Marias River near Shelby, MT
Missouri River & Headwaters (Montana) · USGS gauge 06099500 · Updated Oct 25, 11:23 AM PDT · USGS data, provisional
All 2 Marias River gauges in Montana
Reading time: Oct 25, 11:30 AM PDT · Provisional data
Flow is in a typical range for the date. Rivers are generally easiest to fish and float when they are near their normal flow, but this status says nothing about water clarity, hatches, hazards such as wood in the river, or dam releases.
- Vs. normal for this date
- 47th percentile
- Typical range (25th–75th)
- 220–477 cfs
- Median for this date
- 312 cfs
- 7-day low / high
- 253 / 322 cfs
Water temperature & gage height
- Gage height (stage)
- 2.89 ft as of Oct 25, 11:30 AM PDT · USGS 00065 · Provisional
Context only: these readings do not affect the status above, which is based on flow (cfs) alone. Gage height is the water level above this gauge's own reference point, not water depth, and can't be compared between gauges. Temperature converted from °C to °F by Flowcast. Source: USGS, provisional data.
Plain-language explanation
Marias River near Shelby is flowing at 300 cubic feet per second (cfs) as of Oct 25, 11:30 AM PDT. That is in the normal range for this time of year: lower than about 53% of the daily flows this gauge has recorded for this date (give or take 7 days) over 122 years of record (1902–2026).
The middle half of those historical flows runs from 220 to 477 cfs, with a median of 312 cfs; the lowest 10% of days are at or below 167 cfs and the highest 10% at or above 700 cfs.
Over the last 24 hours the flow has been steady (-1.6%). In the last 7 days it ranged from 253 to 322 cfs.
Why this status: Flow is within the range this gauge normally sees at this time of year (or the deviation is too small in absolute terms to matter).
Quick answers
Is the Marias River near Shelby fishable today?
Flowcast's status for the Marias River near Shelby is “Fishable/Floatable”: flow is 300 cfs, within the range this gauge normally sees at this time of year, at the 47th percentile for this date (as of Oct 25, 11:30 AM PDT). That describes flow only. It says nothing about water clarity, temperature, fish activity, access or fishing regulations.
What is the current flow of the Marias River near Shelby?
300 cubic feet per second at USGS gauge 06099500 as of Oct 25, 11:30 AM PDT, provisional data.
Is the Marias River near Shelby too high or too low right now?
Neither: it is inside the typical range for the date (220 to 477 cfs).
Is the Marias River near Shelby rising or falling?
Over the last 24 hours the flow has been steady (-1.6%).
What is a normal flow for the Marias River near Shelby in October?
For this date (give or take 7 days) the median is 312 cfs and the middle half of days runs 220 to 477 cfs, over 122 years of USGS record.
7-day trend
Hourly flow in cfs, Pacific time. The shaded band is the typical range (25th–75th percentile) for this date, shown when it falls within the chart.
| Day (Pacific) | Mean cfs | Percentile | Status that day |
|---|---|---|---|
| Mon Oct 19 | 265 | 40th | Fishable/Floatable |
| Tue Oct 20 | 264 | 40th | Fishable/Floatable |
| Wed Oct 21 | 258 | 36th | Fishable/Floatable |
| Thu Oct 22 | 268 | 40th | Fishable/Floatable |
| Fri Oct 23 | 287 | 45th | Fishable/Floatable |
| Sat Oct 24 | 303 | 48th | Fishable/Floatable |
| Sun Oct 25 (so far) | 302 | 48th | Fishable/Floatable |
Seasonal context
Shaded band: 10th–90th percentile of daily flows through the year; dashed line: median. Log scale. Dot: today's flow. Based on 122 years of USGS daily data (1902–2026).
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Official resources
- USGS site page for gauge 06099500 (USGS: live readings, history, station details)
- Montana fishing regulations (FWP)
- Montana aquatic invasive species (FWP)
- Montana waterbody restrictions and closures (FWP)
- Montana fishing access sites (FWP)
Links go to the agencies' own websites and were checked as working. Flowcast does not summarize fishing or boating rules: regulations and closures change, and the agency pages are the authority.
About this gauge
- USGS site
- USGS-06099500
- USGS name
- Marias River Near Shelby Mt
- Drainage area
- 2,716 sq mi
- Location
- 48.4272, -111.8898
- Record in this analysis
- 1902–2026
Nearby gauges
- Sun River at Simms, MT Use caution 313 cfs · about 64 mi away (straight line)
- Sun River near Vaughn, MT Use caution 571 cfs · about 65 mi away (straight line)
- Marias River near Loma, MT Fishable/Floatable 504 cfs · about 69 mi away (straight line)
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