BAY DELTA SCIENCE CONFERENCE: Drought, climate change, and restoration resiliency
John Durand looks at the effects of the 2012-2016 drought on the Delta from the environmental, economic, and stakeholder perspectives
The 2012-2016 drought is one for the records in that, while not necessarily the driest or the longest for California since the state has been keeping records, it was the hottest drought with many scientists saying that we can expect similar droughts in the future. John Durand, a research scientist at UC Davis, gave this presentation at the 2018 Bay Delta Science Conference that looked at the impacts of the drought on the Delta from the perspectives of the environment, the economy, and Delta stakeholders.
John Durand began by saying he has been spending a lot of time, thinking about the big picture around restoration strategies for the Delta and the Suisun Marsh, and how the recent drought and climate change factor into it.
“I’m going to look at the recent drought and try to apply it, because with the trend that we’re seeing in these droughts, for the first time, it really seems like climate change is real,” he said. “I feel like from our data and from our daily experiences, there’s many aspects of the last drought that give us some idea about how climate change is scaling down to California, which has been an outstanding question for many years now.”
The trends that were seen in the last drought should drive our thinking about not only preparing for future droughts, but also preparing for climate change. The 2012-2016 drought wasn’t the driest or longest drought in California history, but it was in some ways the driest, longest, hottest drought, he said.
Temperatures exceeded the norm (above, left), and along with that, there was very little snowpack (above, right). “I argue that the characteristics of the drought give us an idea about how things are going to downscale, particularly the heat, the low snowpack, and the length,” he said. “So I’m going to offer these three perspectives of drought and climate change: The first is going to be an environmental perspective of what’s been happening. The second perspective will be economic, looking at the economics of the recent drought and how we can think about that going forward, and then third, from the perspective of three important stakeholders.”
Increasing Delta salinity was a feature of the recent drought and it will be a feature of climate change, Mr. Durand said, presenting a slide showing Delta salinity in high and low flows, noting that it was from a model done by RMA. During the recent drought, salinity was largely managed by the implementation of a barrier in West False River, but there were salinity exceedances throughout the Delta, and these had an impact, not only on fish communities and the aquatic community, but also on soil salinization in the Delta, and Delta agriculture, he said.
Mr. Durand said there was a lot of anecdotal evidence that soil salinity increased and that it had some affect on crops. There was a voluntary fallowing program which turned out to be beneficial for a number of reasons for growers because of the increasing salinity as it minimized their risks and gave them a plan B.
He presented a model of decreasing crop revenues as a function of increasing salinity in the Delta, depicting the trend of loss of agriculture revenue as a function of increasing salinity in the Delta.
“The thing about soil salinity is once we start applying to the soil, it has a sort of resilience in that it’s difficult to reverse that process without using a lot of water, which we don’t often have in California,” he said. “These soil salinity effects can be chronic and ongoing over a longer period then with drought and unless we can manage salinity in the Delta, we would expect that that would continue.”
Aquatic vegetation spread tremendously in the drought. He presented some plots showing that the overall the spread of submerged aquatic vegetation as well as floating aquatic vegetation throughout the Delta increased throughout the drought. On the maps, red is submerged aquatic vegetation on Liberty Island. “Liberty Island and the Cache-Lindsay complex was the place that was kind of resistant to this stuff for many, many years,” said Mr. Durand. “But the truth is with the trend we saw during the drought, the ongoing trend is that the North Delta is becoming more and more like the South Delta, and that’s a trend that we’ll continue to see marching into the future.”
There is an increasing extinction risk. Mr. Durand presented a slide showing plots for the Delta smelt for the Fall Midwater Trawl and the Summer Townet survey. “This has been a decadal decline, but during the drought, they all but disappeared,” he said. “In our own surveys up in the north Delta, we saw very few Delta smelt at the beginning of our surveys in 2012, we saw more longin smelt occasionally, but they pretty much dropped off all detection.”
Unlisted species declines is something that can be expected. He presented a plot showing populations of tule perch, noting that it’s a rather ubiquitous species, but by the end of the drought, tule perch populations had dropped significantly and hasn’t really recovered since then. “This is a trend that we could expect to see, not only for tule perch but for splittail, hitch, pike minnow and all non-listed species that have local importance as indigenous coldwater fishes that are unique to this area.”
Then there was the reverse trend for invasive fishes, whose populations increased. He presented a slide showing the populations of centrarchids or sun fishes (all introduced fishes) in the North Delta, noting that the increase in that region probably mirrors the increase in submerged aquatic vegetation which provides habitat for them. “These plots reflect the increase in blue gill, sunfish, large mouth bass and other invasive fishes across the drought. They increased during the drought and they haven’t subsided since the drought, and I think in many ways, they are probably there to stay.”
“One of the implications is not just of the loss of intertidal habitat and island flooding risks which jeopardize agriculture, but these change the tidal prism that’s operating through the system,” he said, noting that the plot in the middle is from a Chris Enright talk he gave a few years ago. “As we have a finite amount of tidal energy and as sea level rise increases the volume on the surface area of the Delta, it distributes that tidal energy across that plane. That finite amount of energy means the tidal prism shrinks so as sea level rise goes up and as islands flood, it means that tidal prism will diminish over time. That’s a critical thing to think about in terms of restoration and also supporting native fishes, as there are processes tied into that that essentially defined this region as a tidal estuary.”
The economic perspective
Mr. Durand then turned to the economic perspective. During the recent drought, the state’s total economic losses totaled about $10 billion, which is less than .1% of the California’s $2.5 trillion economy. “It turns out that the drought impact on the economy was much less than the impact from just standard business cycles, from federal policies, and international exchange,” he said.
The reason is that California’s infrastructure and geography is built for some kind of resilience. “We have the elevation so the snowpack, although diminished, provides a lot of resilience. We have springs and groundwater resources in the valley, and we’ve learned to exploit all these resources through the California water system, which includes dams, canals, and aqueducts.”
More recently in the past couple of droughts, innovations have occurred including interties between water systems which can be used in conjunction with water markets to get water from where it is to where it is needed. It has provided a lot of flexibility that in many ways sustained a variety of communities and a lot of industrial sectors across California.
“During the drought in spite of the crisis, in spite of the overall trend, California’s probably well suited to manage changing climate going into the future with an abundance of resources,” he said.
He presented a pie chart (lower, left) showing the different crops grown in California, noting that most of the value in agriculture is in tree crops. “Very little of this value derives from other crops,” he said.
He then presented a plot showing cumulative ag jobs and revenue plotted against crop acreage (upper right). “This is the cumulative irrigated crop area in relationship to the contribution to ag and ag jobs and revenue. 50% of the cumulative ag area provides 80-90% of the jobs and revenue, so if you cut back by half, you can still maintain almost all the revenue from ag, so it has a lot of resilience baked into it.”
Agriculture uses about 80% of California’s water while urban and industrial gets about 20%, but ag is contributed just 2% to the overall California economy. “It’s not a big part, but it’s a very essential part of the economy and it has a critical role in our society, almost like a utility function,” he said. “We support ag because it’s necessary to feed people … but the fact is that our economy and agriculture is quite resilient to changes in water supply, so if we took off half of ag’s irrigable crop area, it would result in an impact of about 0.4% – that is it would reduce ag to about 1.6% of the total state economy.
“My point is that our economy is very robust to drought and California has the resources to mitigate environmental problems during this if we choose to apply those resources,” he continued. “We’re a very rich state and we’ll continue to be a rich state.”
The Delta stakeholder perspective
Mr. Durand then lastly turned to the perspective of three Delta stakeholders: The environment, agriculture, and water exports. “These three stakeholders face similar threats, and I’m going to argue that they have much more interests that are aligned rather than separate,” he said. “The main threats are island flooding, salinity encroachment, invasive plants and animals, and tidal energy loss.”
“Agriculture and export rely on levees, so there is the threat of flooding; invasives which can get in the way of moving water around, and salinity encroachment all affect agriculture and export in the same way. They also affect the environment.”
Tidal energy loss is a threat to the environment that doesn’t affect the others but the interests of agriculture and water exports largely overlap, he said. The threats of island flooding, salinity encroachment, invasive plants, and tidal energy loss can be managed with habitat restoration, levee maintenance, and managing water inflows, which he acknowledged are all expensive propositions that require a lot of effort. There’s broad overlap in how they’ll be managed as well as broad overlap in terms of ag, exporters, and the environment relying on these same tools, he said. Tidal energy loss can be managed mostly through careful habitat restoration but also requires the levee system, he noted.
“What I’m trying to get at it here as I run out of time, is that the three big stakeholders have a lot of interests that overlap,” he said. “They face a common enemy which is the changing climate, and the fact is that the historical antagonism between these three groups is more and more misplaced as we march into the future.”
In conclusion …
“Climate change is like the Gollum and it’s the enemy,” said Mr. Durand. “We can use the Gollum as a tool to force us to engage and collaborate and find solutions that will march us into the future, or we can panic and do nothing, which has been a large part of the federal strategy and have the Gollum wreck Progg. I don’t want it to wreck Progg, I’d like to work on the Delta. And I think we have the resources to implement changes and so I’m going to conclude my talk with the key collaboration goals that these stakeholders have in common which is to keep the Delta fresh, maintain it as a tidal system, maintain the levee system, and control invasive vegetation.”
“To make that happen, there are a series of goals that we can agree on broadly among the stakeholders. Some of these we’re implementing but we should do it much more aggressively because the change is coming and it’s coming already.”
“The key things we need to do is engage or expand our levee maintenance system to buffer not only against sea level rise but also earthquakes; it’s a huge effort but we have the resources to do it,” he said. “Use marsh restoration to buffer those levees in transition zones which will be compromised in the future. Embrace comprises that maintain fresh water in the Delta, preferable with a dual intake system which benefits more stakeholders in the process. Support ag that reverses subsidence, which is being done but not enough. Support long-term water efficiency standards among urban users as well as ag, although ag has done a lot in this realm and in the last drought, urban users did as well. Negotiate voluntary settlements agreements with the watersheds; I didn’t talk about what’s going on up river but that’s a key part of what’s going on for the Delta, support south of Delta that can maintain profitability to support Delta. South of Delta agriculture is going to contract, it has to contract, but there are profitable enterprises there that can help support restoration in the Delta. And then finally, raise fees on stakeholders. We have to do it. We have the resources, we have to make the decision.”
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