Delta Independent Science Board: Water Supply Reliability Panel

A look at the operations of the State Water Project and the Central Valley Project

‘Water supply reliability’: It’s a term you hear quite often, but it can be hard to pin down what exactly people mean when they say it, as the term seems to mean different things to different people.  At the February meeting of the Delta Independent Science Board, a panel of water resource engineers and project operators gave their perspective on what water supply reliability means in terms of water project operations.

Seated on the panel were John Leahigh with the Department of Water Resources’ State Water Project and Ron Milligan with the Bureau of Reclamation’s Central Valley Project; accompanying them were water resource engineers Walter Bourez, Armin Munevar, and Erik Reyes.  Here’s what they had to say.

Walter Bourez, Senior Water Resources Engineer for MBK, led off the presentation by saying that when he was asked to talk about water supply reliability, the first thing that came to his mind was how reliability was being defined, as almost everybody has a slightly different definition.

You can actually Google it and find definitely dozens and dozens of different definitions of water supply reliability,” he said. “CUWA defines it as the ability to consistently meet demands, CalFed defined it as the probability that a system does not fail, and a famous UCD professor is quoted as saying, ‘the likelihood that I can get all the water I want cheaply.’”

It does mean different things to different people,” he continued. “Some folks think it means that average annual deliveries get me as much water as I can and I have alternative supplies, some people are very concerned about it as they have only one supply and they have to meet dry year demands. For biologists, it may mean cold water supply. If you’re a Delta smelt biologist, you need enough Delta outflow and that has to be reliable, so there are lots of different ways of looking at this.”

DISB WSR PPT_Page_03Armin Munevar, Senior Water Resources Technologist with CH2M Hill, added that water supply reliability or water delivery reliability needs to be thought of within the context of an integrated hydrologic cycle. “When we talk about water supply and water delivery reliability, we’re not talking about a concept that’s very distinct from what we’re trying to manage in the overall hydrologic systems,” he said. “We need to understand and talk about the ripple effects that we have for various impacts within the hydrologic cycle or on water deliveries have impacts on other aspects.”

California has an intertied water system that allows water managers to divert, store, and deliver water to various parts of the state through an array of networks of conveyance facilities and storage facilities. “So when we look at water supply reliability, we’re looking not just at the local effort in terms of improving diversification or improving reliability of local supplies, we’re looking at how do we improve the system function to improve reliability for those who have challenging reliability concerns,” said Mr. Munevar.

DISB WSR PPT_Page_05Some regions of the state have incredibly diverse water supply portfolios which include desal, Colorado River water, recycled water, and large investments in groundwater and recharge; other regions such as many parts of the Central Valley, there are far fewer options for water supplies, Mr. Munevar noted. “These portfolios are what determine a water delivery or water supply reliability for that particular entity,” he said. “So as we talk about water supply reliability, it’s important to understand, water supply reliability for whom? Depending upon who we are talking about, we have very different opportunities for looking at reliability.”

Mr. Munevar pointed out the many drivers that affect reliability. “Certainly climate and hydrology are probably the major drivers, certainly in the near term and drought aspects,” he said. “We have both a very diverse and variable climate, we also have a climate that’s evolving, we have a hydrology that’s responding to that climate, and we have a spatial variability of that climate. There are operational strategies that determine individual reliability in various parts of the state; the opportunities for alternative supply vary considerably, and institutional constraints on the system challenge water supply reliability.”

DISB WSR PPT_Page_08We have an extremely variable system here in California, it’s what makes it so much fun for us on the panel here to evaluate and such a challenge for you folks to explore opportunities,” he said. “We have large precipitation in the northern part of the state, a relatively dry southern part of the state, and the population mostly exists in the southern portion of the state. Climate change and projections of future climate suggests we’re going to have more variability in the system, certainly a higher degree of warming and likely a more variable precipitation arena that may not necessarily mean the drying of California but that may mean a more variable hydrology and climate for California.”

DISB WSR PPT_Page_09Mr. Bourez then presented a graph of the Sacramento Valley Water Year Index from 1905 to present day. “One of the largest factors in water supply reliability is the highly variable water supply we get each year,” he said. “There are periods of long droughts … but what’s really interesting is that the last several years, we have had one wet year, 2011, but we’ve all been below normal, dry, and recently, very critical years.”

The bottom graph is the top one sorted,” he explained. “We looked at probability of exceedance for 2016, and so there’s a 90% exceedance level, it would be exceeding critical years, and with the recent rains we’ve had, our 90% exceedance forecasts are looking a lot better than they have the last couple of years, which is good news. But with this highly variable water supply, back-to-back droughts, and single year droughts, and sometimes we’ll get four or five years that are very wet. This makes it very difficult for planning and trying to operate and balance the system out, and it means something different for water supply reliability throughout the system.”

DISB WSR PPT_Page_10Mr. Bourez then presented a similar slide for the San Joaquin River basin, noting that it is a different index but it’s also similar. “This is in my mind the most difficult or the biggest factor in water supply reliability,” he said. “If we had all wet years, we’d be out of a job. But with this highly variable climate, it’s difficult.”

One thing the annual plots don’t reflect is that not all critical years are created equal, he pointed out. “It depends on the timing of when you get that precipitation. If you get precipitation late in the spring, it helps meet a lot of the agricultural demands, it helps with migrating fish, and it really changes the operation of the system. If we get a lot of snow, we’re going to get late runoff. If that comes in warmer storms, that water has to be captured earlier in the year, and with our flood diagrams, we can’t capture it all, so within this hydrologic variability from year to year, every year has a different pattern of precipitation which is also difficult to manage.”

DISB WSR PPT_Page_11Mr. Bourez then presented another slide, noting that the numbers indicate average annual flows below the reservoirs. “It’s just an indicator of how much water is leaving below those particular reservoirs,” he said. “There are a lot of districts in the San Joaquin that have one district and one reservoir … Water supply reliability means something different to different entities. If you’re an entity that is more concerned about the minimum year delivery because you have to protect M&I uses, that’s different than if you are an ag entity that has supplemental supplies such as groundwater, so average annual water deliveries may be your best indicator for reliability, whether than just a dry year delivery.”

Mr. Bourez noted that the State Water Projects has a provision where contractors can take some of their State Water Project allocation and store that in an SWP facility for use in a drier year, so the different districts can manage their own risk; the Central Valley Project has something similar called rescheduled water.

DISB WSR PPT_Page_14He then presented a slide of a hypothetical reservoir operation to illustrate the concept. “You empty that reservoir every year, and you have very little reliability, and if it doesn’t rain, you’re going to have a lower delivery,” he said. “As you go through this from wet year to dry year, your dry year yield is 25, and that may not be enough to meet the demand. In a more conservative operation, it has a lower average annual delivery but the critical year delivery can be much higher. These are two very distinct operational strategies that the operators have to grapple with on a regular basis on how to allocate that supply and how to protect the upstream for reliability. It depends on who the reliability is for, whether it’s for cold water for upstream fisheries, or if it’s for average annual deliveries south of the Delta. This has a very large influence on the operation of the system.”

Alternative water supplies are an important component to reliability and, one of the keys in California is conjunctive management as there are a lot of entities who rely on groundwater for their supplemental supply and sometimes their primary supply. The Sustainable Groundwater Management Act is changing the way we look at groundwater, reliability, and sustainability, he said.

DISB WSR PPT_Page_17Mr. Bourez presented two maps showing reductions in groundwater levels: on the left from 2005 to 2015, and on the right, 2012 – 2015. He noted that the chart doesn’t show the single year drop from 2013 to 2014 where some areas dropped as much as 50-feet in on year. “That is very substantial,” he said. “It’s more prevalent in the Tulare Basin and the San Joaquin, not so much in the Sacramento River basin where the surface water and groundwater system are more interactive as they are highly linked.”

DISB WSR PPT_Page_19He then presented a historical plot of groundwater in the Tulare Basin near Delano from 1920 forward, noting that the groundwater levels were dropping until around 1955, when they started going back up again. “That’s when the Friant Division was built, and we started diverting water from Friant Dam,” he said. “The CVP was originally developed to deal with the groundwater overdraft problem and the reliability in the Tulare Basin and the San Joaquin.”

We fixed the problem, and now it’s back because we have recognized that we need to provide more for environmental conditions,” Mr. Bourez said. “This is one of the tradeoffs in the state that we’ve had. We’ve had more export restrictions and now Friant is going to be releasing more water for restoration, and we can’t just build another Friant Dam to cure that problem. Even with a lot of new storage, it won’t cure that problem. We have to look for different solutions for water supply reliability throughout the state, and that is demand management at this point. Folks are coming to grips with that and it’s a very difficult situation; it’s difficult to deal with.”

DISB WSR PPT_Page_20There are a lot of tradeoffs in the system,” he continued. “Water supply reliability in one area of the state could mean less reliability in another area. There are tradeoffs between water deliveries, Delta outflow, and environmental flows. North of Delta deliveries versus south of Delta. The balance between Shasta and Folsom the past few years has been a very difficult balance, because the State Water Board ordered reduced releases from Shasta last year and put a greater burden on Oroville and Folsom, so Folsom went very low and the reliability for American River folks was at risk. How do you balance that out? We have an environmental need versus an urban need, and that tradeoff between the reservoirs and that operation defines what the reliability is for those different geographic regions.”

There are many, many tradeoffs in the system,” he said. “It’s a management issue, it’s a policy issue, and it’s one that we’ve been grappling with for many years. Environmental flows versus water deliveries. Protecting cold water pool for salmon versus Delta outflow for smelt. Where do you want your reliability?

DISB WSR PPT_Page_21Mr. Bourez then presented a graphic showing some of the characteristics of the State Water Project and the Central Valley Project. He noted that for the Central Valley Project in terms of storage, there is Trinity at 2.4 MAF, Shasta at 4.5 MAF, and Folsom at 1 MAF, while the CVP can pump 4600 cfs out of the Delta.  On the other hand, the State Water Project has Oroville at 3.5 MAF for storage and can pump 10,300 cfs, but the permit capacity is 6680 cfs. “So the CVP has about 8 MAF upstream, compared to 3.5 MAF on the SWP side, and the opposite is true for the pumps out of the Delta,” he said.

Each one of the reservoirs has different characteristics,” he said. “With Trinity, the average inflow is about half the capacity of the reservoir, Shasta the average inflow is about 1 MAF or so more than the storage, Oroville is about 500,000 acre-feet and Folsom is completely opposite of Trinity. So Folsom has a very high probability of refill because the inflow is so much more higher than the storage of the reservoir. When you’re looking at reliability in operating the system, you have to operate the system as a unit, and you typically draw Folsom down more because it has a higher probability of refill. So all these go into the equation of balancing the system and optimizing water supply reliability.”

DISB WSR PPT_Page_22He then presented a graphic showing how water moves from the Sacramento and the San Joaquin Rivers to the export pumps in the south Delta. He explained that water is released from Shasta, Oroville, and Folsom, comes down to the Delta, to the Delta cross channel, which can be closed to stop the flow coming down the Mokelumne; water comes down through Georgiana Slough, and it comes down through the Delta channels, or it can go out toward the ocean. Water from the San Joaquin comes from the south; he noted that the San Joaquin is saltier and has much less flow than the Sacramento; he also noted that water coming to the export pumps can also go around Sherman Island and come back in.

These are reverse flows which are not the best for fish migration when we have a net flow coming back in, so some of the environmental criteria that are the most constraining for water supply reliability in the southern part of the state are criteria on flows in Old and Middle River,” said Mr. Bourez. “Preventing that reverse flow to keep the Delta smelt away from the Delta pumps is our biggest constraint right now in terms of water supply reliability south of Delta. If you noticed during the storms, we may have had 50,000 cfs of Delta outflow and maybe pumping 2000 or 4000 cfs out of the south Delta, and it’s all governed by the flow in these two corridors.”

One of the main drivers of change in water supply reliability are changes in the regulatory environment. “In the late 1980s, we operated to D-1485; then in the mid-90s we had CVPIA, that’s public law 102575, and then we had the adoption of the biological opinions in 2008 for salmon and smelt,” he said. “These added a lot of constraints and it changed the way the whole system operates.”

DISB WSR PPT_Page_25 He then presented a graph to show how much things have changed. “In terms of total Delta outflow, D 1641 increased Delta outflow by an average of 300,000 acre-feet. When we look at the biological opinions compared to D 1641, it’s about another million acre-feet of outflow; that’s primarily because of the Old and Middle River flow criteria and the San Joaquin I-E. In other words we prevent the system from pumping in the spring and taking surplus out of the system, so all in all over the past 20 years, 15, years, we’ve dedicated about 1.3 MAF more to Delta outflow.”

DISB WSR PPT_Page_26Mr. Bourez acknowledged these are all from modeling studies. “One of the things that the modeling does show that is key is the reduction in Shasta storage,” he said. “We’ve seen this in actual operations. It may not look like much on this line here but in some of these critical years, the reduction in storage is a big deal for protection of winter run and cold water pool management; it’s also a real big deal for water supply reliability. Protecting the reservoir storage for cold water pool management for fishery and urban water supply reliability and dry year supplies go hand in hand. We’ve changed the way the system operated and put a greater burden on storage. You can see with Oroville, the state has a much greater capability of moving stored water from north of Delta to south of Delta than the CVP does, so you see a pretty quick linkage between the two.”

DISB WSR PPT_Page_27Mr. Bourez said that with D-1485, the projects were operated by taking as much surplus out of the system as they could when the surplus was available, and didn’t draw the reservoirs upstream down; the upstream reservoirs were used more for dry year reliability. “What’s happened with the biological opinions is that we can’t take the surplus out of the system anymore so we rely much more heavily on releasing that stored water beginning in July, so it’s pulled the reservoirs down more, and it’s changed the way we operate the system,” he said. “We used to make yield on the State Water Project side by taking surplus out of the system and leaving Oroville high. Now, we have to pull Oroville down and capture the surplus there. So it’s a different mechanism for reliability.”

DISB WSR PPT_Page_28Another alternative supply besides groundwater is water transfers. “When we were looking at D-1485, we had a lot of capacity to move water in a critical year, so you could go buy water and have high confidence that you could move that water to your location,” he said. “Now, with the biological opinions and the pumping restrictions, we have much more limited capability of purchasing transfer water from north of Delta to move to south of Delta. Last year, there was water stranded upstream, and we had to deliver the transfer water after the irrigation season, so there’s a huge risk in transfers. Folks are wondering what to do about this ability to convey water.”

DISB WSR PPT_Page_29He then presented a slide showing the historical Folsom operation from 1960 up to 2014, pointing out that back in the 80s, Folsom wasn’t exercised as much as it is being exercised now. “We pull the reservoir down much more,” he said. “In our operation since D-1641 was adopted, we rely more on stored water and Folsom is one that get exercised the most.

Mr. Bourez recalled that in 2011, a very wet year, there were relatively low flows in June in the American River, and then in July, the flows went up to 5500 cfs because that was the first opportunity to export that water. “So we’re relying on that stored water, and it has changed the flow regimes upstream, cold water pool management, and temperature management, so that’s a tradeoff we’ve made, and that’s changed the reliability of cold water upstream as well as our dry year protection upstream.”

DISB WSR PPT_Page_30He then presented a similar plot for Shasta, noting that in 1977, they brought the reservoir down to about 560,000 AF, whereas last year it was about 1.3MAF and this year about 1.6MAF. “The difference in that is in 1977, we met the contractual obligations of the projects,” he said. “We had 25% ag allocation, and both 2014 and 2015 that was 0 for the CVP and this last year, we didn’t meet exchange contractor demands so we had to release water from Friant. If we were to operate in 1977 with same criteria we have today, we would see something more like 2015 where we didn’t meet all of those. So it’s been a big change in reliability for environmental conditions, and for water supply reliability throughout the state.”

John Leahigh with the Department of Water Resources then gave the perspective from the State Water Project. He began by noting that the State Water Project (SWP) primarily serves municipal and industrial purposes with about two-thirds to three-quarters of contracted deliveries going to M&I uses; SWP also serves 750,000 acres of farmland in the Central Valley.

Lake Oroville is the primary storage reservoir for the State Water Project. “The yield of the project doesn’t come primarily from Oroville storage,” he said. “It comes from the unregulated flows that are in the system that are generally picked up during the winter and spring periods, so there’s a vast amount of runoff in the system that occurs from precipitation downstream of the major project reservoirs, and from unregulated rivers in the system. For example, there are no major dams on the Middle and South Fork of the Yuba Rivers, and to a lesser extent, Mill Creek, Deer Creek, and Butte Creek up on the Sacramento system, so besides Oroville storage, the other place we’re picking up the supply is at the export facilities in the south Delta at Clifton Court and Banks Pumping Plant. That water is stored in San Luis Reservoir for later use when the demand is higher.

That is supplemented by storage in Lake Oroville, but to a large extent, the Oroville piece is on the reliability component,” he continued. “It’s first reliability is to meet Delta standards during the summer, and to meet senior water contractors, settlement contractors that existed before the project was built. Subsequent to that, the storage could be used to bridge the gap between our contractor’s requests and the actual deliveries that we’re able to make to them.”

DISB WSR PPT_Page_31Mr. Leahigh noted that similar to Folsom, Oroville’s storage is being exercised to a much greater degree. “That is due to the loss of a lot of access to the unregulated flows that are occurring in the winter because of the new biological restrictions,” he said. “In recent times, we’ve been in a bit of a dry stretch with the last 10 to 15 years have been on the dry side as compared to the longer term record so there’s a little bit of that going on as well.”

DISB WSR PPT_Page_32He pointed out that the demand for state water has been increasing over time, reaching full build out essentially around the year 2000. “You can see the blue line here is the requested amounts of deliveries,” he said. “We’ve contracted for 4 MAF for the entire project; about half of that goes to Metropolitan Water District, about a quarter to Kern County Water Agency, our largest agricultural contractor, and then the other 27 contractors make up the remainder of that total. What you can see over time when the project was essentially demand limited, starting from early 70s through about the mid 80s, and as that demand was growing over time, we were able almost every year, with the exception of 1977 in there and the one drought year, we were essentially able to fulfill requests of the project.”

After the first long-term drought in the late 80s and early 90s, demand went up. “Part of the reason is as the other sources dried up, folks became more reliant on the State Water Project for their supply, so we then became supply limited at that point,” he said. “We saw a series of wet years here in the late 90s, there was an abundance of water from other sources to our contractors and they were less reliant on the SWP so there was a reduction in the demand and we were able to fill the requests.”

Moving into the 2000s, there are a number of things going on, he said. “We’re at full build out so this demand remains essentially full contract, or 4 MAF,” he said. “Part of the way that our contractors got to this high demand is by investments in infrastructure within their local areas, so for example, Kern County has invested in infrastructure for some major groundwater recovery in the Tulare Basin, and so when there are excess flows, we are able to deliver that, Kern County is able to recharge some of those depleted groundwater basins.”

Metropolitan has also made investments, he noted. “There are some groundwater programs, but also surface water infrastructure, so there’s been much investment. Diamond Valley is most notable example of that.”

Mr. Leahigh then laid it out straight for what it means for State Water Project reliability. “What we’re seeing now to a large extent is a combination of three things: one is the full build out of demand – you see the big shortage between what they are requesting and what they are actually getting over the last few years. We’ve seen very dry years in the last four years, but really the last 8 out of 9 have been either below normal or drier for the Sacramento Valley and the San Joaquin Valley. It’s also been the added restrictions because of the conflict between the fishery that are most vulnerable to the pumping operations at the same time we would be accessing a large part of our yield, which are those excess flows coming in in the winter and the spring period. So from this point on, if the system stays the way it is, we anticipate chronic shortages on the State Water Project.”

Mr. Bourez then presented a graph showing total exports from the Delta for both the State Water Project and the Central Valley Project. “You can see the influence towards the end here of both the drought and the new restrictions that came online in the biological opinion for Delta smelt in 2008, and the NMFS biop in 2009. So both of those are having an impact there.”

In terms of straight water supply development in the state, we’ve taken a step backwards as far as our ability to actually develop the water in the system,” he said. “Coming off this historic four year drought, we now have some very decent flows in the system. To a large extent we’re able to divert a lot of that runoff upstream as a lot of it is in the snowpack for later snowmelt and later management later in the year. There is a huge amount of untapped supply that is flowing out of the system right now but given the current regulatory environment and the operating rules, there’s no opportunity to really capture much of this flow, and really what we’re talking about here is new investment in infrastructure would be perhaps one way to recover some of this lost opportunity that we’ve had, and we’d be able to manage some of the excess flows.”

DISB WSR PPT_Page_34Another graph is presented, with a panelist (sorry, unsure of whom) recalled how last year, there were two storm events, one in December and one in February, and pumping was restricted because of the Old and Middle River flow criteria, and there was water that could not be captured. “There’s two ways that could have been captured that are projects under investigation: one is the California Water Fix, the other is Sites Reservoir,” the panelist says. “Last year, we could have captured 400,000 AF during those two high flow periods and store that in Sites Reservoir. 400,000 AF last year would have been night & day difference for water supply in the state and could have helped out a lot of the fish species. The number this year is roughly the same. Just this last month, we could have captured about 400,000 acre-feet and put that into Sites Reservoir as well, so even when we have these drier times, there are periods of surplus and a lot of water supply in the state enters the system below our major reservoirs and we can’t capture that. The CVP and SWP were designed to pull that out of the Delta, now we have restrictions and can’t do it, so we’re looking for other opportunities to capture that water. Delta tunnels are one, Sites Reservoir is another, and this is just looking at that opportunity and what those projects could add to the system.”

DISB WSR PPT_Page_35The panelists explain that Sites is a proposed reservoir south of Redding that would work functionally similar to San Luis as an off-storage facility, but since Sites Reservoir would take directly off the Sacramento River further up the Valley, it wouldn’t have those restrictions that exist in the Delta because it’s tapping into the water prior to it reaching the Delta. They note that on the Sacramento River, Cottonwood Creek’s average annual flow is 680,000 acre-feet, Cow Creek is about half a million, so average annual accretion in the system just in this area is about 2.5 MAF, so that’s the water that would be stored in Sites.

DISB WSR PPT_Page_36Mr. Bourez presented another slide, saying it was anecdotal look at what surplus flows within the recent month that might represent a missed opportunity. He explained that the solid blue line is the actual Delta outflow that’s occurred since early January, the solid red is the actual combined CVP-SWP exports, and the dashed green line is the required outflow as it exists today under the water quality control plan under the State Water Board. “You can see the difference between the actual, the solid blue line and the dashed green, I’m calling it excess outflow for these purposes, and just within a little over a month, there’s been excess outflow of over 1.6 MAF, so that’s about 1/3rd of the full Table A for the SWP.”

He noted that there isn’t the capacity to pick up that kind of flow, “but this is an example of if the California Water Fix (the tunnels) were in place, including all of the requirements that would be associated with that, for example certain bypass flows that would need to be achieved before we could start diverting any water from that facility – that’s all taken into account in this graphic. The dotted red line represents the total diversion capability with the California Water Fix in place, so the difference between the solid red and the dashed red would be the additional theoretical north Delta diversion volumes would be attained. Of course, that comes off of the outflow, so that would mean less outflow, so the dotted blue line here would be the resulting outflow that would occur during the same period, so we’d be skimming off the top of this excess flow. It could be argued that’s still well over a million acre-feet of excess outflow, even if we had diverted this extra water, so this is just anecdotal as far as how the interaction is occurring in the system.”

DISB WSR PPT_Page_04Ron Milligan with the Bureau of Reclamation then discussed the operations of the Central Valley Project. Redirecting to an earlier slide, he noted that if you take a slide like this and then superimpose all the local projects on top of this, you realize how intertwined and complicated it is. “We have operational partners in the Sac Valley, San Joaquin Valley, in the Delta, and the Tulare Lake basin, and a lot of these things connect up,” he said. “What we are seeing more over the last couple years than ever before is how a decision, whether it’s operational or regulatory, up in the very northern part of the system, has implications for the CVP that can extend all the way south of Bakersfield, and/or have implications certainly for the SWP that go all the way to southern California.”

This goes back to the point that reliability depends on the entity that’s asking the question, he said. “A good point about the portfolio concept is what part of these bigger statewide or regional projects make up what part of your portfolio and how does that mix into your reliability? Because very few folks are relying on just one source and the ones that do really struggle when we get into a drought period, so that’s really important.

Mr. Milligan also pointed out that power generation is an important function of the Central Valley Project, where they market the excess power not needed for operations to other customers. “There’s always a discussion about what’s a base resource, meaning power through the day, and then certain customers want that because they don’t have a lot of other resources. Then there are also folks that would like to see our power generation for the CVP be more peaking power, because that’s more expensive, and they can go out and find their own base resource, so understanding the needs of the customer is important as well.

He noted that the precipitation comes mainly in the north during the winter and spring, and the areas in the south need their water more in the spring and summer, so there is a geographic as well as a timing issue that has to be dealt with. In 1977, there was about half of the population that we have now. “So as the demands continue to change, and as we talk about scenarios with climate change, this timing question is going to be even more difficult,” he said.

DISB WSR PPT_Page_09Mr. Milligan then referenced the graph of the Sacramento Valley index, and said if you were to look at Delta pumping as an indicator of generic CVP-SWP production yield, it would look similar to this graph. “The question is if you just drew a line through all of those peaks, is that reliability? Is it the steepness of that line? If this is really steep, then you have a big variation between dry and wet, and if it’s fairly flat, you’d say it’s maybe a very reliable supply, it doesn’t have that big variation, so is that what we’re trying to achieve when we’re talking about reliability? We do talk a lot about that, as to when you put your pieces of your portfolio together, can you help flatten out this curve or use some kind of a gap analysis, how do you fill in for those critical years.

The one thing we didn’t talk about that’s important to think through is the water rights priorities we have in the state,” Mr. Milligan said. “Some of our most senior water right holders have been there a long time, but we find those folks tend to be more agricultural based … Those water rights priorities also need to be thought through as to how do we rate overall system reliability, particularly for the CVP that has a lot of different both regional and water use types mixed into that … how do we then navigate through that in terms of the question of the senior water right holders?

That’s where the question about transfers comes in. Transfers, is that a way we mix this altogether and try and even that out, and this gets into the good questions about marketing and economic water dynamics as well, so that’s a tool,” Mr. Milligan said. “We didn’t really talk about the water rights mix, but John and I don’t get to really pick where we think we would like the water to go in that sense. A lot of the Sacramento Valley operation is dealing with that dynamic as we go through this. So that balance of cold water and even senior water rights and how to balance those has also been taking up a lot of time and ordinarily we can check that box off pretty quickly in the winter periods and the last couple of years, that has become the real cutting edge as to where we have to do our work.”

Erik Reyes with the Department of Water Resources then added that the water projects were originally constructed to improve reliability by dealing with two central problems: a spatial problem and a temporal problem. “You have the supply happening in the northern part of the state mostly and the demand mostly in the south, so that’s a spatial problem. The way the project dealt with that is conveyance. You’re going to move water from where it is to where it’s needed. The other aspect is the temporal matter where the supply is arriving in the wintertime and the demand is mostly in the summertime, so you want to shift that from where it is in winter to where you need it in the summer. That was largely achieved through storage, so you have storage and conveyance trying to deal with both the spatial and temporal aspects of dealing with reliability.”

Over the years with increasing regulations, I think we’ve been losing the flexibility to deal with this temporal and spatial problem,” he continued. “Then with climate change, you’re also reducing flexibility, and so essentially these projects you hear about now like conjunctive use, alternate conveyance, offstream storage – these are all projects that are trying to restore flexibility to the projects and so these operators like Ron and John can deal with issues that were facing now.”

Discussion period highlights

The panelists were asked what their outlook for the future is.

Going forward, as we get through what’s probably not just a three year drought, but probably the dynamics of the last eight years in California, is to pull what we’ve learned from this and use this as more of a model that brings in a lot more of the variables that we’re having to deal with,” said Ron Milligan. “One of the things that we need to think about as we predict forward is the effects of drought and things that are beyond just water project operations, such as the effects on some of the species, what did those mean and how do we address those, because if we continue to just focus on the project operations, we may be missing some stressors out there that are probably very significant.

What I predict is that we’re going to have a group of folks that are probably going to be very smart, looking at what we learned and what were the difficulties that we didn’t necessarily anticipate coming into this last drought sequence, and the nature of it going forward so that we can protect ourselves, because we’ve stressed out parts of the projects or part of the state water infrastructure where the resource itself, from the fisheries standpoint and I think the groundwater piece of this, isn’t going to be able to rebound, so I think that’s going to be a concern,” continued Mr. Milligan.

We probably need to be really smart about what pieces of infrastructure that we both put into place that’s new and where do we invest our dollars on maintaining and maybe enhancing the existing infrastructure, because some of our components are nearly 70 years old, and we need to decide how we’re going to put our investment dollars there,” he continued. “One of the things we didn’t talk about was flood control and flood management, and if we have climate change differences, and if we do get a different mix of rain-snow with these multi-purpose reservoirs for water supply, we probably need to think about it using all of our tools and how we most dynamically manage potentially large precipitation events that have a different snow-rain mix to them, so that we’re not just blowing out a lot of water and not being to manage it later on. I think these are areas where we can bring some new technologies to bear.”

Jay Lund asked about water markets. “How do you see that as affecting water supply reliability and our ability to estimate the reliability of water, not necessarily for projects, but for its availability for water users?

Ron Milligan said its been a struggle to define transferrable water. “Part of the struggle is there are a lot of things that are on paper that says the project will deliver this amount of water under these circumstances, even if it’s a critically dry year measured by such an index, this is what the project will do,” he said. “Sometimes what we’ve seen is if you pile up all those papers together, there’s just not enough water to do that, so what does that mean? The concern for us in a dry sequence – those agreements are great and they probably function 95% of the time, but it’s that 5% of the time where people really want to execute on those and how do we know we have the right elements in there? This goes to the question of real water versus paper water, and I think that’s part of our largest struggle is what is the right mechanism where we’re not being too burdensome on the parties to know that this is real, but we’re doing due diligence so it’s not basically coming out of the hide of all the other folks that are operating the system, because in large part, there’s a lot of interconnectivity. So having some of those things lined out up front and being consistent and rigorous in applying some of that criteria is really important. I think the Department and Reclamation have worked a lot to try to come up with workable ideas in the form of white papers about what’s transferrable, what are the conditions, do these make sense, so we can create a network of things so we know that if you do these things, that we know that there really will be water in the system that can be transferrable.”

Then it’s a question of is there physical capacity at a particular place, and trying to think if we knew better from a forecasting standpoint, we would know if there’s going to be an opportunity to actually move this water, because a lot of it’s tending to move from Sac Valley,” Mr. Milligan continued. “The big quantities are north of the Delta and the Sac Valley to points south, and that’s … the first thing we want to know is that real water that’s moving and secondly being able to know that the movement of that water in a conveyance sense is not displacing someone else’s opportunity like the basic operation of the CVP or SWP.”

Another perspective on the water markets and the water transfers and the physical capacity aspect of it,” said John Leahigh. “One is the variability that we talked about, as far as the supply. California has the most varied water supply of any state in the entire country. It always rains in the winter and it never rains in the summer, but the amount of the rain that occurs, it varies substantially from year to year. And it really comes in a handful of storms every year, so its’ very streaky. That variability is in combination the fundamental paradigm shift where the projects are getting less of their water from the winter, the direct runoff in the winter time, and relying more on their stored water to meet their demands. So what’s happening also is we’re filling up much more of that; typically the north to south transfers are happening in the summer months, with unused capacity that the projects aren’t using for their own supplies, and so what we’re finding is that capacity is getting squeezed, that window is getting squeezed, so it’s making it more sensitive to late season rain events where there’s got to be several months of lead time on these water transfers. I think one of the things that’s becoming very important is options on these water transfers because the picture can really turn on a dime. … We’re running out of capacity to move water transfers from north to south because the more reliance on project supplies through those summer months so it’s kind of squeezing that window and that window can close, it can turn on the dime, so an option is important.

During the public comment period, Thomas Zuckerman with the Central Delta Water Agency noted that during the presentation, it seemed like most of the blame was placed on environmental restrictions. He reminded that the State Water Project was originally designed with the plan to increase yield from operations largely on the north coast rivers never were built. “So now we’re in this terrible operational dilemma now, not just because of the fact that fish and wildlife requirements came along, which were contemplated at the time,” he said. “We’ve come down to a situation that’s untenable. The drought has done us a big favor maybe in bringing us up full face against the dilemma that we’re in, which is trying to do an awful lot of things with a limited supply of water, and the question becomes, what are we going to do about it.

Mr. Zuckerman said that he thought the chart that showed what the twin tunnels or Sites Reservoir could do to mitigate the problem was interesting because he thought they didn’t do a very good job of it. “It looks like there’s 1.63 MAF of excess outflow that occurred over the last couple of months, and neither one of these projects is really capable of taking advantage of most of that,” Mr. Zuckerman said. “The question that I would pose, is how much of this dilemma, this shortage that we’re looking at could be resolved through conjunctive use of additional utilization of the vacated groundwater storage that we have in the San Joaquin Valley, and who is looking at that? There are a lot of local projects that have been proposed that have gone unfunded, individually they are not huge, but collectively they provide an opportunity to this enormous problem you are talking about. Are you looking at this?

Walter Bourez responded that he’s done quite a bit of work looking at conjunctive management, and he agreed more could be done. “One example of an area that’s doing an outstanding job on that is the American River basin. They have linked their systems together; there are districts that are only on groundwater, some that are only on surface water, and they are joining up so that they can get more surface water in the wet years for all of those areas and then have reliability for the drier years, and they are expanding those programs so there is work going on and actual projects that are going on to do just that.

The problem is when you get to the south of Delta and the Kern area and the lower San Joaquin, no matter what we do, we cannot get enough surface water down there for conjunctive management,” he said. “Friant was built as a conjunctive management project, that is by its very nature its design; the one plot I showed where the groundwater levels were going down, so Friant was built and they came back up – that was to address that problem, it was a conjunctive use problem. I’m not saying that it’s good or bad, it just is that we have more restrictions on what we can take out of the Delta. That’s the fact, that’s the way we’re operating the system now, so our ability to replenish those groundwater basins is limited, we can’t get enough water. Even if you look at Delta tunnels, we don’t get enough water to offset that groundwater overdraft in the Tulare basin.”

Dr. Lund notes that with SGMA, it’s going to be even more difficult.

Yes, there’s only one way to do it, and that’s demand management, ie land retirement,” said Mr. Bourez. “There’s got to be some degree of that, and that’s a really hard pill to swallow for a lot of those folks.

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