Big Sioux River At Watertown Flow Report
As of July 16, 2026, Big Sioux River At Watertown is flowing at 137 cfs with a gage height of 6.22 ft, receding 12% over the past 24 hours. Source: USGS gauge #06479500, refreshed throughout the day.
Historical Data
Big Sioux River At Watertown at a glance
How Big Sioux River At Watertown is running right now, where it sits on the map, and the key gauge stats.
Big Sioux River At Watertown is flowing at 137 cfs, with the water sitting 6.22 ft at the gage. Flow is down 12% since yesterday as the gauge recedes.
This is USGS gauge #06479500 in South Dakota. Over the past 10 days the average has been 182 cfs, peaking at 430 cfs.
For real-time updates and historical context, see the realtime view or the historical comparison. Browse other gauges in the South Dakota flow report.
Engineering Data
Flow-duration statistics and observed peak-flow context computed from this gauge’s complete daily record (USGS #06479500).
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, Big Sioux R At Watertown Sd is expected to recede from today's 137 cfs, toward roughly 107 cfs by 2026-07-21 (likely range 3-3744 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.
Big Sioux River At Watertown
The river is fed by several tributaries, including the Little Sioux River, and is regulated by a series of dams. Seasonal trends show increased flow during spring rains and decreased flow during summer droughts. Interestingly, a significant portion of the river's flow comes from groundwater discharge. The river is also popular for recreational activities such as fishing and kayaking. Overall, the Big Sioux River plays a vital role in the hydrology of the region and is closely monitored by authorities.
Nearby streamflow levels
Cross-check Big Sioux River At Watertown's discharge against nearby gauges to spot whether the change here is local or regional.
| Gauge | Streamflow |
|---|---|
| Big Sioux R At Watertown Sd | 137 cfs |
| Big Sioux R Near Watertown Sd | 62 cfs |
| Big Sioux R Near Castlewood Sd | 263 cfs |
| Big Sioux River Nr Florence Sd | 5 cfs |
| Big Sioux River Near Bruce | 534 cfs |
| Whetstone River Near Big Stone City | 52 cfs |
Nearby snowpack data
Snowpack at SNOTEL stations near Big Sioux River At Watertown. 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 |
|---|---|
| Hayti 1w | 0 in |
| Huron-33mi.E | 0 in |
| Doland | 0 in |
| Brookings | 0 in |
| Browns Valley | 0 in |
| Andover No. 2 | 0 in |
Plan a trip
Reservoirs, boat launches, river runs, and fishing spots within driving distance of Big Sioux River At Watertown.
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 Big Sioux River At Watertown in the Snoflo app
Save this gauge as a favorite, set push alerts when streamflow crosses a threshold (e.g. "alert me when Big Sioux River At Watertown crosses 5,000 cfs"), and Snoflo's iOS app will push the moment USGS reports the crossing.
About Big Sioux River At Watertown
Where does the streamflow data for Big Sioux River At Watertown come from?
Discharge, gage height, and water temperature come directly from the USGS streamflow gauge 06479500. 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 Big Sioux River At Watertown 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 Big Sioux River At Watertown report
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