USGS Streamgage 12147600
South Fork Tolt River near Index, WA
South Fork Tolt River near Index, WA is USGS streamgage 12147600 in Washington, monitoring river discharge in hydrologic subbasin 17110010. It drains a watershed of about 5 square miles. Discharge records at this site go back to 1959. Typical flow runs near 19 cfs in July and 48.6 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- Washington
- Drainage area
- 5 sq mi
- Gauge elevation
- 1,841 ft
- Subbasin (HUC-8)
- 17110010
- Coordinates
- 47.70677, -121.60011
- USGS site number
- 12147600
- Records begin
- 1959-12-01 (67 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 67 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 | 12.4 | 34.7 | 201.4 | |
| February | 12.2 | 30.3 | 134.7 | |
| March | 13.8 | 31.4 | 107.4 | |
| April | 24.3 | 48.6 | 119.5 | |
| May | 35.4 | 67.3 | 142.5 | |
| June | 22.3 | 54.4 | 122.9 | |
| July | 8.3 | 19 | 59 | |
| August | 3.6 | 6.5 | 27.5 | |
| September | 3.3 | 9.3 | 58.3 | |
| October | 6.3 | 24.2 | 126.9 | |
| November | 14 | 45.7 | 207.9 | |
| December | 13.6 | 34 | 181.5 |
All values in cubic feet per second (cfs).
Other gauges in this subbasin
- Phelps Creek below Unnamed Tributary near Index, WA
- South Fork Tolt River near Carnation, WA
- SF Tolt River below Regulating Basin near Carnation, WA
- Tolt River near Carnation, WA
- Snoqualmie River near Carnation, WA
- Snoqualmie River at Duvall, WA
- Middle Fork Snoqualmie River near Tanner, WA
- NF Snoqualmie River near Snoqualmie Falls, WA