7 USGS Streamgages · Mississippi River system
Musselshell River flows and levels
Musselshell River is gauged at 7 USGS streamgages in Montana, each tracked by Rivermatics. The mainstem runs about 372 miles (599 km) from headwaters to outlet. It drains into the Mississippi River system. Drainage area at the gauges ranges from 537 square miles at Musselshell River near Martinsdale, MT up to 7,784 at Musselshell River at Mosby, MT. The gauged reach falls about 2,163 feet, from 4,663 feet down to 2,500. Rivermatics issues a daily machine-learned 14-day flow outlook for every one of them.
Gauges on this river, upstream to downstream
Ordered by drainage area, which is how far down the river each gauge sits. April and July figures are long-term median daily flows for that month from the USGS record — historical normals, not a forecast and not today's reading.
| Gauge | State | Drainage sq mi | Elevation ft | April p50 cfs | July p50 cfs | Forecast |
|---|---|---|---|---|---|---|
| Musselshell River near Martinsdale, MT | MT | 537 | 4,663 | 63 | 52.5 | 14-day |
| Musselshell River at Harlowton, MT | MT | 1,108 | 4,173 | 113.7 | 111.8 | 14-day |
| Musselshell River ab Mud Creek near Shawmut, MT | MT | 1,518 | 3,782 | 17 | 62 | 14-day |
| Musselshell River ab Big Coulee Creek at Lavina, MT | MT | 2,691 | 3,423 | 63.8 | 238.3 | 14-day |
| Musselshell River near Roundup, MT | MT | 3,998 | 3,193 | 81.1 | 204.8 | 14-day |
| Musselshell River at Musselshell, MT | MT | 4,534 | 2,993 | 88.2 | 147.1 | 14-day |
| Musselshell River at Mosby, MT | MT | 7,784 | 2,500 | 135.4 | 114.9 | 14-day |
Typical flow by month at Musselshell River at Mosby, MT
The furthest-downstream gauge on this river, so the fullest flow it carries here. Long-term daily discharge percentiles from the USGS record (up to 96 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 0.9 | 50.4 | 200.7 | |
| February | 4.5 | 80.4 | 356.8 | |
| March | 29.2 | 165.5 | 948.4 | |
| April | 15.2 | 135.4 | 790.7 | |
| May | 5.1 | 203 | 1,543.9 | |
| June | 15.4 | 338.8 | 2,678 | |
| July | 0.4 | 114.9 | 986.5 | |
| August | 0 | 61.6 | 293.5 | |
| September | 0 | 64.4 | 263.3 | |
| October | 0 | 66.9 | 219.3 | |
| November | 0.1 | 66.9 | 208.9 | |
| December | 0.5 | 54.5 | 192 |
All values in cubic feet per second (cfs).
Common questions
- When does the Musselshell River run highest?
- June, on the long-term record at Musselshell River at Mosby, MT — the furthest-downstream gauge Rivermatics tracks on this river. Median daily flow there is about 338.8 cfs that month, against 50.4 cfs in January, the lowest. Upstream gauges peak on their own schedule; the table on this page gives April and July for each.
- How many gauges are on the Musselshell River?
- Rivermatics tracks 7 USGS streamgages on the Musselshell River, across Montana. Each has its own page with the site's full flow record and monthly normals. The river may carry other gauges that publish neither daily values nor discharge statistics; those are not tracked here.
- Is there a flow forecast for the Musselshell River?
- Yes, at 7 of the 7 gauges. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on each basin's observed flows, weather and snowpack, and issues a daily 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 each gauge's live screen.
- What river system is the Musselshell River part of?
- The Musselshell River drains into the Mississippi River system — it is a tributary somewhere in that chain, following the flowpath down to its terminal river. Rivermatics builds this from the USGS/geoconnex reference-mainstem network rather than from names.
- Can I use Musselshell River 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.
Other rivers in the Mississippi River system
- Missouri River 52 gauges
- Big Sioux River 17 gauges
- James River 15 gauges
- Kansas River 12 gauges
- Smoky Hill River 12 gauges
- Platte River 11 gauges
- Rapid Creek 11 gauges
- Republican River 11 gauges