DR. BRUCE HERBOLD: Delta Flows and the effects of water transfers
Dr. Bruce Herbold is a retired EPA fish biologist and now a consultant on the same issues. In this presentation from the AquAlliance conference last fall, Dr. Herbold discusses drought, flows in the Delta, and the effects of transfers on the fish in the Delta.
Dr. Herbold began by saying that managing water in California is fraught with difficulties, and one of the things you learn early on is that our climate makes it totally unpredictable. He presented a graph showing the water year types in the last 100 years, and said, “I draw your attention to the blue wet years and the bright yellow critically dry years, because you can predict this, and if you can predict this, then it becomes much more solvable problem than the kind of urgent catastrophe that nobody expected that we’ve been treating them as,” he said.
He presented a table compiled by Jay Lund and Jeff Mount at UC Davis, noting that it shows that critical years are usually followed by critical years. “When somebody says multi-year droughts, they are being redundant,” he said. “Droughts are always multiple years, and in fact, there hasn’t been a single year drought in our record. So if you get hit with a drought, you can expect the next year to be a drought also. It does eventually end, so we do end up having critical years followed by abnormally wet year, but most are followed by critical years or dry years. That’s true for the Sacramento as well as for the San Joaquin, so you can start predicting the future.”
He returned to the chart of water years and pointed out that they do agglomerate. “Critical years tend to follow critical years because that’s the way droughts are, and in fact, they usually come along at least in pairs and usually longer than that,” he said. “Critically dry years on the Sacramento side are followed by critical dry years 2 out of 8 times, and 4 other times they are followed by dry years … In 1994, we had a critically dry year followed by a wet year, but that’s actually the end of a drought. We had six years of a drought, then we had wet year, and then we had a critically year, so that fell into this critical year was the first one, but it was actually part of an 8-year drought. We just happened to luck out in the 7th year.”
With respect to California’s climate, we’ve been lucky in the last 100 years, he pointed out. “In the 20th century, we were fat and happy,” he said. “We got hit by one drought, the dust bowl drought, and that initiated us trying to conserve a lot of water, so we built a lot of dams, but if you look back, those droughts don’t agglomerate in just two years or six year patterns – in the 1800s there were a couple of decadal droughts, and if you go back further, there were 200 year long droughts, back in the medieval years. It’s probably the impacts of that 600 years or so of drought that decimated the Native American sites that were here and really opened the door to European settlements into a situation which had been really devastated by natural drought.”
Dr. Herbold said that instead of talking about climate change, he was going to focus on looking back at our climate history. “The book, The West Without Water, is a great compilation book about water which is not limited by tree rings,” he said. Instead, the book discusses research done with sediment cores. “Looking at how thick sediment layers are tells you how much water and sediment was flowing into the lakes, except they aren’t limited by how long the tree can grow, so you can look at the sediment rings. You can also look at sediments off the coast, because the rivers dump into the ocean so those go back even further; you can look at the pollen in the sediments because pollen is carried along with sediments, and that will tell you what kind of plants were growing, whether it was dry or whether it was wet. So we have a lot of information, and in the last 20 years, a lot of that work has been done in a lot of detail, and it paints a pretty terrifying picture of what California’s historical paleoclimatology was.”
So climate change is terrifying, but simply going back to the way it was before 1900 is scary enough, he said. “On the other extreme, the worst flood in California’s history was in 1863, and USGS did a study. They’ve done all these studies on the impacts of earthquake … they looked at if we had half the size of the flood we had in 1863, and the damage caused by that flood was much greater than any earthquake scenario they have put forward for the State of California. So, climate change is really something to worry about, but just simply being in California is scary enough.”
So how do we respond to droughts when they hit us? “We move a lot of water in this state, so what we do when we run out of water? We drain the reservoirs,” he said, presenting a chart showing exports, and noting that the droughts outlined in rectangles. “The first year or the first few years, we have set records on how much water we export out of the system in those years, and then we run out. Backing that up with the fact that almost all the time, a first critical year is followed by another critical year or another dry year or the start of at least a 2 – 6 year drought, then probably that’s not the wisest thing one could do, in my opinion.”
Let’s take a look at it in terms of what we have on the table, Dr. Herbold said. “We have those nice wet years where precipitation and uncontrolled riparian flows give us all the water we want and everyone is happy,” he said. “If we run out of that or we get into the summertime, then we have reservoirs. We’ve built a number of reservoirs, and reservoirs are really well understood. They are really important. They provide us with power, they provide a lot of local fish benefits, the ones that have salmon below can be managed to improve salmon issues, they are subject to evaporation but they do help groundwater recharge. They are really well understood and they are really tightly regulated. Lovely stuff.”
Groundwater is expensive to draw out, but we have so much less understanding. “As you are well aware, it’s very lightly regulated, so we reach the reservoirs, we drain them down, and we lose all those benefits, and then we start, as the drought proceeds, using our groundwater in poorly understood, lightly regulated ways,” he said. “That’s probably not the wisest thing to do.”
The other options are to modify demand or transfer surface water, he said.
The Army Corps counts 1594 dams in the State of California; the graphs on the right show the size of them. There are 278 dams that are greater than 100 feet tall, and another 329 that are 350 feet tall. “This is a fair amount of earth and a fair amount of water storage,” he said. “I don’t know about you, but I don’t think my grandparents were all that stupid. I think that they built dams where they could, and if you look at the dams by completion date, you see that they really, really built a lot of dams back there in the 50s or 60s after World War II. And then they stopped building dams.”
“There are two reasons they might stop building dams: either those draconian environmentalists didn’t allow them to build any or they ran out of places to build them,” he said. “With 1594 dams built, I tend towards thinking the second. So the state has been looking at building more dams, they found four water storage options … but if all four were built, looking at the contribution to water supply and the ability to weather droughts – some dams are better ideas than others, but none of them are going to get us out of dealing with California’s water supply problems.”
Dr. Herbold presented a map of the state of California when it was first surveyed and noted that all of that gray space in the middle was wetlands. “All of that valley flooded regularly and became an inland sea and we had a huge sponge, so there was a lot of water storage from the top of the mountains all the way down to the Golden Gate,” he said. “There were a lot of places where water was stored and kept our state fresh. The upper end of Suisun Bay at the upper end of San Francisco Bay, they were getting drinking water from that most of the time. Contra Costa Water District still has an intake off of Suisun Bay; they never use it because it’s too salty now.”
“Partly to get rid of flood problems, we facilitated the movement of water out of the system during flood season, and then we built all these canals and got rid of those nice sponges, and that helps contribute to the state we’re in now,” he said.
Because of the dams, we’ve lost the salmon habitat above them, he pointed out. “We’ve lost a lot of the resilience in salmon,” he said. “There was a question of how do the salmon survive and bounce back before humans built the dams, and that’s because they could swim up to where there was cold water. All of that black stuff that is now inaccessible to them is lovely habitat. The spring run was the most abundant run of salmon that we had, and now they’re pretty much restricted to Butte, Deer, and Mill Creek because those don’t have big dams on them and they can still access that cold water habitat to lay eggs in.”
Dr. Herbold presented a picture of the Delta in 1873, and noted that it might look confusing, but most of the water bodies were flowing in one direction in what are called dendritic channels. “It means if you’re on one of the upper twigs, if you keep going downstream, you will find your way to the ocean. And salmon did find their way through. Migratory fish of all sorts could find their way up the rivers and down the rivers because the rivers had a direction to them. This all gave you lots of habitat … there was lots of time for food to grow, lots of connections to marshes that were on surrounding lands, and both rivers connected to the bay. These are all good things if you are a migratory fish.”
He then presented a slide of the modern Delta, noting that it looks simpler, but now all the connections make for circles, and tidal flows mix things up further. “If you are a migratory salmon, you now have no clear sign of which way is downstream. We’ve changed substantially the flows in the rivers, so on the San Joaquin side, there’s pretty much no water during the time of the fall run are trying to migrate upstream, so all those habitats have gone away.”
“Some things we can do for fish is to change some of those things,” he added. “We can change way the cues for salmon migration happen, and we get some habitat. Those things are being worked on. I’m less hopeful all the time, but it’s something.”
He presented a conceptual model that shows the physical habitat, the salinity gradients and flows across the physical habitat. “The better that those line up with what the fish need, the better you get your fish,” he said. “In this system, the river flows change a lot from season to season and from year to year. So the overlap of the good movable habitat over that stationary habitat which controls good the fish are changes a lot from year to year. But that’s why I find this useful. Can you make the stationary habitat generally better so for wherever that salinity and flow happens to be is better for fish, or can you change the way that mobile salinity and flow habitat moves so that it more often coincides with what makes good fish habitat.”
Most fish follow salinity, he pointed out. The Department of Fish and Wildlife has been sampling all the fish in the Bay from San Jose up to the Delta. “Where they catch most of their fish really changes with what the salinity is, so if you’re looking for American shad or threadfin shad, all the fish they will have caught is when that cumulative percentage is over 80 … for the marine species, you don’t see them until you start getting into waters that are more than 20 parts per thousand. Others like staghorn sculpin there in the middle, just don’t care. But where the salinity is controls where the fish are, and then what that salinity is in terms of the physical habitat that it’s lying on top of will control whether the fish are happy or not. I like happy fish.”
That does change a lot in wet years, he noted. “Dry years are like happy families, they are all the same; wet years are like unhappy families, they are all different,” he said. “We have 1997 where we had a huge flow in late December, the Christmas storm, which pretty much washed away Sacramento and by the time that the fish were arriving at the Delta in April, all that flow disappeared so we had a dry spring and a really, really, wet Christmas. Other years, like 1983, it started raining in November and it just simply kept on raining through June. A whole different kind of wet year. All that changes what the salinity distribution is; all that changes what the fish need.”
Dr. Herbold said a lot of his career has been focused on that low salinity zone. “As flow goes up, that low salinity zone and all the other zones of salinity move up and down the estuary,” he said. “Also as you get more flow, more of that freshwater scoots along the top, as it tends to be warmer and less salty than the ocean water so it goes out along the top. The ocean flows in along the bottom so you get this stratification. Freshwater fish, salmon and others are really being helped by those freshwater flows going out to the bay and out to the ocean, and marine fish that use the estuary as a nursery have their young come in on the bottom flows, so the more flow we have, both those currents improve.”
There is also more floodplain inundation, he said. “People in Mississippi come out here to try to figure out how they can put some floodplain back on the Mississippi where they just built levees,” he said. “We tried building levees and our climate did not make that a success so we were experimental. There’s a book called Battling the Inland Sea about how some really forward thinking people thought, no, building higher levees isn’t going to work, let’s build floodplains, and how they were laughed out of the Army Corps. But they ended up being right.”
“So as flows change, you have all kinds of other things physically changing,” he said. “Also there’s a limit on how much can be exported so once you hit that limit; more flows means that there’s more water going to the Bay, and that’s a good thing. You get all kinds of habitats inundated at higher flows that you don’t get at lower flows, and all that is generally good for fish.”
There are also chemical changes. “My favorite story on pollutants in the Delta is, I had a friend who was going out looking at orchard sprays and how much they were in the water, and she was finding they were much higher when it was wet than when it was dry,” he said. “That was weird, but it was because not only was the rain carrying the pesticides off the orchards into the nearby waterways where she was measuring them, but that meant that they had to go out and spray the orchards again, and then it would rain again, and so the increasing loads of pesticides outweighed the expected decrease in concentrations due to dilution. Cool things. Not always good for fish but cool interactions, so all these things happen with flows.”
Finally, fish move, he said. “Because California is hard place to be a fish, they are migratory. They come up when its wet and they move out when its dry, mostly. Winter run. So salmon, sturgeon, smelt, splittail, shads, herring, all really respond to first pulses of flows. They come up to spawn then. If we don’t get them, they stay out. That matters a lot more for a fish that only lives for one year, like Delta smelt. If they don’t get that pulse, then they don’t get that trigger. If they are a sturgeon that lives until 50 years old, they can wait.”
“We also have those fish that are produced, the young fish, moving up from outside the Golden Gate into the estuary where they are safer, because they are small so they are food if they are out in the ocean, but they are not food when they are in the estuary,” he said. “And we have those spawned fish moving down, so all of these things are depending on flows. I fight for those flows, and that makes me fighting with the people who want water for their other uses.”
In terms of the physical habitat and that salinity moves from year to year, what does that mean for fish? “We’ve managed to make it so the Delta is completely inhospitable for fish,” he said. “If the salinities move up into [the more channelized areas], than that’s where we lose our fish. The more we move down into the marshy areas, the better those fish do. Right now there’s a lot of effort to create more marshes in the Delta. I don’t know if it’s going to succeed or not, but it certainly is opening up our options without having to spend more water on the fish.”
With respect to transfers, Dr. Herbold said that water transfers happen in dry years when those fish are up in the Delta, when they are most at risk in the poorest habitat. “It’s hitting them when they’re down to send more water downstream to be exported because often they go with the water or that movement of water through the Delta, and that produces less food for them because it’s moving through more quickly, it’s just generally hitting them when they’re down. It does increase those exports so you get more fish salvage.”
There are other water transfers. “Contra Costa Water District is a master at negotiating water transfers from one agency to another that don’t change any operations in the Delta,” he said. “That’s because they have built a nice storage reservoir and they are tying it into everybody else’s distribution systems, so you can move water that belongs to one party in the Delta into the reservoir that doesn’t need it right now to somebody who does need it right now, so there’s lots of great stuff in their regional water planning. I really want to salute them. That sort of thing where you’ve already paid one cost of getting the water into storage and then not having to have other impacts; you’re just making responsive decisions to the changing needs of different parties. Great stuff. Love it.”
“On the other hand, all the things we’ve been talking about at this conference generally involve changes in upstream flows that decreases at times, increases at times, decreases groundwater so that streams dry up more quickly – all of which tend to have bad effects on fish.”
“Single year transfers are emergency actions,” he said. “I don’t see any value in them. We come along into critical years as if they are surprises and they are not surprises. We suddenly have to develop new rules to operate by because we didn’t do it when we weren’t under emergency. I’m encouraged that the State Board is grappling with this right now in the new water quality control plan that it won’t be filled with off-ramps for critical years but will in fact set up a system that responds to critical years, I hope. I’m ever the optimist, that’s why I get out of bed in the morning.”
“There are a lot of opportunities that if you think about it beforehand, to line up a series of transfers,” he said. “It requires time to work out; doing CEQA rather than an urgency change requires time, so all of that negotiation, all of that determination of impacts, all that negotiation around it is not the sort of thing you do in a single year transfer. I think that’s the sort of thing, whatever it is, you do it in advance of need and you set up so when it does happen, you don’t have a lot of lawsuits filed against you to keep it from happening.”
Dr. Herbold then closed with the recent developments with salmon. “For a long time, there have been a lot of good things for birds and rice fields and other agriculture in the Delta, but we’ve been working to maximize salmon survival and the debacle of winter run salmon in 2014-15 seems to have changed,” he said. “In 2016, we had enough experience with the problems that maybe it was done a little bit better. We seemed to have more fish that survived. That’s the kind of folk where agriculture, water management, and fish management, if you give it time, it’s going to stumble but it’s likely to end up with people figuring out how to do it right. And that’s why I’ll get out of bed tomorrow.”
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