Details include the flexibility and constraints, transfer capability, and water quality benefits of the Delta tunnels project, plus an analysis of it’s ability to capture excess stormflows
On Monday, August 17, the Metropolitan Water District’s Special Committee on the Bay Delta heard more details on the California Water Fix project, formerly known as the Bay Delta Conservation Plan, and more commonly known as the Delta tunnels.
Bay Delta Program Manager Steve Arakawa gave more details on the proposed project’s supply reliability and added flexibility, the water quality benefits, and operations.
Mr. Arakawa then gave a brief history of the regulatory restrictions that have been imposed on the state and federal water projects. He said that over the last 25 to 30 years, the operational flexibility of both the State Water Project and the federal Central Valley Project has been reduced due to various actions to try to manage between fisheries, environment, and water supply going all the way back to the late 80s and into the early 90s with some of the initial proposed listings of fish, including the winter run salmon and the Delta smelt; later on other proposed listings or other listing occurred. In 1992, the Central Valley Project Improvement Act affected the Central Valley Project. A lot of important decisions were made in the 1994 Bay Delta Accord to try to resolve some of the operational issues that had accumulated up through then. Then the Trinity River Operations in 2000 for the Central Valley Project, San Joaquin settlement in 2006 on the federal project, and then for both projects, the 2008 and 2009 biological opinions for Delta smelt and salmon.
“So there’s a trend of reduction in flexibility and reduction in water supply, and so that’s the context that we’re facing when trying to understand how to manage the system more effectively and more efficiently, and how to best balance the needs of fish and people in terms of how the system could be managed,” he said.
He then presented a slide showing average annual deliveries for both the state and federal water projects under different regulatory scenarios, noting that it is taken from information contained in the environmental documents. “It’s looking at long-term hydrology and various hydrologic conditions from 1922 through 2003, and then it’s also looking at what kind of conditions would we expect in terms of hydrology and potential climate change as that affects the system over time in this case, 2025,” he said. “The year 2025 is called Early Long Term in the environmental document and is the time frame that is cited quite a bit in terms of how the project performs, so that’s the citation that we’re using for describing the supply conditions for the various scenarios.”
Moving from left to right, Mr. Arakawa pointed out that the first bar represents the water supplies with existing infrastructure and regulations or no action. The second bar represents water supplies with operational constraints but no northern intake, “This was a scenario that was evaluated by the state in its Bay Delta Conservation Plan draft and Dr. David Sunding did an economic analysis of the value of improving the system, when you compare it to how increased regulation can cut back water supply.”
The third bar is the earthquake scenario, which was also included in Dr. Sunding’s analysis. “In that analysis with multi-island failure, the projects would be able to have intermittent operations over a period of three years or so, and probably range in delivery amounts from about 1 to 1.5 MAF,” he said.
The next bar, second from the right, shows the average annual supplies of 4.7 MAF to 5.3 MAF under the latest version, the California Water Fix; Mr. Arakawa explained that it is a range, showing with and without spring outflow.
The last bar shows the original BDCP proposed project which is a range as well; the capacity is still the same, but the range for the BDCP is higher. “That’s because at that point, the fall X2 was being considered as part of the project, whereas today, where we sit today with the regulation, the fall X2 is being part of the biological opinions is assumed in the existing baseline,” he said. “It’s in the regulatory baseline, so that’s the main difference between looking at the 5.6 versus the 5.3, the last bar being what was proposed previously under the BDCP.”
He then presented a slide contrasting deliveries under the existing regulations versus the BDCP/California Water Fix. “Each year type presents different opportunities and with this project,” he said. “It’s fair to say that much of the flexibility comes in the average to wetter years and that’s basically the story of how all of the parties that use Delta water or use watershed water are trying to manage things, trying to be able to store water and manage it for dry years.”
Mr. Arakawa then gave some background on how the regulations are controlling the operations of the facilities to better understand how the project would provide water supplies and where there may be some flexibility, as well as future efforts in science and adaptive management.
Today, the existing regulations are operated by the State Water Resources Control Board under the D-1641 water right decision, Mr. Arakawa said. “The State Water Board sets water quality objectives which include water quality parameters and export limits and flows, and then those are implemented through a water rights decision; the state water project’s water rights permits are amended in order to comply with those kinds of operational limits that are in the plan,” he said. “So things like Delta outflow for fish, water quality for fish and for agriculture, for export quality, both M&I as well as agriculture – all of those things are part of the water quality control plan under State Water Resources Control Board.”
“Over the last 20 years, the export limits have expanded to more months,” Mr. Arakawa said. “Back in 1987 when I first started at Metropolitan, there were export limits in 2 months; May and June, and today we pretty much have some kind of limits all around the calendar, so that’s a way of characterizing the increasing limits on exports and the decreasing flexibility.”
In addition to the State Water Board’s regulations, there are Endangered Species Act regulations that are applied on the existing system, such as fall X2 and export limits, he said. “Those are implemented in different ways, but one example of that is the Old and Middle River flows or the south Delta reverse flows; those are a key part of how the endangered species act biological opinion regulates the two projects to protect both salmon and Delta smelt,” he said. “There are other export limits that are intended to help migrating salmon and steelhead down the San Joaquin River to assure that during those periods of migration that based on what the agencies feel, those fish are able to migrate down the San Joaquin River towards Chipps Island and out to the Bay, rather than being diverted towards the export pumps.”
“With the California Water Fix or the preferred option under the endangered species act, they needed to identify what kind of operational limits are necessary with the added facilities, so they identified those, and then they also identified amended or added regulations to the existing facilities to balance between the use of the north facilities and the use of the south facilities,” he explained. “So, for example, for the north intake, there are flows that are necessary or required in order to make sure that the fish that are bypassing those screens are able to get past those screens effectively and not either be impinged or actually cause stress to the fish where they are more susceptible to predation. There are bypass flows, making sure that flows that make it downstream of the intake area, that they are adequate to move those fish to the downstream portion of the system, down towards the Suisun Bay area.”
“There are proposed regulations that would allow for not diverting very much water at all when the first flush flows that occur every year,” he continued. “Every year around December or so, there’s the first big storm of the year, so making sure that when the fish take the cue and they are migrating down, that the intakes do not cause impact to those fish when they are migrating, so there are regulations that limit how much the intake can take during those periods of time.”
There are fish screen efficiencies that have to be met to be sure that the water is not moving so fast that the fish get drawn towards those screens but rather instead the screens are acting as a deterrent, that they pass the screens and go downstream where they are safe, he said.
The existing State Water Board standards would still be in place, such as the Delta outflow, the water quality requirements, the export limits, he said. “Today under the biological opinions, there’s the Old and Middle River limitations and there’s what’s called the import-export ratio which is another way of making sure that the exports don’t harm the fish that are migrating down the San Joaquin River. Those have been adjusted to balance between the north intake and the south intake, as well as making sure that there’s enough capability to move water to the south Delta pumps during the middle of the summertime when water quality in the interior Delta and the south Delta channels.”
In addition, there is the Endangered Species Act limitations on incidental take. “They monitor the number fish showing up at the fish screening facilities, and there are certain levels that are identified that if you hit those levels, you have to go back and reconsult with the fishery agencies, so those are safety factors to make sure that the project is being operated in a way that was intended,” he said.
Mr. Arakawa then turned to address the flexibility that would be provided with the proposed project and how operating requirements would be blended with that.
Adding the new intake in the north Delta is an added physical feature that adds flexibility to the operations, he said. “It would have new modern screens with technology as far as how those screens would be designed and operated to make sure that the fish are able to move downstream and not get into the tunnel system,” he said. “There would be flexibility to divert water during real high flow periods; particularly once those first flush situations occur, the intake would be able to capture the surplus stormwater that’s coming down the system, and try to capture that for storage so that stored water could be used in dry times, trying to minimize the effects, because of the ability to take that gulp in the big wintertime flows or in the wetter years, and using that same flexibility so that you’re not having to have any impact in the drier times.”
In the south Delta, the facilities would allow for a blend of diversions from the south Delta and from the north Delta, he said. “Today, the projects are only diverting from the south Delta, and that is much of the concern about fish and how the projects are affecting the fish,” he said. “Based on what the fishery agencies are thinking, the reduced reverse flows as a result of having those north intakes is also an added flexibility. Because of the physical features being added, there is less fish salvage, because you’re able to take your exports to a great degree from the north intake where those fish are able to move past the screens and down the system.”
In addition to the physical flexibility, there are the operational constraints that were defined by the fish agencies to try to balance between the use of these different intake systems, Mr. Arakawa said. “In the north Delta, limiting the diversions based on the amount of flow going down the river, trying to stay away from diverting too much flow during the low flow periods, and making sure there are enough bypass flows to make sure that the fish are moving down the system and not being caught in a maybe a tidal back and forth pattern in front of those screens, and assuring that there are flows downstream at Rio Vista. In addition, in the proposed operations, they’ve added the spring outflow that is expected to provide benefit to the longfin smelt. So those are constraints that would be part of this project or requirements.”
“In the south Delta, there would be some added restrictive reverse flow elements, so for example, rather than the Old and Middle River flows starting in December, they could start as early as October; there are also periods where the constraints are more constraining then they would have been under the biological opinions,” said Mr. Arakawa. He noted that included in the proposed facilities is an operable gate for the Head of Old River barrier, explaining that the purpose is to try to keep migrating fish moving down the San Joaquin River rather than moving towards the export facilities.
Excess Stormflow Analysis
Mr. Arakawa then talked about the added water supply benefits this added flexibility would provide in capturing excess storm flows. He began by noting that in the Sacramento watershed, the range in hydrology is pretty varied, going from the very dry years situations like in 1977 or 2014 which are on the left of the graph, up to the very wet years shown on the right. “The average has been about 18MAF over a period of 1906 to 2014, so a wide ranging hydrology I think is the story of this,” he said.
He noted that state and federal water projects, and particular the State Water Project, have only a fraction of the storage on the system in comparison with what storage is available on the Colorado River system. “The Colorado River has somewhat less variability in hydrology, so instead of 38 MAF, it’s about 20 MAF, and in addition, the Colorado River system has 60 MAF of storage, as compared to the 4.5 MAF of Oroville for the SWP along 1 MAF on the SWP down in San Luis Reservoir, south of the Delta. So significantly less capability to store water and so you have overlaid on that a wide range of hydrology, limited storage, and then increased constraints in the Delta, so the Delta and the constraints there is really the big issue in terms of how do you get flexibility.”
He then presented an example from the fall of 2009 to early spring of 2010, noting that the dark blue is the amount of flow coming into the system on the Sacramento River and the San Joaquin River from the south, and the lighter blue is the amount of exports that occur during that time period. “These are the actual amounts of flow that were measured and exports that were monitored on a daily basis, so in this Metropolitan analysis, we looked at daily amounts of flow coming in and daily amounts of exports. The amount that could be diverted if there were a north intake is depicted by the white line. The white line shows that in certain periods, when you have these peak storm flows, you would be able to meet the added requirements that are in the proposed project but still gain that added flexibility of diverting a portion of those stormflows during periods when it’s less impactful to the system.”
“So in this particular year, we looked at the January through March period and identified meeting the proposed requirements, but having the benefit of that added flexibility of the north intake, we estimate that about 450,000 acre-feet of supply could be available to divert and put into storage for use during a later time,” he said.
He then presented the same graph but for the December 2010 and January 2011, which a wet year. “I believe we had 90% allocation on the SWP so there was a lot of water, but again the blue shows the inflows into the Delta, the light blue shows the exports of the two projects, and the white shows the added flexibility of capturing stormwater flows, and so there, if we had added flexibility, and as that flexibility leads to increased storage capability south of the Delta, or for that matter even north of the Delta, that adds added water management capability within the whole system.”
“Part of how water agencies try to deal with a wide range of hydrologies in years when it’s wet is to try to store that water and then pull that out of storage in dry years,” he said. “In medium, normal years or even on the dry side, when there is transfer water available, they try to utilize the voluntary transfer water market as a means of supplementing supply, and recently with the added biological opinions, it’s been very constraining to try and move that transfer water because of the increased limits and the narrow windows that are provided by those biological opinions.”
He then presented a graph showing the difference in water transfer capability between the existing facilities, depicted with the gold line, and then with the added California Water Fix option shown in blue. “Think of this graph along the x axis or the horizontal axis going from wet period down to dry, so the left is dry and the right is wet,” he said. “In the wet periods, there’s all kinds of water so the capacity of moving transfer water is going to be much more limited than in dry periods. In dry periods, the State Water Project and the Central Valley Project has less water, and so there’s more empty capacity to be able to utilize, so this is showing the difference in those various years, ranging from dry to wet, of what kind of transfer capability could be regained, because in fact this capability did occur in the past to some degree, and this is trying to capture back some of that flexibility to allow for water transfers to be a part of our water management strategy.”
He noted that the difference between the existing system and the existing system with the new facilities is 224,000 acre-feet. “Now that’s not to say that all of that water is available or has willing sellers; this is just an analysis to show what kind of capability would be in the system, and because it has a benefit in most of all of these different year types, it gives you an ability to determine when would you want to buy transfer water and how would you want to manage it.”
Collaborative Science and Adaptive Management
With the proposed facilities, there are new spring flows, fall X2 as part of the baseline, Old and Middle River flows, so what is the science behind those proposed operating measures or the existing operating measures? “As part of the proposed project, there is a intention of building off of today’s system of collaborating on science that’s occurred since the federal court decision, trying to get the fish agencies, the water contracting parties, and non-governmental organizations to collaborate on the science, to identify where the gaps in the science are, to target some studies to try to fill in those gaps, and then utilize that information by policymakers, management decision makers, to make better informed decisions about how to protect both the fish but also provide for water supply reliability,” he said.
The ongoing collaborative science program includes Fish and Wildlife Service, National Marine Fisheries Service, Department of Fish and Wildlife, water contracting entities, and other non-governmental organizations and environmental interests such as the NRDC, the Nature Conservancy, and the salmon fisherman. “They’ve been part of the science collaborative process to identify how to answer some of these scientific uncertainties to better manage the system,” he said.
Mr. Arakawa said that the proposed project would have an adaptive management and monitoring plan that would be based on collaborative science that builds from that existing effort underway, and to model after that and to broaden it so that the existing regulations that we’re operating under today as well as the newly proposed operations where there are scientific uncertainties, to fashion tests and studies to attack those issues scientifically to better understand what kind of better decisions can be made to manage the system.
“This is really key, because with today’s system, we’re operating to regulations that may or may not be working as well as they could,” he said. “Many on the water agency side believing that the standards tend to be calendar based or rigid, rather than maybe being informed by increased monitoring and additional science effort that really could help inform how the project could be operated.”
Mr. Arakawa then discussed water quality benefits, first presenting a slide showing salinity or total dissolved solids (TDS) from selected water sources. He noted that the Sacramento River has an average TDS of 100 milligrams per liter; the San Joaquin has an average TDS of 320 milligrams per liter, and the Colorado River has a long term average being 650 milligrams per liter.
“The important thing for us in our region is how do we manage our water quality in a way that helps with our water management activities because local water supply development through recycling and through groundwater management are very much linked to the quality of our imported supply,” he said.
He noted that the Sacramento and San Joaquin River numbers are from historical data, and the SWP and California Water Fix are both modeled outcomes. “Here we’re showing the comparison of the modeled outcome between having no north Delta diversion versus having that diversion, and there is a 27% reduction in total dissolved solids when having that northern Delta diversion,” he said. “The reason being that being able to divert from that north end provides a means of blending the Sacramento River at about 100 milligrams per liter along with the south Delta diversions that we would continue to divert. The San Joaquin River quality is higher because of agricultural drainage and such, and so when you have the ability to divert from that north intake, you’re able to avoid the land-derived salts from the San Joaquin system or even the in-Delta agricultural returns that do return salinity as well in the Delta, and also avoid the salt water intrusion from the San Francisco Bay, so it has that value.”
Bromide is also very important because when water is treated, it creates byproducts, particularly for Metropolitan with our ozone treatment plants, he said. “Bromide comes mainly from seawater, and when it is present in the water, it can help contribute towards production of these byproducts that are regulated under state and federal requirements, so bromide levels are also very important from a public health standpoint.”
He noted that the difference between the existing versus the proposed project is a 37% improvement in bromide level, and that would have a significant benefit to Metropolitan and other agencies that are using ozone treatment and are concerned about those byproducts.
Mr. Arakawa noted that in his presentation, he covered the details of the operations for the new facilities versus the existing facilities; how the new intake provides added flexibility, and added reliability by being able to capture those stormwater flows; and by being able to get back some of the lost transfer capability that the project at one time did have, and that the project does improve water quality both for water management, for local supply in Southern California, as well as for public health.
“Overall, with these proposed operations that are tied to the project, the key is how will the decision making occur under the collaborative adaptive management system, so that the best information can be used to manage the system,” he said.
More on the California Water Fix project with the first of two-day coverage from the recent informational legislative oversight hearing by the Senate Select Committee on the Delta, led by Senator Wolk.