Montana · Alberton, MT

Clark Fork float season

Gauge 12353000 on the Alberton Gorge, Cyr to Tarkio. Alberton Gorge's roomy summer waves are Missoula's go-to whitewater day, with jumping rocks and swim beaches between the rapids.

raftkayak Fullest: Apr–Jun Leanest: Dec–Feb
Clark Fork — typical flow through the year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2k 7.5k 20k 30k
median flow for the date middle half of years (25th–75th percentile) most years (10th–90th)

Right now at this gauge

loading CFS

Checking the live gauge…

Live reading from the USGS gauge page for Clark Fork. Provisional data — subject to revision.

The year on this river

In a typical year at the Alberton gauge, the Clark Fork runs fullest Apr–Jun and leanest Dec–Feb. Where today's reading falls inside that rhythm matters more than the raw number — the same flow that feels thin in spring can be the summer norm. Half of all past June days at this gauge ran above 15,400 CFS; the August median is 2,030 CFS.

Median of daily flows in each month across this gauge's full record — half of past days ran above these figures, half below.
Month Typical flow (CFS)
January 2,060
February 2,240
March 2,670
April 5,310
May 12,100
June 15,400
July 4,530
August 2,030
September 2,115
October 2,520
November 2,580
December 2,250

Record context

This gauge has measured daily flow since 1930 — 95 years of record. The largest daily average ever logged here was 54,100 CFS, in May 1997. Rivers do that sometimes; it's why the safety panel above isn't decoration.

Planning dates? The trip-window checker shows what flows have historically looked like on any week you pick for this river, or see what a CFS actually looks like.

More Montana float rivers

Common questions

When is the Clark Fork usually at its fullest?

At the Alberton gauge, the fullest stretch of a typical year is Apr–Jun, with the single highest monthly median in June (about 15,400 CFS). The leanest months are usually Dec–Feb.

What is a typical summer flow on the Clark Fork?

The July median at this gauge is about 4,530 CFS — half of past Julys ran higher, half lower. Late summer is this river's lean season, so expect readings to drift down as the season goes on.

Is the Clark Fork safe to float right now?

No flow number can answer that, and this site never labels a river safe. What the data can tell you is how today's reading compares with 96 years of this date's history — well above typical means pushier, colder, faster water. Pair that context with a PFD, a look at the river from the bank, and a call to a local outfitter before you commit.

Which USGS gauge does this page use?

USGS gauge 12353000 (Clark Fork below Missoula MT), chosen because it best represents the Alberton Gorge, Cyr to Tarkio. Daily records here reach back to 1930.

Data: USGS gauge 12353000, approved daily records 1930–2025, retrieved 2026-08-07. Live readings are provisional and subject to revision. U.S. Geological Survey data is public domain.