Water giveaways during a drought invite conflict

In the summer of 2014, UC Davis researchers recorded the effects of the drought on California streams, including this isolated pool on Hatch Creek near Don Pedro Reservoir. Photo by Andy Bell, UC Davis

In the summer of 2014, UC Davis researchers recorded the drought’s effects on California streams, including this isolated pool on Hatch Creek near Don Pedro Reservoir. Photo by Andy Bell, UC Davis

                                                This article first ran in the San Francisco Chronicle on March 20, 2015.

By Jay Lund and Peter Moyle

When labor is scarce, people move to better jobs with higher wages. When land is scarce, landowners are offered higher prices for its use. When drought makes water scarcer in California, those with senior water rights are offered more money to move their water to other users.

But fish are asked to give up their water for free.

California would do better if it cultivated a more civilized ethic where there is no free water during a drought. Perhaps we should treat environmental uses of water more as a matter of economics, to help the environment and the economy.

This year and last year, the State Water Resources Control Board relaxed environmental protections for fish to export more water from the Sacramento-San Joaquin Delta for farms and cities. Reducing fish flows without compensation during a drought has some attractions, but overall seems like a risky idea.

On the plus side, it’s a principle that, during a drought, everyone should get less water, including the environment. The reality is that some small reductions in environmental flows may not harm fish, but would have great economic value to cities and farms. Variability in flows is natural for many of California’s native ecosystems. Droughts might provide useful variability, if properly managed.

However, reductions in environmental flows during drought usually have costs, including:

Potential direct harm to fish in the short term, and in the longer term, severely reducing native fish populations and sometimes making it easier for invasive species to become established.

Risks that additional native fish or other aquatic species will become legally listed as threatened or endangered, which can reduce long-term water withdrawals for economic water uses.

Encouraging water fights, rather than using negotiation or markets to rebalance and reallocate water. This is uncivilized and encourages greater conflicts over water.

The amount of environmental flows that cities and farms will gain this year is relatively small, about 40,000 acre-feet of water. But in a drought year, 40,000 acre-feet of water south of the delta is probably worth more than $1,000 an acre-foot or about $40 million. While this is a tiny proportion of agricultural production or urban economies, those next in line for this water will find it worth fighting for.

The high value of small amounts of water during droughts is a harsh challenge for science, environmental advocates and those interested in thoughtful water policy. How can we make this a more civilized choice?

Let the fish sell their water.

Peter Moyle reacts to finding some rare Red Hills roach on Horton Creek, a tributary of Six-bit Gulch. The UC Davis professor of fish biology feared the species had gone extinct because of the drought. Photo by Karin Higgins/UC Davis, Aug. 14, 2014

Peter Moyle reacts to finding some rare fish on drought-stricken Horton Creek, near Sonora, in August 2014. He  feared the species — Red Hills roach — had gone extinct because of the drought. Photo by Karin Higgins/UC Davis

That is, convert some drought portion of environmental flows to a marketable water quantity, owned by the fish agencies. This would allow environmental water uses to be fairly compensated by those gaining from reductions in environmental flows, just as other high-priority water rights holders are compensated for their reductions in water use during a drought. This seems more fair, gives incentives to water users to behave better, and encourages conflicts to be speedily negotiated instead of indefinitely litigated. [1]

Prices could be set by the fair market value of the water made available, by having a regulatory agency fix or negotiate a fee, or by assessing the cost of compensatory environmental actions such as buying water for environmental purposes elsewhere in the state or creating a reserve fund to aid native fish after the drought.

Creating such an environmental water market during a drought would help limit the reductions in environmental river flows, while ensuring that those negatively impacted by such reductions receive some compensation.

For California, even partial markets for environmental water would satisfy the state’s stated “co-equal” environmental and economic goals for water management.

Overall, fish have suffered at least as much as humans during the drought, certainly in terms of habitat loss.

We can’t equalize the burdens of severe drought across all water uses, but we can share the pain more fairly in ways that help fish and other species that depend on our rivers for their survival.

Jay Lund is director of the UC Davis Center for Watershed Sciences and a professor of civil and environmental engineering. Peter Moyle, the Center’s associate director, is a professor of fish biology.

[1] Reductions in environmental flows could be compensated through existing legal mechanisms such as negotiated agreements with water users; fixed penalties for violating flow and water quality standards; or Endangered Species Act regulatory actions — adding environmental market provisions to biological opinions, incidental take permits or habitat conservation plans (Lund et al, Feb. 2014).

Further reading

Lund, J. and P. Moyle. “Is shorting fish of water during drought good for water users?” California WaterBlog. June 3, 2014 

Lund, J., E. Hanak, B. Thompson, B. Gray, J. Mount and K. Jessoe (2014), “Why give away fish flows for free during a drought?” California WaterBlog. Feb. 11, 2014

Manfree, A. “Drought Journal: Search for Sierra fish goes from bad to worse.” California WaterBlog. Aug. 18, 2014

Moyle, P. “Saving California’s salmon during a severe drought.” California WaterBlog. Feb. 17, 2014.

Posted in Uncategorized | 5 Comments

Prepare for extinction of delta smelt

Photo: UC Davis

An adult delta smelt caught in a survey of fish in the Sacramento-San Joaquin Delta. Photo: UC Davis

By Peter Moyle

I saw my first delta smelt in 1972, during my first fall as an assistant professor at UC Davis. I was on a California Department of Fish and Wildlife trawl survey to learn about the fishes of the Sacramento-San Joaquin Delta. The survey then targeted young striped bass, but the trawl towed behind the boat captured large numbers of the native delta smelt.

I remember a single haul with a couple hundred of these iridescent finger-length fish being dumped into a container on deck. I decided to study smelt biology because these fishes were so abundant and yet so poorly studied. I would have no trouble collecting enough of them for my research.

Fall midwater trawl. Photo: California Department of Fish and Wildlife

A mid-water trawl used in fall surveys of Delta fish. Photo: California Department of Fish and Wildlife

Lee Miller, the biologist in charge of the surveys, started preserving the smelt catches for me. Each year for three years a pickup loaded with quart bottles of delta and longfin smelt would arrive at my laboratory. For a diet study alone, my technician and I dissected 1,055 delta smelt.

Today, few delta smelt remain in the wild. Researchers get their samples from special labs where the smelt are bred in captivity.

The state’s 2014 fall mid-water trawl survey showed the lowest number of delta smelt in 47 years of recordkeeping (See chart below). Last week, the state conducted its annual spring Kodiak trawl survey, which is designed to capture delta smelt as they aggregate to spawn. They caught only six smelt — four females and two males [1] [2].

Delta smelt annual abundances as determined by fall midwater trawl surveys. Source: California Department of Fish and Wildlife

Delta smelt annual abundances as determined by fall mid-water trawl surveys. Source: California Department of Fish and Wildlife

The dismal catch prompted me to advise the state’s Delta Stewardship Council on Monday that delta smelt appear to approaching the point of no return, with extinction in the wild possible in the next year or two.

Source: California Department of Fish and Wildlife

Distribution of female delta smelt in March 2015, as determined by the annual spring Kodiak trawl survey. Source: California Department of Fish and Wildlife

I say “in the wild” because there are two captive populations of smelt. The U.S. Fish and Wildlife Service manages a backup population at its fish hatchery below Shasta Dam, and UC Davis produces smelt for experimental and conservation purposes at a lab in the Delta, just south of Stockton. Both facilities raise hundreds of smelt at a time through their entire life cycle. Each fish is tagged and its genetics recorded for precise mating, to maximize genetic diversity. Each year a few wild smelt are brought in to mix their genes with those of the captive brood stock. 

Delta Smelt Refuge facility with tanks for genetically diverse smelt populations.

Delta smelt rearing tanks in captive breeding facility run by UC Davis near Stockton. Photo by Dale Kolke California Department of Water Resources

We don’t know what the minimum population size has to be for successful reproduction to occur in the wild. But it must be hard for males and females to even find one another today, and even harder to find partners that are in the right stage of maturity for spawning. Most of these fish have a one-year life cycle, apparently dying after spawning. A few live two years. This means a bunch of them have to spawn successfully every year to maintain a viable population.

We don’t know with absolute certainty that wild delta smelt will disappear within the next couple of years. But the likelihood is high enough that we should be prepared for it. We need to start answering questions like these:

  • How do we know when the delta smelt is truly extinct in the wild? Who makes the decision? It is worth noting that the last thicktail chub was caught in the Delta’s Steamboat Slough in 1957 but not recognized as extinct for at least 30 years — and without an official declaration.
  • Should the last of the delta smelt be captured so their genes can be added to the captive population, as was done for the California condor?

    Counting Delta Smelt eggs, one inch in the tube means 1000 eggs. Dale Kolke

    Counting delta smelt eggs. One inch in the tube means 1000 eggs. Photo by Dale Kolke, California Department of Water Resources

  • Can captive populations be used to restore the delta smelt in the wild? This is not easy to answer. Obviously, this would not work as long as conditions that caused the smelt to decline remain. These conditions include competition and predation by alien species, altered food supply, multiple water contaminants and water exports upstream and within the Delta. The extended drought presumably has worsened these conditions and pushed the smelt over the edge of the extinction cliff, or at least close to it [3].
  • How does management of the Delta change if delta smelt are extinct in the wild? It is hard to do anything water-related in the Delta without considering its impacts on delta smelt, particularly operation of state pumping facilities and wastewater treatment plants. For example, in the past year federal fish officials placed no restrictions on pumping from the South Delta because the smelt were mostly not there.

Presumably, protecting delta smelt has benefited other native fish because it is the species most sensitive to changes in the Delta’s waterways. Other listed fish species that affect and are affected by Delta management include winter- and spring-run Chinook salmon, longfin smelt, green sturgeon and Central Valley steelhead.  

We need to prevent more fish from achieving the cliff-hanger status of delta smelt. We need to extend proactive management from species already listed to those headed in that direction, including hitch, blackfish, splittail, tule perch and white sturgeon. This requires learning more about their requirements and managing parts of ecosystem specifically for their benefit, including tidal marshes.

I hope we still have enough smelt and enough time to keep the species from altogether disappearing from the Delta. But, as my geologist colleague Jeffrey Mount is fond of saying, “Hope is not a strategy.” We need to be planning for delta smelt extinction and, perhaps, its resurrection.

Peter Moyle, a professor of fish biology, is associate director of the Center for Watershed Sciences at UC Davis.

[1] Numbers were much higher in 2002 – 2014 (e.g., Bennett 2005). Intensive Kodiak trawl surveys near the state and federal water projects (Jersey Point) in 2014 caught so few fish that the U.S. Fish and Wildlife Service placed no restrictions on Delta pumping that year. In 2013, this survey captured 329 smelt in 737 tows of the trawl, with 78 percent of the tows catching no fish. This may seem like a high number but the high-intensity sampling spanned a two-month period when smelt populations should be at their peak. Presumably few, if any, of the highly sensitive fish survived the experience.

[2] The numbers of delta smelt are only a fraction of what they were in 1993 when both the state and federal governments listed the species as “threatened” with extinction.. The designation occurred because its numbers were a small fraction of those in the early 1980s when the population decline began..

[3] At the very least, reintroduction would have to wait until we had some wet years with lots of inflow from the rivers. But if we wait too long for reintroduction, the smelt may not be capable of living on their own in the wild. Having multiple generations in captivity tends to alter behavior and general ‘fitness’ of fish. The problems hatchery salmon have surviving in the wild are a reflection of this lack of natural selection.

Further reading 

Bennett WA. 2005. “Critical assessment of the delta smelt population in the San Francisco Estuary,” California. San Francisco Estuary & Watershed Science 

Quinton, A. 2015. “Endangered delta smelt may be extinct.” Capital Public Radio. March 16, 2015

Ruyak B. 2015. “UC Davis fish biologist: delta smelt ‘functionally extinct’.” Capital Public Radio, Insight with Beth Ruyak. March 18, 2015


Posted in Uncategorized | 1 Comment

Salmon finding a home in my backyard – Could it be?

Chinook salmon spawning in Lower Putah Creek, 2014. Photo by Ken Davis/Wildlife Survey and Photo Service

Chinook salmon spawning in Lower Putah Creek, 2014. Photo by Ken Davis/Wildlife Survey & Photo Service

By Peter Moyle

The sound of splashing drew me to the stream. A dark finned back cut the surface. Salmon? The fish came into view and its snout was a giveaway, maroon-hued and curved like a hook.

This was a spawning male Chinook salmon. It alternated between chasing another hooknose and two jacks, small males that sneak in to add their sperm to the mix when a standard male and female are spawning.

The source of the commotion soon became clear: A mottled female was turned on her side and fluttering her tail in a patch of clean gravel, digging a nest, or redd. Several small rainbow trout hovered nearby, waiting to feast on loose eggs.

Video shows Chinook salmon spawning in Lower Putah Creek, Yolo County, in fall 2014. No sooner does a female lay her eggs than she is flanked by two males, mouths agape as they release clouds of sperm. The female attempts to bury her eggs as several rainbow trout attempt to eat them. Poor girl even hits her head on a rock while covering the eggs. Video by Ken Davis/Wildlife Survey & Photo Service

The scene I’m recalling from December was not the Sacramento River or some other salmon highway, but a lowly back alley long associated with carp and suckers: Putah Creek, my hometown stream west of Sacramento.

Shortly after my find, I was involved in a discussion about a new bridge being built on the creek in the Yolo County community of Winters. Chinook salmon had recently been seen spawning at the construction site. Workers were preparing to remove temporary supports from the span. Would the embryos buried in the gravel be destroyed in the process?

Until recently, such concerns would have been inconceivable. Though Putah Creek has been heralded since 2000 as a success story in stream restoration, salmon have been regarded mainly as a bonus. Few salmon have responded each year to a special pulse flow designed to coax them upstream to spawn in the cold waters at the foot of Putah Diversion Dam.[Listen to Peter Moyle’s story of how Putah Creek got its fish flows back (2 mins)]

Lower Putah Creek. Source:

Lower Putah Creek. Source: Teale GIS Solutions Group, US Census Bureau, USGS


This past fall, however, more than 200 salmon came up the creek and spawned, or tried to, using every patch of gravel between the dam and the UC Davis campus, including the patch by the new bridge.

The number is tiny compared with the thousands of salmon that return annually to California’s Central Valley. But it’s the highest population recorded in the 30 years, when my UC Davis students began taking annual fish surveys of Putah Creek. The previous high was about 70 salmon, a decade ago. In most years fewer than 10 salmon can be found in the 27-mile-long stream below the diversion dam. Putah Creek has its headwaters in the Mayacamas Mountains that divide the Napa and Sonoma valleys and once spawned in the now-drowned Berryessa Valley.

Most of this past fall’s salmon run used the freshly “ripped” gravel in the first few miles below the diversion dam. The Solano County Water Agency, which operates the dam, greatly increased the chances of a productive spawn by ripping through the concrete-like layer of clay and sand covering the gravel. Using heavy machinery, the agency’s Rick Fowler uncovered smooth stones of many sizes, ideal for spawning. As an experiment, alternating stretches of the creek were left as they were. Not surprisingly, no salmon spawned in these areas.

So why the sudden influx of salmon into Putah, during a drought no less? The reasons reflect the many challenges California faces trying to retain self-sustaining salmon populations.

Ken Davis

Ken Davis, a Sacramento wildlife photographer and aquatic biologist, recorded salmon spawning last fall here on Lower Putah Creek. Photo by Peter Moyle

The most optimistic reason is that this year’s spawners are progeny of earlier spawners, 2 to 3 years ago. We have observed juvenile salmon migrating downstream during the spring, and local naturalist Ken Davis has recorded juveniles summering in the cold water below the diversion dam. Presumably these fish moved out as the water cooled in the fall, especially after a rain.

However, it is more likely that most of this year’s salmon were strays from hatcheries. About 25 percent of hatchery fish are marked by removing the adipose fin and we observed carcasses with this fin missing.

The large number of hatchery strays could be explained by a series of events in the first week of December.

At the mouth of Putah Creek, a man-made canal known to trap wayward salmon drew an unusually large number of strays. The heavy rain that week could have accounted for this. Flush with stormwater runoff, water flowing from Cache Slough into the Sacramento River could have been as attractive as the low flows from the drought-stricken river itself.

The wrong turn at Cache took salmon up the dead-end canal, known as the Toe Drain of the Yolo Bypass. (A small board dam that sends water to the Yolo Basin Wildlife Area keeps fish from entering Putah Creek until the first week of December, when the boards are removed.) California Department of Fish and Wildlife crews with nets rescued some but not all of the trapped strays and returned them to the Sacramento River.

To salmon remaining in the muddy Toe Drain, Putah Creek would have seemed like an attractive option – especially once the stormwater started flowing down the stream. The first fish up the creek would have found a small board dam in the bypass blocking their way; the dam sends water to the Yolo Basin Wildlife Area until the first week of December, when the boards are removed. Salmon were observed swimming upstream immediately after the boards went off. The biggest influx apparently occurred during with the five days of pulse flow from the diversion dam, which coincided nicely with the inflow of stormwater runoff.

Photo by Chris Jasper

UC Davis science students recently found some small salmon fry in Putah Creek. Photo by Chris Jasper, March 7, 2015.

Whatever the reason for the surge in Putah Creek salmon, I will be watching for young out-migrants in the creek this spring. Earlier this week, a team of UC Davis undergraduates led by Chris Jasper found some small (1.5 inch) fry in the creek on campus. These fish had clearly just emerged from a redd. I can only hope some of these fish are the progeny of naturally produced adults from previous years.

Studies elsewhere have shown that juveniles of wild salmon parents have much higher survival rates than those of hatchery-born salmon, even if those parents spawned in the wild.  

If wild fish are not swamped out each year by less fit hatchery fish, natural selection – evolution – can start to work again, producing fish better able to live under the changing conditions of our rivers.

It would be good to see what is going on in Putah Creek occur in larger rivers, with thousands of fish. This can happen only if we radically change our management of hatcheries and salmon in dammed rivers (Katz and Moyle 2012).

It would be wonderful if every fall families could go to bridges and banks and look down on huge salmon spawning in their local creek. Putah Creek as salmon stream – hold that thought!

Peter Moyle, a professor of fish biology, is associate director of the Center for Watershed Sciences at UC Davis.

Further reading

Case, E. and LeCompte, C. 2014. The Putah Creek Legacy. A five-part multimedia series by The Davis Enterprise and Climate Confidential.

Davis, K. 2014. “Report 4963: 2014 Putah Salmon Run“. Wildlife Survey & Photo Service

Katz, J. and Moyle, P.B. 2012. “Have our salmon and eat them too: Re-thinking Central Valley salmon hatcheries“. California WaterBlog. Feb. 29, 2012

Kiernan J, Moyle P, Crain PK.  2012.  “Restoring native fish assemblages to a regulated California stream using the natural flow regime concept“. Ecological Applications.

Putah Creek Council


Posted in Uncategorized | 2 Comments

Creating effective groundwater sustainability plans

measure and record a pumping water level in a production well. Photo by XXX, DWR

A California Department of Water Resources (DWR) geologist measures and records a pumping water level in a production well. Photo by John Chacon,/DWR, 2013

Jay Lund, Thomas Harter, Robert Gailey, Graham Fogg, Richard Frank, Helen Dahlke, Timothy Ginn, Sam Sandoval Solis, Thomas Young — UC Davis
Andrew Fisher, Ruth Langridge — UC Santa Cruz
Joshua Viers, Thomas Harmon — UC Merced
Patricia Holden, Arturo Keller — UC Santa Barbara
Michael Kiparsky — UC Berkeley
Todd Greene, Steffen Mehl — California State University, Chico
Jason Gurdak — San Francisco State University
Steven Gorelick, Rosemary Knight — Stanford University

California is entering a new era in how it manages its largest source of water storage — groundwater. Initial efforts implementing the state’s new Sustainable Groundwater Management Act must focus on getting local and state agencies organized and able to communicate with each other. Having common expectations for the contents of the law’s required “Groundwater Sustainability Plans” will save the agencies and stakeholders considerable grief and confusion. Here is how the contents of the local plans might be organized to support both local and statewide objectives for groundwater sustainability.

Groundwater plans

The new law, which took effect Jan. 1, broadly defines “sustainability” as avoiding “undesirable results,” [Section 10721 (u)-(w)] in terms of groundwater overdraft, land subsidence, water quality degradation, seawater intrusion and groundwater-surface water interaction. The local sustainability plans are not required to address undesirable results that occurred before Jan. 1 [Section 10727.2 b (4)].

The law requires regional agencies to prepare the Groundwater Sustainability Plans for groundwater basins that the California Department of Water Resources has designated “high” and “medium” priority. The department has preliminarily assigned these designations to 127 of the state’s 515 basins [1].

The law provides a framework for the plans (Section 10727) but refrains from a prescriptive state role. It requires the department to create technical criteria and regulations by which it will evaluate the appropriateness of the local plans and their implementation (Section 10733). The department must adopt the regulations before June 1, 2016. The design of these regulations and their technical and scientific requirements will be critical to the success of the plans.

In the coming months, there will be much discussion on the content of these rules among department staff and advisors and in public meetings. The initial 2016 regulations will likely be refined over time [Section 10733.2 b (1)], but all parties have an interest in a well-designed initial regulatory framework to guide the development and evaluation of the local sustainability plans.

Making the local plans effective

To be effective, the plans must be based on the physical realities of geology, hydrology and land use. Groundwater balances are central. However, groundwater sustainability might not simply balance basin pumping with natural recharge; under natural conditions inflow is balanced by natural outflow to streams and groundwater-dependent ecosystems. Today, additional stream depletion and deep percolation of irrigation water increase total basin inflows.

Photo by Kelly M. Grow/California Department of Water Resources

Delivery point of the Coachella Valley Water District’s groundwater replenishment facility. Photo by Kelly M. Grow/California Department of Water Resources

Plans also should be realistic on local, economic, political and legal conditions, including logistics in implementation and relationships to neighboring plans and finances. The plans also must clarify the responsibilities and authorities of local agencies for implementation, and specify contingencies for when conditions deviate from plan assumptions or projections (including surface water deliveries and inflows from other basins).

“Groundwater Sustainability Agencies” responsible for developing basin plans will need to make controversial decisions. The state regulations should require transparent development of sustainability objectives and analysis to inform decision-makers, regulators and courts. The technical information should include:

  • Local concerns, objectives and definition of “sustainability”
  • Water balances for the basin under present and potential future conditions
  • Data collection and reporting to inform, monitor and evaluate analyses and plans
  • Overall assessment of groundwater basins
  • Management alternatives available to achieve local sustainability objectives
U.S. Geological Survey scientists say cracks and buckles along the Delta-Mendota Canal are likely caused by subsidence from groundwater overdraft. Photo by Amy Quinton, Capital Public Radio, November. 2013 by Amy Quinton, Capital Public Radio

U.S. Geological Survey scientists say cracks and buckles along the Delta-Mendota Canal are likely caused by subsidence from groundwater overdraft. Photo by Amy Quinton, Capital Public Radio, November. 2013 

Each major management alternative should be technically assessed on its likelihood of success as well as its cost (including delayed costs and those to third parties) and performance — physical, economic, social and environmental. Science-based planning and management requires that contingencies be flexible enough to accommodate major unavoidable uncertainties.

Clear and timely communication among stakeholders will be critical to reduce conflict and build creative solutions with broad local support. This requires:

  • Data organization, transparency and availability
  • Sharing knowledge, concepts, management options and assessment of desirable and undesirable outcomes
  • Examination of uncertainties in knowledge, data and predictability of outcomes
  • Clear analytical comparison and discussion of alternatives leading to a preferred plan

Crafting the Groundwater Sustainability Plans so they can be effective on (and under) the ground and fairly evaluated by state regulators and courts is an immense technical and institutional challenge. Thoughtful state regulations on the development and contents of these plans will be essential.

A proposed table of contents

Here we propose a preliminary table of contents for a typical Groundwater Sustainability Plan. More details and structure are suggested in an outline that can be downloaded here. This outline includes technical items we believe are needed for effective plans. Tiers of content depend on basin complexity. Additional items might also be useful, and some items might not be needed for simpler cases.

A Table of Contents
Groundwater Sustainability Plans 

  1. Summary statement of local basin sustainability objectives and approaches
  2. Basin geography and GSP organization: description of basin, water sources and uses; Summary of major basin problems related to groundwater; organization of local Groundwater Sustainability Agencies; defining roles and authorities relative to other local and regional agencies
  3. Summary of basin hydrogeology: geologic context of local groundwater; major water flows in and out of basin; changes in storage with time; variability in flows and storage; how flows are likely to change with climate, population, and land use; susceptibility to land subsidence, saltwater intrusion, loss of habitat and other problems related to groundwater use
  4. Sustainability objectives, options and analysis: basin-specific definition and objectives for sustainability (quantity, quality, land subsidence and groundwater/surface water interaction); options and effectiveness for achieving sustainability; groundwater deliveries for different water budget management options, including uncertainties
  5. GSP activities: management activities; implementation responsibilities and enforcement; timelines, funding, measurement and verification; agreements with neighboring and regional basins, water suppliers and land-use authorities on water management and supply and information sharing; strategies for moving forward in the absence of ideal data, including additional near-term data gathering; monitoring plans; recourse contingencies for changes in surface water availability, to make implementation more robust; monitoring plans
  6. Implementation actions supporting GSP activities: near-term actions and responsibilities; efforts and responsibilities for improving information and reducing uncertainties to manageable levels; efforts to assess achievement of plan objectives

Technical appendices:

  1. Basin hydrogeology
  2. Details of water budget component calculations
  3. Water quality, including natural and anthropogenic sources of contamination
  4. Options considered for achieving sustainable management
  5. Process of GSP development, including local and stakeholder engagement and analysis
  6. Details of monitoring and assessment plans
  7. Other supporting documents

PDF file of table of contents
PDF file of more detailed table of contents

[1] Links to further information on the Sustainable Groundwater Management Act of 2014:

Posted in Uncategorized | 4 Comments

The 2015 Drought so far – March 1

By Jay Lund

Droughts are strange, and this one is becoming scarier.

February began with a nice few stormy days, but has since looked like this January – very dry. And so far, the March forecast is not wet.

At the beginning of March, the Northern Sierra (Sacramento Valley) Precipitation Index was down to 88% of average to date, although it already almost equals total precipitation for all of 2014 (both good and bad news). For the San Joaquin Valley and Tulare basin (where most water use occurs), precipitation is about half of average for this date – slightly wetter than this time last year.  Snowpack is roughly like last year – among the driest on record.

Will March will be as dry?  Statistically, little can be said. There is little correlation in monthly precipitation during Northern California’s wet season, but droughts are inherently unusual.  The forecast and climate conditions so far look dry.

The best news is a bit more overall reservoir storage than last year at this time (but still about 5 maf below average for this time of year).   The big reservoirs in the Sacramento Valley have 1.3 maf more than last year at this time – this is the good news.  South of the Delta surface storage is about the same overall, but differently distributed.  San Luis reservoir, which serves the west side of the valley and southern California is about 600 taf higher, but the large reservoirs on the San Joaquin River tributaries are about 600 taf lower.

Groundwater storage is probably about 6 maf less than last year.

Without a miracle March, we will have another critically dry year for 2015.  Northern California is likely to be a bit better off than last year, but could be about the same (very dry).  In the southern Central Valley and southern California conditions could easily be as bad or worse than last year.

The state is likely to protect environmental flows more carefully this year, probably a good thing to reduce potential for more endangered species listings after the drought.  The State Water Project has said they expect about 15% deliveries.  The federal Central Valley Project has now announced initial 0% deliveries for regular agricultural water contracts, likely cutbacks (of 25%?) for water right exchange and settlement contractors, and 25% urban deliveries for 2015.  While these percentages might improve in the remaining month of the wet season, there is a good chance that water allocations will be similarly dismal to 2014, with less groundwater available in some parts of the state.


Fortunately, some Northern California reservoirs have more storage than a year ago, while reservoir levels elsewhere are more mixed. Overall, we remain about 6 million acre-feet below average for reservoir storage this time of year.  In the southern Central Valley, west side reservoirs (San Luis) have much more water than last year, but the east side tributaries to the San Joaquin River are very low (Exchequer at 8% of capacity).

Aquifer levels will generally be lower than a year ago in the areas highly dependent on groundwater.

Source: California Department of Water Resources

Source: California Department of Water Resources


Snowpack is truly sad, about 16% of average for this time of year.


The 2014 water year ended at 60 percent of average annual precipitation for Sacramento Valley. For 2015, we’re already about at this total, so 2015 is very likely to be at least a bit wetter than 2014 for the Sacramento Valley.  A very wet March and early April sure would help.

<span style="color: #000000;">For updates, <a style="color: #000000;" href="http://cdec.water.ca.gov/cgi-progs/products/PLOT_ESI.pdf">click here</a>. <em>Source: California Department of Water Resources</em></span>

For updates, click here. Source: California Department of Water Resources

Both the San Joaquin and Tulare basins are slightly wetter than this time last year.  2015 could be better than 2014, but could also easily be drier.

Source: California Department of Water Resources

For updates, click here. Source: California Department of Water Resources

Source: California Department of Water Resources

For updates, click here. Tulare basin has a shorter record though it has the most water use in California. Source: California Department of Water Resources

The difference between a drought and a wet year in California is just a few storms. We are at two significant storms so far, mostly in the northern state.  There is little time left to make this up, particularly south of the Delta.

Sadly, our standard for 2015 is not  average, but  the miserable conditions of 2014.  That’s how dry it is.

Beware the dries of March.

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

Further Reading

The links above can help keep you up to date. For more data, explore the California Department of Water CDEC web site http://cdec.water.ca.gov.

Lund, J. The 2015 drought — so far. California WaterBlog. Jan. 5, 2015

Lund, J. and J. Mount. “Will California’s drought extend into 2015?California WaterBlog. June 15, 2014

Swain, D. “The Ridiculously Resilient Ridge Returns; typical winter conditions still nowhere to be found in CaliforniaCalifornia Weather Blog. Feb. 16, 2015

Posted in Uncategorized | Tagged | 16 Comments

Dutch lessons on levee design and prioritization for California

Dutch flood safety standards, established by economic risk analysis. Source: Flood Defence Act of 1996

Dutch flood safety standards, established by economic risk analysis. Source: Flood Defence Act of 1996

This is the second of an intermittent series of articles on the future of the Sacramento-San Joaquin Delta.

By Jay Lund

In any lowland, levees define how humans live and how they disrupt native habitats. This is as true for the Sacramento-San Joaquin Delta as it is for coastal Louisiana, Vietnam and the Netherlands.

Flood safety in the Delta is a statewide concern because the region serves as a hub for delivering water to most Californians and supports native fish.

Like many Dutch lowlands, the Delta became low from the conversion of tidal marsh to farmland. Once diked and drained, peat soils (accumulating over millennia with sea level rise) were exposed to air, decomposed and subsided. Dutch lowlands have sunk about 6 feet in 300 years, while some islands in the western and central Delta have subsided much more — up to about 25 feet over 150 years — because of California’s warmer and sunnier climate.

Administration of Dutch polders (islands)

The Dutch have a long and distinguished record of managing floods in their lowlands. They have been reclaiming dry land from the sea and marshlands since the Middle Ages. They have suffered and learned from centuries of flooding.

Local landowners did most of the land reclamation and paid for the work themselves. As the country grew, it consolidated the governance of reclamation from what were once thousands of local “water boards” to 24 regional boards, which maintain levees and dikes and treat wastewater.

Consolidation and growing prosperity brought more state involvement and funding for flood protection, along with more formal state protection standards and prioritization. Investments in flood protection are now guided by formal analyses of risks, costs and benefits (van Dantzig 1956).

Risk analysis

The Dutch risk analysis has provided a rigorous, understandable and widely accepted basis for flood management decisions and investments for nearly 60 years (Eijgenraam et al 2014, Schweckendiek 2013). The level of flood protection is chosen to minimize the total costs of flood damage and protect investments.

Using risk analysis to balance benefits and costs of flood protection (Schweckendiek 2013)

Using risk analysis to balance benefits and costs of flood protection Source: Schweckendiek 2013

Having risk analysis drive the setting of flood safety standards and investment priorities follows a long Dutch tradition of improving analytical tools to solidify the scientific basis of decision-making (Disco and van der Ende 2003).

The risk analysis has grown to include loss of life, longer planning horizons, sea level rise and more subtle aspects of levee system reliability – aspects that have led to better management of levees and floods (Eijgenraam et al. 2014, Jonkman et al 2011; Schweckendiek 2013).

The Dutch sometimes have retreated from the sea following catastrophic storms, or by design to increase flood conveyance capacity, restore natural areas and reduce costs. The Netherlands has setback some levees, widened some channels and “de-poldered” or abandoned some subsided land under its “Room for the River” program (van Staveren et al. 2014).

Implications for California’s Delta?

For the Delta, state levee decisions are probably the single most important and defining policy area. Living in the Delta and in lowlands elsewhere in the world is largely defined by the design and maintenance of levee systems and the prioritization of levee projects. The flow and mixing of water is shaped by the configuration and reliability of levee systems and how they fail. (In any system, levees will fail, and part of levee policy is what to do when they fail.) Levee systems also shape the remaining natural habitat for native species and other important habitat, such as the Delta’s famous bass fishery.

Where levee system design is so fundamentally important to so many interests, it is tempting to perform highly complex analysis of many alternative management strategies for each of the many social, economic and environmental interests in the region. However, thoughtful analysts and policymakers know such analyses can do more to confuse than enlighten.

The Dutch have brought three useful ideas to the design of their lowland levee system:

  • Define problems in ways they can be solved. The Dutch have defined their levee problem in a way that can be usefully solved, even if the definition is necessarily incomplete. Indecision or perpetuation of a deteriorating status quo is dangerous in lowlands. The Dutch begin by examining the economic benefits, costs and risks in levee system design. Economic sustainability and public safety are the major objectives for levees below sea level. Additional social and environmental concerns are considered separately. This process clarifies trade-offs and avoids more complex approaches that tend to add more confusion than insight.
  • Base levee standards and safety levels mainly on risk analysis. Economically and environmentally, some areas merit higher levels of flood protection than others. Some areas may deserve no flood protection at all. In other cases, flooding may benefit the environment.
  • Consolidate levee districts. Most levee maintenance is a local responsibility that is funded and inspected by the state. Long-term consolidation has resulted in more responsible use of state funds and better flood protection for more land.

California’s Delta has many unique challenges (Finch 1985; Lund et al 2010; Lund 2011), but much can be learned from the efforts and successes in the Netherlands (Woodall and Lund 2009; Ertsen and Lund 2011).

If we want to solve hard problems, we must define and organize them in ways that can be solved, even imperfectly. Indecision risks everything in lowlands – local lives and livelihoods, a water system serving millions of Californians and acres of farmland, and important habitat for native aquatic species. Nostalgia for the Delta of the 1950’s or 1850’s cannot prevail for long over the hard physics and economics of lowland risks.

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

A note on Delta terminology

California has a long tradition of improperly naming physical features in the Sacramento-San Joaquin Delta, beginning with the term delta.

A river dike between Kesteren and Opheusden, the Netherlands, at high water levels oo the river Nederrijn in 1995. Photo by Henri Cormont/Wikimedia Commons

Throughout the rest of the world (with the exception of the Okavango Delta), deltas are formed where rivers disgorge into open bodies of water, leaving a prism of sediment shaped like the Greek letter Δ (delta)The Sacramento-San Joaquin “Delta” does not qualify as a traditional delta since it is formed at the tidally influenced confluence of two large floodplain rivers, which was submerged more than 6,000 years ago by sea level rise.

Other common misnomers are levees and islands. Levees are earthen embankments that hold back water during floods. The Delta “levees” are actually dikes because they hold back water all the time.

Islands are lands of positive relief surrounded by water. The Delta’s “islands” are reclaimed lands that form topographic depressions surrounded by water. In this regard, they are polders, not islands.

The Dutch, who have many dikes maintaining polders in their delta landscape, go by more authoritative terminology.

Further reading

Buijs, F.A., P.H.A.J.M. van Gelder, J.K. Vrijling & A.C.W.M. Vrouwenvelder, J.W. Hall, P.B. Sayers, M.J. Wehrung (2003), “Application of Dutch reliability-based flood defence design in the UK,” Safety and Reliability – Bedford & van Gelder (eds), Swets & Zeitlinger, Lisse, ISBN 90 5809 551 7

Disco, C. & J. van der Ende (2003), “Strong, Invincible Arguments?: Tidal models as management instruments in twentieth-century Dutch coastal engineering,” Technology and Culture, Vol. 44, July, pp. 502-535

Eijgenraam, C., J. Kind, C. Bak, R. Brekelmans, D.k den Hertog, M. Duits, K. Roos, P. Vermeer, W. Kuijken (2014), “Economically Efficient Standards to Protect the Netherlands Against Flooding,” Interfaces, Vol. 44, No. 1, January–February, pp. 7–21

Ertsen, M. and J. Lund, “Drowning Men Will Clutch at Straws – A Short Comparative History Of Dutch And Californian River Flood Management,” 25th ICID European Regional Conference Proceedings, Paper IV-5, 2011

Finch, M. (1985), “Earthquake Damage in the Sacramento-San Joaquin Delta, Sacramento and San Joaquin Counties,” California Geology.

Jonkman,S.N, R. Jongejan, and Bob Maaskant (2011),”The Use of Individual and Societal Risk Criteria Within the Dutch Flood Safety Policy—Nationwide Estimates of Societal Risk and Policy Applications,” Risk Analysis, Vol. 31, No. 2

Kind JM (2013) “Economically efficient flood protection standards for the Netherlands,” Journal of Flood Risk Management

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

Lund, J.R. (2011), “Sea level rise and Delta subsidence—the demise of subsided Delta islands,” California WaterBlog, posted March 9, 2011

Mostert, E. 2012. “Water management on the island of IJsselmonde 1000 to 1953: polycentric governance, adaptation, and petrification.” Ecology and Society 17(3): 12

Room for the River program

Schweckendiek, T. (2013), “Dutch approach to levee reliability and flood risk,” presentation to the National Research Council

Suddeth, R., J. Mount, and J. Lund (2010), “Levee decisions and sustainability for the Sacramento-San Joaquin Delta,” San Francisco Estuary and Watershed Science, Volume 8, No. 2, 23 pp

Suddeth, R. (2011), “Policy implications of permanently flooded islands in the Sacramento–San Joaquin Delta,” San Francisco Estuary and Watershed Science, 9(2)

van Dantzig, D. (1956), “Economic decision problems for flood prevention,” Econometrica 24(3):276–287

van Staveren, M.F., J.F. Warner, J.P.M. van Tatenhove, and P. Wester (2014), “Let’s bring in the floods: de-poldering in the Netherlands as a strategy for long-term delta survival?”, Water International, Vol. 39, No. 5, pp. 686-700

van der Vleuten, E. and C. Disco (2004), “Water Wizards: Reshaping wet nature and society.” History and Technology 20 (3), 291-309

Voortman, H.G. (2003), “Risk-based design of large-scale flood defence systems” PhD thesis, TU Delft, The Netherlands. Also published in the series “Communications on Hydraulic and Geotechnical Engineering” Delft University of Technology, Report no. 02-3

Voortman, H.G. and J.K. Vrijling (2004), “Optimal design of flood defence systems in a changing climate.” Heron, Vol. 49, No. 1

Vrijling, J.K., W. van Hengel, and R.J. Houben (199), “Acceptable risk as a basis for design.” Reliability Engineering and System Safety, 59:141-150

Walker, W. E., A. Abrahamse, J. Bolten, J.P. Kahan, O. Van De Riet, M. Kok, and M. Den Braber (1994), “A Policy Analysis of Dutch River Dike Improvements: Trading off Safety, Cost, and Environmental Impacts,” Operations Research, Vol. 42, No. 5

Woodall, D.L. and J.R. Lund (2009), “Dutch Flood Policy Innovations for California,” Journal of Contemporary Water Research and Education, Issue 141

Posted in Uncategorized | 2 Comments

21st Century Delta: Reconciling the desired with the possible

The Sacramento - San Joaquin Delta, as seen from a ship traveling through the Stockton Ship Channel on September 24, 2013. Photo by Florence Lo, California Department of Water Resources

The Sacramento – San Joaquin Delta, as seen from a ship in the Stockton Deep Water Ship Channel in 2013. Photo by Florence Lo, California Department of Water Resources

This is this first in an intermittent series of articles on the future of the Sacramento-San Joaquin Delta.

By Steven Culberson

Estuaries are hard places to understand and even harder to explain. Estuarine scientists, myself included, have struggled to learn how changes in the San Francisco Estuary led to declining fish populations and waning productivity, particularly in the Sacramento-San Joaquin Delta.

We keep searching for what is broken or missing so we can fix or replace it. The thinking is that if we can return or repair these parts of the ecosystem, native aquatic species will recover sufficiently to be resilient in the future.

The trouble is we can’t go back to the way things were more than 150 years ago, before engineers repurposed the Delta’s maze of marshy islands, channels and sloughs for agriculture and water delivery. As fish biologist Peter Moyle has said, “How do you bring back tule or cattail marsh to an island that has sunk 30 feet from decades of farming its peaty soil? You can’t.”

Likewise, fixing what is broken in the Delta has been a daunting if not quixotic pursuit. Scientists for the most part take the classic “reductionist” approach of breaking down complex problems into smaller and simpler units: (1) Identify the ecological features that are damaged or in short or excess supply, (2) pinpoint factors responsible for these problems, then (3) take steps to improve conditions factor by factor or species by species.

This painstaking process has unquestionably improved our understanding of how the Estuary works. But for all the reams of studies produced over the past 30 years we have yet to arrest, let alone reverse, the ongoing decline in pelagic fish populations and ecological health of the Delta.

I propose an alternative but complimentary “reconciliation” approach to restoring the Delta:

  • Reconcile what we would like to have the Delta be like with what is possible, using our understanding of the historical landscape and its remnant physical features as design guides.
  • Focus on returning the physical features where ecological processes occur — islands, marshes, deep areas, shoals, shallows, littoral edges, eroding streambeds and riparian corridors — without necessarily worrying about identifying or understanding the precise effect these actions will have on the species of concern.
  • Put mud flats where mud flats would go, tidal marshes where tidal marshes have been and are likely to endure. Put open water next to shallows.
  • Work with alien species as part of new, unprecedented estuarine ecosystems.

Return estuary-like features to the estuary and the natural arrangements between geomorphic elements and habitat will re-establish and re-configure themselves. Ecosystems are, after all, self-regulating and self-organizing, even as they change through time. Systems ecologists have struggled to teach us this and we should be willing to learn, given our relative lack of restoration success in the estuary (see Jorgensen 2012).

Creating habitat interfaces or “edges” like those visible in the photograph below would be a good start on fixing our estuarine system.

In Sherman Lake, just north of Antioch

Sediments emerging on ebb tide from submerged vegetation in the Sacramento-San Joaquin Delta. The strip of non-native vegetation here in Sherman Lake, just north of Antioch, traps sediment when plentiful and releases it back into the water column over time. Re-introducing geomorphically active sites like this will help return some ecological dynamism to support desired species, native and alien. Source: Google Earth

We need to make choices and invest resources in the absence of perfect knowledge of the ecosystems being managed. This doesn’t mean we dispense with scientific rigor or altogether abandon the reductionist or species-based investigations. Rather, we should view the estuary more as a system than an assembly of parts and let the ecosystem itself sort out the particulars.

We cannot afford to wait until we’re sure about what will work. Because the pace of rigorous science proceeds slowly we’re unlikely to gain sufficient additional understanding about estuary functions over the next decade to make bold, large-scale changes in management. Yet the demands for a better functioning Delta ecosystem exist now.

It’s questionable whether we can even predict the total outcome of our restoration actions in a changing self-regulated system. Species in ecosystems as complex as estuaries can change roles in unexpected ways, like switching from one prey to another or shifting habitat use in response to a competitor.

We must take the ecological gamble. Provide the types of flows, landscapes and habitat mix we already know make for a better functioning ecosystem. Stand back and let the Bay-Delta reorganize itself the way estuaries do – and learn to live with the outcome.

Steven Culberson is a senior ecologist with the U.S. Fish and Wildlife Service in Sacramento. “The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service (117 FW 1)”

Further reading

Jorgensen, S.E. 2012. Introduction to Systems Ecology. CRC Press. 360pp.

Moyle, Peter. “Ten realities for managing the Delta.” California WaterBlog. Feb. 26, 2013

Rosenzweig, M.L. 2003. “Win-Win Ecology: How the Earth’s Species Can Survive in the Midst Of Human Enterprise. Oxford University Press, 209 pp.








Posted in Uncategorized | 3 Comments

The romance of rain barrels

Photo By Bo Peng, UC Davis

A Davis, Calif. home advertises its rainwater collection system. Photo by Bo Peng, UC Davis

By Jay Lund

Imagine capturing some of the heavy rain that has been draining off Northern California roofs lately to water yards this summer, for what will likely be a fourth year of drought.

The drought has generated interest in household cisterns commonly known as “rain barrels” that collect and store rooftop runoff for when it is most needed – during the dry season – to irrigate landscapes and replenish community groundwater supplies. Advocates of these rainwater collectors point to their prevalence in Australia following its decade-long Millennium Drought.

But how cost-effective are rain barrels for individual home and business owners, compared with the more communal approach of adding storage capacity behind a dam upstream?

Here are some back-of-the-envelope calculations:

The cost of household cisterns includes the storage tank, installation and connection to a roof, maintenance and the value of land for the cistern’s footprint. A 50-gallon rain barrel costs about $100, and a 300-gallon tank runs about $600.

The cost of the storage tank or barrel alone amounts to $652,000 an acre-foot of storage capacity (summed over many households). This compares with about $2,000 an acre-foot for expanding storage capacity at large upstream dams.

But storage capacity for water supply is useful only to the extent water is available to capture. Most recent proposals for expanding upstream reservoirs in California yield annual water deliveries of only 5 to 20 percent of the additional storage capacity. In California’s climate, the additional storage space can refill only every few years, implying water delivery costs of $500 to $2,000 per acre-foot of water delivered (annualizing the initial cost at a 5 percent interest rate).

2015-02-08 05.35.30

“This site is now collecting rainwater” boasts this Davis, Calif. home. A set of 50-gallon rainwater barrels is connected to a downspout. Photo by Chris Bowman

Rainwater cisterns in California might be drained several times during the wet season to replenish groundwater or even out stormwater flows, and once or twice during the spring for landscape irrigation.

For a typical home in coastal California, the annual pattern of storms might allow filling and emptying a 50-gallon cistern one to three times (with considerable overflow possible each time), yielding 50 to 150 gallons a year – less than 0.1 percent of a household’s annual water use in California. For inland homes, the actual water produced would be much less because the rain barrel is capturing runoff that likely would have been used by others downstream anyway.

Indeed, if a rain barrel’s installation removes 8 square feet of a highly watered lawn (1 to 2 acre-feet a year), the gallons saved from reducing the irrigated area would be similar to the water provided by the rain barrel.

So the cost of water supplied by household cisterns in California for landscape irrigation or groundwater recharge could be $11,000 to $32,600 an acre-foot. This is 10 to 20 times the wholesale cost of water in Southern California and 5 to 10 times the cost of desalinating seawater.

While the economics of household cisterns for water supply in California are unattractive, cistern collection systems do provide some environmental benefits. Evening out stormwater flows reduces the costs of managing it downstream. And the prominent display of rain barrels at homes and businesses serves as a constant reminder of the scarcity of water in California, perhaps increasing water conservation more generally.

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

Further reading

Portland’s Regional Water Providers Consortium has a nice primer on rain barrels

American Rainwater Catchment Systems Association has a large collection of additional information.

San Diego posts a Rainwater Harvesting Guide for homeowners.

Alliance for Water Efficiency provides an overview on the history and effectiveness of rain barrels and other useful resources, including:

Posted in Uncategorized | 27 Comments

Rain or shine, California drought still kicking

Source: National Weather Service

California’s drought is still very much alive, despite all appearances from this Feb. 4 – 9 precipitation forecast. Source: National Weather Service

green-audio-iconFeb. 4, 2015 drought update on Capital Public Radio

By Jay Lund

Odds are exceedingly good that February will top January’s contribution to precipitation in California. It’s hard to be drier than what was essentially zero rain and snowfall last month.

The state’s driest January on record dropped the Northern Sierra Precipitation Index down from 145 percent of average at the end of stormy December to 84 percent of average today, Feb. 4. And this is for California’s wettest region, the Sacramento Valley. For the San Joaquin Valley and Tulare basin (where most water use occurs), precipitation is, respectively,  43 percent and 45 percent of average for this date.

What does this mean for the usually wet months of February and March?

Statistically, not much can be said. There is little correlation in monthly precipitation during Northern California’s wet season. But droughts by nature are exceptional, so we should prepare for yet a fourth straight year of exceptionally dry conditions.

Summary of conditions statewide

Despite December’s storms, California’s drought remains very much alive. The heavy rain forecast for Northern California this weekend won’t wash it away.

We are halfway through the wet season and our reservoirs overall are holding little more than they did a year ago. Our aquifers are holding less. The snowpack is 25 percent of average and precipitation statewide is well below average for this time of year. Native fish are worse off in many areas.

A drought worse than last year’s whopper is unlikely but remains a possibility, especially for the southern Central Valley.

We still can’t say much for sure about the 2015 water outlook until March. But with only two months left in the wet season, continued drought seems likely.


Fortunately, many Northern California reservoirs have more storage than they did a year ago, while reservoir levels elsewhere are more mixed. Overall, we remain about 6 million acre-feet below average for reservoir storage this time of year.

Aquifer levels are slowly rising but still probably much lower than they were a year ago in the areas highly dependent on groundwater.


For updates, click here..  For more detailed data on other reservoirs, click hereSource: California Department of Water Resources


Snowpack is sparse throughout the Sierra Nevada, about 25% of average for this time of year.





Last year ended at 60 percent of average annual precipitation for Sacramento Valley. For 2015, we’re already at about 50 percent, thanks to a wet December. It seems unlikely this year will be drier than last, but it could happen if February and March are a bust.

For updates, click here. Source: California Department of Water Resources
For updates, click here. Source: California Department of Water Resources

So far, both the San Joaquin Valley and Tulare basin are wetter than this time last year, but not by much.

For updates, click here. Source: California Department of Water Resources

For updates, click here. Source: California Department of Water Resources

For updates, click here. Source: California Department of Water Resources

For updates, click here.  Tulare basin has a shorter record though it has the most water use in California. Source: California Department of Water Resources

Remember, the difference between a drought and a wet year in California is just a few storms. We still have months to go.

Further Reading

The links above can help keep you up to date. For more data, you might enjoy poking around the California Department of Water CDEC web site http://cdec.water.ca.gov. Some statistical views of drought and El Nino in California can be found in the further readings below.

Lund, J. The 2015 drought — so far. California WaterBlog. Jan. 5, 2015

Lund, J. and J. Mount. “Will California’s drought extend into 2015?California WaterBlog. June 15, 2014

Schonher, T. and S. E. Nicholson (1989), “The Relationship between California Rainfall and ENSO Events,” Journal of Climate, Vol. 2, Nov. pp. 1258-1269

Swain, D. “An exceptionally dry January…once again.” California Weather Blog. Feb. 1, 2015

Posted in Uncategorized | 2 Comments

How dam operators can breathe more life into rivers

Folsom Dam and lake full of water. Photo by Paul Harnes, California Department of Water Resources

Folsom Dam and lake full of water. Photo by Paul Harnes, California Department of Water Resources

By Sarah Yarnell

Dams are no friend to biodiversity. Once impounded, a river answers first and foremost to human needs, be it water supply, energy production or flood protection. Releases are measured and timed to satisfy these demands.

As a result, the river downstream loses much of its natural variability in timing, volume and spread of flows. Dams also block passage of sediment that scours the stream channel and deposits fresh cobble bars. These activities create and maintain habitats for multiple species, contributing to biodiversity.

But dams don’t have to be death knells of biodiversity. Operators can manipulate flows in ways that restore some of their ecological functions that promote diverse riverine animal, plant and fish communities.

Releasing flows for environmental purposes is not new. California has long required dam owners to release enough flow “at all times” to keep fish “in good condition.” Further, some water and power suppliers are required under the federal Endangered Species Act to release flows at biologically important times for imperiled native fish.

These “environmental flows,” as water managers call them, may help fish survive, but they do not necessarily create habitat that promote high biodiversity. For that you need to implement a suite of well-timed flow patterns that move sediment and can access floodplains and over-bank areas.

My research colleagues and I recently identified five types of flows that are key to creating multiple habitats. We presented them recently at the annual meeting of the American Geophysical Union in San Francisco.

We call these “functional flows,” as distinct from fish-saving “environmental” ones, because they provide certain geomorphic, ecological or biochemical functions that support breeding, migration, habitat diversity and, ultimately, biodiversity.

We build on a term originally coined by Escobar-Arias & Pasternack in 2010 and define a functional flow as a component of the hydrograph that provides a distinct geomorphic, ecological or biogeochemical function. Physical processes and biotic interactions in rivers operate in three dimensions—longitudinally, laterally and vertically—and are intimately tied to the timing, duration and frequency of natural flows, so functional flows must also be reflective of the natural patterns that occur in both space and time. We illustrate the approach in med-montane systems with a distinct high and low flow seasonality, such as mixed rain-snow Sierra hydrograph shown here.  These systems are highly sensitive to hydrological change, exhibiting relatively short relaxation times to flow regulation. A functional flows approach would retain particular components of the hydrograph that provide ecogeomorphic functions.  Here we emphasize 5 flow components that should be retained.

This hydrograph shows the typical natural and “functional flow” patterns of  rivers in the Sierra Nevada and five components that provide distinct geomorphic, ecological or biogeochemical functions that help create and maintain habitat for multiple native species. Source: UC Davis Center for Watershed Sciences

Five functional flow patterns key to creating and maintaining habitat for multiple species:

1.  Wet season initiation flow

  • Clears riverbed of organics, fine sediment
  • Reconnects stream with riparian and over-bank areas
  • Kick starts nutrient cycling
  • Provides ecological cues for native species such as the delta smelt to migrate upstream

In many river systems, these actions can be accomplished simply by letting the first major, sediment-loaded storm runoff of the season – known as the “first flush” – pass through dams.

2.  Peak flow

Flooded oaks on Cosumnes River. Photo: UC Davis

Flooded oaks on the Cosumnes River south of Sacramento. Photo: UC Davis

  • Timed to coincide with the natural season of high flows and floods, ideally during big storms and other correlative weather conditions that native fish may respond to
  • Should last long enough to scour out pools, form channel bars, activate floodplains and otherwise create diverse habitat
  • Redistributes large amounts of sediment, creating geomorphic diversity
  • Reduces extent of exotic species that are not adapted to these disturbances
  • Keeps vegetation from encroaching on stream channels
  • Resets the natural process of ecological succession

Water spilled from flooded reservoirs also is good for moving sediment. But these events happen only once every five to ten years. The annual peak flow helps maintain the form and structure of river channels, however these flows are often captured behind dams rather than passed downstream.

The free-flowing nature of the Cosumnes River allows frequent and regular winter and spring flooding that fosters growth of native vegetation and wildlife.

The free-flowing Cosumnes River south of Sacramento regularly floods during the wet season, promoting growth of native fish. UC Davis researchers Carson Jeffres (left) and Eric Holmes capture, measure and identified fish that took advantage of the flooding in December 2012. Photo: UC Davis

3.  Spring recession flow


California’s rare foothill yellow-legged frog breeds only in rivers and streams and lays its eggs in clusters that attach to submerged rocks. Photo by Ryan Peek, UC Davis

  • Timed to coincide with the springtime transition between high and low flows
  • Mimics the natural rate of decline in snowmelt flows, which is gradual
  • Provides distinct annual cues for native aquatic species to reproduce and out-migrate
  • Should last long enough to sustain habitats that species need to successfully reproduce and to redistribute sediment throughout the stream

As dam operators in the Sierra Nevada fill reservoirs, river levels can drop sharply, from the peak spring flows spilling over dams to the low, flat-lined summer flows. Gradually ramping down the spill flows can provide the in-stream conditions needed for survival of native species, such as the rare foothill yellow-legged frog, whose submerged eggs could get stranded and left to bake in the sun.

4.  Dry season low flow

  • Timed to occur during the warmest and driest part of the year (typically September in California)
  • Should be low enough to disconnect the stream from its floodplains, to create a variety of ecological niches that promote a medley of riparian plants and trees
  • Should maintain the natural ephemeral or perennial conditions

Releasing artificially high base flows often benefits non-native species that are not adapted to the biologically stressful low-flow periods.

5.  Inter-annual flow variability

  • Mimics the natural variability between years in magnitude, timing and duration of specific flow events
  • Supports diversity in habitat and native species over the long term

Bigger, longer floods should be planned for years when water is plentiful, while smaller, shorter peak flows should occur in drier years.

Dam operators need to bring greater sophistication into the design and implementation of flows for multiple uses, including ecosystem services, water supply and flood control.

To maximize the limited allocations of water for ecosystem purposes, the focus of discussions should shift from flow volume to “functional flows” that support natural disturbances, promote certain physical dynamics and drive ecosystem functions.

When geomorphology and sediment processes are considered with flow magnitude, timing and duration, the creation and maintenance of habitats for multiple species can be sustained, and biodiversity is supported. A functional flows approach provides the best opportunity to encompass these ecosystem processes alongside human needs.

Sarah Yarnell is a senior researcher with the UC Davis Center for Watershed Sciences. 

Further reading

Arthington AH. 2012. “Environmental flows: Saving rivers in the third millennium.” University of California Press

Beechie TJ, Sear DA, Olden JD, Pess GR, Buffington JM, Moir H, Roni P, Pollock MM. 2010. “Process-based principles for restoring river ecosystems.” Bioscience 60:209-222

Escobar-Arias, M. I. and G. B. Pasternack (2010). “A hydrogeomorphic dynamics approach to assess in-stream ecological functionality using the functional flows model, Part 1- Model Characteristics.” River Research and Applications 26(9): 1103-1128

Greco SE, Larsen EW. 2014. “Ecological design of multifunctional open channels for flood control and conservation planning.” Landscape and Urban Planning 131:14-26

Kiernan JD, Moyle PB, Crain PK. 2012. “Restoring native fish assemblages to a regulated California stream using the natural flow regime concept.” Ecological Applications 22:1472-1482

Lund JR, Moyle PB. “Is shorting fish of water during drought good for water users?California WaterBlog, June 3, 2014

Moyle PB, Mount JF. 2007. “Homogenous rivers, homogenous faunas.” Proceedings of the National Academy of Sciences of the United States of America 104:5711-5712

Petts GE. 1996. “Water allocation to protect river ecosystem.” Regulated Rivers-Research & Management 12:353-365

Suddeth, Robyn. “Reconciling fish and fowl with farms and flooding.” California WaterBlog. Dec. 2, 2014

Wohl E. 2012. “Identifying and mitigating dam-induced declines in river health: Three case studies from the western United States.” International Journal of Sediment Research 27:271-287

Yarnell, Sarah. “Life springs in Sierra rivers and springtime flows recede.” California WaterBlog, May 4, 2013

Yarnell, Sarah. “Sierra frogs breed insights on river management.” California WaterBlog, Oct. 3, 2012

Yarnell SM, Viers JH, Mount JF. 2010. “Ecology and management of the spring snowmelt recession.” Bioscience 60:114-127

Posted in Uncategorized | 3 Comments