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

⏳

Lake Frances Reservoir — data sourcing in progress

Storage is monitored by the US Bureau of Reclamation (BOR RISE), but the live feed is currently stale — we are working to restore it. Known capacities: Lake Frances Reservoir (0.1 km³).

Lake Frances Reservoir

Sourcing

Capacity: 136 hm³⏳ Pending

About reservoirs in Montana

As of July 29, 2026, the reservoirs we track across Montana that report live levels hold roughly 29,231 hm³ of water — about 84.6% of their combined capacity. Taken together, Montana's reservoirs are high.

Across the region, 3 are low. Hungry Horse Reservoir, Dam, and Powerplant (HGH) is the fullest at 97.9%, while Lima Reservoir Upstream of Clark Canyon Reservoir is the lowest at 29.0%.

Over the most recent week on record, 2 reservoirs fell across Montana.

Storage figures for Montana 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.

Montana at a glance

Reservoirs tracked: 24
Average fill: 84.6%
Water stored: 29,231 hm³
Combined capacity: 34,535 hm³
Fullest: Hungry Horse Reservoir, Dam, and Powerplant (HGH) (97.9%)
Lowest: Lima Reservoir Upstream of Clark Canyon Reservoir (29.0%)
Last updated: July 29, 2026

Frequently asked questions

How full are reservoirs in Montana right now?

As of July 29, 2026, the reservoirs tracked in Montana that report live levels are 84.6% full overall, holding about 29,231 hm³ of water.

How many reservoirs are there in Montana?

reservoirs.earth tracks 24 reservoirs in Montana, with a combined storage capacity of 34,535 hm³.

Which reservoir in Montana is the fullest?

Hungry Horse Reservoir, Dam, and Powerplant (HGH) is currently the fullest reservoir in Montana, at 97.9% of capacity.

Which reservoir in Montana is the lowest?

Lima Reservoir Upstream of Clark Canyon Reservoir is currently the lowest in Montana, at 29.0% of capacity.

Where does the reservoir data for Montana come from?

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

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