Drought indicators surface for county
Several water suppliers are considering putting in place water-use restrictions
As cherry blossoms and calla lilies spring to life, the sun shines and rain showers begin to seem like a distant memory. Spring is here, and with it Santa Cruz County has begun to show early indications of drought, with little reprieve in sight.
Rainfall levels in the city of Santa Cruz and in the mountains are well below average. Loch Lomond is at a little more than 70% capacity and the San Lorenzo River is low for this time of year, according to officials. Several water agencies are considering implementing water-use restrictions — including rationing.
The region’s current drought conditions are less severe than elsewhere, though.
“Santa Cruz County is actually sort of in a regional minimum of drought severity in Northern California, so as bad as it is, it’s worse almost everywhere else currently,” Daniel Swain, a UCLA climate scientist and California climate fellow with The Nature Conservancy, said.
The Sentinel obtained 40 years of National Weather Service rainfall data between the months of October and March. As of Saturday in Santa Cruz, 16 inches of rain in total has fallen during this year’s wet season — 11 inches less than normal. That’s a 40% deficit compared to the average expected rainfall for this time of year.
The data is more stark in the Santa Cruz Mountains. This time of year 44 inches of rain would have been expected in Ben Lomond, but so far just 18.75 inches of precipitation has fallen in total. That’s 58% below what would be expected during a normal rainy season.
“We’re already in year two of this drought,” Swain said. “And the problem is we kind of already know where things are headed until next autumn ... it’s not going to rain a lot between now, and the next rainy season.”
During the 2019-2020 wet season, Santa Cruz received 80% of its typical yearly rainfall totals, while in the mountains, Ben Lomond fared worse, and got just 56% of its annual normal.
This week’s U.S. Drought Monitor map classifies the Santa Cruz region in the lowest category of drought. As part of that designation, active fire season is already underway. Drought development is likely in Santa Cruz County, according to the most recently released U.S. Seasonal Drought Outlook.
Santa Cruz County depends solely on local rainwater to recharge underground aquifers, and supply streams and drinking water reservoirs. Unlike many other parts of the state, no drinking water is imported from outside sources – the region relies only on water that falls from the sky.
Like other regions of California that depend only on local water sources — Marin, Shasta and Santa Barbara — Santa Cruz is particularly vulnerable during dry years, Swain said.
“The fact that there has been extremely low precipitation and warm temperatures in those regions … that’s probably where the first water supply issues are going to arise in this drought because they have less interconnectedness, less resilience,” Swain said.
Local impacts
The Santa Cruz Water Department is considering implementing water rationing, but other drinking water suppliers in the county are also deliberating cutbacks.
“Several water agencies considering whether water-use restrictions would be necessary this summer,” said Sierra Ryan, interim water resources manager with the Santa Cruz County Water Resources Division.
Those measures, according to Ryan, could also include voluntary curtailments.
No significant rainfall is predicted for the Central California Coast for the next two weeks. At this point, Ryan said she doesn’t expect that any spring rains occurring over the next months could make up for the current deficit.
“We are experiencing some degree of drought,” Ryan said. “This is the second consecutive dry year in a row and all of the water managers throughout the county are certainly keeping our eyes on streamflow and groundwater elevations.”
Some local water suppliers are harder hit than others by dry conditions. While 80% of Santa Cruz County’s drinking water supply is sourced from groundwater — water that seeps into underground reservoirs, or aquifers — the rest comes from local streams, creeks and rivers.
Those surface water sources make up the bulk of the water supply for Santa Cruz, San Lorenzo Valley, and Davenport residents. Those stream flows, including water diverted from the San Lorenzo River, make up 95% of the cty’s drinking water supply.
The San Lorenzo River is the county’s major surface source, according to Ryan. Those waters are running low — less than 25% of average documented flows for this time of year.
The San Lorenzo Valley Water District has also been forced to divert more water from local streams to customer’s taps as a result of the CZU Complex Fire. More than 7 miles of the district’s water pipeline was damaged or burned in the blaze.
“They don’t have all their surface water sites back online so they’re relying more on groundwater, and that groundwater is not being recharged because we’re not getting a lot of rain,” Ryan said.
Still, Ryan said in the near-term she’s not concerned about the stability of the county’s drinking water portfolio.
Water restrictions possibility
Rosemary Menard, water director of the Santa Cruz Water Department, and department staff have been analyzing weather data, reservoir elevations, customer demand and stream flow rates. The decision to implement rationing is a tight-rope walk between using the available data and a deeper insight into the water needs, and limitations of Santa Cruz, under dry conditions.
“Rationing and telling people ‘this is how much water you get’ is not easy for us to do, and it’s not easy for a community to live with,” Menard said. “I don’t want to do that unless I really, really feel that it’s absolutely necessary.”
Water conservation efforts in Santa Cruz have been extremely successful. So successful, in fact, that Menard said that further conservation programs wouldn’t make a significant dent in water availability — the tactic has been maxed out. Customer demand has also significantly lowered compared to years past, according to the water director.
How long drought conditions persist — on scale of a year, or five years, Menard said, matters. And the uncertainty of what the 20212022 wet season will look like is weighing on her mind.
“I have to make decisions to make sure the community doesn’t run out of water,” Menard said.
At the heart of the water supply issue, is storage. Santa Cruz County has one reservoir, “the hidden gem” of the redwoods: Loch Lomond. That storage becomes particularly important to augment drinking water supplies during the summer and autumn months, and more critically, during dry years.
“Our storage, our single storage reservoir — Loch Lomond — isn’t large enough to get us through multiple drought years in a row,” Menard said.
The water director will make a recommendation the first week of April on if rations will be necessary.
The biggest challenge, she said, is trying to forecast what comes next.
“It’s really about what happens next year. That’s always a problem when I’m trying to make a decision in April or March,” Menard said. “If somebody can tell me when it’s going to rain and how much, I can make it a perfect decision, but I don’t know when it’s going to rain.”
Fire risk amps up
Less than average precipitation is one drought metric, but so are warming temperatures, UCLA’s Swain said.
“We’re in pretty serious territory with the precipitation deficit and then on top of that we have multiple decades of global warming,” Swain said. “The other big concern is in the past couple years, temperatures have been really really warm as well, and that just compounds the water availability.”
That’s playing out in Santa Cruz County, as the underbelly of sunny spring weather could emerge in the coming summer and autumn months, nearly six months after the CZU Lightning Complex fire burned more than 86,500 acres.
“If we don’t get any significant spring rains in April, this fire season could start earlier and be worse than last year,” said Craig Clements, director of San Jose State’s Fire Weather Research Laboratory.
For Ryan, with the Water Resources Division, the silver lining in Santa Cruz County’s low rainfall totals, is a dodged bullet. This last winter could have meant destructive debris flows occurring in fire-scarred areas.
Between historic fires, debris-flow risk, and earlyonset drought, Ryan said it’s clear impacts of a warming planet have arrived locally.
“We’re experiencing climate change already,” Ryan said. “It’s already happening here and that means the kind of rain patterns we used to see, we’re already not seeing them, and that’s going to continue into the future.”