The public has a little more than 30 days to comment on a report released by the engineering firm Luhdorff and Scalmanini detailing hydrologic conditions for the Santa Maria Valley Management Area.
On June 12, at the Santa Barbara County Board of Supervisors hearing room in Santa Maria, Senior Hydrologist Liese Schadt told a small crowd of stakeholders that area groundwater levels were “similar or substantially higher” than those just a year before. She said nitrate and mineral content (mostly salt) in the water sat at historic levels, and except for a few hotspots, notably Orcutt Creek, all fell within ranges that did not appear to be health risks to the public. Supplies, she noted, looked good for the most part.
“Water requirements for the Santa Maria Valley Management Area in 2017 were essentially equal to the previous year,” she added, noting that the region only used roughly 250 extra acre feet of water. The report noted that State Water Project (SWP) allocations for the area increased from 10,480 acre-feet to 11,525 acre-feet, while groundwater pumping declined.
Schadt said Santa Maria city officials were continuing to work to increase long-term water supply, in particular, “securing up to about 12,000 acre-feet of additional SWP entitlement.” She noted this could be a challenge due to limited surface water supplies from the program because of California’s recent spate of droughts.
“The availability of state water is almost half of what it used to be, when the SWP was first rolled out,” Schadt explained, noting that precipitation fluctuations from wet to dry periods put a significant amount of strain on the state’s water systems. “There’s apparently no getting out of that. … Welcome to California.”
Daniel Swain is a climate scientist at UCLA’s Institute of the Environment and Sustainability. He is also the lead author of a paper that came out this year detailing how those fluctuations in wet and dry periods will only increase in intensity over the course of the next century.
“We’ve seen that illustrated the past couple years where we really only had a few days of rain in LA, but one of them killed 20-something people with the mudflows in Montecito,” Swain told the Sun, noting that that while the floods were mainly related to fires that preceded them, they were still related to those fluctuations. “That sort of flashiness of these flows and streams and intensities of the big bursts of precipitation are characteristic of what we’ll see moving forward.”
Recently, California has seen what Swain calls a “bounce,” or where the state experienced more dry than wet years.
“That’s the part that might not continue,” he said, “and as we move forward over the next few decades, much of the state will experience pretty big flood events on a much larger scale than we’ve seen previously.”
He said many of the changes in California’s climate can be attributed to rising temperatures.
“That rising temp. will affect how much water is in [the state’s] water systems, even if precipitation changes very little,” he said, adding that an overall drying effect due to higher temperatures is one problem water managers in the state will have to grapple with in coming years.
“Superimposed on that are these periods that will either be quite wet or quite dry,” Swain said. “What we really see is a future that sort of has these ‘amplified extremes,’ and they’re both sort of indirectly driven by temperature.”
The role of temperature is an important detail to remember because there’s a chance that rainfall levels stay relatively the same in the future, but due to higher temperatures and the increased evaporation that comes with it, water agencies will have less to work with.
“This is the interesting thing about California’s future,” Swain added. “There’s a pretty good chance that the overall average precipitation won’t change very much, so some folks have interpreted that to mean, ‘OK great, we will have the same amount of water to work with, even if it’s warmer.'”
However, the truth is far more complicated due to three reasons. One of the most basic involves water input, he said, likening the area’s aquifers to surface water and reservoir storage.
“Just because you are putting the same amount of water in, doesn’t mean you get to take the same amount out because some of that is being lost to the warmer atmosphere, and to the plants, animals, and humans using that extra water due to that warmer atmosphere.”
Another reason involves intense rainfall over shorter periods than their historical average.
“For example,” Swain said, “if you have 2 inches of rainfall over the course of a storm, but historically that fell over two days, and in the future it falls in 18 hours, less of that water is actually going to soak into the ground because obviously it takes time [to filter into the aquifer].”
Water doesn’t soak into the ground instantaneously, Swain explained, and if the soil is already dry because it’s been warm, that makes it even harder. “So you increase precipitation intensity and the infiltration rate in the soil decreases, and the result is a lot of that runs off into rivers and streams, and unless you’re capturing that, it’s not going to end up in the groundwater,” he said.
Moreover, if it’s warmer and dryer in general, the soil becomes a little more impervious to water to begin with.
“You sort of have a double whammy there,” Swain said, “with how much water might actually make it into the groundwater aquifers given that we do get precipitation, even if it’s more intense.”
The last big factor affecting water supplies is the general decrease in snowpack, which would limit Santa Maria’s SWP allocations, which rely on snowmelt. Swain said that while the issues related to wider precipitation swings were still being observed by scientists, the snowpack problem had become irrefutable fact.
“This is one of those projections that became a reality and is now the world we live in,” he added.
And that world is one where California’s water purveyors attempting to manage a precious, finite resource will need to prepare for both sides of the extreme scale.
“What we are going to have to expect from year to year is going to be challenging, and we can’t manage the risk of drought without the risk of flood and vice versa,” he said. “We have to be thinking about both of these things at the same time.”
Staff Writer Spencer Cole can be reached at scole@santamariasun.com.
This article appears in Jun 21-28, 2018.