At the February 25 meeting of Metropolitan Water District’s Special Committee on the Bay-Delta, Committee members heard a presentation how climate change is incorporated into the Bay Delta Conservation Plan (BDCP). During the presentation, BDCP Project Manager Jennifer Pierre told Committee members that the BDCP itself was never meant to be a project that addresses climate change, but several components of the plan will provide a level of adaptation for the Delta.
Cassandra Enos, program manager for the BDCP in charge of environmental compliance, began by giving the legal background for the climate change analysis. “Under CEQA, we are required to look at the impacts of a project on climate change, and more recently, under the Delta Reform Act, we were required to evaluate the impacts of our alternatives on climate change as well as evaluate the impacts of our alternatives that will be affected by climate change itself,” said Ms. Enos. “We’re also required through the ESA, Section 10 process to look at climate change.”
It’s a very valuable exercise to evaluate climate change impacts, she said. “The BDCP is probably the first project that has evaluated climate change at the level that we have. Typically we speak of climate change as changes in precipitation, changes in snowpack levels, but the analysis that BDCP has done has looked at climate change to the level of how much more often or how often will we go to dead pool conditions in the reservoirs.”
The climate change analysis also shows the benefits of implementing the BDCP, Ms. Enos said. “We see an effect with the BDCP that compared to the no action alternatives, we provide much more resiliency and adaptability within the plan area, and that is seen in many species,” said Ms. Enos. “Within the EIR/EIS we look at 24 resource areas, and 22 of those resource areas are impacted by climate change, so as you can see it’s a big issue.”
Ms. Enos then turned it over to Jennifer Pierre, ICF International’s project manager for the BDCP, to discuss the BDCP’s climate change analysis.
Climate Change Effects in the Sacramento and San Joaquin Rivers and Delta
Jennifer Pierre, Project Manager for the Bay Delta Conservation Plan, ICF International
“There are several different factors that are expected to change over the 50-year BDCP permit term, such as precipitation timing and runoff, sea level rise and how that interacts with overall project operations, as well as temperatures that are driven by atmospheric temperature changes,” began Jennifer Pierre, “So what we know is that these changes in the climate do affect how BDCP will perform in the future, and so for that reason as well as legal requirements is why the BDCP planning process is now, to an extent, incorporating some of the climate change assumptions into how we’re evaluating the effects and the benefits of BDCP.”
“The BDCP models do incorporate a set of climate change assumptions, but the BDCP itself was never meant to be a project that addresses climate change,” said Ms. Pierre. “However, what we found in our analysis is that there are components of BDCP within the Delta that do provide for a level of adaptation in the Delta.”
She then presented a slide depicting the expected effects of climate change on the Delta. “Changes relative to climate change include things like flow and hydrodyanmics, salt water intrusion, and habitat changes related to invasive species, temperature changes, and loss of habitat, etc,” said Ms. Pierre. “A lot of those things are driven by physical changes from climate change that affect the ecological condition in the Delta.”
When BDCP began in 2006, there had been no comprehensive studies of climate change in the Delta and tributaries, so BDCP is providing the first opportunity to understand climate change in Delta system, she said. “We needed to do that because we were seeing these models and we were seeing that there were going to be potential changes over the 50 year planning horizon, so BDCP really bore the burden of taking a comprehensive look at what that no action climate change condition looks like.”
We used a conservative analysis using average projected climate change and focused on the Delta driven changes that are occurring because of BDCP, she said. “What we found is that within the Delta, BDCP is addressing a lot of the climate change effects we see, but that outside of the plan area for BDCP, there’s a lot of very dire predictions going on. It will really require another set of planning activities, including possibly storage, to really deal with the effects that BDCP has brought to light,” she said, noting that the recently released California Water Action Plan calls for a more comprehensive approach to the state’s water resources and potential actions for planning.
For the BDCP’s climate change assumptions, we looked at all information available from 2006 up until now, she said. “There are actually 20 global climate models and 112 downscaled models that look more at a regional scale for the Bay Delta system and the western US. We looked at what sea level rise projections were being published – 1 ½ to 4 ½ feet of sea level rise was being projected.”
“A climate action team looked at what different climate projections may occur in California and the Delta in particular and one of the things that they found was that one of the most important changes that we can expect in California is a change in the timing and pattern of when the runoff is occurring,” Ms. Pierre said. “This is really important because reservoirs are operated for flood control, water supply, cold water pool, etc, and when you change how and when that water is entering the reservoir, you can have pretty drastic effects on how those reservoirs can be operated.”
She then presented a slide showing projected temperature changes for the Sacramento region as well as statewide. She noted that for the graph on the left, the black represents what was observed and the red represents what was projected, and the bottom graph also shows a black trending line. “So even though we’re looking at all sorts of varied environments throughout the state, we still are showing a trend of increasing temperatures,” she pointed out.
Ms. Pierre next presented a slide of projected and observed sea level rise, noting that for their analysis, they used a 45 cm increase in sea level rise over the 50 year planning horizon. “There certainly is quite a range of what might happen, but bottom line is what has been observed is about half a foot, and we expect to see at least the same sort of increase over this century.”
There are a lot of different models trying to project what precipitation will look like in the future, and those results are varied, she said, “but I think one thing that has emerged is a pretty common theme is that we’re going to see longer, drier spells and wetter wet spells and it’s going to be less “average” that what our historic record has shown, which is how we normally do our planning,” she said. “The BDCP analysis tries to take that into account, looking at a shift in the types of water years we see over time.”
The BDCP analyzes two points in time: the Early Long Term and the Late Long Term. The Early Long Term is the time frame at 10 years out. “We wanted to look in front of us and say, when the tunnels come online, what does the projected climate change look like and how will BDCP perform under that condition? And so we have an analysis of what we call the Early Long Term.”
The Late Long Term is at 45 years, and incorporates projected climate changes with all of BDCP functioning including habitat restoration. The habitat restoration is a key point, she said. “The BDCP includes quite a bit of tidal wetland restoration, and depending on where you put the restoration and how you do that restoration, it can help to buffer some of those sea level rise salt intrusion effects. Not all of them, but it is an important piece that’s part of both the early and late long term analysis with assumptions associated with the level of restoration that would occur.” She noted that a No Action Alternative was built into the analysis.
We were able to look at the effects of climate change over time even without a BDCP and what we discovered is that there are substantial effects on upstream reservoirs on both the Sacramento River basin and the San Joaquin River basin that are primarily related to changes in the timing of precipitation and snow melt, she said,noting that other impacts include increased Delta salinity and X2 intrusion due to sea level rise. “Especially in the Late Long Term period at the end of the BDCP permit period, trying to balance salt water intrusion, storage for water supply, flood control needs, and cold water pool for fish that are spawning and rearing and living in the upstream environment is going to be incredibly challenging under the configuration that we have today,” said Ms. Pierre, noting that BDCP itself isn’t addressing these upstream conditions but within the Delta, the BDCP is providing quite a few adaptations for species and for other uses.
She then presented a slide of projected storage in Lake Shasta at the end of September. “What we’re looking at here is an exceedance plot and what this is saying is that 50% of the time there’s about 3 MAF in Shasta in September, but what happens under the future condition, even without BDCP which is represented by the dotted black line, is that the storage level is dropping to about 2.5 MAF at 50%, and you can see it drops across all exceedances.” She noted that the other colored lines represent the BDCP models, but pointed out: “The take home message here is that BDCP isn’t causing this reduction in storage; it’s climate change,” she said. “The only difference between the orange line and these lines are the climate change assumptions that are built in, and this is the Late Long Term. Of course, there are a lot of uncertainties associated with the inputs that we put in our model, but the BDCP is a very conservative approach that uses what we called a centroid, so out of all the different potential outcomes, we look at what is most average of those conditions.”
She then presented a graph of projected storage at the end of May in Folsom Reservoir, noting that the orange line is the existing condition on average over the long term. “Again you see that under BDCP and future conditions without BDCP, we see a pretty substantial noticeable drop in those storage levels.”
Ms. Pierre then presented a graph of projected storage at the end of September in Lake Oroville, noting the drop in storage from the orange line to the black line. “The BDCP has variability related to what the storage looks like under BDCP operations, but always the same or better as what we would expect to see, even without BDCP.”
“What we can’t do is manage for water temperatures,” said Ms. Pierre. “Water temperatures in the Delta have been found to be 100% related to atmospheric temperatures, and so that’s a really big deal because a lot of the water quality and ecological benefits is very much related to temperature. It has something to do with invasive species, oxygen in the water, temperature tolerances for fish, and all of these things are then related to water supply as well.”
“But what BDCP can do is provide some reduction of stressors of things not related to climate change,” she said. “For example, the habitat restoration that we’re proposing will provide some buffering. … Entrainment is reduced by moving the point of diversion from the south to the north, and in many years, we are able to substantially reduce entrainment of salmon, up to 50% sometimes, so taking that entrainment stressor off of that species helps them better cope with some of the climate change effects, and it is possible, based upon how we do habitat restoration, to create safe areas of good quality habitat with the right temperatures that they can find refuge in.”
Other benefits of the BDCP in the Delta related to climate change include a reduction in the risk of Delta levee failure due to climate change and sea level rise as habitat restoration reduces the number of levees required, the developed wetlands have the potential to sequester carbon, and floodplain restoration in the south Delta will help the Lower San Joaquin River deal with extreme high flow events.
“There’s also operational flexibility, and I don’t think we can overemphasize this enough, but it’s very difficult to model and to pinpoint, but just having a second point of diversion in the Delta I think will prove to be very huge as the effects of climate change play out,” she said.
“So in conclusion, I think the take home message today is that what we found with our analysis is that unrelated to BDCP, climate change is going to be a major challenge for state water management in the future, even as soon as 50 years out,” said Ms. Pierre. “The BDCP is not exacerbating these changes, but it is providing some buffering of the changes that are happening in the Delta. But outside of the plan area, additional actions will be needed to really address the climate change effects that we are seeing in our model results.”
For more information …
- Click here to listen to the February 25th meeting of Metropolitan Water District’s Special Committee on the Bay-Delta.
- Click here to view Jennifer Pierre’s power point presentation.
- Click here to view climate change portions contained in the BDCP and it’s environmental documents.
