Folsom Lake water level chart
By Michael, independent developer behind zovo.one. Latest CDEC month October 2026.
CDEC's latest monthly storage figure for Folsom Lake is 372,351 acre-feet, for October 2026, 38 percent of its 977,000 acre-foot capacity. It is the 21st lowest of the 70 October figures from 1957 to 2026.
Where October 2026 sits in 71 years of readings
CDEC's latest monthly storage figure for Folsom Lake is 372,351 acre-feet for October 2026. That is 38 percent of its 977,000 acre-foot capacity.
The file holds 70 October figures from 1957 to 2026. This one is the 21st lowest of them. The average October figure across those years is 472,182 acre-feet, so the lake holds 79 percent of its average for the month.
Across every month from January 1957 on, 123 of 838 months were lower than today. That is 15 percent of those months.
The record low and the record high
The lowest monthly figure since January 1957 is 136,980 acre-feet, in November 2015. The highest is 1,013,300 acre-feet, in June 1958. That high is above the capacity CDEC lists today.
CDEC lists 1956 as the year Folsom Lake first filled. So the ranks, the average and the record low on this page count months from January 1957 on. That boundary is ours, not CDEC's. The file itself starts in October 1955.
How to read this chart
The line is storage, the volume of water in the reservoir, in acre-feet. It is not the surface elevation. CDEC publishes storage as one figure per month back to the start of the record, which is why this chart uses it. The dashed line is the capacity CDEC lists for the reservoir. The dotted line marks January 1957, where the ranks start.
Want today's elevation and percent full rather than the monthly record? The Folsom Lake water level page carries the latest daily CDEC reading.
Questions about the Folsom Lake record
How far back does this chart go? To October 1955, the first month in CDEC's monthly storage file for station FOL. The file carries 853 monthly readings through October 2026.
Is Folsom Lake low for October? It is the 21st lowest of 70 October readings, at 79 percent of the October average.
What is the lowest it has been? 136,980 acre-feet in November 2015, counting from January 1957.
How often does this page update? The build fetches the CDEC file again every day and recomputes each figure. A new month shows up once CDEC publishes it.
Where these numbers come from
Every figure on this page is computed in code from CDEC's monthly reservoir storage file for station FOL. The capacity and the first fill year come from CDEC's reservoir information page for the station. The build drops months that CDEC marks as missing. None of the numbers is typed by hand.
The same chart exists for 11 other California lakes. They are Shasta Lake, Lake Oroville, Lake Berryessa, Pine Flat Lake, Lake Isabella, Millerton Lake, New Melones Lake, Don Pedro Reservoir, San Luis Reservoir, Cachuma Lake and Casitas Reservoir. The California lake levels page covers every reservoir in CDEC's daily storage summary.
Levels are point-in-time readings and can lag real conditions. Confirm ramp and hazard status with the lake operator before heading out. Not affiliated with any government agency. Data is republished from public USGS, CDEC and USBR feeds.