USGS Streamgage 06307500
Tongue River at Tongue River Dam near Decker, MT
Tongue River at Tongue River Dam near Decker, MT is USGS streamgage 06307500 in Montana, monitoring river discharge in hydrologic subbasin 10090101. It sits on the Tongue River, alongside 5 other gauges Rivermatics tracks on the same river. It drains a watershed of about 1,784 square miles. Discharge records at this site go back to 1939. Typical flow runs near 454.7 cfs in July and 279.4 cfs in April, with the higher of the two arriving in July. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.
View live conditions & forecast →
Gauge details
- State
- Montana
- Drainage area
- 1,784 sq mi
- Gauge elevation
- 3,352 ft
- Subbasin (HUC-8)
- 10090101
- Coordinates
- 45.14128, -106.77136
- USGS site number
- 06307500
- Records begin
- 1939-05-18 (87 years)
- Rivermatics forecast
- 14-day flow outlook
14-day flow forecast
Based on observations through for Tongue River at Tongue River Dam near Decker, MT. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.
| Date | Low p10 | Expected p50 | High p90 | Range |
|---|---|---|---|---|
| 76.5 | 84.5 | 90.9 | ||
| 73.6 | 82.9 | 91.5 | ||
| 70.9 | 82.1 | 92.6 | ||
| 70.1 | 82.4 | 95.5 | ||
| 69.1 | 82.2 | 97.6 | ||
| 66 | 81.1 | 98 | ||
| 64.2 | 81.9 | 104 | ||
| 62.8 | 80.7 | 108 | ||
| 61.2 | 80 | 111 | ||
| 60.6 | 80.2 | 116 | ||
| 59 | 79.7 | 118 | ||
| 58.5 | 79.9 | 120 | ||
| 57.6 | 79.4 | 120 | ||
| 57.2 | 79.5 | 122 |
All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 87 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 96.1 | 169.1 | 219.3 | |
| February | 88.9 | 167 | 230.3 | |
| March | 79 | 179.8 | 389.9 | |
| April | 80.7 | 279.4 | 701.2 | |
| May | 233.1 | 706.4 | 1,789.5 | |
| June | 329.3 | 1,246.2 | 2,999.7 | |
| July | 253.4 | 454.7 | 1,062.4 | |
| August | 163.2 | 376.8 | 516.8 | |
| September | 133.4 | 292.2 | 464.6 | |
| October | 102.4 | 227.1 | 480.5 | |
| November | 94.6 | 208.9 | 447.4 | |
| December | 98 | 179.2 | 253.6 |
All values in cubic feet per second (cfs).
Common questions
- When does Tongue River at Tongue River Dam near Decker, MT normally run highest?
- June, on the long-term record. The median daily flow that month is about 1,246.2 cfs, against 167 cfs in February, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Tongue River at Tongue River Dam near Decker, MT?
- It depends on the month. In January, half of days historically fall near 169.1 cfs, with the middle 80% of days between 96.1 and 219.3 cfs. The month-by-month table on this page gives the full range.
- How long has Tongue River at Tongue River Dam near Decker, MT been measured?
- Discharge records at USGS site 06307500 begin in 1939, about 87 years, covering roughly 9,199 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Is there a flow forecast for Tongue River at Tongue River Dam near Decker, MT?
- Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
- Where is Tongue River at Tongue River Dam near Decker, MT?
- The gauge sits at 45.14128, -106.77136, in Montana, in hydrologic subbasin 10090101, at an elevation of about 3,352 feet, draining roughly 1,784 square miles.
- Can I use Tongue River at Tongue River Dam near Decker, MT data for flood or safety decisions?
- No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.
Upstream and downstream on the Tongue River
Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Tongue River in full.
- Tongue River at State Line near Decker, MT 1,453 sq mi
- Tongue River at Tongue River Dam near Decker, MT this page
- Tongue River at Birney Day School Br near Birney, MT 2,634 sq mi
- Tongue River at Ashland, MT 2,900 sq mi
- Tongue River below Brandenberg bridge near Ashland, MT 3,882 sq mi
- Tongue River at Miles City, MT 5,405 sq mi