At the January meeting of the Delta Independent Science Board, the board members heard a series of presentations on water management in the Delta to orient new members to the complexities of science and management issues in the Delta. The presentations were also in response to the recent review of the DISB that suggested the Board become more familiarized with the realities of Delta science and management.
The first presentation was from Kristin White, operations manager for the Bureau of Reclamation’s Central Valley Project (or CVP). She was followed by John Leahigh, the Deputy Division Manager for Water Operations for the State Water Project, and Carrie Buckman, Environmental Program Manager with the Department of Water Resources provided an overview and an update on the Delta Conveyance Project. Those presentations will follow next week.
The Bureau of Reclamation operates in the 17 Western states; they manage over 300 dams and over 400 reservoirs with a storage capacity of over 200 million acre-feet. The Bureau of Reclamation is the largest wholesaler of water in the US and a significant power producer, producing power for about 3.5 million homes.
The Central Valley Project is within the Great Basin region of the Bureau of Reclamation, which is one of five regions. Unlike other Reclamation projects in other basins, Ms. White noted that the Central Valley Project was ‘a little bit late to the game’ in California, having been constructed after many irrigation and water projects had already been developed.
The Central Valley Project has over 270 contracts and agreements, delivering water to 29 of the 58 California counties. The CVP provides 20% of the total water supply, 30% of agricultural water supplies, and 13% of the M&I, mostly urban users. The CVP delivers water to 19 wildlife refuges.
The CVP produces 2.8 billion kilowatt-hours, equivalent to about 650,000 people served. The CVP produces more power than it uses, so it is a net power producer. The excess power above the project needs is sold to other users.
The Central Valley Project is unique in that it is closely operated with the State Water Project and other local systems because they are all diverting water from the same rivers.
The need for the Central Valley Project
The reason the Central Valley Project and the other water projects were built was to resolve the mismatches and the variability of the state’s hydrology.
Most of the state’s precipitation falls in the north, and most of the water demand is in the central and southern parts of the state. Also, the precipitation falls in the winter and spring, but the need for that water is in the summer and fall.
Ms. White noted that it could be hard to imagine if you’re not familiar with California, but once it stops raining, usually in the early summer, it is almost completely bone dry until the end of the fall. “So without irrigated agriculture, you wouldn’t be able to grow a tomato plant in the Central Valley,” she said.
Precipitation also varies significantly from year to year. For example, 2017 was the wettest year on record, and 2019 was also very wet, but 2020 and 2021 were some of the driest years on record.
“So precipitation is extremely variable,” she said. “Our demands, however, are not very variable; we have constant demands, particularly in the central and southern parts of the state.”
Challenges for the Central Valley Project
There are many challenges in moving water around from season to season, from north to south, and from wet to dry.
The Central Valley Project is operated for several purposes. The primary purpose is flood control, and almost all of the dams are sized for flood control. Other project purposes include river regulation, fish and wildlife, water supply, power generation, and recreation.
Some of the challenges include drought, floods, and climate change, which is changing how they look at the historical datasets that have been in use for quite a long time.
Aging infrastructure is a challenge, with most of the infrastructure constructed in the 1940s, 1950s, and 1960s and nearing the end of its lifespan. With wind and solar projects coming online, that has changed the demand for hydropower, which causes challenges in how the project manages their hydropower system. In addition, groundwater and subsidence challenges increase uncertainty in the operations, as do invasive species, regulations and coordination, water quality compliance, and endangered species protection.
Central Valley Project facilities
Construction of the Central Valley Project facilities started in the 1940s with Shasta Dam on the Sacramento River, Friant Dam on the San Joaquin River, the Jones Pumping Plant, and related canals. Ms. White noted that the Jones Pumping Plant was built before the other Delta systems were in place.
Folsom Dam was built in the mid-1950s, a ‘workhorse’ dam for the project with a high potential fill rate every year. In the 1960s, the Trinity Division was constructed, which diverts water from the Klamath system via the Trinity River into the Sacramento River. In the late 1960s, the State Water Project was built; the San Luis unit followed that, and in 1968, the San Felipe Unit.
The last large construction was New Melones Dam, completed in 1979. An intertie canal between the California Aqueduct and the Delta Mendota Canal was constructed in 2011.
Shasta Dam
Shasta Dam, the CVP’s keystone dam, is located on the Sacramento River north of Redding. Shasta is the state’s largest dam at 4.5 MAF. It is operated for flood control primarily in the wetter years, water supplies, temperature management, power generation, and water quality benefits.
Trinity Dam
Trinity Dam, smaller than Shasta at 2.4 MAF, is up near Weaverville within the Klamath River Basin on Trinity River. The dam is operated for water supply in the Sacramento River system, regulatory requirements in the Sacramento and Klamath systems, and hydropower.
“If we say that Shasta is our Keystone facility for water supply within our projects, then Trinity would be the keystone facility for power,” said Ms. White.
Folsom Reservoir
Folsom Reservoir is a much smaller reservoir and a much larger watershed. The capacity is under 1 MAF, but the average inflow is 3-4 MAF.
“It has a very high potential of filling, which means we rely on it a lot for meeting various demands throughout the system,” she said.
Folsom Reservoir is located on the American River. It is a key component of the flood control system for Sacramento, which has a very high flood risk as well as infrastructure challenges. Folsom Reservoir is operated for flood control, water supplies, temperature management, power generation, and water quality benefits similar to Shasta.
Ms. White noted that Shasta, Folsom, and Trinity are all operated in an integrated fashion together to try to meet various objectives within the system.
New Melones
New Melones is the opposite of Folsom; it’s a very large dam on a very large watershed. The reservoir is about 2.4 MAF, but the inflow is about 1.2 MAF. So with the reservoir double the size of the average inflow, it has a very low refill potential.
The dam is about 40 miles east of Stockton, and it provides water for fishery requirements, water quality, water rights, agricultural, municipal, and industrial water needs.
Friant Dam
Friant Dam, near Fresno, is the smallest reservoir at about half a million AF (520 TAF). The dam diverts water into two large canals that deliver water in the San Joaquin Valley. The dam is also operated for the San Joaquin River Restoration Program.
San Luis Reservoir
San Luis Reservoir is off-stream, meaning water is pumped into it as it doesn’t have much natural inflow; it stores water pumped from the Delta. The project was jointly constructed and is jointly operated with the state of California.
The federal portion mainly supplies water to the western San Joaquin Valley, primarily for agriculture but also for some municipal, industrial, and refuge supplies.
Jones Pumping Plant
The Jones Pumping Plant, located near Tracy, pumps water into the Delta Mendota Canal. It has a license to pump 4600 CFS from the South Delta, but due to aging infrastructure and subsidence on the Delta Mendota Canal, there are major challenges with being able to pump that amount.
“Right now, we’re probably closer to 4200 as a max, although we are working on an effort to try to maintain those facilities and get the capacity back,” said Ms. White.
Delta Mendota Canal
The Delta Mendota Canal carries water from the Jones Pumping Plant in the Delta, 116 miles south, and terminates at the Mendota pool. At San Luis Dam and the O’Neill Forebay, there is a turnout to pump water into the reservoir.
Hydropower
Ms. White said that Shasta is the keystone for water supply, and Trinity Dam is a keystone of power; the graph shows why.
“We often think about power in our project as ancillary to water supply,” said Ms. White. “When we release water for water supply or to meet a regulation or to meet to a fish requirement or some other purpose, then then we produce power off of whatever was released.”
The larger the drop, the more power produced. From Trinity Dam, the drop is almost 2500 feet into the Sacramento River. The water passes through four power plants on its way to Keswick and the Sacramento River.
“So it generates quite a bit of power for a single drop of water whereas some of our other facilities only go through one or maybe two facilities and a much smaller drop,” she said. “That’s why we say Trinity is really the keystone of our power operation throughout the Central Valley Project.”
Challenge: Central Valley habitat
Ms. White then drilled down into some of the challenges, noting that many of them stem from how the Central Valley habitat has been modified. There are dams throughout the system, Central Valley Project facilities and others, local water systems, and a slew of different owners around the rim of the valley floor. Historically, the salmon would migrate upstream through the foothills into the Sierra to reach cold water for spawning and rearing, but now dams block access to that habitat.
“That creates a lot of challenges for them because now their habitat is not only limited, but it’s also significantly warmer,” she said. “So that’s a huge challenge for both the fish and for us as operators, as we are often trying to operate our facilities to try to mimic some of those temperatures so they can have a chance of completing their lifecycle.”
She also noted that levees isolate the fish from their historical floodplain habitat throughout the system. Water diversions throughout the entire system are pulling water from rivers and streams, as well as the large export facilities in the South Delta that alter the hydrodynamics of the Delta; this impairs how the fish are moving and where they are going, especially when they are small.
Challenge: Delta operations and constraints
In the Delta, the Sacramento River flows in from the north, and the San Joaquin River flows in from the south; they meet in the Delta and flow out to the San Francisco Bay and the Golden Gate. Delta outflow is the water leaving the Delta and flowing into the Bay.
One of the primary functions of both the Central Valley Project and the State Water Project is salinity management. Ms. White explained that as the tides come in, salty water from the Pacific Ocean is pushing into the Delta, and the projects are trying to release enough water to push that water out to keep that salinity out closer to the Bay.
“We do that so that the water is usable within the Delta where our pumps are, where there are other diversions at, where the parts of our projects are, and where there are a number of other projects and urban users and other agricultural users throughout the system,” she said. “So that’s a big piece of what we do.”
The Delta Cross Channel Gate is located near Walnut Grove. The Delta Cross Channel brings water from the Sacramento River into the interior Delta and to the export facilities in the South Delta.
The Old and Middle Rivers are two channels that lead to the pumping facilities. The Delta is a tidal system, which means the tides move the water back and forth. When the pumps in the South Delta are pumping at a high rate, Old and Middle rivers tend to start flowing in a reverse direction – towards the pumps rather than flowing out towards the ocean.
“That can cause a lot of confusion for the fish who are trying to return to their stream or who are trying to get out of the Delta, so we have limitations on how reversed that flow can be to try to limit that impact to those fish,” she said. However, she acknowledged that it doesn’t always work, so the fish that end up at the export facilities are collected and taken to another place where they have a better chance of making it to the ocean.
Finally, she noted the limitation on the Jones Pumping Plant due to aging infrastructure, which she said is ‘always causing new challenges by the day.’
Water supply
Ms. White then turned to water supply. She began by noting that there are two distinct types of CVP contractors:
The first group are those who were already using water before the Central Valley Project was constructed. Since those water users are senior to the Central Valley Project, the Bureau of Reclamation had to figure out how to satisfy their rights first, before those of the Project. These contractors are on the Sacramento River and the San Joaquin River, and they account for about 4 MAF or 55% of the Project’s total contracts.
“The settlement contractors are where we developed a contract to settle how we would meet their water rights from the Sacramento River when we constructed and operated Shasta Dam,” she said. “The exchange contractors are those where we developed an agreement to exchange the water that they were getting from the San Joaquin River, to instead come from our Jones pumping plant that we constructed in the Delta. So they get water from the Delta in exchange for water from the San Joaquin.”
The remaining 45% of the water is water developed for the project and delivered to those with contracts for CVP water. That water is developed by region: North of Delta, American River, Eastside for New Melones and the Stanislaus, Friant, South of Delta, and in-Delta.
Determining the allocation
The allocation applies to the CVP contractors, as the project has to meet the senior rights for the settlement and exchange contractors first. Once those are met, the graph shows the big picture of how the remaining water is allocated.
“We take all of our conditions that we know, so we know where the reservoirs are right now, we know what the seasonal forecast is for how much runoff we should get in the future,” explained Ms. White. “We have other project inputs: What are the other projects doing? How are they operating? What do we think the demands are going to be? What are those estimated minimum river flows? What do we think the requirements will be to keep in the river? What are the requirements going to be in the Delta, and how much water needs to be released to meet those?”
“Then, we know what we want to get out of that, which is the forecasted river releases, storages, exports (meaning pumping in the Delta), and the operations in San Luis. We take all of those and we iterate amongst a variety of goals, such as maximizing those deliveries while meeting reasonable upstream carryover storage, fishery requirements, water quality requirements, and minimizing excess conditions. Excess basically means there’s water going out past the Golden Gate Bridge that doesn’t have a designated purpose, so we try to minimize that. We try to minimize our flood control encroachment because we don’t want to have reservoirs that are too high; that can cause us to have huge releases once the storm comes in that then causes major downstream impacts. We want to meet our share of the requirements. And then we want to minimize San Louis carryover storage.”
“With the upstream reservoirs, we want to have a reasonable carryover storage to protect against what future water supply might look like,” she continued. “For San Luis, it’s an off-stream reservoir, so we only pump water into it. So we want to maximize that use where it can ideally fill in the spring and then pull all the way down by the maximum demand period, usually sometime around August or September.”
“And from that, we get estimated water supply allocations.”
Operating agreements and standards
Some of the key operating agreements:
- SWRCB Permits and Conditions -Instream Flow and Delta Standards, Water Rights Decision 1641: This primarily dictates the requirements to meet in the Delta, such as how far out the projects need to push the ocean water and how much is flowing past the Golden Gate Bridge, among a slew of other requirements.
- US Fish and Wildlife Service Biological Opinion (2019) and NOAA Fisheries (NMFS) Biological Opinion (2019): This regulates how they operate to protect endangered species, per the federal Endangered Species Act.
- Coordinated Operations Agreement: This determines how the Bureau of Reclamation and the Department of Water Resources will meet the requirements that are common to both projects. “For example, we’re both using the Sacramento River, and we both have a requirement to meet a Delta outflow. So how are we going to make sure that Delta outflow or the salinity barrier is maintained? So we have an agreement that defines how that is shared.”
- Central Valley Project Improvement Act –Section 3406 b(1), b(2), b(3): This law, passed in 1992, has requirements such as required deliveries to wildlife refuges both north and south of the Delta.
- The Water Infrastructure Improvements for the Nation Act (WIIN) directed Reclamation to convert water service contracts to repayment contracts upon a contractor’s request
- There are also agreements with the Army Corps, Department of Fish and Wildlife, the Federal Energy Regulatory Commission, and many others.
“So there’s quite a number of things that we’re looking at on a regular basis to make sure that we’re that we’re meeting our requirements,” said Ms. White.
The slide on the lower left shows the state permit requirements that must be met from January to December. “The intent of this slide is to show you that every month has some requirement that needs to be met,” said Ms. White. “This is what we’re looking at on a regular basis to see what the requirement is. There’s a whole slew of footnotes in here that modify some of the requirements, so we take those into account. Where are we at? And where do we think we’re going?”
This slide on the upper right shows the requirements for protecting endangered species included in the biological opinions from October through September.
“Again, you can see that there is something in every single month, so there are constant requirements that were that we’re watching, monitoring and meeting,” she said.
She said that coordination with other projects and agencies is a big part of their work. “We coordinate probably most with the Department of Water Resources as the project operators since we are sharing the river systems, and we’re sharing the regulations,” she said. “We’re also coordinating heavily with the State Water Resources Control Board, US Fish and Wildlife, State Department of Fish and Wildlife, and the National Marine Fisheries Services as a regulator. They provide us with a permit so that we can operate, so we’re constantly working with them on how we’re meeting the objectives of the permit.”
“We also coordinate heavily with the Army Corps, who is both a project operator and a regulator. They operate facilities that affect our facilities, such as Pine Flat Dam, which, under certain conditions, can flow into our system and make it to the Delta. They are also a regulator as the manager of our flood control, so we’re constantly working with them. We also work a lot with the Western Area Power Administration … their role is the transmission and the marketing of the power produced by the Bureau of Reclamation.”
“Then, of course, we coordinate heavily with a number of local system operators and various stakeholders such as Delta Stewardship Council.”
Typical operational planning schedule
Ms. White noted that this is an example, but it’s not meant to be a full list. They are constantly looking at things on a monthly, weekly, and daily basis. “We’re looking at it monthly, but each month we’re looking at it seasonally, so we’re looking at a seasonal runoff forecast, with both short term and long term forecasts. And that leads into an operational forecast which says, what do we think the next 12 months is going to look like?”
There are monthly watershed technical team meetings where operations and fishery conditions are discussed, and adjustments are made based on the fishery conditions. In addition, weekly salmon and smelt technical teams are looking more closely at the fishery conditions and making adjustments to operations based on that data.
“We are regularly reviewing our regulations and agreements, looking at those bars, and seeing if there’s anything new that is coming out based on the conditions,” said Ms. White. “Then we’re forecasting our changes to the operations about three to five days out. We produce more power than then what we use. So we try to schedule those changes three to five days out so that we have an accurate depiction of what power we’re not using so that WAPA can sell power.”
Every day, operators discuss current conditions and make adjustments as needed, based on conditions. They are coordinating with the State Water Project operators and are co-housed in the same building with them.
The initial allocation is issued in February, with updates as needed from March through June, although Ms. White noted that they have come out as late as September due to significantly changed conditions.
QUESTION: How much of an issue is siltation or sedimentation of reservoirs?
“It can be,” said Ms. White. “A lot of our reservoirs have other reservoirs upstream of them. So we get a little bit less of it in our bigger reservoirs. But we are still monitoring that and doing regular bathymetric surveys to look for it. For example, Folsom Dam is under a million acre-feet, about 977,000 acre-feet as constructed. Our last survey found that in the first 50 years of operation, it had accumulated about 10,000 acre-feet of sediment. So that gives you an indication of kind of where the issue is. But Folsom has a number of upstream reservoirs, so those upstream reservoirs might have a different opinion on how much of a factor that is.”
