Grand Coulee Dam · Columbia River · WA
Franklin D. Roosevelt Lake
The pool behind the largest power plant in the United States. No public storage series reports here, so this page shows elevation only.
Water surface elevation
1,284.2 ft
USGS gage, 15-minute · Aug 4, 12:00 PM PDT
Water in storage
no reading
daily record
Share of capacity
no storage figure
storage ÷ capacity; ships only where both halves are verified
Below full pool
5.8 ft
full pool at 1,290.0 ft
This month in the record
lower than 60% of the 87 Septembers on record
monthly mean elevation; record low 961.2 ft (1938), record high 1,290.1 ft (1943)
30-day trend
-0.09 ft/day
elevation, 2026-07-04 → 2026-08-03; over the year 0.00 ft/day. Measured change, not a forecast.
Drought at the dam
D1 — Moderate drought
US Drought Monitor at the dam's coordinates, released 2026-08-27; the feeding basin can differ.
elevation only
No public storage series reports for this reservoir, so no percent ships.
The water line is elevation (NGVD29); 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.
Snowpack in the feeding basin
Measured across the US side of the upper Columbia — roughly half this basin's snow falls in Canada, beyond SNOTEL's reach.
Snow season
typically Oct 20 – Jun 18
0 in on the ground, 2026-09-01; median peak 25.2 in around Apr 24
Last winter's verdict
104% of median peak
water year 2026 — the snow that fed this year's pool
5 highest active SNOTEL stations in the basin (Barker Lakes, Saddle Mtn., Warm Springs, …), NRCS AWDB REST (SNOTEL), station set pinned 2026-08-31. Daily snow-water equivalent against the stations' own 30-year medians; off season the percent is withheld rather than divided by zero.
The last 91 days
Daily water-surface elevation in feet. The axis hugs the data — it does not start at zero. Source: USGS NWIS daily values.
See the numbers as a table
| Date | Elevation (ft) |
|---|---|
| Aug 3 | 1283.98 |
| Aug 2 | 1284.17 |
| Aug 1 | 1284.26 |
| Jul 31 | 1284.45 |
| Jul 30 | 1285.13 |
| Jul 29 | 1285.38 |
| Jul 28 | 1285.70 |
| Jul 27 | 1285.99 |
| Jul 26 | 1286.36 |
| Jul 25 | 1286.50 |
| Jul 24 | 1286.86 |
| Jul 23 | 1287.77 |
| Jul 22 | 1287.77 |
| Jul 21 | 1288.07 |
| Jul 20 | 1288.36 |
| Jul 19 | 1288.32 |
| Jul 18 | 1288.55 |
| Jul 17 | 1288.61 |
| Jul 16 | 1288.65 |
| Jul 15 | 1288.42 |
| Jul 14 | 1288.43 |
| Jul 13 | 1288.40 |
| Jul 12 | 1288.85 |
| Jul 11 | 1288.85 |
| Jul 10 | 1289.03 |
| Jul 9 | 1289.03 |
| Jul 8 | 1288.88 |
| Jul 7 | 1288.49 |
| Jul 6 | 1287.82 |
| Jul 5 | 1287.13 |
Most recent 30 days shown.
The whole record
Monthly mean elevation, May 1938 to Jul 2026. The axis spans the pools, not zero; elevations in NGVD29. Months with fewer than 15 gaged days are dropped, and gaps in the record break the line. Source: USGS NWIS, retrieved 2026-08-31.
See the numbers as a table
| Month | Mean elevation (ft) | Days gaged |
|---|---|---|
| Jul 2026 | 1287.4 | 31 |
| Jun 2026 | 1281.4 | 30 |
| May 2026 | 1260.6 | 31 |
| Apr 2026 | 1253.2 | 30 |
| Mar 2026 | 1254.9 | 31 |
| Feb 2026 | 1271.5 | 28 |
| Jan 2026 | 1281.7 | 31 |
| Dec 2025 | 1285.5 | 31 |
| Nov 2025 | 1286.0 | 30 |
| Oct 2025 | 1285.9 | 31 |
| Sep 2025 | 1279.3 | 30 |
| Aug 2025 | 1281.3 | 31 |
| Jul 2025 | 1287.1 | 31 |
| Jun 2025 | 1282.4 | 30 |
| May 2025 | 1268.3 | 31 |
| Apr 2025 | 1272.7 | 30 |
| Mar 2025 | 1276.9 | 31 |
| Feb 2025 | 1280.9 | 28 |
| Jan 2025 | 1286.4 | 31 |
| Dec 2024 | 1283.3 | 31 |
| Nov 2024 | 1284.3 | 30 |
| Oct 2024 | 1285.6 | 31 |
| Sep 2024 | 1282.1 | 30 |
| Aug 2024 | 1281.9 | 31 |
Most recent 24 months shown; the full monthly series is in the page's API response.
Where these numbers come from
Readings at Franklin D. Roosevelt 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 Grand Coulee project data number; sedimentation slowly shrinks real capacity, so the vintage travels with the percent.