Sun River At Simms Flow Report
As of July 21, 2026, Sun River At Simms is flowing at 140 cfs with a gage height of 2.56 ft, holding steady over the past 24 hours. Source: USGS gauge #06085800, refreshed throughout the day.
Historical Data
Sun River At Simms at a glance
How Sun River At Simms is running right now, where it sits on the map, and the key gauge stats.
Sun River At Simms is flowing at 140 cfs, with the water sitting 2.56 ft at the gage. Flow has held roughly steady over the past 24 hours.
This is USGS gauge #06085800 in Montana. Over the past 10 days the average has been 130 cfs, peaking at 154 cfs.
For real-time updates and historical context, see the realtime view or the historical comparison. Browse other gauges in the Montana flow report.
Engineering Data
Flow-duration statistics and observed peak-flow context computed from this gauge’s complete daily record (USGS #06085800).
Estimate flows at an ungauged site
Drainage-area ratio transfer from this gauge . Most reliable for hydrologically similar sites in the same watershed with area ratios between roughly 0.5 and 1.5.
Percentiles are flow-duration values computed from this gauge’s observed daily record as archived by Snoflo. Return periods are Weibull plotting-position estimates from observed annual maxima, provided as general reference context only. Always verify against official USGS NWIS records. Part of Snoflo for Engineering.
Streamflow Forecast
Over the next 5 days, Sun River At Simms Mt is expected to recede from today's 140 cfs, toward roughly 120 cfs by 2026-07-26 (likely range 81-177 cfs) -- drier than normal for the date.
Powered by PULSE — Snoflo’s forecast engine, trained on this gauge’s full record of storms, snowmelt, and dry spells.
| Date | Expected (p50) | Likely range (p25–p75) | vs normal | Projected stage |
|---|
How does this compare to past years?
Year-over-year overlay, annual peak discharge, the full distribution of daily flows on record, and the gauge's rating curve.
Weather Forecast
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day forecast
Daily temperatures, snow, and rain projected over the next two weeks.
Sun River At Simms
The river is fed by several tributaries, including the North Fork, South Fork, and Middle Fork. There are three significant dams on the river, which are used for irrigation purposes. The water flow in Sun River at Simms MT stream gauge varies throughout the year, with peak flow during spring and summer months due to snowmelt and precipitation. Winter months see low flow rates. Some quirky facts about the hydrology of the river include the presence of hot springs that flow into the river, creating pockets of warmer water.
Nearby streamflow levels
Cross-check Sun River At Simms's discharge against nearby gauges to spot whether the change here is local or regional.
| Gauge | Streamflow |
|---|---|
| Sun River At Simms Mt | 140 cfs |
| Muddy Creek At Vaughn Mt | 300 cfs |
| Missouri River At Cascade Mt | 3,770 cfs |
| Sun River Near Vaughn Mt | 683 cfs |
| Sun River Bl Willow Cr Nr Augusta Mt | 247 cfs |
| Dearborn River Near Craig Mt | 116 cfs |
Nearby snowpack data
Snowpack at SNOTEL stations near Sun River At Simms. Spring snowmelt is the dominant driver of streamflow in mountain basins -- a deep snowpack upstream means more runoff later in the season.
| SNOTEL station | Snowpack |
|---|---|
| Nohrsc Fairfield 6.0 Ese | 0 in |
| Nohrsc Fairfield 5.6 Ne | 0 in |
| Sun River Se | 0 in |
| Nohrsc Fairfield 5.0 Nne | 0 in |
| Mt Mesonet Benton Lake | 0 in |
| Choteau | 0 in |
Plan a trip
Reservoirs, boat launches, river runs, and fishing spots within driving distance of Sun River At Simms.
Boat launches
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River runs
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River levels & flood safety
- Read the level before you go
- A river that's runnable at one flow can be deadly at another. Check current discharge and gage height — like the values shown above — against the flood-stage thresholds, and remember levels can spike fast after rain or a dam release.
- Respect cold water
- Snowmelt rivers run cold even in summer. Sudden immersion triggers cold-water shock and saps strength within minutes. Wear a PFD, dress for the water temperature (not the air), and never wade or paddle alone.
- Watch for swiftwater hazards
- Strainers (downed trees), undercut rocks, and low-head dams are the deadliest features on moving water. High, fast, muddy water hides them. If in doubt, scout from shore and portage.
- Mind flash floods & releases
- Narrow canyons can flood from a storm miles upstream, and dam-controlled reaches can rise without warning. Know the forecast, the release schedule, and your exit before you launch.
Track Sun River At Simms in the Snoflo app
Save this gauge as a favorite, set push alerts when streamflow crosses a threshold (e.g. "alert me when Sun River At Simms crosses 5,000 cfs"), and Snoflo's iOS app will push the moment USGS reports the crossing.
About Sun River At Simms
Where does the streamflow data for Sun River At Simms come from?
Discharge, gage height, and water temperature come directly from the USGS streamflow gauge 06085800. Snoflo refreshes the time series throughout the day. Forecasts come from the NOAA / yr.no feed Snoflo's iOS app uses.
How often is the report updated?
USGS gauges report continuously (typically every 15 minutes). Snoflo pulls fresh values throughout the day — look for the "as of" timestamp on the streamflow hero card.
What's the difference between discharge and gage height?
Discharge (cubic feet per second, or cfs) is the volume of water flowing past the gauge each second. Gage height is how high the water sits at the gauge (feet). They're related by a rating curve specific to each gauge — higher water means more flow, but the exact ratio depends on channel shape.
How is "percent of median" calculated?
Today's discharge is compared to the historical median discharge on this calendar day across the gauge's full record. 100% = right on median; 200% = a very high year; 30% = a drought-level low.
What are flood stages, and is this river safe right now?
Flood stages are NWS-defined gage-height thresholds — Action, Minor, Moderate, Major — marking when nearby roads or floodplains start to be affected. "Safe" depends on your activity and skill: a level that's a fun paddle for an expert can be lethal for a wader. Always check the current level against the thresholds above and the safety links, and when in doubt, stay off the water.
Can I get alerts when Sun River At Simms rises?
Yes — flow alerts are managed in the Snoflo iOS app. Favorite this gauge, set a streamflow threshold (e.g. "alert me when discharge crosses 5,000 cfs"), and you'll get a push the moment USGS reports the crossing.
Access the free Sun River At Simms report
Create your free account to track this river — and everything else you love on the water.
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