Work by the Department of Water Resources (DWR) to dismantle an emergency drought barrier that has spanned West False River in California, between Jersey and Bradford islands since June, is underway with a breach in the barrier on October 1, 2015. The barrier was erected to block salt water from pushing into the central Sacramento-San Joaquin Delta from San Francisco Bay. The Delta’s water is used by 25 million Californians, including residents of the Delta and Contra Costa, Alameda and Santa Clara counties. DWR’s State Water Project and the federal Central Valley Project convey Delta water through their aqueducts to distant parts of the state. Florence Low / California Department of Water Resources, FOR EDITORIAL USE ONLY

DELTA LEAD SCIENTIST REPORT: Overview of paper on the 2012-2016 drought in the Delta

Dr. Laurel Larsen officially started September 1st as the new Delta Lead Scientist; however, she is finishing up a sabbatical in Finland, and so she will be part time until she returns to California in December.  At the September meeting of the Delta Stewardship Council, Dr. Larsen gave her first report to the Council, providing an overview of a recent article in the San Francisco Estuary and Watershed Science and other news and events that are happening with the Delta Science Program.

Paper: Drought in the Delta

The article Dr. Larsen profiled is called, Drought in the San Joaquin Delta, 2012-2016: Environmental Review and Lessons.  The study was led by John Durand at the Center for Watershed Sciences at UC Davis; other coauthors included Yumiko Henneberry who was a Senior Environmental Scientist in the Delta Science Program until May 2020, and the Independent Science Board’s Dr. Jay Lund.   The research was published in San Francisco Estuary and Watershed Science which is funded by the Council with support from UC Davis John Muir Institute of the Environment and the eScholarship publishing group. 

The San Francisco Estuary and Watershed Sciences is unique in that it publishes research specifically about the science and resource management of the San Francisco Bay, the Delta, and upstream watersheds, and this scope allows managers and stakeholders in these areas to have access to high quality geographically specific science to inform their management needs,” Dr. Larsen said.

The focus of the article was the severe drought in California from 2012 to 2016 which prompted the Governor to declare a State of Emergency.  The authors of the paper conducted a review of environmental management and the use of science in management during the drought.  The review was based on a number of available reports and syntheses, available data, and discussions with 27 agency staff, stakeholders, and researchers.

In terms of the conditions of this drought, the years 2012 to 2016 experienced below average precipitation, but not extraordinarily low precipitation, given the historical record,” said Dr. Larsen.  “What was extraordinary about this drought period and made the drought so severe is that this somewhat low precipitation was coupled with extraordinarily hot temperatures, and this created a set of unique management challenges that the paper goes into.”

The paper focused on four major drought water management priorities, as stated by the water managers:

    • Support public health and safety
    • Control saltwater intrusion
    • Preserve cold water in the Shasta Reservoir essential for releases that sustain chinook salmon, particularly winter-run chinook salmon
    • To maintain at least a minimum level of protection for state and federal endangered species within the Delta.

It’s interesting that these four sets of management priorities are a really nice embodiment of what it means to manage the Delta for coequal goals of providing a reliable water supply for California and protecting the Delta ecosystem,” said Dr. Larsen.

The paper was focused on lessons learned and insights during this period of challenging management of the Delta. 

The authors pointed out that the drought management in particular is particularly tricky because sometimes the four goals that I just highlighted come into direct conflict with each other,” she said.  “One example is the need for salinity control within the Delta through water releases from upstream, which could conflict with the need to preserve cold water in Shasta reservoir for releases timed with winter-run chinook salmon.  This was a particularly difficult management objective during the 2012 to 2016 drought because these challenges were really exacerbated by the warmer temperatures experienced during this period of time, and despite managers’ best efforts, 95% of larval winter-run salmon were decimated in 2014, a particularly hot year.”

However, despite the challenging conditions, there were success stories.  One of those was that to minimize the need for reservoir releases to maintain fresh water inflow to the Delta, a temporary salinity barrier was installed on the False River. 

Installation of drought barrier in 2015. Photo by DWR.

According to the authors, this project was one of the best examples of science-informed management, not just during the drought period, but in recent history,” Dr. Larsen said.  “Scientists were able to quickly mobilize to conduct baseline surveys of salinity, water quality in general, food web dynamics and invasive clam distribution prior to installation of the barrier, and having this baseline then enabled them to specifically attribute changes in salinity and species abundance and species dynamics to the installation of the dam in a statistically robust manner.  Their studies also showed that this barrier was quite effective at mitigating salinity and detrimental ecological change.  This is a great example of how science can respond to rapidly changing conditions and inform management strategies, but it does require resources.”

The paper did discuss resources that might be needed in order to enable future rapid responses to drought or other extreme conditions within the Delta.  Funding is one important resource; the paper recommends that funds be made available to scientific studies and management activities in response to drought conditions, similar to how funds are available to respond to other extreme events, such as earthquakes and floods.  The paper also recommends that there be dedicated drought response funds in order to support the development of interagency plans, implement regular drought exercises similar to earthquake or flood exercises, and establish emergency authority mechanisms.

The authors note that drought-based studies are relatively rare often because the drought is nearly over by the time the opportunity to conduct the research is recognized.  One example is the enhanced monitoring of Delta smelt through the Delta Smelt Resiliency Strategy began in the last year of the drought, after it was already recognized that the species was spiraling towards extinction as a result of conditions during the drought.

Data resources also are important to enable science to work most effectively with management during extreme conditions.  The authors point out that during interdrought conditions, science priorities naturally shift to other things, and so agencies do not invest in the type of monitoring that is needed to establish a baseline from which throughout effects can be assessed in a statistically robust manner.  The researchers noted that many long-term monitoring records in the Delta have gaps at critical times, which usually are just before the next drought, so there is a challenge of knowing what the baseline is from which assessments of drought impacts can be made, so monitoring resources need to be prepared for the next drought.

The Suisun Marsh Salinity Control Gates maintain proper salinity levels in the Suisun Marsh during periods of low Delta outflow.  Photo by DWR.

The authors emphasized the need for long-term monitoring.  “Much of our understanding of the effects of management actions comes from long-term continuous surveys,” said Dr. Larsen. “One example of this that was highlighted in the paper is the example of an ecosystem-wide study of the Montezuma Salinity Control Gates reoperations.  The study was conducted after the drought was finished and it relied on long-term survey data in order to compare fish and water quality response within and between drought years.”

Other effects do require monitoring across several droughts in order to draw management relevant conclusions, Dr. Larsen said.   There were studies that took place during the drought that were inconclusive on how the drought impacted specific environmental processes within the Delta. 

One example of this is research that was done on the response of harmful algal blooms, particularly microcystis blooms to drought conditions,” she said.  “Basically that study pointed to a likely impact of the higher temperatures during the drought, but it was not statistically robust.  The authors were saying that intensive monitoring through the interdrought period and into the next drought could provide the weight of evidence needed in order to make statistically robust statements about whether drought conditions do increase the incidence of harmful algal blooms and by how much.”

Another success story highlighted in the article was the importance of interagency collaborative teams that can resolve management conflicts through careful consideration of tradeoffs and to assemble interdisciplinary teams of experts to resolve scientific uncertainties. 

The Interagency Ecological Program or IEP is one good example of an interagency collaborative scientific team that can collectively address a wide range of scientific uncertainties associated with the drought,” she said.  “The IEP is an association of state and federal agencies who have collaborated to provide timely highly specialized ecological data for management of the Bay Delta system since the 1970s.”

A few other key insights and recommendations from the paper:

    • A state declaration of pre-drought conditions would allow scientists and managers to potentially better prepare for worsening conditions.
    • Improved transparency and documentation of institutional drought knowledge
    • The development of a drought management plan
    • The need to rebuild vulnerable fish and wildlife populations during anti-drought of non-drought periods to promote ecosystem resilience; this might involve operations of salmon fish hatcheries during those non-drought periods in order to restore runs that were previously almost decimated.
    • Consideration the influence of climate change

The study was relevant to chapter 3 of the Delta Plan which addresses a more reliable water supply by highlighting the need to increase water conservation and improve water management information as a core strategy to achieve the coequal goals; the study also shows the value of capitalizing on existing data through increasing science synthesis as well, which is an action identified in the 2016 to 2021 Science Action Agenda.

Click here to read the full paper.

Delta Science Program Activities

Sacramento River Drainage Spring Run Chinook Salmon Workshop

The Sacramento River Drainage Spring Run Chinook Salmon Workshop was held between September 8 and 10; the workshop was hosted by the Delta Science Program in coordination with the Department of Water Resources and the California Department of Fish and Wildlife.  The 3-day workshop was attended by over 200 subject matter experts.  The goal of the workshop was to assess the state of the science needed to generate spring run chinook salmon population estimates and identify knowledge and monitoring gaps that might exist prior to the generation of these estimates; these population estimates are needed in order to inform management of the State Water Project.

The first day of the three-day workshop consisted of expert presentations that were topically focused and question and answer sections which provided fodder for breakout session discussions on the second day.  The third and final day included a recap of the outcomes of the breakout sessions, a workshop synthesis, and the outlining of next steps by the Department of Water Resources Lead Scientist Ted Sommer, and also the Delta Stewardship Council’s Deputy Executive Officer for Science Louise Conrad.  There was a general discussion that occurred on that third day.

One of the interesting things about this workshop is that it provides a model for future workshops organized by the Delta Science Program, such as the Steelhead Science and Monitoring Workshop which is now being planned for February 2021,” said Dr. Larsen.  “The US Bureau of Reclamation has requested that workshop in order to help them comply with mandates under the biological opinion for the Central Valley Project.  The lessons learned from the chinook salmon workshop will certainly inform the planning of the February steelhead workshop.”

2022 to 2026 Science Action Agenda Delta Management Questions Workshop

The 2022 to 2026 Science Action Agenda Delta Management Questions Workshop was held on September 29.  This goal of this workshop is to discuss and refine the top Delta management questions that were received as part of the process to update the Science Action Agenda.  Dr. Larsen said that Delta Science Program staff reached out to a wide range of managers and stakeholders asking them to contribute management questions that were top priorities for them in the coming years; 1181 questions were received, so the workshop was needed to really go through and refine those questions, merge them into themes, and work towards developing the priority actions that will be highlighted in the 2022-2026 Science Action Agenda. 

Science Needs Assessment Workshop

The Science Needs Assessment Workshop will be held from October 5 to 6.  The Science Needs Assessment Workshop focuses on the science needed to underpin long-term management needs decades out, rather than short-term actions as in the Science Action Agenda.  The workshop is hosted by the Delta Plan Interagency Implementation Committee or DPIIC and the Delta Independent Science Board.

The workshop will consider physical, chemical, biological and human processes as well as the infrastructure needed to integrate and support efforts for developing a bolder and more forward looking Delta science strategy. 

The Science Needs Assessment Workshop came about as a result of recommendations by the Independent Science Board to consider long-term climate change in a more regimented way in the planning.  The workshop takes a step forward towards fulfilling the DISB’s 2019 Delta Science Plan’s call for anticipatory science that considers long-term change.

Zooplankton Ecology Symposium

The Zooplankton Ecology Symposium will take place on October 27 to 28.  The symposium will focus on the latest research on zooplankton ecology and monitoring.  It will take place over two consecutive half days that will consist of talks and panel discussions focusing on the San Francisco Estuary as well as the larger Delta system.  The primary audience for this symposium and scientists and will include content on zooplankton biology and ecology, monitoring programs, data collection methods, and the IEP’s integrated zooplankton data set. 

New Science in Short Podcast

Maven’s Notebook has partnered with Estuary News Service to produce a podcast featuring scientists doing science in the estuary.  The purpose of this podcast is to provide air space to scientists so that they can highlight what they are doing and how their work is relevant to management.  The first podcast features David Ayers, a current science fellow and a PhD student at UC Davis where he is studying predator prey interactions and the environmental factors that shape those interactions. 

By the numbers report …



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