Castor River At Zalma flow report
As of July 13, 2026, Castor River At Zalma is flowing at 693 cfs with a gage height of 4.58 ft, receding 20% over the past 24 hours. Source: USGS gauge #07021000, refreshed throughout the day.
Historical Data
Castor River At Zalma at a glance
How Castor River At Zalma is running right now, where it sits on the map, and the key gauge stats.
Castor River At Zalma is flowing at 693 cfs, with the water sitting 4.58 ft at the gage. Flow is down 20% since yesterday as the gauge recedes.
This is USGS gauge #07021000 in Missouri. Over the past 10 days the average has been 527 cfs, peaking at 2,690 cfs.
Over the next 5 days, Castor River At Zalma is expected to recede from today's 871 cfs, toward roughly 488 cfs by 2026-07-17 (likely range 218-1092 cfs) -- about normal for the date.
For real-time updates and historical context, see the realtime view or the historical comparison. Browse other gauges in the Missouri flow report.
Streamflow Forecast
Powered by PULSE — Snoflo’s Predictive Unified Learning & Simulation Engine, which learns from how this river has answered every past storm, snowmelt, and dry spell to forecast where it’s headed with a precision generic models can’t match.
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.
Castor River At Zalma
The Castor River flows for 84 miles before joining the St. Francis River. The primary flow providers for the Castor River are springs and tributaries, with the largest tributary being Little Castor Creek. The river is not affected by any major dams. The flow of the Castor River varies greatly throughout the year, with the highest flows occurring in the spring and the lowest flows occurring in the late summer and fall. The river is known for its excellent smallmouth bass fishing and its scenic beauty, with limestone bluffs and crystal-clear water.
Nearby streamflow levels
Cross-check Castor River At Zalma's discharge against nearby gauges to spot whether the change here is local or regional.
| Gauge | Streamflow |
|---|---|
| Castor River At Zalma | 693 cfs |
| St. Francis River At Wappapello | 2,680 cfs |
| St. Francis River Near Patterson | 1,880 cfs |
| St. Francis River Near Saco | 869 cfs |
| Little River Ditch No. 1 Near Morehouse | 2,650 cfs |
| Little St. Francis River At Fredericktown | 77 cfs |
Nearby snowpack data
Snowpack at SNOTEL stations near Castor River At Zalma. 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 |
|---|---|
| Clearwater Dam - Black Rvr | 0 in |
Plan a trip
Reservoirs, boat launches, river runs, and fishing spots within driving distance of Castor River At Zalma.
Nearby reservoirs
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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 Castor River At Zalma in the Snoflo app
Save this gauge as a favorite, set push alerts when streamflow crosses a threshold (e.g. "alert me when Castor River At Zalma crosses 5,000 cfs"), and Snoflo's iOS app will push the moment USGS reports the crossing.
About Castor River At Zalma
Where does the streamflow data for Castor River At Zalma come from?
Discharge, gage height, and water temperature come directly from the USGS streamflow gauge 07021000. 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 Castor River At Zalma 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 Castor River At Zalma report
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