After winter storms, local reservoirs at Lake Piru, Lake Casitas hit milestones

Lake Piru has inched toward its capacity as recent storms drenched the area, pushing the eastern Ventura County reservoir close to spilling in back-to-back years.

Last March, water breached the Santa Felicia Dam's spillway for the first time in nearly two decades. Now, it is just a storm or so away from doing it again. That rarely happens in consecutive years, said Mauricio Guardado, general manager of the United Water Conservation District.

“It has only happened three times since the Santa Felicia Dam was constructed in 1955,” Guardado said.

The latest round of storms boosted two local reservoirs, marking a second straight year of gains after more than a decade of drought. Some local spots have already recorded more than a season's worth of rain, according to preliminary figures from the Ventura County Watershed Protection District. That's on top of one of the the wettest rainy seasons in years in 2023.

The water level at Lake Piru reached nearly 94% by Monday. Meanwhile, the much larger Lake Casitas in the Ojai Valley rose to more than 86%.

Why did Lake Casitas drop so low?

Just a year earlier, Casitas, which gets no imported water, climbed past the half-way mark for the first time since 2015.

Eight years earlier, the drought-stressed reservoir fell to that 50% mark for the first time since it filled in the 1970s. The lake never climbed back to even half full until a series of storms soaked the county last winter.

The lake, which provides drinking water for the Ojai Valley and part of Ventura, was OK'd by federal officials in 1956. Construction on the dam was completed a few years later. But it took more than a decade before the lake filled, slowly covering old ranches, roads and a school.

As drought conditions worsened between 2012 and 2016, the shoreline moved, exposing trees, the site of a school and old roads not seen in decades.

The Casitas Municipal Water District, which manages the lake, was looking at severe water restrictions in late 2022, General Manager Mike Flood said. Within months, things started to turn around as storm after storm soaked the area.

By last spring, the lake reached over 70% capacity. For the first time in years, Ojai Valley residents weren't required to curb their water use or risk fines.

"I'm very encouraged," Flood said. "Our job is to get water to people, farms and businesses, and we've got plenty of water to do that now."

At capacity, the lake is designed to hold enough water to make it through a 20-year drought, he said.

Will Lake Piru spill again this year?

The county could see light rain Monday afternoon and overnight, but totals are expected to stay below a quarter of an inch or slightly higher in the mountains, said David Gomberg, a meteorologist with the National Weather Service in Oxnard.

Things should start drying out Tuesday morning. Then, toward the end of the week, the forecast calls for a colder storm to bring more rain and some snow, he said. Totals could reach 0.75 to 1.5 inches of rain in coastal and valley areas and 1 to 3 inches in the mountains.

Those totals are lower than the area saw with recent atmospheric rivers that drenched the region. But even more moderate rainfall could raise concerns about already soaked hillsides, officials said.

Whether Lake Piru spills remains to be seen, officials said. Once at capacity, the spillway reroutes water so it doesn't go overtop the dam. Instead, water flows down a sort of concrete funnel into Piru Creek.

What happens when the lake spills?

United Water, which also gets deliveries of imported water, built the Santa Felicia Dam in the 1950s to capture runoff in the Lake Piru reservoir and use it to recharge groundwater basins downstream.

Once released, the lake water flows down creeks and the Santa Clara River past Fillmore and Santa Paula to United's Freeman Diversion near Oxnard. From there, the water heads to pipelines as well as spreading ponds near Saticoy and El Rio.

With the forecast calling for a wet winter, United released water late last year to create additional storage and let areas downstream recharge, Guardado said.

"We were about 40% full when we started getting these storms at the beginning of the year," he said.

Cheri Carlson covers the environment and county government for the Ventura County Star. Reach her at cheri.carlson@vcstar.com or 805-437-0260.

This article originally appeared on Ventura County Star: Lake Piru close to spilling; Lake Casitas reaches new milestone