Rivermatics

USGS Streamgage 06120500

Musselshell River at Harlowton, MT

Musselshell River at Harlowton, MT is USGS streamgage 06120500 in Montana, monitoring river discharge in hydrologic subbasin 10040201. It sits on the Musselshell River, alongside 6 other gauges Rivermatics tracks on the same river. It drains a watershed of about 1,108 square miles. Discharge records at this site go back to 1907. Typical flow runs near 111.8 cfs in July and 113.7 cfs in April, with the higher of the two arriving in April. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.

View live conditions & forecast →

Gauge details

State
Montana
Drainage area
1,108 sq mi
Gauge elevation
4,173 ft
Subbasin (HUC-8)
10040201
Coordinates
46.4288, -109.84119
USGS site number
06120500
Records begin
1907-08-01 (119 years)
Rivermatics forecast
14-day flow outlook

14-day flow forecast

Based on observations through for Musselshell River at Harlowton, MT. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.

Forecast daily mean discharge in cubic feet per second, by date
Date Low p10 Expected p50 High p90 Range
27 29.9 33.3
25 30.5 38.9
23.8 30.6 40.8
22.5 30.1 41.4
21.4 29.7 41.6
20.6 29.4 42.4
19.3 28.9 42.2
18.5 28.4 42.7
18.2 28.5 44.5
17.1 27.6 43.4
16.2 26.9 43.7
15 26 42.9
14.1 25.5 42.5
13.7 25.1 42.5

All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.

Typical flow by month

Long-term daily discharge percentiles from the USGS record (up to 119 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.

Historical monthly discharge percentiles in cubic feet per second
Month Low p10 Typical p50 High p90 Range
January 29.2 50.6 88.5
February 29.7 56.7 108.5
March 39.9 73.5 204.4
April 39 113.7 364.8
May 44.4 264.4 928.5
June 61 320.2 1,171.2
July 20.2 111.8 379.5
August 1.6 61.3 163.6
September 3.2 48.7 130.6
October 15.9 66.5 136.7
November 30.3 71.3 131.1
December 29.4 59.7 108

All values in cubic feet per second (cfs).

Common questions

When does Musselshell River at Harlowton, MT normally run highest?
June, on the long-term record. The median daily flow that month is about 320.2 cfs, against 48.7 cfs in September, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
What is a normal flow for Musselshell River at Harlowton, MT?
It depends on the month. In January, half of days historically fall near 50.6 cfs, with the middle 80% of days between 29.2 and 88.5 cfs. The month-by-month table on this page gives the full range.
How long has Musselshell River at Harlowton, MT been measured?
Discharge records at USGS site 06120500 begin in 1907, about 119 years, covering roughly 9,080 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for Musselshell River at Harlowton, MT?
Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
Where is Musselshell River at Harlowton, MT?
The gauge sits at 46.4288, -109.84119, in Montana, in hydrologic subbasin 10040201, at an elevation of about 4,173 feet, draining roughly 1,108 square miles.
Can I use Musselshell River at Harlowton, MT data for flood or safety decisions?
No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.

Upstream and downstream on the Musselshell River

Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Musselshell River in full.

Other gauges in this subbasin