Au Sable River At Mio Flow Report
As of July 21, 2026, Au Sable River At Mio is flowing at 1,060 cfs with a gage height of 3.25 ft, holding steady over the past 24 hours. Source: USGS gauge #04136500, refreshed throughout the day.
Historical Data
Au Sable River At Mio at a glance
How Au Sable River At Mio is running right now, where it sits on the map, and the key gauge stats.
Au Sable River At Mio is flowing at 1,060 cfs, with the water sitting 3.25 ft at the gage. Flow has held roughly steady over the past 24 hours.
This is USGS gauge #04136500 in Michigan. Over the past 10 days the average has been 1,095 cfs, peaking at 1,280 cfs.
For real-time updates and historical context, see the realtime view or the historical comparison. Browse other gauges in the Michigan flow report.
Engineering Data
Flow-duration statistics and observed peak-flow context computed from this gauge’s complete daily record (USGS #04136500).
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, Au Sable River At Mio is expected to recede from today's 1090 cfs, toward roughly 970 cfs by 2026-07-25 (likely range 816-1154 cfs) -- about 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.
Au Sable River At Mio
The river is fed by multiple tributaries and contains a variety of aquatic species including brook trout, brown trout, and smallmouth bass. There are several dams along the river, including the Mio Dam, which was built in the early 1900s and provides hydroelectric power. Seasonal trends include higher flows in the spring due to snowmelt and rain, and lower flows in the summer and fall. Interesting facts include the Au Sable River being a designated National Wild and Scenic River, and that it was featured in Ernest Hemingway’s novel, The Big Two-Hearted River.
Nearby streamflow levels
Cross-check Au Sable River At Mio's discharge against nearby gauges to spot whether the change here is local or regional.
| Gauge | Streamflow |
|---|---|
| Au Sable River At Mio | 1,060 cfs |
| Au Sable River Near Red Oak | 950 cfs |
| Au Sable River Near Mc Kinley | 1,230 cfs |
| South Branch Au Sable River Near Luzerne | 207 cfs |
| Au Sable River Near Curtisville | 1,240 cfs |
| Au Sable River Near Au Sable | 1,420 cfs |
Nearby snowpack data
Snowpack at SNOTEL stations near Au Sable River At Mio. 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 |
|---|---|
| Mio Wwtp | 0 in |
| Glennie 2se | 0 in |
| Loud Dam | 0 in |
| West Branch 3se | 0 in |
| West Branch 2.1 Ssw | 0 in |
| Gaylord 9ssw | 0 in |
Plan a trip
Reservoirs, boat launches, river runs, and fishing spots within driving distance of Au Sable River At Mio.
Boat launches
See all →
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 Au Sable River At Mio in the Snoflo app
Save this gauge as a favorite, set push alerts when streamflow crosses a threshold (e.g. "alert me when Au Sable River At Mio crosses 5,000 cfs"), and Snoflo's iOS app will push the moment USGS reports the crossing.
About Au Sable River At Mio
Where does the streamflow data for Au Sable River At Mio come from?
Discharge, gage height, and water temperature come directly from the USGS streamflow gauge 04136500. 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 Au Sable River At Mio 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 Au Sable River At Mio report
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