Rivermatics

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 sits on the South Fork Tolt River, alongside 1 other gauge Rivermatics tracks on the same river. 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. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead, alongside daily high and low water-temperature forecasts.

View live conditions & forecast →

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)
Rivermatics forecast
14-day flow outlook + water temperature

14-day flow forecast

Based on observations through for South Fork Tolt River near Index, WA. 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.

Forecast daily mean discharge in cubic feet per second, by date
Date Low p10 Expected p50 High p90 Range
2.2 2.4 2.5
2.2 2.5 3.1
3.3 7.6 28
3.6 8.1 22.2
3.2 5.7 12.1
2.8 4.1 7.2
2.5 3.4 5.5
2.3 3 4.5
2.2 2.8 4.1
2.1 2.7 3.8
2 2.6 3.5
1.9 2.5 3.4
1.8 2.4 3.2
1.8 2.3 3.1

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 67 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.

Historical monthly discharge percentiles in cubic feet per second
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).

Common questions

When does South Fork Tolt River near Index, WA normally run highest?
May, on the long-term record. The median daily flow that month is about 67.3 cfs, against 6.5 cfs in August, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
What is a normal flow for South Fork Tolt River near Index, WA?
It depends on the month. In January, half of days historically fall near 34.7 cfs, with the middle 80% of days between 12.4 and 201.4 cfs. The month-by-month table on this page gives the full range.
How long has South Fork Tolt River near Index, WA been measured?
Discharge records at USGS site 12147600 begin in 1959, about 67 years, covering roughly 9,191 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for South Fork Tolt River near Index, WA?
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. A companion model forecasts each day's water-temperature high and low. 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 South Fork Tolt River near Index, WA?
The gauge sits at 47.70677, -121.60011, in Washington, in hydrologic subbasin 17110010, at an elevation of about 1,841 feet, draining roughly 5 square miles.
Can I use South Fork Tolt River near Index, WA 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 South Fork Tolt River

Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the South Fork Tolt River in full.

Other gauges in this subbasin