Dr. Bruce Herbold and Sandi Matsumoto discuss the potential impacts of single-year transfers on the Delta’s ecosystem and wildlife
During the development of the first Delta Plan, one of the many issues considered by the Delta Stewardship Council was water transfers and their possible impact on the Delta and the coequal goals. While water transfers are an important tool for statewide water reliability, do they pose a threat to the Delta’s ecosystem and wildlife?
In this second of three panels, retired fish biologist Dr. Bruce Herbold and the Nature Conservancy’s Sandi Matsumoto weigh in on the ecological impacts of water transfers.
Note: This is part three of four-part coverage of water transfers. For previous coverage, see:
- Water transfers and the Delta Plan, part 1: The basics
- Water transfers and the Delta Plan, part 2: The agency view
DR. BRUCE HERBOLD, retired fish biologist from EPA
Dr. Bruce Herbold began by presenting a graph of Sacramento Valley precipitation from 1906 to present day. “There’s a long standing effort to try to predict from the past what the future is going to look like and no one has, but I do think there are some patterns that are worth noting,” he said. “A lot of us were born in the middle of what were the good old days – 40 years of wet years in a row. I was born right in the middle so my parents and I expected things to be like that. A lot of us still do, despite the evidence of the right hand side of the graph.”
He directed attention to the yellow lines which represent the critically dry years. “They almost never occur alone; they are either followed by another critical year or by a dry year,” he said. “When I started working in here, it was explained to me that droughts cannot happen in one year; it takes two years to be a drought. I have come to understand that backwards – that a critical year signals the start of a drought, and it’s almost always at least two years, and often longer. … You could look at the most recent drought as an 8 year drought with a happy intermission.”
“We have enough history to look at and say that if we hit a critical year, there’s going to be another one, or a dry year afterwards – a drought has begun,” he said. “Since we rely on snowmelt so we can know that in the March of that year. It doesn’t take two years of history to inform us that we are in drought. Our history informs us that if we don’t have snow by March, we should take issue, and we don’t. We need to be more anticipatory.”
“So my main point is that single year transfers are an emergency response to something which we can anticipate and therefore an emergency reaction to them, and everything we have done to make them go more quickly is not necessary and is in fact counter to I think wise use of all the resources,” said Dr. Herbold.
He presented a slide showing how wet years and dry years are different. “Our wet years are all different – they are like unhappy families; our dry years are all the same – they are like happy families,” he said. He pointed out that in 1983, it started raining in October and kept raining through May; in 1986, it rained in February, and was pretty much critically dry the rest of the year. “Those are all dumped into being wet years, they all present very different environments to the fish.”
“Dry years are all the same,” he said. “The way they are the same is that fish follow salinity. We have a suite of fish in the upper estuary that hang out in low salinity areas and wherever that low salinity area is, they go to it. We have a whole bunch of other fish, more marine, that follow higher salinities and can move up into the estuary when those salinities move upstream also.”
There is a lot of work going on to restore tidal wetlands to the Delta, an effort he is supportive of, Dr. Herbold said. “What we have right now are tidal marshes with shallow embayments next to them down in Suisun, and so if the salinities are appropriate down there, then that’s great habitat for them,” he said. “But when those appropriate salinities move out of those physical areas, they get up into the deep dark channels of the Delta where they are exposed to a variety of stressors: their food is in the dark and many of them are visual predators so they can’t see their food most of the time, and the water is clearer so that large predators can find them more easily – it’s just not a good place to be a fish. So these times when outflows are low cause salinities to move upstream and put the fish at what we have created as a very risky situation for them to be in.”
“Our response for humans to droughts is different,” he said, presenting a slide showing the State Water Project and Central Valley Project exports from the Delta. “What we do in droughts is the first year of the drought, we know it’s a drought because it’s critically dry, demand goes up and we take all the water out of the reservoirs. Then we have the second of year drought, and classically, 76-77 this is where we lost the winter-run salmon. We drained Shasta because it was the first critical year in 40 years and we couldn’t possibly have another critical year after that; then we had the driest year on record. And it’s actually still the driest year on record. That eliminated all of the cold water pool from Shasta so the winter-run came up, there had been hundreds of thousands of winter-run fish still surviving and spawning below Keswick Dam and then they all cooked in 77. So that response, if we had taken half the water and kept some for the next year, and droughts come in at least two years, that would seem to be a reasonable thing to do.”
“We keep on not doing that,” he said. “We had the semi-eight year drought of the late 80s into the 90s where it was a drought but we still could move a lot of water, but then we did run out. But recent ones, we still respond to the immediate demand with little trying to hold stuff over for the future. I think single-year water transfers are another tool like that where we respond to the immediate demand and don’t think about what we are going to do next year.”
Dr. Herbold them summarized his thoughts on water transfer impacts. “In non-drought years, the agencies are busy moving water that they own, so there aren’t water transfers, so water transfer impacts are going to only occur when the fish populations are stressed already by drought,” he said. “They are upstream, they are less dispersed, they don’t have the resources at their call to do well, so we’re hitting them when we’re down. At those times they are closer to the Delta facilities, so increases in pumping from the facilities are likely to draw fish up into the Delta, and just as it would decrease water quality, which we can mitigate for, we can increase the mortality of fish, which we can’t mitigate for. So they are risky.”
Dr. Herbold said that some transfers can involve no change in Delta operations, noting that Contra Costa Water District has made a cottage industry of figuring out how to do water transfers that don’t actually change operations in the Delta. “But a lot of them do affect upstream flow patterns and upstream storage and groundwater depletion and the rest,” he said.
“So my recommendations on single year transfers is just don’t do them,” he said. “They are an emergency reaction to an anticipatable problem … So if somebody comes to the board or other agencies proposing a transfer, I would say off the top of my head, that’s at least a two year issue. You can do half of it this year and half of it next year so that we have some water next year when the water is likely to be more valuable. If it all gets wet, okay, fine there’s ways we can hedge those bets, but trying to lengthen our response to drought which also reduce those impacts in each of the drought years. We’ll have more water in storage upstream, we will have less streamflow modifications, and we’ll have less exports out of the Delta in each year. The slower those go, the lower the impacts go, so two small impacts are better than one medium impact in one year, I think.”
“Contra Costa has done this sort of kidney transplant model for water transfers where these people need it at this time and these people need it at this location and these other people need something at some other time or location, and you can start doing a series,” he said. “Fish agencies can say, in a given year we need to back water up behind a given reservoir … they can set those priorities and we have tools then to make water transfers that allow water to be held back in those reservoirs and stretch out those transfers over more than one year.”
“Those are all things I think we can do,” he said. ”It will require some smart people but DWR is filled with smart engineers and optimization problem is an engineer’s dream, so we can do this, and if it goes through that process, I think you could sign off on it, because it would then come having met environmental agencies’ needs, yes or no, whether water transfers were successfully being pursued or not, yes or no. You have two questions, they give you answers and that review is very simple. But I think the implications could be very beneficial.”
SANDI MATSUMOTO, Associate Director for California Water Program at the Nature Conservancy
Sandi Matsumoto began by stating the mission of the Nature Conservancy, which is to conserve the lands and waters on which all life depends. “In pursuit of this mission in California, the Conservancy’s invested over two decades of work on the Sacramento River and in the Delta,” she said. “We’re pretty significant land owner in the Delta, and all of this is because we believe that there are better ways to manage the system to benefit ecological resources, and we’re trying to improve both the health and function of the river and the Delta ecosystems.”
“I think for us generally speaking, we believe that transfers are an important tool in the water management system here in California,” she said. “Like all good tools, tools have a time and a place and a specific use and so it matters a lot about what the details are related to the transfer. As we look at those details, we should really be examining the details and thinking about them in the context of the best available science. I think some of that science is available today, but we still have a lot of work to do to build the science and to more adaptively make better decisions in the future that are better informed and connected to each other across years.”
Ecological impacts include fish, feathers, and flows, and since Dr. Herbold covered the fish issues, she said that she would focus on the latter two: issues related to the Pacific Flyway and impacts to flows related to groundwater substitution transfers.
She then reminded what the Valley and the Delta used to be. “Historically speaking, we had over 4 million acres of seasonally flooded wetlands,” she said. “You hear the historic accounts of the bird densities being so great that it darkened the sky as they flew over in clouds; you hear accounts of people who complained because they couldn’t sleep in the valley because the birds were squawking so much, so there are these densities and abundance and this amazing natural phenomena that was related both to our salmon and to our migratory bird species.”
“Fortunately, while much of our habitat has declined and in fact we’ve lost over 90% of our historic extent of wetlands, we have managed to hang on to these incredible phenomena, these great migrations,” she said. “A large way that we’ve done that is that the birds and the fish have adapted to the new environment … They come in every winter and there’s millions of them. We have in fact some of the largest concentrations of water fowl in all of North America, so we’re a globally significant place for these birds, and they are managing to survive despite the fact that we’ve lost a lot of wetlands.”
They are able to survive because over the years public dollars have been invested in a system of state and federal wildlife refuges scattered across the Central Valley, as well as a lot of agricultural lands that are compatibly managed to benefit these species, she said. “It’s this complicated combination that we see, both within the Delta as well as within the rest of the Central Valley of compatibly managed agricultural land as well as the refuges which are the backbone of the habitat,” she said.
With transfers, there are impacts at the place where the water comes from, and the context of that place matters, she said. “It’s not just taking a certain amount of water and fallowing acreage in a certain area – there’s a context around that. Number one, the context is 90% of the wetland habitat is already gone, so we’re working with very small fractions that are incredibly important. And these transfers tend to happen when it is already dry, and so if you’re thinking about the context of a place like the Sacramento Valley where a lot of this water is coming from, there’s already fallowing going on.”
Ms. Matsumoto pointed out that water restrictions also impact the refuges. “In a good year, the refuges are not getting their mandated levels of water, so you can imagine in a drought year, they are getting hit again,” she said.
“The way that I think about the impacts to migratory birds is kind of death by a thousand cuts,” she said. “The refuge water is getting cut so there’s limited habitat availability there. There’s limited compatible agricultural lands, which limits the food availability and habitat that further limits the amount of winter flooded habitat that’s available, so the impact of all of this is that migratory birds suffer in terms of space, so with less habitat available, they crowd into smaller and smaller patches of habitat. This can enable a lot of transmission of disease faster and more readily and result in mortalities.”
Limited food availability can also compromise their general body health, she pointed out. “These birds are going to travel thousands of miles as they depart the Central Valley, so that’s their job here when they are wintering in the Central Valley is to bulk up,” she said. “If there’s less food available, then they can’t do that, and that affects their ability to survive that return migration and also can affect their ability to reproduce once they are back in their summering grounds, so the overall impact of all of these things is a decline in bird populations.”
“Transfers do have an exacerbating impact in all of this in terms of further fallowing the lands that are available, the food availability,” she said.
She then turned to groundwater substitution transfers, and the connection between groundwater and surface water. “The Nature Conservancy undertook a study that was completed in 2014 titled The Groundwater and Surface Water Interaction in California’s Central Valley: Insights for Sustainable Groundwater Management,” she said. “This study was really conceived as a way to buttress our working hypothesis that in order to improve our water management system for nature. To provide the flows and the water needed to support our ecosystems in California, we need to do that in tandem with improving the overall water supply for the people of the communities and industry that rely on this water system, and in order to do that, we really need to understand the sources of water contributing to our water supply. Two big components are that surface water and groundwater. And we need to think about those together because they are in fact interconnected.”
The study was completed prior to the Sustainable Groundwater Management Act and in fact informed a lot of our work on that legislation, she said. “What it did is it looked at the historic record between 1922 and 2009 using the Central California groundwater surface water simulation model to basically go back and look at the effects of groundwater pumping on our rivers,” she said. “At the beginning, back historically, the vast majority of the rivers in our Central Valley were considered gaining streams, so in other words, they are the surface expression of a very healthy groundwater system – so they are the low points in the land where there is so much groundwater that it’s feeding groundwater up into the surface water and that’s what we see flowing. So we would think rivers are a great indicator of a healthy groundwater system.”
Over time, the models show that as groundwater pumping has increased, the surface flows have decreased, she said. “What’s happening essentially is that the pumping is pulling water away from the rivers and compromising the ability of groundwater to contribute to our river systems,” she said. “In the really bad cases, it’s actually pulling water so much so that these streams that have been gaining groundwater begin losing surface flows to groundwater, and in the very worst cases, probably most acutely seen in the Tulare Basin, we actually can disconnect our rivers from our groundwater.”
Perhaps most disturbing of our findings is that we believe we may be at a tipping point in the Sacramento Valley in terms of our ability to sustain reliable water supplies for the entire state,” she said. “Some of the reaches of the rivers up in the Sacramento Valley could be at that tipping point where they’ve gone from gaining flows to actually losing flows, and that has implications for transfers.”
In addition to the historic assessment of the interaction between groundwater and surface water across the Central Valley, the study also simulated some potential management scenarios, one of which included a groundwater substitution transfer, she said. “We came up with a hypothetical transfer and wanted to understand what the stream impacts could be, and what this showed was that the impacts are complicated and have a long duration, so as groundwater is pumped out of the system, initially that water comes from groundwater storage. Over time, the groundwater is replenished from stream depletion, so again, water flowing out of our rivers to recover the groundwater system. That happens most acutely in the years around the transfer, but in fact in order to get to full groundwater replenishment which is a pre-transfer scenario, it takes decades. In our simulated model, it took 25 years to get to full replenishment for that one transfer.”
“The other thing to be aware of is that actually those stream depletions that we saw accounted for 95% of the recovery of the groundwater system, so we know that the vast majority of the water that’s replenishing that groundwater is coming from our rivers,” she said.
So there are a number of considerations you have before you as you are thinking about how to act, she said. “There are environmental impacts and ecological impacts and they are very real, both at the area of origin up in the Sacramento Valley as well as in the Delta,” Ms. Matsumoto said. “They include impacts to fish, birds, things that are wetland dependent species like the giant garter snake. It’s also important to know that our information is limited and we really need better and transparent monitoring to understand what’s going on with these systems. This includes having better gauges in our streams to understand stream depletions, potential impacts to our streams, and in fact, the Nature Conservancy has compiled a ranking of stream gauges that we think should be reactivated or installed to better get a handle on the system throughout California that we’d be happy to discuss.”
“We also think that groundwater levels and monitoring needs to be done on a transparent basis so we can all see what these decisions are, what the impacts are, and the duration over which they are happening and make better decisions in the future,” she said. “And the final point here is that our studies suggest that while we think about them as single year decisions, that they have potentially an impact that could last for well into my little boy’s life, and better understanding this is really important. I think there’s a lot of specifics that go around it, where’s the water coming from, what’s the status of that groundwater system, what are the soils around there, what’s the status of the river – there are a lot of details that need to be worked into this, so I think our study is a great starting point for this discussion and this is something that has already been beneficial in terms of opening a dialog with the Sacramento Valley water users.”
“So with that … “
“To clarify, I do think that most transfers will have an ecological impact that needs to be at a minimum at the area of origin in terms of terrestrial species, particularly migratory birds and wetland dependent species, that impact should be minimized, avoided, and mitigated,” Ms. Matsumoto replied. “In terms of what a good transfer could look like, I think there are times when we have significant water needs south of the Delta, that include needs for nature as well as communities and agriculture, and that the transfers can be used to solve that, and that includes water for refuges. If we are to use the tool in a good way, we should be looking to do it on a magnitude that’s acceptable to the area of origin; we should be doing it from relatively healthy systems, so not avoiding places where there’s already overdraft problems and problems with the groundwater; and we need to be thinking about the interconnected impacts related to flows for fish and the water quality in the Delta. So in a nutshell, there’s a number of factors that would go into determining what a “good transfer” versus a “bad transfer” would be.”
“I don’t think we have all the answers, frankly, and so because we don’t, the more people we can involve in these discussions and decisions, we can get to a place where we’re making better decisions in the future,” Ms. Matsumoto continued. “Ideally a decade or two from now, we would have those parameters, a list of these conditions, the following conditions is a good groundwater transfer situation, and if these following conditions exist, it is not a good opportunity for a transfer. So I think we need to get there, but I don’t think the list yet exists, but there are a number of factors we can point to to evaluate.”
“The point I was trying to make is that we’ve scratched the surface of getting actual environmental benefits and since your task is to protect the two coequals goal, I think we need to bolster that,” responded Dr. Herbold. “I think we have the ability to do that, but I think we’ve just scratched the surface in showing that we can. It would be easy to set some goals in a given year, okay, 2016 looks like it’s not going to give us any snow so what are we going to do. That’s a hard one, but if this was 2012 and it looks like we’re not going to get any snow, then we could take some real serious actions and DFW would say, hey look at that, we got changes in operations from what they forecast that are beneficial to our species, and people who wanted to transfer water managed to sell and buy it, so everybody’s happy let’s all go home. So I think we started, but we could do a lot more.”
So out of the 420,000 acre-feet, 600,000 acre-feet a year being transferred, you would suggest something less than that – a quarter, a half under a drought condition or low water supply circumstances?, asked Ms. Piepho.
“We’ve had environmental water accounts, we have had a drought banks – we’ve had that kind of accounting system used to varying degrees of success, but we have that experience and I think that multiple year approach is how you get water supply reliability,” said Dr. Herbold. “I keep asking what that phrase means but nobody tells me except more water, and we don’t get more water, and I think reliability is reducing those ups and downs of deliveries that we can do. Where transfers are a significant part of dry year water motions, we should try to do it there, that’s my point. I think we can, and I think, God forbid, everybody wins.”
“I think we can do more,” added Ms. Matsumoto. “I think there are things we can do to minimize the impacts that we haven’t fully explored, and I also think there are things we can do to mitigate, both in terms of area of origin and then thinking about how we’re replenishing the groundwater system after a groundwater substitution.”
Kevan SamSam reminded that the first panel had stated that while the amount of water that is transferred within the state is in excess of a million acre-feet a year, the amount of water that transfers through the Delta and down to Southern California is a small subset of that. “So some of the impacts that we’re hearing, I’m sure they include transfers that don’t involve DWR or the State Board.”
Coming up tomorrow …
The buyers and sellers perspective: Water attorney Dustin Cooper, San Luis & Delta-Mendota Water Authority Frances Mizuno, and Metropolitan Water District’s Steve Hirsch talk about the complexities of water transfers
For more information …
- Click here for the report, Water Transfers and the Delta Plan.
- Click here for DWR’s Report to the Council on the Background and Recent History of Water Transfers in California (July 2015)
- Click here for the agenda and meeting materials for the September meeting of the Delta Stewardship Council. This is agenda item 7.
- Click here to watch the webcast.
- For part 1 of this series, see Water transfers and the Delta Plan, part 1: The basics
- Water transfers and the Delta Plan, part 2: The agency view
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