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

⏳

4 major reservoirs — data sourcing in progress

Storage is monitored by the US Bureau of Reclamation (BOR RISE) / the US Army Corps of Engineers (USACE CWMS), but the live feed is currently stale — we are working to restore it. Known capacities: Lake Frances Reservoir (0.1 km³), Gibson Dam on NF Sun River, MT (0.1 km³), Hebgen Dam on Madison River, MT (0.5 km³), Lima Dam & Reservoir (0.1 km³).

Lake Frances Reservoir

Sourcing

Capacity: 136 hm³⏳ Pending

Gibson Dam on NF Sun River, MT

Sourcing

Capacity: 122 hm³⏳ Pending

Hebgen Dam on Madison River, MT

Sourcing

Capacity: 476 hm³⏳ Pending

Lima Dam & Reservoir

Sourcing

Capacity: 93 hm³⏳ Pending

About reservoirs in Montana

As of June 11, 2026, the reservoirs we track across Montana that report live levels hold roughly 29,259 hm³ of water — about 84.7% of their combined capacity. Taken together, Montana's reservoirs are high.

Across the region, 2 are low. Lake Como and Como Dam (CMO) is the fullest at 101.2%, while Fresno Reservoir nr Havre, MT is the lowest at 30.3%.

Over the most recent week on record, 1 reservoir rose across Montana.

Storage figures for Montana come from USGS · USACE · BOR · CDEC; the most recent reading is from June 11, 2026. Each reservoir below links to its own page with full history and seasonal context.

Montana at a glance

Reservoirs tracked: 24
Average fill: 84.7%
Water stored: 29,259 hm³
Combined capacity: 34,535 hm³
Fullest: Lake Como and Como Dam (CMO) (101.2%)
Lowest: Fresno Reservoir nr Havre, MT (30.3%)
Last updated: June 11, 2026

Frequently asked questions

How full are reservoirs in Montana right now?

As of June 11, 2026, the reservoirs tracked in Montana that report live levels are 84.7% full overall, holding about 29,259 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?

Lake Como and Como Dam (CMO) is currently the fullest reservoir in Montana, at 101.2% of capacity.

Which reservoir in Montana is the lowest?

Fresno Reservoir nr Havre, MT is currently the lowest in Montana, at 30.3% 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 June 11, 2026.

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