After declining for more than 15 years, the water level in southern California’s Lake Casitas has made a sharp turnaround. The lake dipped to historic lows in November 2022 following several multi-year droughts. Then two wetter-than-normal winters set off a rapid rebound.
In April 2024, the reservoir reached full storage capacity for the first time since 2006 and sent water over the dam’s spillway for the first time since 1998. Lake Casitas supplies water to tens of thousands of people and hundreds of farms in Ventura County. As it refilled, managers eased water use restrictions that had been in place for years.
These images show Lake Casitas before and after its recovery. In November 2022 (left), the lake’s capacity had dropped below 30 percent, one of the lowest levels since 1970. Two years later, on November 18, 2024 (right), the reservoir held 96 percent of its capacity, or 126 percent of its historical average for that date. The images were acquired by the OLI-2 (Operational Land Imager-2) on Landsat 9.
The dramatic change follows prolonged stretches of drought conditions in California since 2013 and mandatory water conservation measures in the Casitas Municipal Water District starting in 2015, according to news reports. The situation began to improve with a series of storms during the winter of 2022–2023. Lake Casitas filled to 70 percent capacity in April 2023, allowing use restrictions to be eased. The rainfall total for that water year was more than double the 1957–1992 average.
The winter of 2023–2024 also delivered consistent rain, water managers said, with 150 percent of the normal total falling during that water year. On April 23, 2024, water in Lake Casitas reached the level of the spillway. The Casitas General Manager told news outlets this was the “fastest rebound in the lake’s history.”
The lake’s trajectory mirrors that of others in the state. Big Bear Lake in the San Bernardino Mountains went from its lowest level in recent history in 2018 to the highest in a decade in May 2024. In Northern California, the state’s two largest reservoirs, Shasta Lake and Lake Oroville, reached full capacity in 2023 and 2024 after drought conditions left them low in previous years. Both reservoirs stood at above-average capacity in early December 2024, helped in part by a strong atmospheric river that lashed Northern California in late November.
NASA Earth Observatory images by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story by Lindsey Doermann.
