Folsom Dam · American River · CA
Folsom Lake
Sacramento's flood shield and water supply in one structure — it swings between full and drained faster than any big CVP reservoir.
Water surface elevation
411.4 ft
Bureau of Reclamation, daily · daily value, Sep 1
Water in storage
460,470 acre-feet
Bureau of Reclamation, daily · daily value, Sep 1
Share of capacity
47.1% full
against the project figure capacity figure (USBR Central Valley Project data)
Below full pool
54.6 ft
full pool at 466.0 ft
This month in the record
lower than 68% of the 69 Septembers on record
monthly mean storage; record low 156,287 acre-feet (1977), record high 846,583 acre-feet (1969)
30-day trend
-6,087 af/day
storage, 2026-07-31 → 2026-08-30; over the year -29.4 af/day. Measured change, not a forecast.
Drought at the dam
D0 — Abnormally dry
US Drought Monitor at the dam's coordinates, released 2026-08-27; the feeding basin can differ.
47.1% full
of capacity, by storage (project figure figure, USBR Central Valley Project data). Sedimentation slowly shrinks real capacity.
The water line is elevation (USBR project datum); the percentage is storage ÷ capacity. They are different measures — a reservoir's volume is not linear in its depth, so the line's height in this column is not the percentage.
The last 120 days
Daily water-surface elevation in feet. The axis hugs the data — it does not start at zero. Source: committed snapshot (USBR RISE, retrieved 2026-08-31).
See the numbers as a table
| Date | Elevation (ft) |
|---|---|
| Aug 30 | 412.13 |
| Aug 29 | 412.41 |
| Aug 28 | 412.68 |
| Aug 27 | 412.87 |
| Aug 26 | 413.24 |
| Aug 25 | 413.78 |
| Aug 24 | 414.23 |
| Aug 23 | 414.74 |
| Aug 22 | 415.29 |
| Aug 21 | 415.89 |
| Aug 20 | 416.61 |
| Aug 19 | 417.47 |
| Aug 18 | 418.29 |
| Aug 17 | 419.09 |
| Aug 16 | 419.97 |
| Aug 15 | 420.82 |
| Aug 14 | 421.61 |
| Aug 13 | 422.53 |
| Aug 12 | 423.48 |
| Aug 11 | 424.40 |
| Aug 10 | 425.38 |
| Aug 9 | 426.31 |
| Aug 8 | 427.17 |
| Aug 7 | 427.97 |
| Aug 6 | 428.78 |
| Aug 5 | 429.54 |
| Aug 4 | 430.42 |
| Aug 3 | 431.23 |
| Aug 2 | 432.12 |
| Aug 1 | 433.02 |
Most recent 30 days shown.
The whole record
Monthly mean elevation, Mar 1955 to Aug 2026. The axis spans the pools, not zero; elevations in USBR project datum. Months with fewer than 15 gaged days are dropped, and gaps in the record break the line. Source: USBR RISE, retrieved 2026-08-31.
See the numbers as a table
| Month | Mean elevation (ft) | Days gaged |
|---|---|---|
| Aug 2026 | 421.1 | 30 |
| Jul 2026 | 445.0 | 31 |
| Jun 2026 | 461.5 | 29 |
| May 2026 | 463.6 | 31 |
| Apr 2026 | 458.1 | 30 |
| Mar 2026 | 445.3 | 31 |
| Feb 2026 | 423.1 | 27 |
| Jan 2026 | 426.6 | 31 |
| Dec 2025 | 414.1 | 31 |
| Nov 2025 | 407.4 | 30 |
| Oct 2025 | 407.9 | 31 |
| Sep 2025 | 411.3 | 30 |
| Aug 2025 | 417.1 | 31 |
| Jul 2025 | 439.0 | 31 |
| Jun 2025 | 457.4 | 30 |
| May 2025 | 460.8 | 31 |
| Apr 2025 | 458.9 | 30 |
| Mar 2025 | 436.8 | 31 |
| Feb 2025 | 426.0 | 28 |
| Jan 2025 | 397.8 | 31 |
| Dec 2024 | 389.5 | 31 |
| Nov 2024 | 396.8 | 30 |
| Oct 2024 | 407.5 | 31 |
| Sep 2024 | 413.8 | 30 |
Most recent 24 months shown; the full monthly series is in the page's API response.
Storage against capacity
Monthly mean storage in acre-feet, zero baseline. The dashed line is the project figure capacity figure (USBR Central Valley Project data) — sedimentation slowly shrinks real capacity. Storage can legitimately rise past a conservation-pool line when the flood pool is in use.
See the numbers as a table
| Month | Mean storage (acre-feet) | Days gaged |
|---|---|---|
| Aug 2026 | 538,849 | 30 |
| Jul 2026 | 756,092 | 31 |
| Jun 2026 | 926,960 | 29 |
| May 2026 | 949,937 | 31 |
| Apr 2026 | 891,152 | 30 |
| Mar 2026 | 758,641 | 31 |
| Feb 2026 | 554,727 | 27 |
| Jan 2026 | 584,063 | 31 |
| Dec 2025 | 481,274 | 31 |
| Nov 2025 | 430,668 | 30 |
| Oct 2025 | 434,168 | 31 |
| Sep 2025 | 459,607 | 30 |
| Aug 2025 | 505,318 | 31 |
| Jul 2025 | 699,182 | 31 |
| Jun 2025 | 882,586 | 30 |
| May 2025 | 919,123 | 31 |
| Apr 2025 | 898,949 | 30 |
| Mar 2025 | 677,190 | 31 |
| Feb 2025 | 584,014 | 28 |
| Jan 2025 | 364,970 | 31 |
| Dec 2024 | 313,711 | 31 |
| Nov 2024 | 359,157 | 30 |
| Oct 2024 | 431,452 | 31 |
| Sep 2024 | 479,032 | 30 |
Most recent 24 months shown.
Where these numbers come from
Readings at Folsom Lake are the measuring agencies' own: each value above names its source (USGS gage, Bureau of Reclamation daily record, Army Corps project data, or this desk's committed copy) and its observation time in the reservoir's own time zone. The capacity figure is the project figure USBR Central Valley Project data number; sedimentation slowly shrinks real capacity, so the vintage travels with the percent.