CA WATER COMMISSION: State Water Project Delivery Reliability Report; Planning for a dry 2022

At the February meeting of the California Water Commission, the commissioners began their 2022 State Water Project review by hearing a series of presentations on how the Department of Water Resources (DWR) is adapting its planning and operations to prepare for climate extremes.

The first two presentations covering DWR’s Climate Action Plan and forecasting improvements is posted here.  In this post, Andrew Schwarz, State Water Project Climate Action Advisor with the Department of Water Resources, discussed how the State Water Project Delivery Capability Report is being updated to incorporate climate change.  He was followed by John Yarbrough, Assistant Deputy Director of the State Water Project, who discussed the Department’s drought planning for 2022.

ANDREW SCHWARZ: Climate Change in the SWP Delivery Capability Report

The State Water Project Delivery Capability Report, part of the Monterey Plus Agreement, is important for climate change planning within the Department of Water Resources, water contractors, and communities throughout the state.

The purpose of the report is to provide information to the water contractors and the public about the capability of the State Water Project to deliver water.  The report is issued every two years and provides existing delivery capability over a range of hydrologic conditions, including information about historic and extended drought cycles, long-term average deliveries, and future delivery capabilities 20 years into the future.

Key information in the report includes the long-term averages, single dry year deliveries, and the different components of SWP water delivery, such as Table A, article 56, and article 21.  The information is given for the project overall and for each individual contractor.

This information is really important because they use it,” said Mr. Schwarz.  “It shows up in urban water management plans and agricultural water management plans for all of our contractors and downstream water users of those folks.  In addition, it is used in some local land-use decisions from time to time, as well as other administrative decisions such as Delta Plan consistency.  So this is one of the single most important sources of information that the Department puts out in terms of climate change information as it funnels downstream to water users.”

The 2021 version of the State Water Project Delivery Capability Report was recently released in draft form for comment.  The final report is anticipated to be released in April.

The graphic compares the 2019 report with the 2021 report.  Mr. Schwarz noted that the 2021 report is the first to use the new Cal Sim 3 model; previous versions used Cal Sim 2.  The new regulatory rules were applied in the modeling, as well as 12 additional years of hydrologic data.    

The delivery capability has actually fallen about 100,000 acre-feet from that what was what was reported in the 2019 report for the 2021 report in terms of a long-term average,” Mr. Schwarz said.

We used 1922 to 2015 historical hydrology to run through the system with current capabilities, facilities, and regulations, and we can then get the average long-term delivery capability of the system.  We can also look at historical drought periods and wet periods and report on how those droughts and wet periods would look under future or current regulations.”

The Delivery Capability Report is important for informing local agencies about the current and future capabilities of the State Water Project, and it’s also important within the Department for State Water Project planning.  For example, the Power and Risk Office, which manages the energy resources needed and produced by the State Water Project, uses this report’s information and scenarios for current and future conditions.  It is also used for the ongoing Oroville cold water and pump back studies and the California Aqueduct subsidence program.  

So it is one of the most important pieces of where climate change information is coming from,” said Mr. Schwarz.  “Although we have lots of different sources of climate change information that the Department has developed and put out over the years, this is the one that appears to be really penetrating the most and being used quite extensively.  And that’s why we’re targeting it here.”

The Delivery Capability Report has evolved over time since it was first issued in 2003.  The first couple of reports included current and future land use and did not contemplate climate change or other factors that would affect project deliveries.  In 2007, the Department began incorporating climate change and its effects into future projections. 

In 2015, they began using the ‘last big project approach’ in the analysis, leveraging the climate change information and scenarios developed by the Bay Delta Conservation Plan, WaterFix, and now the Delta conveyance and incidental take permits.

Because those are such large and well-resourced projects, they’ve been able to develop climate change information for those projects, and those scenarios have been adopted and presented in the DCR as the future climate condition that was evaluated,” he said.  

In its current form, the report provides the existing delivery capability and future delivery capability informed by climate change; the climate change information is given in years aligned with urban water management plans so the information can be incorporated into those plans and used by local agencies.

Mr. Schwarz noted that the State Water Project contractors have expressed a desire for a single number for future conditions or a scenario that they can incorporate into their urban water management plans and ag water management plans to reduce the uncertainty.  So the Department has tried to be sensitive to that.

Looking forward, the Department is considering the state laws and executive actions that have been taken recently, such as AB 1482, which concerns planning and informing state investment decisions with climate change information, and AB 2800, which requires state agencies to incorporate current and future impacts from climate change when planning, designing, building, operating, maintaining and investing in state infrastructure.  In addition, there are also executive orders that have focused on climate adaptation and resilience.

All of these have ramifications for the users of State Water Project water, their planning, and how the Delivery Capability Report filters into those,” he said.

Mr. Schwarz also noted that phase two of the Department’s Climate Action Plan includes a framework for climate change analysis and consistency throughout the Department.  So the Department is bringing all these things together and incorporating them into the Delivery Capability Report to provide more comprehensive climate change information to all of the users of the State Water Project.

They acknowledge that significant shifts in the climate have already occurred, and these shifts need to be accounted for in the baseline conditions.  The report utilizes historical hydrology as a basis for calculating averages and conditions, so we need to understand how that historical hydrology has already changed and incorporate that into the current conditions.

We’re diligently working on that,” said Mr. Schwarz.  “We’ve made a lot of progress on developing some methods, analysis, and updates to that, and we expect to have an adjusted baseline scenario that will help us estimate the current SWP capability and reliability for use in both operations and planning studies.  And that will be it, at least in the 2023 DCR, if not sooner, for use in other processes.  Then moving forward, that new baseline would be the basis upon which additional climate shifts that we expect to see in the future would be added.

The Department coordinates closely with the Bureau of Reclamation and other state and federal agencies to ensure alignment with the efforts.  The Department also is looking to move to a more collaborative climate change scenario development approach so that, rather than basing the climate change future conditions on the work of the last big project, the scenarios are developed in a more holistic way to provide complete and comprehensive information that more adequately explores the uncertainty around future climate conditions and provide more information that the contractors and others can use in their planning.

The report is aligned with other actions underway, such as the forecast improvements underway, the update of the Central Valley Flood Protection Plan, and the watershed studies in the Tuolumne and Merced.  In 2023, the report will be aligned with the new California Water Plan update and the final Delta Conveyance Project environmental documents, expected in early 2023.

In 2025, the urban water management plans and ag water management plans will be due, so the information in the 2023 report will be important for those local planning efforts.

In closing, Mr. Schwarz reiterated that the Delivery Capability Report has become the most consequential source of climate change information for the State Water Project, both for local agencies and internally.  “That’s why we’re focusing on it here,” he said.  “We really want to move forward to more intentional and collaborative development of climate change information.  We hope that it improves the actionability and the comprehensiveness of the information that we’re providing to our stakeholders.”

JOHN YARBROUGH: State Water Project drought planning

John Yarbrough, Assistant Deputy Director of the State Water Project, discussed the Department’s drought planning for 2022.

In 2021, the lack of precipitation and the dry conditions resulted in very low runoff into the reservoirs.  As a result, the water year ended with record low levels in Shasta, Oroville, and Folsom, the state’s key reservoirs, shown in the orange bars.  The blue bars shown on the graph on the lower right show the water in storage at the end of 2020; the orange bars show water in storage at the end of 2021.

 “That’s about the lowest we like to see those reservoirs as we go into the next year, so this year, they are much lower than where we like to have those reservoirs,” Mr. Yarbrough said.  “That’s significant because the water supply is being driven by the hydrology in Northern California, and with the hydrology being so variable, these reservoirs really provide the buffer that lets us address that hydrology.  The demands on the system, both from the environmental needs within the Delta, senior water, right holders, and other water supply users will exceed what we might get in a very dry year from hydrology.  And so we use the storage to buffer those low hydrology events and get through the year.”

Spring of 2021 was the warmest and the driest on record.  It challenged the hydrological forecasting and the forecasting of how the systems would operate and what water would be available.

So what we take from that is that we need to be considering even more extreme scenarios than we have done previously, as we are looking at future years and as we think about our forecasting,” said Mr. Yarbrough.  “Because of the changes, we just have a lot more uncertainty in those forecasts.  So, because of the extra uncertainty that we didn’t have decades ago, we really need to be looking at and thinking through what happens if we get what we maybe would call a one in a 100-year or 99 percentile event.  We are spending more time thinking those through because maybe it is more likely than then than calling it a 99 percentile event would lead you to believe.”

2022 Objectives

Considering the low storage and dry conditions, the Department has set the following objectives:

  • Provide minimum health and safety needs: ensuring the ability to meet the domestic, sanitary, and fire suppression needs.
  • Maintain Delta water quality:  Maintaining salinity in the Delta is important for the environment and the water users who divert water from the Delta. 
  • Meet environmental needs to protect endangered species
  • Conserve water storage to meet future critical needs: While the Department is planning for the rest of 2022, they also need to consider 2023 and beyond and have a buffer for those years should dry conditions continue.
  • Deliver water based on priority to different water users and meet the minimal health and safety needs, acknowledging other important needs wouldn’t be met.  “So where we can deliver water, we’re doing that,” he said.

The Department started the year assuming conditions would stay dry and took some initial actions, such as leaving the salinity barrier in place in the Delta and submitting a temporary urgency change petition for February through May.

At the time in December when we’re making these decisions, we had a lot of uncertainty in our forecasts, and we don’t know if the benefits of that change petition will outweigh the costs of it,” said Mr. Yarbrough.  “So the proactive action was getting that in front of the board to start the public process and the dialogue.”

For the first time, the Department set an allocation focused on meeting their customer agencies’ unmet health and safety needs, rather than based on a percentage of the Table A amount. 

That’s where we started the year, and then the plan was to then as we go through the year, conditions would either get drier or wetter,” he said.  “If they were to get drier, we could intensify our actions.  This would be things like installing additional salinity barriers, further modifications of Delta operations through a Water Resources Control Board process through the temporary urgency change petition process, and additional conservation.  So there are a handful of actions we could take to intensify our actions.”

Alternatively, if the hydrology improves, we could start relaxing these actions, so that would be returning more normal Delta operations, removing barriers, and providing more traditional water project allocations.”

He presented a slide showing the precipitation in the Feather River watershed for October through January, noting that the Feather River is what drives the water supply in Lake Oroville.

Maybe we’re about average with total precipitation to date, but the way that average showed up was really a story of extremes,” said Mr. Yarbrough.  “October was wettest on record, then one of the driest Novembers, one of the wettest Decembers, and one of the driest Januarys.  So this oscillation between extremes becomes a challenge as we’re planning and making decisions about what drought actions are needed, what kind of allocation would be appropriate, and whether we needed to the temporary urgency change petition.”

The map shows where the early drought actions were focused. 

We’re starting to look at two main parts of the system,” said Mr. Yarbrough.  “So the first part is Lake Oroville and north of the Delta, and how Lake Oroville storage is being used.  We’re counting on Lake Oroville storage being used to control salinity in the Delta; we’re looking at using that to meet senior water right needs up north of the Delta and then conserving water for the future, for a drier 2023.  Unless we see much more hydrology than what we’ve observed, we’re not expecting here to be able to use Oroville storage to export down further south to meet new water needs south of the Delta.”

For south of the Delta, we’re looking at what water is going to be in San Luis,” he continued.  “Because the water supply to the water users, most of that we’re able to access out of San Luis.  So the question is, how much will we be able to move into San Luis, and how much water will be in San Luis for the summer when that water is really needed.  So in January, we were able to make the allocation informed by the large storms we had in December and building on what we did conserve in October.  So with the storms, using some very conservative assumptions, and looking at what water would be available in San Luis, we were able to base that that 15% allocation, not looking up at Oroville and what’s happening on the Feather and not expecting that water really to be available to support an allocation.”

He noted that with the dry conditions since the beginning of January, they will have to evaluate whether they will continue to support that 15% asset allocation.   “Our very conservative assumption, say yes, we absolutely will.  But at the same time, I just want to say that nothing’s set in stone here, as we’re dealing with all the uncertainties that we see in future hydrology.”

On January 18, the Department of Water Resources withdrew the temporary urgency change petition to modify Delta water standards.  “We did this basically looking at February, March, and April, and what benefit they would provide, and weighing that against the concerns with modifying those standards.  And because of the December storms at that time, it didn’t look like that would provide enough benefit to make sense that they go through that process with the Board.  So we withdrew the change petition.”

However, he noted that they are taking the forecast information, running it through the operations models, and re-evaluating decisions going forward.  Continued dry conditions could very well lead to needing to approach the Board to modify standards in the future, most likely later in the spring or summer if the dry conditions continue.

Looking ahead for 2022

So what is the Department doing differently this year?  The Department is considering more extreme scenarios when planning, so they are considering a temporary urgency change petition, the drought barrier, and their benefits.  They are considering a much broader range of possible scenarios than in years past and adjusting to the water supply forecasting approaches. 

There is more frequent and earlier coordination across agencies and more frequent sharing of information so the resource agencies, the operators of the projects, and the Water Board are all looking at a common set of forecasts and have a common understanding of how dire the situation is.

Currently, Mr. Yarbrough said the Department is not expecting to need some of the most intense drought actions at this time (mid-February).  They are coordinating around water transfers.  The Department is continuing the forecast improvements and the ongoing process of putting the information into the operational models, and consider if there is a need to seek the modified Delta standards, refill the notch in the salinity barrier, and other actions.

It’s a very constant process of looking at how conditions are changing to decide whether these different actions need to be triggered,” said Mr. Yarbrough.


QUESTION:  Commissioner Makler asked John Yarbrough if he thinks there are sufficient institutions in place to allow for water transfers?  What else is in the toolkit, whether it’s a trading of allocations, trading and making available groundwater, or other river allocations?

John Yarbrough:There’s a lot of infrastructure in place already.  But as far as implementing transfers, a lot of the feedback is that there’s always room to improve.  I talked about really looking to facilitate transfers and that the Department of Water Resources, the Bureau of Reclamation, and the Water Board are looking at how we can continue to make that an easier process for folks.”

The other part that we’re continuing to tie in now is the with our Sustainable Groundwater Management Office as they’re implementing SGMA, that gives us more data.  As we look at some of these different transfers, especially ones relying on groundwater, what are the effects of those transfers?  So I think the improvement of continuing to streamline the process between the Bureau, the Board, and DWR, and also streamlining the consideration of the information needed by the SGMO office are just a couple of term near term areas that would continue to benefit from an improvement.

QUESTION: Commissioner Solorio asked how the Department will use this type of data and information in the short-term, mid-term, and long-term for the state to decide what percentage allocations of water to give to the contractors.  How will climate, data, and related information be used to inform that decision?

John Yarbrough:  “The general process is that Dr. Anderson’s group does a snow survey.  So they’re collecting data that they produce at the beginning of each month for Bulletin 120.  It is the forecast of conditions for the remainder of the year, looking at precipitation, snowfall, and inflows; that information is then turned over to the Water Project staff with their own operational models.  And so then we run the models to say, Okay, if this much inflows coming into the reservoirs, that’s where the water showing up, then, and here are all the different requirements we have an operating the project.  How do we do that safely?

What we’re looking for is, what water do we see being down south of the Delta, because, with Oroville so low, we’re not able to use Oroville to provide water down south to make an allocation.  So we’re looking at other flows, which we can pick up and move into San Luis Reservoir; we’re looking at what we have already in San Luis.  So that’s our process … so the question is, what precipitation is expected through the rest of the year?  Where would you expect it to show up?  And what’s the inflow into the Delta that would allow us to move some of that water into San Luis?  Then looking at what that volume is, that’s where we look at what kind of allocation could we support.”

The uncertainty is around how much water is there going to be there.  Typically in our process, we wouldn’t look at such extreme conditions this year.  But just being more conservative because of all the discussion around the uncertainty, we are being more extreme with what water we think we’d have available.  So we started with that 15% allocation.  And we’re continually going through that process of taking that Bulletin 120 forecast Dr. Anderson’s group produces, running through the operational models, seeing where the water would be available.  And then seeing from that, what could we use to support any changed allocation.”

Andrew Schwarz:  “Depending on the point at that we’re at in the year, we’re trying to use the best information that we have available.  So the earliest stage of the year, in September, we have very little idea at all about what the winter is going to bring us.  And so we’re using historical statistics and annual values from our historical record to kind of project out how the year might unfold.  And that part of the adjustment to historical data that I talked about would be something that could inform that in the future and give us a better sense of the distribution of years that we might end up with as we sit in September.”

As we move into the October, November December, the information that the snow surveys and Dr. Anderson’s group provides is the best information that we can use because it is so much more real-time and it is so much more informed by what we already have seen and where we are in the year.  So we can do a better job of operating based on what we already know about the year and what might be coming at us in the coming months.  But still, even as we sit in the middle of February right now, there’s still a tremendous amount of uncertainty about how the rest of the water year will unfold.  So we can look out about two, three weeks max, at what’s happening out over the ocean, but much beyond that, we don’t have very good predictive capabilities.”

QUESTION: Commissioner Gallagher noted that Mr. Yarbrough mentioned that one part of the allocation is water for the next year or future years.  How do you determine how much to keep for the next year?

Mr. Yarbrough: Part of that is looking at Oroville.  So with Oroville each year, we come up with a target that we would like to hit for the coming year.  Back two years ago, it was around 1.3 million acre-feet of water we wanted to see in Oroville.  So we wouldn’t allocate water out and provide that for water supply if it would take us below that amount.  We upped that number to 1.6 million acre-feet back before last year.  And that was because as conditions seem to be changing, we have a little bit of a larger buffer.  That’s less water available for any one year for water supply, but it’s adding a little bit of a buffer.  We’re glad we did because that extra 300,000 acre-feet was meaningful in a year like last year.”

The other tool is that our customer agencies are able to make those sorts of decisions, so as we make an allocation to those agencies, they can choose to carry some of that water over into the next year.  So they’re also making decisions on how much of a buffer they want agency by agency, because they’re looking at their total supply, their different sources, and the reliability of each of those sources.  So they can make that decision as well.”

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