Storage from official US gauges (USGS, USACE, Bureau of Reclamation, CDEC). Fill % uses design capacity from the National Inventory of Dams where available; a few sites without a match fall back to the 5-year maximum.

Major reservoirs — data pending

⏳

ALDER RESERVOIR AT ALDER, WA — data sourcing in progress

Storage is monitored by the US Geological Survey (USGS NWIS), but the live feed is currently stale — we are working to restore it. Known capacities: ALDER RESERVOIR AT ALDER, WA (0.3 km³).

ALDER RESERVOIR AT ALDER, WA

Sourcing

Capacity: 265 hm³⏳ Pending

About reservoirs in Washington

As of July 29, 2026, the reservoirs we track across Washington that report live levels hold roughly 2,152 hm³ of water — about 51.4% of their combined capacity. Taken together, Washington's reservoirs are within their normal operating range.

Across the region, 1 reservoir is at critically low levels and 3 are low. MAYFIELD RESERVOIR NEAR SILVER CREEK, WA is the fullest at 96.5%, while MUD MOUNTAIN LAKE NEAR BUCKLEY, WA is the lowest at 0.0%.

Storage figures for Washington come from USGS · USACE · BOR · CDEC; the most recent reading is from July 29, 2026. Each reservoir below links to its own page with full history and seasonal context.

Washington at a glance

Reservoirs tracked: 16
Average fill: 51.4%
Water stored: 2,152 hm³
Combined capacity: 4,183 hm³
At critically low levels: 1
Fullest: MAYFIELD RESERVOIR NEAR SILVER CREEK, WA (96.5%)
Lowest: MUD MOUNTAIN LAKE NEAR BUCKLEY, WA (0.0%)
Last updated: July 29, 2026

Frequently asked questions

How full are reservoirs in Washington right now?

As of July 29, 2026, the reservoirs tracked in Washington that report live levels are 51.4% full overall, holding about 2,152 hm³ of water.

How many reservoirs are there in Washington?

reservoirs.earth tracks 16 reservoirs in Washington, with a combined storage capacity of 4,183 hm³.

Which reservoir in Washington is the fullest?

MAYFIELD RESERVOIR NEAR SILVER CREEK, WA is currently the fullest reservoir in Washington, at 96.5% of capacity.

Which reservoir in Washington is the lowest?

MUD MOUNTAIN LAKE NEAR BUCKLEY, WA is currently the lowest in Washington, at 0.0% of capacity.

Where does the reservoir data for Washington come from?

All storage figures for Washington come from USGS · USACE · BOR · CDEC, an official source, last updated July 29, 2026.

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