Heavy rainfall in San Luis Obispo County is causing area reservoirs to swell with water, some with more than they’ve seen in four to five years, according to county water officials.
The storms that began just after New Year’s Day and continued through the week have yielded some measurable results. Rocky Butte near San Simeon has received the most rain — about 35 inches — since July 1, the official start of the rain season, while Shandon has received the least — about 5.5 inches — PG&E meteorologist John Lindsey said.
The rain has pumped the ground full of water, which means reservoirs have started to fill rapidly, said Ray Dienzo, a technical unit supervisor in the Water Resources division of county Public Works.
“All the lakes and creeks are starting to go up again,” he said.
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Although the rain is recharging reservoirs quickly, Dienzo said none are close to capacity yet. Mountain snowpack levels are also an important factor in diminishing the effects of the drought, he said.
“It’s definitely a combination of all those,” Dienzo said.
In North County, Lake Nacimiento has made huge gains in just a few days, according to the Monterey County Water Resources Agency. Rain added nearly 40,000 acre-feet of water to the lake, increasing its total storage — the amount of water it contains — by more than 30 percent since Saturday.
The body of water, which is maintained by Monterey County but used by residents throughout San Luis Obispo County, is about 43 percent full at 163,827 acre-feet. The last time the lake topped 150,000 acre-feet was in late 2012 or early 2013.
Water levels have risen so quickly that some residents of Cal Shasta, a private community on the shores of Lake Nacimiento, have had to retrieve their docks, which broke free and floated away, according to resident Phil Humfrey.
Santa Margarita Lake has increased its storage by 84 percent since New Year’s Eve, and it has doubled in the past two days, according to San Luis Obispo County Public Works. The lake was last this full in March 2015, and current levels place it at about 18 percent of its full capacity, according to county Public Works data.
Runoff from the rain also filled the Salinas River this week, causing a “live stream” of water to flow from Santa Margarita Lake to the Nacimiento River junction, according to Andrea Montes, a program manager for the county Utilities Division.
In South County, Lopez Lake near Arroyo Grande has gained about 13 percent in storage since Jan. 3, remaining near 25 percent of full capacity, according to county Public Works data.
Whale Rock Reservoir near Cayucos has also made gains because of the rain, reaching its highest level since June 2015, according to Mychal Boerman, the San Luis Obispo Water Resources program manager. Whale Rock was about 41 percent full on Tuesday morning, according to city data.
“We still have a long way to go on our reservoirs (especially Salinas Reservoir, also called Santa Margarita Lake),” Boerman said. “But this is a great start and has been a good year overall.”