Climate change and the potential effects on water operations
PCWA’s Andy Fecko looks at what projections for sea level rise and warming temperatures could potentially mean for water operations at Folsom and in the Delta
Climate change models predict a wide range of impacts that a warming climate will bring; most often discussed are warming temperatures, changing precipitation patterns, reduced snowpack, and rising sea levels. In this presentation from the recent Mountain Counties Water Resources Association event, Andy Fecko, Director of Resource Development for the Placer County Water Agency, built his case for how these climate change impacts could affect operations at Folsom Reservoir and in the Delta.
Here’s what he had to say.
Mr. Fecko started with some data. “Antarctica has a lot of ice and that ice layers itself every year, and it picks up carbon isotopes when it layers,” he explained. “Every winter, more ice is added, so when you drill down through those layers, what you can figure out is that the temperature and the amount of carbon in the air has changed over time.”
He presented a chart showing air temperature over about the last 400,000 years. “This chart shows is that essentially the amount of carbon in the atmosphere varies tremendously through time, and if you happen to think as climate scientists do that temperature is related to the amount of carbon in the atmosphere and you correlate those two things, what you come up with is a range of temperatures from about where we are today which is in the +2 degree Celsius range down to that -8 Celsius range. That is a very cold planet; that is ice caps down to about the Tropic of Capricorn and up to about the Tropic of Cancer; there’s no way to grow food there, so actually for humans, where we are right now is a really great place to be. And there’s no mastadons or anything either so that’s helpful.”
With those changes in carbon and changes in temperature, the result is sea level rise, he said, presenting a chart showing sea level rise. “Here’s a quote from the IPCC: ‘The global sea level rose by about 120 meters during the last several millennia that followed the end of the last ice age, and stabilized between 3000 and 2000 years ago.’ That’s absolutely true, so when you look at the steepness of that sea level rise, that’s all the glaciers from the last ice age melting off and filling the ocean and the sea rising by 120 meters. This was literally a sea change in how the planet operated and where the coastline was. This represents the beach of California being at the Farrallon Islands – that’s where 120 of 140 meters of sea level rise is, so quite a distinct change.”
He then presented a graph of sea level rise at the Golden Gate for the last 100 years, noting that the gauge is one of the longest running tidal gauges on the West Coast. “What it shows is here the average tide; the red line is a 19 year mean and we just fit a line to it. What you see is that the ocean in San Francisco has come up 7 to 8 inches, and it’s come up a little bit more since then, but that’s a rough number to think about as we go forward.”
While the sea level was rising, the climate in California has been remarkably stable, said Mr. Fecko. “Here are all the big rivers in the north and all of their runoff put in a graphic,” he said. “It’s a messy graphic, of course, because California has sort of a messy climate. The amount of precipitation varies, but what you’ll is that we haven’t lost any precipitation in the last 100 years. We get the same amount of precipitation that we always have.”
“Look what happens when you look at it April through July period – remember same precipitation, but now you have a compressed runoff pattern,” he said. “This chart shows about a 10 to 11% decrease in the April through July runoff over the last 100 years – definitely a declining trend. That means one of two things: either or both. You’re getting more precipitation as rain rather than snow, or you’re getting the same amount of snow, but it’s just melting earlier, which is a phenomena we’re experiencing this year.”
As for California’s air temperature, Mr. Fecko presented a chart of from the temperature gauge at Blue Canyon on Highway 80, showing from mid-1940s to present day. “The August temperatures are about 3 degrees Fahrenheit warmer over the last 60 or so years, and the average annual temperature is about plus 2 degrees Fahrenheit which tends to support the more precipitation as rain vs. snow theory.”
“Keep those trends in mind – they are definitely trends, but they are not what I would call as devastating as the melt at the end of last ice age,” he added.
Mr. Fecko then turned to the forecasts. “Here’s the federal government’s official view, published earlier this year on what the future for California holds,” he said, presenting a graphic from the Bureau of Reclamation Basin Study for the Sacramento and San Joaquin valleys. The vertical line in the middle is a 0% precipitation change, and the y axis is temperature change for up to 2 ½ degrees of temperature change.
“They’ve taken all the of global climate change models and the global circulation models and downscaled them to a California scale and they’ve drawn some envelopes around quartiles of which they are going to study,” he said. “So they studied a drier pattern with more warming, a wetter pattern with more warming, and then wetter and drier with less warming, but they always studied warming over the next 100 year period.”
This is important because it forms the basis of what the demand from domestic and industrial users of water and what crop water demands will be like, and it also translates out into how the Delta is managed. “You can do water temperature analysis for the tributaries and the reservoirs from this, so this really is the basis of what the Bureau’s view is going forward. If you look at that middle box, generally what you can think of is that for the next 100 years, a 1 degree temperature change and about plus or minus 8% of precipitation.”
He then presented a slide showing the Bureau of Reclamation’s forecasts for Sacramento Valley temperatures and precipitation. “Essentially what you have here is warming of about a degree every 25 years all the way out through 2100. Sacramento Valley precipitation, much like what we’ve seen – about even. The view is that essentially the historical trend will continue. Temperature will continue to go up but the precipitation will be about even.”
Mr. Fecko then related these projections to the management of Folsom Reservoir. “We don’t manage Folsom Reservoir but we watch it closely,” he said. “These are historical modeled results back to 1902 of how Folsom Reservoir would be operated with the unimpaired inflows into Folsom Reservoir. 1977 inflow was right around 225,000 acre-feet – very, very low, and the high is almost 6 ½ million acre-feet. A tremendous variation and no one year is tied to the next.”
If we are already managing for an order of magnitude change from year to year, does 10% matter? “I don’t know, here is 10% is that on top of that and it still looks really messy. It still means you have to manage the reservoir conservatively in our view to make sure that you have enough water that carries from one year to the next because you never know what the next year brings.”
“If you think about being upstream and you think ok, it’s going to get warmer and the runoff’s going to be a little compressed, so you may have to change your reservoir management a little bit,” Mr. Fecko said. “But then you get to the Delta and I think this is where the big change occurs.”
He then presented a graphic showing predictions of sea level rise from Reclamation’s basin study. “Every one of these trend lines, even the lowest trend line on this chart, is roughly double the amount of sea level rise that we saw over the last hundred year period, so to buy into this, you really have to think that things are going to get a lot worse. Nevertheless this is their official view: 16”, 35”, or 66” is the bounds that they’ve studied over the next 80-100 years, what does that mean?”
“For one thing, it means the Delta has to get saltier,” Mr. Fecko said. “You have an ocean that’s rising and pushing salt water inland through the Carquinez Strait, and every day that those tides are higher, it pushes more water in. We have belief in this state that we cling to, that the Delta has to be fresh. The Delta is a freshwater estuary and you want to keep it fresh. That’s what our whole regulatory paradigm is built around. When you see the EC in the Delta go up to these kinds of levels, it makes you really question, can you have a freshwater estuary going forward, is that even a reasonable goal, and what do you give up by trying to do that?”
He then presented a picture of the Delta, noting that the brackish zone is where the tidal flow pushes back and forth every day; Clifton Court forebay is where exports occur; and the blue line is the flow of the Sacramento River around Chipps and back down the San Joaquin channel to the existing export facilities.
“The brackish water zone is the part of the Delta where the salt water and fresh water mix, right about 2 parts per thousand of salinity. You can’t really grow crops with salinity of 2 ppt, and so it’s really good to keep that salinity pushed out past the Carquinez or around Chipps as far as you can get. So we try to keep it pushed out, and we do it by making reservoir releases all summer.”
Mr. Fecko noted that on the morning of the conference, the Bureau of Reclamation sent out a notice that flows out of Folsom were going to be increased from 4500 cfs to 5000 cfs for Delta outflow requirements. “That’s happened three times in the last week that they’ve bumped flows up,” he said.
“Right now, it’s kind of on a pattern of what you might expect from a snowmelt hydrology so it’s not so bad,” he said. “But what happens is as the American River system would normally do, flows from June would taper down through July and through August and by September, the American would be very low. The American now is used all summer long to keep this paradigm in place, and so it’s exactly what you wouldn’t have under a natural condition. You have lower flows in the spring, and then very, very high flows in the summer to keep the Delta fresh, and then you taper flows off in the fall to conserve water for next year, just as the fish are starting to come upstream. It’s not how you would run a system to benefit the species of the tributaries. It might be how you run a system to keep the Delta fresh.”
What happens under a sea level rise condition? “Here’s what we think happens,” Mr. Fecko said. “Now your brackish water zone is all the way in the path of the folks that want to export water. And you can’t irrigate with 2 ppt water, so you end up in a situation where not only are you trying to keep this water out using tributary water with releases from Shasta, Oroville, and Folsom, but now you’ve got this brackish water inland, all the farmers in the Delta are suffering, maybe inevitably. But not only that, but all the folks that are exporting water out of the Delta are starting to pump salty water around the corner at Chipps.”
“To us, this is crash course,” he said. “There’s no good outcome of this situation. I don’t think anybody wants to drink salt water. 25 million people south of the Tehachapis certainly don’t want to drink salt water, and I don’t think farmers in the San Joaquin want to be using it either.”
“The inevitable result of trying to keep the Delta fresh is this chart,” said Mr. Fecko, presenting a chart from the BDCP now California Water Fix. “What it showed was Folsom going dry in that late long term in roughly 10 to 11% of years. That is current regulatory paradigm in the Delta – a fresh Delta, so how do you keep it from getting salty? You make releases, and this is the inevitable result is that you end up with a dry Folsom Lake. So clearly we’re concerned about that.”
“Maybe some good news,” Mr. Fecko said. “We’ve been there before. The Governor and others like to talk about how droughts are getting worse and they are getting longer, but this is paleo reconstruction from tree ring records that shows we’ve had long droughts in this Mediterranean type of climate for a long, long time – longer than any of us have been around. This is something we ought to be prepared to deal with. Just because we haven’t had them in the last hundred years doesn’t mean that it shouldn’t be something that we deal with.”
“The good news is and our hypothesis is that things you do to get ready for a changing climate – rising sea levels and warming temperatures are the same things you’d do to prepare yourself for drought, and so there’s no loss in doing those actions because they benefit you either way,” he said.
“So what are the upstream actions? We’re a firm believer in this. More rain, less snow, it demands more upstream storage. If you’re not having a slow trickling of snow melt to fill your reservoirs all summer long, then you better have a place to catch water when it’s available. In terms of upstream reservoir operations, we need carryover and we need smarter flood control operations. Using the existing reservoirs to their maximum capacity and exercising them as fully as you can. And ending each year, remember that chart showing that dramatic hydrology from year to year, it means that you have to have a buffer in those reservoirs to account for the following year being dry.”
“Finally, we think that particularly in the Sacramento area, we have the ability to much more effectively utilize conjunctive use – groundwater and surface water together. We have reservoirs here, we have groundwater, we don’t’ exercise groundwater in the Sacramento area as well as we should.”
Mr. Fecko then gave his thoughts for the Delta. “Controversial? Maybe. A saltier Delta requires modified Delta conveyance. If you think this is going to happen and you think salt water is going to be in the way of exports, I don’t think it’s a reasonable solution that San Joaquin farmers and Southern California are going to drink salt water, so we think inevitably in order to not drain upstream reservoirs, you have to have new conveyance in the Delta. And we think it should be big, frankly. The idea that you’d put a small straw in and sip export water – it may make sense right now, but in the long term with a saltier Delta, that’s not possible. What you have to have is when you have high winter flows like we had this winter – Folsom spilled 700,000 acre-feet this year, a very small percentage of that actually got exported. When you have high flows, when you have 100,000 cfs through the Delta, you ought to have as big of a pipe as you possibly can to grab that water.”
“Finally, the regulatory paradigm has to recognize that it’s not going to be a freshwater Delta in the future,” Mr. Fecko said. “We have a firm belief in the climate science and everything in the state of California is driving towards fixing climate change, that’s the goal. We have a fuel tax, we have carbon credits, we’re moving to a 50% RPS so we all the way bought in on climate change – except when it comes to water policy, it seems like. It’s a weird dichotomy that we have in this state, so I think some of this regulatory paradigm, we have an opportunity to discuss this at the upcoming water quality control plan update at the State Water Resources Control Board, and I think this is going to be a theme that many of us are going to have to hit on for that regulatory proceeding.”
Right now it doesn’t make a lot of sense to have storage south of the Delta. “I drove by San Luis Reservoir on the way to ACWA the other day and I was surprised, we had a wet year and it wasn’t full, so right now south of Delta storage may not make a lot of sense. If you had a different conveyance mechanism, it might. Clearly we need to stabilize groundwater levels, we’d hate to see the aquifer collapse down there and then not have the ability to do conjunctive use in the San Joaquin Valley in the future, and then finally all of the above. There’s folks, especially in the populated areas south of the Tehachapis can take more advantage of desal, recycling, and groundwater resources.”
Mr. Fecko then ended with a hopeful note. “This is a poster from1850; it says there’s almost 44 million acres of government lands untaken – I don’t think that’s true anymore. Railroad and private land for a million farmers – maybe I don’t know. And it says a climate for health and wealth without cyclones or blizzards. So the last part’s still true.”
“Thank you very much.”
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