional pattern of flood damages in this event and back through time.  Now is the opportunity to step off the path of repeated flood losses and instead make decisions that will move the region and its residents towards a more resilient future.

Author bios: Nicholas Pinter is the Roy Shlemon Professor of Applied Geosciences in the Department of Earth and Planetary Sciences and an affiliate 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. Kathleen Shaefer is a prospective graduate student at UC Davis, and previously worked as a Regional Engineer for flood projects with FEMA Region IX.

Further reading

National Wildlife Federation, Higher Ground: A Report on Voluntary Property Buyouts in the Nation’s Floodplains. Washington, D.C., July, 1998

NFIP Loss Statistics from Jan 1, 1978 through June 30, 2016.  http://bsa.nfipstat.fema.gov/reports/1040.htm#22 accessed on 8/17/2016.

Map of Baton Rouge Flooding as of August 14th, 2016. https://watershed.ucdavis.edu/experiments/baton_rouge_2016/map

Posted in Planning and Management, Uncategorized | Tagged , , , , , | 9 Comments

Scott Valley pioneers instream flow and groundwater management for reconciled water use

by Gus Tolley


Scott River at Horn Lane, November 2013. Photo credit: Sari Sommarstrom.

The Scott River is one of California’s four major undammed streams and important spawning habitat for coho (a species listed as “threatened”) and Chinook salmon. This peaceful and pastoral agricultural valley is at the center of several water-related conflicts and lawsuits. However, it is also pioneering a range of instream flow and groundwater management activities that could set the example for balanced water use in California.

At first glance, water ScottValleyHLUmanagement in the Scott Valley appears to be a story of farms vs fish, one that is common in California: A dry year results in dry stream reaches near groundwater-irrigated fields in August that persist beyond the irrigation season into September, even October. With the Chinook fall spawning migration arriving in mid-October and coho following soon after, a dry streambed raises valid concerns about how irrigation pumping and the removal of riparian vegetation may have led to warmer and drier streamflow patterns in Scott Valley.

The story behind the valley’s seasonally dry streams is complex. Irrigated pasture, alfalfa, and cattle production have been part of the socioeconomic fabric since it was settled by white people during the mid 1800s. Current dry conditions are partly due to legacy impacts from historical land management policies, flood control, and gold mining, along with natural climatic and geologic variations.

irrigationOn average, the annual discharge of the Scott River is more than five times the total evapotranspiration demand from the 34,000 irrigated acres in the valley; seemingly enough water for fish and farming.  But – like elsewhere in California – surface water supplies usually dry up around July when the last of the snowmelt in the upper watershed disappears. Streamflow from mid-summer until the beginning of the rainy season largely depends on baseflow from the valley aquifer. Fed by recharge from tributaries, rainfall, and excess irrigation, the aquifer acts as a large, sponge-like reservoir that provides a steady contribution to streamflow in the summer and early fall.

In the 1970s, average late-summer streamflow in the Scott River decreased markedly by about 50%, resulting in increased stream temperatures and – during dry years – more pronounced dry stream reaches along the lower valley floor. How did the Scott River get to the condition it is in today?

Figure 1: Late summer streamflow in the Scott River has decreased significantly since the 1970s.

Figure 1: Late summer streamflow in the Scott River has decreased significantly since the 1970s.

A driving factor for the change in average summer flows may be a switch from reliance on surface-water prior to the 1970s to a greater use of groundwater for irrigation. Following the 1977 drought, many farmers moved from using surface water for flood irrigation to pumping groundwater. Groundwater is more reliable and the preferred source for more efficient irrigation methods such as wheel lines and center-pivots that are encouraged by agencies like the National Resource Conservation Service (NRCS). Access to groundwater allows for irrigation after surface water supplies are no longer available, but pumping groundwater reduces discharge from the aquifer to the stream.

Changing sources of irrigation water has had several major impacts in the valley, including:

  1. decreased groundwater recharge in the spring and summer due to increased irrigation efficiency,
  2. increased groundwater pumping, and
  3. net increase in consumptive crop water use (evapotranspiration) due to the ability to irrigate alfalfa into August or September for a third or fourth cutting instead of two cuttings through July.

Notably, with water supplies greatly exceeding water demand, there is no evidence of long-term groundwater overdraft in the Scott Valley. However, pumping near the Scott River seasonally lowers groundwater levels sufficiently to impact streamflow during the late summer, especially during the critical time between the end of the irrigation season and the beginning of the rainy season when Chinook and coho start their fall spawning runs.

Valley residents have been proactive ScottValleyin finding solutions to the problem of decreased late-summer streamflow. The Scott River Water Trust, the first active water trust in California, leases water from farmers with the goal of improving streamflow for salmon and steelhead at critical points during their lifecycle. The Scott Valley Groundwater Advisory Committee was established, which assists with data collection and monitoring, provides information about local farming practices, and suggests potential methods for increasing late-summer streamflow in the Scott River. Additionally, a Community Water Level Measuring Program has been monitoring about 34 wells monthly since 2006. UC Davis professor Thomas Harter and his research group have used this information to develop an integrated groundwater-surface water model of the Scott Valley that can test different management options for increasing late-summer streamflow.

One proposed solution for groundwater recharge is flooding dormant agricultural fields during the winter when streamflow is high and water is available. In January 2016, the Scott Valley received the first temporary groundwater storage permit issued in California to test this option. The goals of the groundwater recharge project, headed by UC Davis professor Helen Dahlke, are to quantify how much water can be recharged on agricultural fields, determine potential negative effects on the crop, and identify best management practices in the hopes this method can be applied to other areas in California as well.

flowdifference3Another management option is the conjunctive use of surface-water and groundwater involving a dual-irrigation system where more surface-water is used while it is available during the spring months to reduce groundwater pumping. Although this would require an investment in infrastructure and coordination among stakeholders, preliminary modeling results show promising streamflow increases when this management scenario is implemented.

Work will continue to improve fish habitat quality and quantity in the Scott Valley while also maintaining agriculture. There is no magic bullet, and the path forward will rely on a portfolio of management solutions, supported by active stakeholder engagement, monitoring, assessment, and modeling. Some actions may be achieved relatively easily, while others will require coordination and cooperation among stakeholders with some significant investments to successfully implement.

Gus Tolley is a doctoral candidate in the Hydrologic Sciences Graduate Group at UC Davis and 2015 UC President’s Global Food Initiative fellow. His work focuses on numerical modeling of interactions between groundwater and surface water in agricultural areas.

Further Reading

Barlow, P.M., and Leake, S.A., 2012, Streamflow Depletion by Wells — Understanding and Managing the Effects of Groundwater Pumping on Streamflow, USGS Circular 1376

Fleckenstein, J.H., Niswonger, R.G., and Fogg, G.E., 2006, River-Aquifer Interactions, Geologic Heterogeneity, and Low-Flow Management: Ground Water, v. 44, p. 837–852, doi: 10.1111/j.1745-6584.2006.00190.x.

Foglia, L., McNally, A., and Harter, T., 2013, Coupling a spatiotemporally distributed soil water budget with stream-depletion functions to inform stakeholder-driven management of groundwater-dependent ecosystems: Water Resources Research, v. 49, no. 11, p. 7292–7310, doi: 10.1002/wrcr.20555.

Hall, M., Harter, T., and Frank, R., Groundwater problems and prospects, part 7: Groundwater-dependent ecosystems and the groundwater-surface water connection, Maven’s Notebook.

Hoben, M. L., 1999, Scott River Coordinated Resource Management Council, in Systematic Assessment of Collaborative Resource Management Partnerships [Master’s Thesis], University of Michigan, 357 p.

Kendy, E., and Bredehoeft, J.D., 2006, Transient effects of groundwater pumping and surface-water-irrigation returns on streamflow: Water Resources Research, v. 42, no. 8, p. n/a–n/a, doi: 10.1029/2005WR004792.

Website for Professor Dahlke’s Research Group

Website for Professor Harter’s Research Group

Posted in California Water, Groundwater, Planning and Management, Salmon, Uncategorized, Water Markets | Tagged | 4 Comments