Lake Oroville hits capacity for second straight year
Lake Oroville, the second-largest reservoir in California, reached capacity on Monday for a second straight year after another relatively wet winter.
The rising waters come as state reservoir managers have been reducing outflows from the lake in recent weeks — as winter inflows tailed off and the threat of downstream flooding waned — allowing the reservoir to slowly fill to its current 899-foot elevation, or 3.52-million acre-feet of water.
“This is great news for ensuring adequate water supply for millions of Californians & environmental needs,” the state Department of Water Resources posted Monday afternoon on X, formerly Twitter.
The agency warned visitors to Lake Oroville of the possibility of waves splashing from the swollen reservoir into the emergency spillway, the chute where excess water can be let out. State officials also said the spillway may discharge small amounts of water from drains built into the structure. They said this was normal operations.
Lake Oroville contains 28% more water than it historically has on this date. While the lake also filled to the brim last year, three years ago water levels sank to their lowest point ever, a testament to California’s increasingly variable climate.
This year, snowpack in the northern Sierra measured 123% at its peak, according to state data, helping boost flows in the Feather River, which feeds Lake Oroville.
Federally managed Shasta Lake, which is California’s largest reservoir, was 97% full on Monday, or about 115% of average.
Even with Lake Oroville at capacity, and other reservoirs above average, state water officials have said they expect to provide only 40% of the water requested by communities and irrigation districts in the coming year. Several Bay Area cities are among those that get water from the State Water Project, the vast network of reservoirs (including Lake Oroville) and canals that supply water across California.
One of the reasons for the limited deliveries, state officials say, is an ongoing issue with the pumps that move the water. The State Water Project pumping facility in the SacramentoSan Joaquin River Delta often draws in fish and kills them, including delta smelt, chinook salmon and steelhead trout. In response, the state reduces how much water is pumped.
“This year highlights the challenges of moving water in wet periods with the current pumping infrastructure in the south delta,” said Department of Water Resources Director Karla Nemeth in a statement. “We had both record low pumping for a wet year and high fish salvage at the pumps.”
Nemeth said the state needs to continue updating its water infrastructure, to improve water delivery, including building the contentious 45-mile tunnel across the delta.