Montana · Bonner, MT

Blackfoot River float season

Gauge 12340000 on the Johnsrud to Weigh Station corridor near Bonner. The river Norman Maclean made famous is a corridor of ledgy rapids and forested pools that Missoulians float all summer long.

rafttubingkayakdriftboat Fullest: Apr–Jun Leanest: Dec–Feb
Blackfoot River — typical flow through the year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 600 2.5k 6k 10k
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 Blackfoot River. Provisional data — subject to revision.

The year on this river

In a typical year at the Bonner gauge, the Blackfoot River 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 May days at this gauge ran above 4,470 CFS; the January median is 523 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 523
February 540
March 648
April 1,740
May 4,470
June 4,265
July 1,470
August 749
September 640
October 610
November 608
December 545

Record context

This gauge has measured daily flow since 1898 — 128 years of record. The largest daily average ever logged here was 18,600 CFS, in May 2018. 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 Blackfoot River usually at its fullest?

At the Bonner gauge, the fullest stretch of a typical year is Apr–Jun, with the single highest monthly median in May (about 4,470 CFS). The leanest months are usually Dec–Feb.

What is a typical summer flow on the Blackfoot River?

The July median at this gauge is about 1,470 CFS — half of past Julys ran higher, half lower. Check the ribbon chart above to see how summer compares with the rest of the year here.

Is the Blackfoot 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 92 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 12340000 (Blackfoot River near Bonner MT), chosen because it best represents the Johnsrud to Weigh Station corridor near Bonner. Daily records here reach back to 1898.

Data: USGS gauge 12340000, approved daily records 1898–2026, retrieved 2026-08-07. Live readings are provisional and subject to revision. U.S. Geological Survey data is public domain.