Montana · Lolo, MT

Bitterroot River float season

Gauge 12352500 on the Lower Bitterroot, Florence to Maclay Bridge. A drift-boat favorite gliding past the Bitterroot peaks, with lazy gravel-bar channels that tubers claim near Missoula in July.

driftboatrafttubingcanoe Fullest: Apr–Jun Leanest: Aug–Oct
Bitterroot River — typical flow through the year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1k 4k 10k 15k
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 Bitterroot River. Provisional data — subject to revision.

The year on this river

In a typical year at the Lolo gauge, the Bitterroot River runs fullest Apr–Jun and leanest Aug–Oct. 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 7,095 CFS; the September median is 776 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 782
February 820
March 1,050
April 2,365
May 6,410
June 7,095
July 1,930
August 782
September 776
October 855
November 1,020
December 895

Record context

This gauge has measured daily flow since 1898 — 127 years of record. The largest daily average ever logged here was 37,400 CFS, in June 1899. 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 Bitterroot River usually at its fullest?

At the Lolo gauge, the fullest stretch of a typical year is Apr–Jun, with the single highest monthly median in June (about 7,095 CFS). The leanest months are usually Aug–Oct.

What is a typical summer flow on the Bitterroot River?

The July median at this gauge is about 1,930 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 Bitterroot River 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 41 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 12352500 (Bitterroot River near Missoula MT), chosen because it best represents the Lower Bitterroot, Florence to Maclay Bridge. Daily records here reach back to 1898.

Data: USGS gauge 12352500, approved daily records 1898–2025, retrieved 2026-08-07. Live readings are provisional and subject to revision. U.S. Geological Survey data is public domain.