DELTA LEAD SCIENTIST REPORT: Climate change and California’s water resources

Dr. Laurel Larsen, the new Delta Lead Scientist, is in the process of moving from Finland to California, so at the December meeting of the Delta Stewardship Council, Dr. Louise Conrad provided the report to the Council on Dr. Larsen’s behalf.

The article chosen for this month’s lead scientist report is a technical report by the Union of Concerned Scientists, titled ‘Troubled Waters: Preparing for Climate Threats to California’s Water System.’ The paper is written by Dr. Geeta Persad at the University of Texas in Austin, and the Union of Concerned Scientists, Dr. Jose Pablo Ortiz Partita who is also at the Union of Concerned Scientists, and Dr. Daniel Swain from UCLA. This publication accompanied the release of a separate article by the same authors in the Journal of Climatic Change. The goal of their work across both reports is to assess how climate change will cause shifts in how where and when we receive precipitation in the state and how these changes will affect water management.

In the climatic change article, the authors synthesized the results of 10 different climate models for California and two emission scenarios. They look specifically at separate regions of California to determine how these changes in water patterns will affect water management on a region by region basis. They projected the percent change in 11 different water metrics between the present day and the end of the century.

The models really showed a high level of agreement in the change of several major aspects of current water patterns, and there was a real emphasis in the articles on the certainty that the authors have with respect to some of these changes. Some of the key ones are that more precipitation is going to be falling as rain rather than snow, and that the rain is going to be coming increasingly inconveniently, particularly during large storm events, making the water much harder to store.  Both wet years and dry years are going to become more extreme, and they will increase in frequency, so extreme dry years may be followed by extreme wet years and vice versa, which the authors refer to as wet year-dry year whiplash.

Taken together, the implications for water management are that we won’t be able to rely on the natural reservoir of snowpack to store water for us and instead, we need additional capacity to store liquid water,” said Dr. Conrad.  “We need this capacity to be able to operate safely under intense storm and inflow conditions.”

A specific example of these implications for current water management practices is the figure from the Union of Concerned Scientists report which shows how the timing, precipitation, and snow melt will decrease the amount of water stored in Oroville reservoir, the second-largest reservoir in the state.  The horizontal black line indicates baseline conditions for both water storage and outflow from Oroville Dam. The green line is showing you the projection of how much water storage will change from these baseline conditions at the end of this century. The figure shows that during summer and fall months when water demand is highest, storage is going to be significantly decreased. This is because inflows in reservoirs will be increasingly concentrated into just a few months, and current operating rules require this excess water to be released in order to reduce flood risk. These increased releases during winter months are shown in the blue line.

While it’s true that some of this water could be better stored by changing flood release requirements, Dr. Conrad noted that taking this approach will require using up much of Oroville’s built in flood protection capacity, or the storage space behind the dam which is shown in yellow on the right side of the figure.

This approach really is a bad idea because of the increased risk of major floods and the added stress on already aged water infrastructure,” she said.  “We can all remember a recent example of the risks and the dangers to infrastructure with this approach when one of the emergency spillways of Oroville Dam failed in 2017. This was the result of a brief but intense series of warm storm events of the type that are likely to increase in the future.”

So taking all these changes into account, the authors conclude that groundwater aquifers present a vital storage resource and a more flexible storage resource for liquid water. Dr. Conrad said it’s not an easy solution, because it’s going to require infrastructure for moving water in the areas of the greatest precipitation to where it can best be stored underground. To support this shift, research on managed aquifer recharge or MAR is needed to find the best places for water storage. The authors specifically note that the Department of Water Resources Flood MAR program is already working in this area, and should continue to be supported and expanded.

From a policy perspective, the authors note that the Sustainable Groundwater Management Act of 2014, or SGMA, takes a step in the right direction, but it doesn’t go far enough. SGMA requires local agencies to plan for long term storage as to the average water supply. But in the emerging climate, averages are not an appropriate metric as a basis for planning. Challenges lie in the wet and dry year extremes that are certain to occur, and the increased precipitation coming as rain rather than snow. The authors recommend that SGMA be updated to require local agencies to assess and account for all climate induced changes in water patterns. State level agencies need to help by providing technical teams and guidance to support climate informed planning efforts.

Importantly, this report also calls out that a lack of guidance at the state level is going to promote climate injustice. Well-funded water agencies such as the Metropolitan Water District of Southern California and the San Francisco Public Utilities Commission are investing in their own climate research in order to include sophisticated climate risk analyses in their planning, and to identify science based adaptation strategies. However, smaller water agencies often lack the resources to do this. And as a result, the residents under their jurisdiction do not stand to benefit from this proactive planning. So to mitigate this emerging injustice, the authors recommend that climate data and projections be made available by the state to all local water agencies, and that those projections consider all impacts of climate change instead of relying on potential and uncertain changes in averages.

Finally, the Union of Concerned Scientists report notes the critical importance of increased interaction between climate scientists and water managers. In their words, these two expert communities really need to become regular collaborators.

I want to end this summary of this report with a little ray of hope,” Dr. Conrad said.  “The need for planning efforts to be well informed by climate models and in a nuanced way does not come as a surprise to the state. Many of the very challenges that are laid bare in this report are acknowledged in the state’s water resilience portfolio.  The Union of Concerned Scientists report confirms and illustrates and offers that we already have good data that can provide the basis for proactive planning now.  It will require increased collaboration and a lot of focus, but needed changes to water management planning are achievable with the data that we have now and we don’t have to operate in the dark.”

Discussion period

During the discussion period, Councilmember Daniel Zingali said it was hopeful that the word achievable was used to describe some of the adaptation strategies.  “Is implicit that this would require a major investment of resources? Is it really just a matter of getting the data right, and then doing it in a more equitable way? Or are we talking about achievable if we have the political will to make major investments?

I think the answer to your question is that we need both additional research and some really proactive work to consider where can we strategically develop our ability to store water below ground, and that’s going to require some changes to infrastructure,” said Dr. Conrad.  “There’s some work at the Department of Water Resources that’s underway, and maybe needs additional support to go farther and faster than it is now.  The other really important point is let’s just use the data in sophisticated ways now.  This is where the role of convening agencies such as the Delta Stewardship Council in bringing together these expert communities.  These water managers are really working hard to be proactive and they need to be informed actively by climate scientists. So we need more regular platforms and forums for dialogue, and for bringing the right analyses for each region together, and then talking about them across regions. I do think that the water resilience portfolio nails that.  It brings into focus the need for stronger connections, but also nuanced and sophisticated planning within regions. So you need both that real strong attention to data and commitment to the science based approach.”

The complexity of this issue is almost so big that it’s hard to get the ball rolling in terms of how we begin to even consider addressing it, but it’s upon us now, and we’re probably already behind the curve on so many levels, not the least of which is the all of the different agencies that have been identified in the water resilience portfolio need to come together to actually begin to move the rock forward,” said Councilmember Oscar Villegas.  “I wonder if maybe having this body serve as a forum to more quickly crystallize who is in charge of making those decisions? I think it has to start there with leadership to say this is priority number one, number two, and number three.  I think this body is perfectly suited, given the science program, to have a workshop where we begin to point out specifically who needs to get the take the ball and begin to move it forward.  I would encourage this body to serve as a platform where that next workshop happens quickly with the informed scientists, helping us identify who’s in charge of making the decision, because if everyone’s responsible, and no one’s in charge, that’s the classic example of where we all end up in trouble. If everyone’s going to take some responsibility that no one’s going to actually take charge to move it forward.”

Dr. Conrad agreed.  “One of the take home messages was the importance of agencies that bring others together, identify the top priority needs, and help advance the conversation and form partnerships to really move the ball forward.  The urgency of it is very clear in the report. Just in our experience, we are already seeing these changes emerge, we don’t have time to wait for the end of the century.

TO READ THE REPORT: Troubled Waters: Preparing for Climate Threats to California’s Water System, from the Union of Concerned Scientists

Update on Delta Science Program activities

Delta science proposal solicitation notice

The Delta Science proposal solicitation notice effort was released on November 9. Prospective applicants were required to submit a short Letter of Intent to apply by December 15. The purpose of the Letter of Intent step is to prepare staff in advance for the number of proposals that are likely to be received and to identify appropriate technical and panel reviewers to review the proposals that we will have. They received a total of 134 letters of intent to apply. This initial response is very strong and puts the proposal on track to see increased and even broader engagement in Delta science than in the previous successful effort in 2018.

Full proposals coming from these Letters of Intent are due on February 12. The Stewardship Council is actively working to address proposers questions as they go about preparing these proposals.  There is a frequently asked questions document on the website and are holding an informational webinar on January 8th.  Click here to register.

Science Action Agenda

The Science Action Agenda is a part of a three prong Delta science strategy that includes the State of Bay Delta Science and the Delta Science Plan. The Delta Science Program is working to identify and lead the community to identify top priorities for science. The agenda will prioritize and align science actions on a 4-5 year time scale to inform pressing management needs.  The collaborative science and peer review unit of the Delta Science Program is in the process of updating this action agenda. It’s a long process to engage all groups, but we’re planning for the updated document to be released in 2022.

In September, the Delta Science Program ran a workshop to refine management questions that it had originally gathered from Delta managers, scientists, and stakeholders; those questions will ultimately form the backbone of the update to the science action agenda. The workshop participants refined an initial list of over 1100 management questions; staff has whittled those down to a shortlist of 110 refined questions, which will soon be posted on the Council’s website.  Next, staff will work to identify clear science actions needed to address these questions through a workshop that will happen in late spring of 2021.

FOR MORE INFORMATION: Click here for the Science Action Agenda.

Upcoming events

The Adaptive Management Forum will take place on February 3 – 5, 2021. This is a biennial event that the science program hosts to provide an opportunity for the Delta community to share knowledge and promote collaboration on adaptive management of the system.  Click here to register.

The Delta science program will host a steelhead workshop on February 17 – 19, 2021.  The purpose of the workshop is to identify challenges to managing and monitoring Central Valley steelhead with the goal of identifying collaborations that are needed to improve the monitoring and science network for the species in the San Joaquin basin.  Registration for the workshop is now available online.  There are already over 150 people registered. Click here to register.

The Bay-Delta Science Conference is set for April 6 – 9, 2021.  The theme for this conference is building resilience through diversity and science.  The conference, all virtual, is jointly sponsored by the Delta Stewardship Council and the United States Geological Survey and is the longest standing and most important platform for broad communication and networking around Delta science.  Click here for more information.

FOR MORE INFORMATION: Click here to visit the Delta Science Program online.

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