Climate change and California water – past, present and future

AppId is over the quota AppId is over the quota  Folsom Lake, 1976. California Department of Water Resources

Everyone talks about the weather, but nobody does anything about it.
– Charles Dudley Warner, 1897

By Jay R. Lund

Talk of climate change and water in California is fraught with handwringing and delusions. Much discussion borders on alarmist or seems to presume magical abilities to precisely plan and prepare for a future climate.

Here are some observations – based on climate statistics and the physics, economics and history of water in California – that may put some concerns in perspective:

1. Californians have experienced abrupt climate change before. Most immigrants to California in the 1850s experienced abrupt climate change, because they came mostly from humid parts of the United States and Europe with wet summers. It took more than 70 years for this society to develop laws, institutions and infrastructure suited to California’s climate (Pisani, 1982; Kelley 1986). Many newcomers adapted to the foreign climate and prospered, as with the development of irrigated agriculture. Still, the process of climate adaptation has been politically intense and lengthy – and continues to this day.

2. Climate change is not the only game-changer. In the past 100 years, California water management has changed tremendously, driven by changes in population, economic structure, technology, and social and environmental objectives (Hanak et al . 2011). Climate change is just one more big driver – and may not be the biggest one (Vörösmarty 2000).

3. We will not know the extent of climate change until long after the change has occurred. Even in an unchanging climate, it takes several hundred years of data to firmly answer such questions as, “How large is the ‘100-year flood?’” With a changing climate it will take decades to make good statistical estimates, even of changes in annual average precipitation and streamflow (Klemes 2000). And there is no reason to expect the climate to stop changing.

4. Climate change is now. In the last 50 years, California has seen a shifting share of runoff from the spring to the winter (Aguado et al. 1992).  Also, sea level has risen about 1 foot in the last 100 years. Both trends are consistent with climate warming.

5. California is prone to massive climate change. In medieval times, parts of California experienced extreme droughts lasting more than 100 years (Stine 1994).

6. Expanding reservoirs is not necessarily useful for climate change. In a much drier climate, such as California experienced in medieval times, existing reservoirs would never fill and expanded storage capacity would be useless (Harou et al. 2010). Climate warming will reduce seasonal snowpack, but with some changes in reservoir management, existing large reservoirs on most of California’s rivers can largely accommodate seasonal shifts in runoff (Connell-Buck et al. 2011). Climate warming will be somewhat costly, but not catastrophic for most conventional water storage operations (Willis et al. 2010; Madani and Lund 2010). Change in total precipitation is more important than warming alone. The physical, economic and ecological instability of the Sacramento-San Joaquin Delta probably poses more risk to California’s water supply than climate warming (Lund et al. 2010).

7. Handwringing is not adaptation. Climate change introduces uncertainties, but California water management has always involved immense uncertainties. Effective water management adaptations to climate change emerge from comprehensive analysis of water markets, conjunctive use of ground and surface waters, water conservation, and from re-operation of some reservoirs (Harou et al. 2010; Tanaka et al. 2006; Medellin et al. 2008; Hanak and Lund 2011; Ragatz 2012).

The key to water management adaptation for climate change is mostly good management. But, as always with California water, good management will involve controversy and require both political and technical leadership (Crawford and Herrick 2006)..

Jay Lund is the Ray B. Krone Professor of Environmental Engineering at UC Davis and director of the university’s Center for Watershed Sciences.

Sources and further reading
Aguado, E., D. Cayan, L. Riddle, and M. Roos (1992), “Climate fluctuations and the timing of West Coast streamflow,” Journal of Climate, Vol. 5, December, pp. 1468-1483.

Connell-Buck, C.R., J. Medellín-Azuara, J.R. Lund, and K. Madani, “Adapting California’s water system to warm vs. dry climates,” Climatic Change, Vol. 109 (Suppl 1), pp. S133–S149, 2011.

Crawford, J. and J. Herrick, “Intelligent Engineering: William Hammond Hall and the state engineering department,” Sacramento History, Journal of the Sacramento County Historical Society, Vol. VI , No. 1-4, 2006.

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

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

Kelley, R. 1998. Battling the Inland Sea. Berkeley: University of California Press.

Klemes V. 2000. “Design Implications of Climate Change.” In Common Sense and Other Heresies: Selected Papers on Hydrology and Water Resources Engineering, ed. V. Klemes (Cambridge, Ontario: Canadian Water Resources Association).

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.

Madani, K. and J.R. Lund, “Estimated Impacts of Climate Warming on California’s High Elevation Hydropower,” Climatic Change, Vol. 102, No. 3-4, pp. 521–538, October 2010.

Medellin-Azuara, J., J.J. Harou, M.A. Olivares, K. Madani-Larijani, J.R. Lund, R.E. Howitt, S.K. Tanaka, M.W. Jenkins, and T. Zhu, “Adaptability and Adaptations of California’s Water Supply System to Dry Climate Warming,” Climatic Change, Vol. 87, Sup.1, March, pp. S75-S90, 2008.

Pisani, D. 1984. From the Family Farm to Agribusiness: The Irrigation Crusade in California, 1850–1931. Berkeley: University of California Press.

Roos, M. (2003), The Effects of Global Climate Change on California Water Resources, A report to the California Energy Commission’s Public Interest Energy Research Program (PIER), Sacramento, September 2002.

Stine, S. 1994. “Extreme and Persistent Drought in California and Patagonia during Medieval Time.” Nature 369: 546–49.

Tanaka, S.K., T. Zhu, J.R. Lund, R.E. Howitt, M.W. Jenkins, M.A. Pulido, M. Tauber, R.S. Ritzema and I.C. Ferreira, “Climate Warming and Water Management Adaptation for California,” Climatic Change, Vol. 76, No. 3-4, pp. 361-387, June 2006.

Vörösmarty, C. J., P. Green, J. Salisbury, and R. B. Lammers. 2000. “Global Water Resources: Vulnerability from Climate Change and Population Growth.” Science 289(5477): 284–88.

Willis, A.D., J.R. Lund, E. S. Townsley, and Beth Faber, “Climate Change and Flood Operations in the Sacramento Basin, California,” San Francisco Estuary and Watershed Science, Vol. 9, No. 2, 18 pp., July, 2011.

Notice
This winter, the UC Davis Center for Watershed Sciences is presenting a weekly speaker series on California water policy. The public is welcome to attend.

Schedule of speakers

Videos of talks available on iTunes and YouTube

Fish and Game name change reflects the broader mission

Joshua offers was a passion for wild pigs, as shown here, in Mendocino County, in January 2012. Photo: Dan Schroeder

Jacob Katz arises a lunker rainbow trout on the river of the Trinity in November 2011. Photo by Carson Jeffres

By Joshua and Jacob Katz, UC Davis Center for Watershed science

The California Department of Fish and game is one of the few agencies of State with a name by sympathetic nature. Bent rods come to mind. Hunting and fishing adventures tickets outdoor and family liaison and licensed to literally bring home the bacon.

It is not surprising that Governor Jerry Brown set fur flying earlier this fall, when he signed a draft law replacing the "game" with "Wildlife" in name by the use of the Agency. The Association of California for recreational fishing, among other sports groups, that the Governor and the legislature have launched the hunters and fishermen in the van. They consider the change of name as a surrender urban environmental and animal rights activists determined to break with the traditional focus of the Department on the hunting and fishing.

Some environmentalists say the change of name, which shall enter into force on January 1, will help the Department move away from practices that promote interests "hook-and-bullet" at the expense of non-game species - those not hunted for sport or food.

In truth, the Department logo makeover is neither victory nor defeat and other. It reflects rather a continuous and long-term expansion in the responsibilities of stewardship of the Ministry of natural resources of California.

The expansion of the mission has multiple causes. They range from the increasing urbanization of California, the increasing complexity and the controversy in its ecosystems, advances in the science of the environment, of the Court of environmental decision-making and climate change. For more than 20 years, these and other factors have led constantly state fish and game managers to an "ecosystem" approach that enjoys a wide range of users species and resources, payment of license hunters for bird watchers.

Ecosystem-based management recognizes a wide range of interactions within biological communities, including the hunting, fishing and other human activities. The approach is consistent with the Department's mission statement: "to"manage fish, wildlife and resources and the habitats upon which they depend for their ecological values and for their use and enjoyment by the public of California."

In addition to issuing permits and hunting and fishing regulations, the Department draws up trout in hatcheries, fish stocks in lakes and rivers, fight against poaching, manages the reserves of the State and supervises the efforts of habitat preservation, among others. The new law does not change the name of the Gaming Commission, which adopts regulations of sport fishing and hunting, and defines the rights of licence and California Fish.

Certain policies of the Department are in contradiction with the best science and holistic management. For example, the use of lead shot - the traditional favorite for many hunters - is still permissible for some species of waterfowl such as doves and rabbits, but no other game like it poisoned pets. In addition, the Department's practice 80-year-old plantation of the hatchery historically Alpine Lakes trout contributed to the decline of frogs native and other wild animals. The money spent on the costly aerial drops of FRY of could go instead to the increase in fishing opportunities more accessible Lakes at low altitude and streams.

Legislation that triggers the change of name, 2402 AB by Assemblyman Jared Huffman, also reinforces the use of the Ministry of science in the development of policies that protect entire ecosystems instead of individual species.

The involvement of the Department in the restoration of the Cosumnes near Sacramento River is an example clear and effective advantages of science-based ecosystem management.

Since 1997, state fish and game officials have worked with landowners to restore habitat for the seasonal floodplain for threatened salmon and other species. The Ministry, the Nature Conservancy and a few breeders sewn together various parcels of land to form the Cosumnes River Preserve. The agreement paved the way for UC Davis researchers to show how ecological restoration can reach several victories of native fish and wildlife species, for the management of water and agriculture.

Research has shown that opening of sections of the levees of the river for the seasonal flooding produces multiple benefits: local aquifers for irrigation and drinking water, reduce the risk of flooding to landowners downstream and offering a superb for juvenile rearing habitat.

Most of the flood plains of the California was isolated behind the dams, which were built to protect the homes and crops of the flood. Before the dams were built, winter and spring flooding in the Central Valley has swept the young, ocean related to the salmon on the flood plains, where they find abundant food, slowly, water and few predators. Drained flood plains, the fish would return to the River, well fed, and worthy of their intense migration to the Pacific ocean.

Fish and Game involvement for Cosumnes River gave its managers and other resources, hands-on science-based organizations need to create Habitat in floodplains in the Central Valley and the Sacramento-San Joaquin Delta. Already, managers use research to support ecosystem restoration efforts in the Yolo bypass and San Joaquin River.

These efforts will give the Department more new uniform patches and paper to header to display the next year when the Agency officially became the "California Department of fish and wildlife."

Further reading

California Assembly Bill 2402

Cosumnes research group

CA Jeffres, DD Opperman, Moyle P. 2008. Ephemeral floodplain habitats provide better conditions of growth of juvenile Chinook salmon in a river in California. Biology of the environment of the fish. 83 (4)

Whitener P Moyle, PK Crain, k. 2007. Trends in the use of A restored California plain of inundation of native and exotic fish. The estuary of San Francisco and the Science of the watershed. 5 (3)

Getting through the dry times

AppId is over the quota AppId is over the quota  California’s extensive network of reservoirs, canals and aqueducts facilitates water marketing. Source: Managing California’s Water, From Conflict to Reconciliation, PPIC, 2011

By Ellen Hanak and Elizabeth Stryjewski

This week, the Public Policy Institute of California (PPIC) released a new report that provides a checkup on California’s progress with two innovative water management tools:  water marketing and groundwater banking.  These tools are part of a modern approach that will enable California to manage its scarce water resources more flexibly and sustainably.

Water marketing involves the temporary, long-term, or permanent transfer of water rights in exchange for compensation. Such transfers can lessen the economic and environmental costs of drought and also help accommodate longer-term shifts in the patterns of water demand.  Groundwater banking is another cost-effective tool:  it involves the deliberate storage of surface water in aquifers during relatively wet years, for retrieval in dry years.

During the late 2000s, California experienced a multiyear drought—the perfect opportunity to see whether the past few decades of state and federal encouragement of these tools have paid off.  We find some progress—but also some backsliding since the drought of the late 1980s and early 1990s.

That earlier drought jump-started California’s water market, thanks in large part to direct state actions. In the late 1980s, the Department of Water Resources (DWR) began purchasing water from a few irrigation districts to make it available to wildlife refuges and State Water Project contractors.

By 1991, when faced with the prospect of draconian across-the-board rationing, DWR launched the state’s first drought water bank, a large-scale brokering program that acquired water from numerous willing sellers and resold it to those facing high costs from shortages.  When the rains returned, the water market continued to grow, as many local districts got comfortable trading with each other (Figure 1).

Figure 1.  The graph shows the evolution of California’s water market. Currently, about 2 million acre-feet of water trades are committed annually, with around 1.4 million acre-feet actually exchanging hands. Source: California’s Water Market, By the Numbers: Update 2012, PPIC

Today, market trades account for roughly 5 percent of all water used annually by the state’s businesses and residents. Water agencies in most counties now participate in this market. Farmers—the largest water-using sector—continue to be the primary providers. Recipients include other farmers, cities, and environmental programs supporting wildlife reserves and river flows for fish. Long-term and permanent trades—especially valuable for supporting shifts in patterns of water demand—now make up well over half of the market.

However, the market did not perform so well during the latest drought, as the graph above shows. To mitigate the drought, overall sales would have been expected to increase considerably relative to the preceding non-drought years. But our study estimates that transfers provided a total of only 500,000 to 600,000 acre-feet in drought-oriented supplies between 2007 and 2010, above and beyond transfers that would likely have occurred anyway (Figure 2).

Figure 2. The slowing market was unable to provide much drought relief from 2007 to 2010 — just 500,000 – 600,000 acre-feet. Source: PPIC, 2012

The market slowdown began in the early 2000s. This slowdown reflects a variety of infrastructure and institutional constraints, including more complicated approval procedures and pumping restrictions introduced in 2007 to protect endangered native fish in the Sacramento-San Joaquin Delta, a key water conveyance hub.

Groundwater banking did a better job mitigating the drought.  For some time now, water agencies in several parts of the state have been recharging aquifers with surface water for local users.  Our study focused on a new form of banking in which local groundwater managers store water for parties located elsewhere in the same county or in other regions.

From the mid-1990s to 2006, these water banks—located in Kern County and Southern California— had built up reserves of nearly 3.4 million acre-feet.  Between 2007 and 2010, they returned nearly 1.9 million acre-feet to their depositors, considerably more than the drought-related water market sales (Figure 3). Groundwater storage likely played an even greater role than these numbers suggest:  DWR estimates that nearly 90 local agencies have been storing water in their local aquifers.

Figure 3. New groundwater banks were useful in the 2007-2010 drought. Withdrawals totaled 1.9 million acre-feet — three times the volume that was traded in the same period. Source: PPIC

What lessons can be drawn from this experience?  Despite its good showing, groundwater banking still faces obstacles.  More comprehensive local basin management—a common practice in Southern California and Silicon Valley—would prevent unsustainable pumping and long-term declines in groundwater levels.  Outside pressure—with a credible threat that the state would step in if local agencies fail to do so—might be the best way to proceed, ideally accompanied by positive financial incentives.

To strengthen the water market, the state needs to clarify and simplify the institutional review process, while continuing to ensure that transfers do not harm the environment or other water users.

Both marketing and banking depend on addressing infrastructure weaknesses that restrict water conveyance through the Delta. Those constraints have already limited both the market’s ability to furnish water supplies in dry years and the availability of supplies to replenish groundwater banks in wet years. Because routinizing marketing and banking transactions will require risk-taking, high-level state and federal officials should be involved, perhaps through a coordinating committee to facilitate decisions.

Attending to these and other priorities described in the report will help ensure the success of two of the state’s most critical strategies for efficiently managing its water resources.

Ellen Hanak is a senior policy fellow and Elizabeth Stryjewski is a policy associate at the Public Policy Institute of California.

Further reading

Governor’s Commission to Review California Water Rights Law. 1978. Final Report. Sacramento, CA.

Hanak, E. 2003.  Who Should Be Allowed to Sell Water in California?  Third-Party Issues and the Water Market.  Public Policy Institute of California.

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

Phelps, C.E., N.Y. Moore, M.H. Graubard. 1978. Efficient Water Use in California:  Water Rights, Water Districts, and Water Transfers.  R-2386-CSA/RF. Santa Monica, CA: RAND Corporation (report to the California State Assembly).

Tanaka, S.K., T. Zhu, J.R. Lund, R.E. Howitt, M.W. Jenkins, M. Pulido-Velazquez, M. Tauber, R.S. Ritzema, I.C. Ferreira. 2006. “Climate Warming and Water Management Adaptation for California.” Climatic Change 76(3-4): 361-387.x

How engineers see the water glass in California

AppId is over the quota AppId is over the quota  Engineering a water glass at 50 percent. Source: xkcd.com

By Jay R. Lund

Depending on your outlook, the proverbial glass of water is either half full or half empty. Not so for engineers in California.

Civil engineer: The glass is too big.

Flood control engineer: The glass should be 50 percent bigger.

Army Corps levee engineer: The glass should be 50 percent thicker.

Mexicali Valley water engineer: If your glass leaks, don’t fix it.

Delta levee engineer: Why is water rising on the outside of my glass?

Dutch levee engineer: The water should be kept in a pitcher.

Southern California water engineer: Can we get another pitcher?

Northern California water engineer: Who took half my water?

Consulting engineer: How much water would you like?

Delta environmental engineer: Don’t drink the water.

Water reuse engineer: Someone else drank from this glass.

Academic engineer: I don’t have a glass or any water, but I’ll tell you what to do with yours.

Jay Lund is the Ray B. Krone Professor of Environmental Engineering at the University of California, Davis, and director of the university’s Center for Watershed Sciences.

Further reading

Munroe, Randall. Glass Half Empty. xkcd.com

Hydrology of Halloween

Cure for unlikely California drought. Frank Tinsley/Mechanix Illustrated, October 1951

Of the UC Davis Center for watershed Sciences staff

If these ideas of the 1950s to resolve California water problems scare you, we do not know what will be. Happy halloween!

The Cornell Plan
Sidney Cornell, a civil engineer from Los Angeles, circulated an idea for the transport of water in Northern California to the arid southern end of the State without any problems and the costs of long channels, pipes and pumps. He proposed to build giant cannons to shoot water into the air for the capture of the km, as shown in a Mechanix illustrated 1951.

Perhaps the time for idea of Cornell. Why spend billions of dollars for the water in the direction of the tunnel under the Delta South when we cannot simply take our way to solve the problem? Just one of these guns of gargantuan Cornell plant intakes from the South to the Sacramento River Delta near the Woods, who could use the tourist attraction. Point the gun to Clifton Court forebay upstream and fire away!

Call the Air Super-Peripheral, or Super Cap gun.

Imagine a column of water produced in top Valley and falling to say cubic 9,000 feet per second. Pretty scary, especially if the barrel is a bit off target and Tracy pipes.
 

The Reber Plan
Unlike Cornell pipe-less dreams, plan John Reber to quench the thirst of the actually took flight - for a spell. Reber, a theatre producer who himself engineer, advertising of the dams on the San Francisco Bay to capture and store the flow of fresh water for the export to the Southern California by channel, not guns.

A dam would be between Richmond and Marin County and another bridge of San Francisco and Oakland, creating two giant fresh water lakes. The dams would be roads that could carry up to 32 lanes of traffic, as well as train tracks. Reber also sought to reduce the Bay with 20,000 acres of fill for development, including military bases.

KQED

Reber idea created a media buzz and enthusiasm of some members of Congress. The public works of the Senate Committee held hearings in San Francisco and then recommended the Army Corps of Engineers to build a model of the Bay to test "the Reber plan." The model of 1.5 hectares, that mimics the action of tides, currents and the mixture of fresh and salt water, showed that the Bay-Delta estuary would be destroyed. Freshwater dams would create only giant evaporation ponds.

You can watch the simulation to model Bay Visitors Center the army in Sausalito. Watch the ghost of John Reber at low tide.

The California Water Plan. State Dept resources. of Water, 1957

1957 California water plan
It is not blood stains that you see in this vision of 1957 the future California water. However, red blobs should send chills down your spine. They mean potential reservoirs. That's right, almost all of the Klamath River and most of the Trinity River systems and eel would become chains of Lakes. Regardless of the salmon.

A series of pumping stations that negated the flow South to the Sacramento Valley and in through giant pumps Delta to farms and cities in the South.

At a time of apparent unlimited growth, the State Department of water resources has developed the California Water Plan (Bulletin n ° 3) to "demonstrate that the capacity exists to meet all foreseeable water needs in all areas of the State.

"We can do it. It is engineeringly and financially viable, said William l. Berry, head of the Ministry of water resources, planning, speaking in 1956 at a Fresno public hearing on the plan. "What is more, we have to start the task - and promptly - whether California should remain the"Golden State"in what some call the"golden age"in which we enter."

The proposed California water system would be the great equalizer of the water resources, redistribute the "excess" of the North of Central California water less gifted and Southern California. But plans for the filming of the rivers of the North coast in the tanks remained just that - plans, which are today better kept in the closet, as skeletons.

References and additional reading
John Metcalfe. October 3, 2012. A look back on "Big Squirt, 1951's' Concept of cure unlikely California drought." The cities of the Atlantic.

Ron Blatman, public television KQED/KTEH. The Reber Plan: A great idea for the San Francisco Bay area.

Library of the University of California, Berkeley. Bay Bridge: bridging the Campus, not built projects.

June Morrall. November 1, 2007. Bay to the Lake: a Plan of the late 1940s have failed would have turned San Francisco Bay in two lakes. Halfmoon Bay memories.
Bay model Visitor Center, US Army Corps of Engineers and

The California Water Plan, Bulletin n ° 3. Sacramento, California. California Department of Water Resources, 1957.

The dog that didn’t bark: Unexpectedly small effects of export changes on Delta farms

AppId is over the quota AppId is over the quota  Sherlock Holmes in The Adventure of Silver Blaze by Sir Arthur Conan Doyle

Inspector Gregory: Is there any other point to which you would wish to draw my attention?
Sherlock Holmes: To the curious incident of the dog in the night-time.
Gregory: The dog did nothing in the night-time.
Holmes: That was the curious incident.

By Josué Medellín-Azuara and Richard Howitt, UC Davis Center for Watershed Sciences

California water analysts – us included – have long assumed that building a peripheral canal to carry exported water around the Sacramento-San Joaquin Delta would significantly harm local farming. Diverting so much fresh Sacramento River water would make the Delta too salty for irrigating high-value crops, we thought.

Delta farmers have assumed as much in opposing Gov. Jerry Brown’s plan to build a pair of giant tunnels beneath the Delta to transport water to the San Joaquin Valley and Southern California.

Yet, for all the pessimistic prognostications, no one had rigorously analyzed how a peripheral conveyance system would likely affect Delta water salinity and crop production. The forecasts were not based on formal hydrodynamic models, which can simulate the movement of water and salt under different conditions.

To remedy this, we recently ran hydrodynamic models to examine changes in water salinity, crop yields and crop revenues under various combinations of water export management and sea level rise in different parts of the Delta.

The study did not consider the specific changes in the state’s proposed Bay Delta Conservation Plan, which includes the governor’s “preferred alternative” to tunnel exported water under the Delta. The modeled tunnel operated under 1981—2000 water conditions with a capacity of 7,500 cubic feet per second – enough to transport up to 59 percent of average annual exports (4.9 million acre-feet), with the remainder continuing to be pulled through Delta channels to the export pumps.

Once we established the salinity changes in irrigation water, we used a detailed model of the Delta’s farming economy to estimate the effects of those changes on crop yields and revenues. (The model includes the role of salinity in farmers’ cropping decisions.) Finally, we ran these revenue changes through an economic model to see their effects on the Delta economy as a whole.

The result: no barking dog, as Sherlock Holmes might say.

Our study showed that the cost of salinity changes under a peripheral tunnel and a range of other conveyance scenarios would be less than 1 percent of the Delta’s total crop revenue – an estimated $2.3 million a year.

That’s a far cry (or bark) from previous estimates. A recent study for the state Delta Protection Commission put the annual revenue loss at $28 million to $54 million. Our earlier study in 2007 also had much higher estimates.

How do we account for such large cost reductions? Four factors explain the difference.

First, our study – Transitions for the Delta Economy, released earlier this year – is the first to forecast salinity levels with hydrodynamic models, which were built by fellow UC Davis researcher William Fleenor. Second, we conducted the analysis island-by-island, which enabled us to show that the islands at risk are those that grow the lowest value crops. Third, these low-value crops are the most salt-tolerant. Fourth, salinity tends to be highest in the late summer and fall, when most irrigation is finished except for relatively low-value pasture and hay.

The modeling scenarios included sea level rise, which would also affect Delta salinity and farm revenues. Many western islands that serve as barriers to sea water intrusion are subsided and expected to become permanently flooded in the coming decades.

As with the introduction of peripheral export infrastructure, Delta water interests and analysts have assumed that sea level rise would cause substantial salinity-related losses to the local farming economy. Our modeling runs, however, showed that sea level rise would have little effect on salinity during the irrigation season — even with the three-foot increase projected for 2050.

Percent change in Delta crop revenues across water quality scenarios, including sea level rise (SLR).
UC Davis Center for Watershed Sciences

The same holds true with the loss of the sea water barriers – namely Bradford, Brannan-Andrus, Jersey, Sherman and Twitchell islands. (Bar graph does not include this scenario.) In addition, most higher value crops are not located in the parts of the Delta that would see the highest salinity increases. Again, no barking dog.

The combined application of hydrodynamic, water quality and agro-economic modeling is a considerable improvement over past analyses, which simply assumed a particular level of salinity change and applied that to the Delta farm economy.

Improved modeling details seem unlikely to change the conclusion that salinity costs of peripheral tunnels or canals are minor, even with sea level rise.

It doesn’t take an elaborate computer modeling exercise, however, to confirm a far bigger threat to Delta farmland: its fragile network of levees. The islands have sunk well below the level of surrounding waterways, and their levees are predicted to fail — with high costs of repair and likely abandonment — causing a loss of farm acreage. This dog is barking, and it could take a bigger bite out of the Delta farm economy.

 Further reading and references

Delta Protection Commission (2012), Economic Sustainability Plan for the Sacramento-San Joaquin Delta.

Fleenor, W., Hanak, E., Lund, J.R., Mount, J., 2008. Delta Hydrodynamics and Salinity Conditions. Public Policy Insititute of California, p. 32.

Hoffman, G. J. 2010. Salt Tolerance of Crops in the Southern Sacramento-San Joaquin Delta. Report for the California Environmental Protection Agency.

Medellin-Azuara, J., Hanak, E., Howitt, R., and Lund, J. R. (2012a). Transitions for the Delta Economy. Public Policy Institute of California, San Francisco, California. (February 2012).

Suddeth, R., Mount, J., Lund, J.R., 2010. Levee Decisions and Sustainability for the Sacramento-San Joaquin Delta. San Francisco Estuary and Watershed Science 8(2).

Van Genuchten, M.T., Hoffman, G.J., 1984. Analysis of Crop Salt Tolerance Data, In: Shainberg, I., Shalhevet, J. (Eds.), Soil Salinity under Irrigation, Processes and Management. Springer: Berlin, pp. 258-271(Ecological Studies, 251).

Sierra frogs breed insight on river management

AppId is over the quota AppId is over the quota  A foothill yellow-legged frog in the shallows of the north fork Feather River. Photo by Ryan Peek/UC Davis CWS

By Sarah Yarnell, hydrologist, UC Davis Center for Watershed Sciences

When dam operators schedule outflows to satisfy their downstream environmental obligations, they typically want to know, “How much?”

How much cold mountain water must Shasta Dam release to preserve the Sacramento River’s imperiled winter run of salmon? How much fresh Sierra water must flow out of New Melones Dam to dilute environmentally harmful salinity levels in the Sacramento-San Joaquin Delta?

The “just add water” recipe, however, is not a cure-all for endangered aquatic species. Increasingly, studies have shown that the pattern of flows from dams can matter as much as the volume.

Consider the foothill yellow-legged frog. It’s a rare frog, the only one in California that breeds exclusively in streams and rivers – not ponds or lakes. Its life strategy evolved to fit the seasonal pattern of river flows in our Mediterranean climate: flush with snowmelt runoff in the spring and anemic through the summer and early fall.

In the Sierra Nevada, early spring is no time for these fist-sized amphibians to breed. Erratic torrents of snowmelt in river channels would wipe out egg masses, which are attached to submerged rocks in the shallows. Mid-spring is no better. Fast-dwindling flows would leave the eggs and tadpoles high and dry. The frog’s sweet spot for reproduction then is usually late spring – late April to June – a period of moderate, gradually declining flows known to hydrologists as the annual “spring snowmelt recession.”

This recession has ecological benefits beyond reproductive cues for the river-breeding frogs. As flows gradually decline, rivers interact with their floodplains, delivering nutrients and providing habitat for aquatic bugs, fish and amphibians. Recession rates also can influence the shape of river bars and how riparian shrubs and trees take root. The magnitude, timing and rate of change of the springtime flows all affect the diversity of native habitat and species in mountain rivers across the western United States.

The importance of the spring snowmelt recession, though, has only recently gained the attention of water managers – mostly in the federal relicensing of northern Sierra hydroelectric projects. In the past two years, negotiators have preliminarily agreed to modify springtime flows to be more like natural rivers.

River flows below dams are unnatural. The typical seasonal hydrograph shows a sharp drop from the peak spring flow to the low, flat-lined summer flows. This abrupt change is the ecological equivalent of pulling the rug out from under the frogs, which see the season suddenly jump from winter to summer. Submerged egg masses and tadpoles are now stranded in the sun. They’re history.

Eggs masses laid by the foothill yellow-legged frog cling to submerged river rocks, as shown here in the north fork Feather River. Photo by Ryan Peek/UC Davis CWS

The foothill yellow-legged frog has disappeared from much of its range in California. Scientists attribute the decline to the unnatural river flows below dams, among other factors. Few knew of the frog’s plight in the northern Sierra until biologists started monitoring their populations on several dammed rivers.

On the north fork of the Feather River, frog surveys grew out of a 2000 legal settlement dictating future operations of Pacific Gas and Electric Co.’s Rock Creek and Cresta hydropower dams in Plumas National Forest. PG&E also agreed to intermittently release high flows for whitewater enthusiasts once a month in the summer, beginning in 2002.

These “recreational” pulses were surreal. Boaters paddled roller-coaster rapids and raft-flipping drops along a stretch that only hours earlier could be waded.

Meanwhile, the frog populations were plummeting.

Scientists monitoring the river found that the whitewater pulses released from the Cresta Dam had flushed tadpoles and other small aquatic species downstream, wiping out a year’s reproduction. At the same time, tadpole production remained stable below the Poe Dam, just downstream of Cresta Dam, without pulsed flows.

Although the cause of the frog’s decline was not definitive, the Forest Service in 2005 suspended the whitewater releases as a precaution. The foothill yellow-legged frog was already under the agency’s watch as a federal “species of special concern” because of population declines in the 1990s.

Parties in the relicensing settlement labored to devise a new flow regime that offered boating opportunities without harming frogs, fish and aquatic life.

Templates for environmental flows from dams are limited. A century-old California Fish & Game law simply requires “sufficient water at all times” to the keep fish below dams “in good condition.” About 15 years ago, operators of some dams began scheduling “peak flushing flows” to clear salmon spawning gravels of sediment. More recently, federal operators of the Trinity Dam added a plateau of consecutive high-flow days in the spring to give young salmon a helpful push on their ocean-bound journey down the Sacramento River.

None of these flow strategies mimicked the pattern of the spring snowmelt recession so crucial to the frog and other riverine species.

To help inform decisions on the Feather River, the UC Davis Center for Watershed Sciences in 2006 launched a series of California Energy Commission-funded studies to investigate the environmental effects of pulsed releases from mountain dams. Field and laboratory experiments and computer modeling all showed such high velocity flows lethal to tadpoles.

Discussion among interests in the Rock Creek-Cresta settlement – resource agencies, environmental and boating advocates and PG&E – eventually sparked a winning idea: Reschedule the water allotted for summertime boating for release in the spring, to benefit both frogs and boaters.

PG&E implemented the innovative flow schedule in 2009 for the Cresta dam. The arrangement allows the utility to support both environmental and recreational benefits without sacrificing any additional water for power generation. The boaters lost the luxury of scheduled rapids in the heat of summer, but gained a longer, albeit less predictable springtime whitewater season.

“While unnatural and unpredictable flows are inconvenient and frustrating for whitewater enthusiasts, it can mean life for our fellow river dwelling species,” said Megan Hooker, a representative of the American Whitewater advocacy group, which has been one of the most influential players at the table. “It’s a clear example of what’s good for the river is good for recreation.”

The modified springtime flows may have come too late for the frogs, however. Their population in the Cresta reach of the Feather has not recovered, perhaps because it was so dismally low in 2005. Scientists who continue to monitor the river are nonetheless confident the new flow regime will significantly improve habitat elsewhere for riverine species.

Just this past year, negotiators preliminarily adopted similar springtime flow patterns as environmental safeguards in the federal relicensing of powerhouses on the Poe reach of the north fork Feather, the middle fork of the American River, the Bear River and the larger reaches of the Yuba River. Researchers at the UC Davis Center for Watershed Sciences have helped to develop the flow schedules with daily percentage declines that mirror the natural pattern of the spring snowmelt recession

The window of opportunity for California water managers to restore some facsimile of this ecologically important flow pattern looks promising: About 50 hydropower projects are scheduled for relicensing in the next 15 years.

Simplified hydrographs for dammed (regulated) and natural (unregulated) rivers showing daily percent change intervals and the typical breeding and egg-laying period for foothill yellow-legged frogs. Graphic by Sarah Yarnell

References and further readings

Epke, GA. 2011.  Spring Snowmelt Recession in Rivers of the Western Sierra Nevada Mountains. Master’s Thesis. Hydrological Sciences, University of California, Davis.

Kupferberg, S., Lind, A., Mount, J., and Yarnell, S. 2009. Pulsed flow effects on the Foothill Yellow-Legged Frog (Rana boylii): Integration of empirical, experimental, and hydrodynamic modeling approaches. California Energy Commission, PIER. CEC-500-2009-002.

Lind, A. J. (2005). Reintroduction of a declining amphibian: determining an ecologically feasible approach for the foothill yellow-legged frog (Rana boylii) through analysis of decline factors, genetic structure, and habitat associations. PhD Dissertation. Ecology, University of California, Davis.

Lind, AJ and Yarnell SM. 2011. Frogs that go with the flow. River Management Society Journal 24(4): 10-11.

Trinity River Restoration Program 

Yarnell SM, Viers JH, Mount JF.  2010.  Ecology and Management of the Spring Snowmelt Recession. Bioscience. 60(2)