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.

About reservoirs in Idaho

As of July 28, 2026, the reservoirs we track across Idaho that report live levels hold roughly 3,035 hm³ of water — about 42.5% of their combined capacity. Taken together, Idaho's reservoirs are within their normal operating range.

Across the region, 5 are low. Black Canyon Reservoir, Diversion Dam, and Powerplant (EMM) is the fullest at 103.4%, while American Falls Reservoir and Dam (AMF) is the lowest at 21.6%.

Storage figures for Idaho come from USGS · USACE · BOR · CDEC; the most recent reading is from July 28, 2026. Each reservoir below links to its own page with full history and seasonal context.

Idaho at a glance

Reservoirs tracked: 20
Average fill: 42.5%
Water stored: 3,035 hm³
Combined capacity: 7,144 hm³
Fullest: Black Canyon Reservoir, Diversion Dam, and Powerplant (EMM) (103.4%)
Lowest: American Falls Reservoir and Dam (AMF) (21.6%)
Last updated: July 28, 2026

Frequently asked questions

How full are reservoirs in Idaho right now?

As of July 28, 2026, the reservoirs tracked in Idaho that report live levels are 42.5% full overall, holding about 3,035 hm³ of water.

How many reservoirs are there in Idaho?

reservoirs.earth tracks 20 reservoirs in Idaho, with a combined storage capacity of 7,144 hm³.

Which reservoir in Idaho is the fullest?

Black Canyon Reservoir, Diversion Dam, and Powerplant (EMM) is currently the fullest reservoir in Idaho, at 103.4% of capacity.

Which reservoir in Idaho is the lowest?

American Falls Reservoir and Dam (AMF) is currently the lowest in Idaho, at 21.6% of capacity.

Where does the reservoir data for Idaho come from?

All storage figures for Idaho come from USGS · USACE · BOR · CDEC, an official source, last updated July 28, 2026.

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