Rivermatics

USGS Streamgage 13120000

NF Big Lost River at Wild Horse near Chilly, ID

NF Big Lost River at Wild Horse near Chilly, ID is USGS streamgage 13120000 in Idaho, monitoring river discharge in hydrologic subbasin 17040218. It drains a watershed of about 115 square miles. Discharge records at this site go back to 1944. Typical flow runs near 166.9 cfs in July and 47.9 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
Idaho
Drainage area
115 sq mi
Subbasin (HUC-8)
17040218
Coordinates
43.93278, -114.11389
USGS site number
13120000
Records begin
1944-04-01 (82 years)
Rivermatics forecast
14-day flow outlook

14-day flow forecast

Based on observations through for NF Big Lost River at Wild Horse near Chilly, ID. 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
26.3 27.9 29.2
25.5 27.4 29
25 27 28.7
24.7 26.9 28.8
24.3 26.5 28.5
24.7 27.3 30.1
25.1 28.1 31.8
24.7 27.6 30.9
24 26.9 29.9
23.5 26.3 29.1
23.1 25.9 28.8
22.8 25.6 28.5
22.5 25.4 28.4
22.2 25.2 28.1

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 83 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 16.6 21.8 29.8
February 15.9 20.2 26
March 15.7 20.3 33
April 23.6 47.9 122.8
May 95.4 226.6 508.9
June 167.3 354.5 700.3
July 65.8 166.9 319.7
August 31.7 58.2 111
September 23.9 38.9 64.6
October 22.9 34.9 53.1
November 19.4 29 39.7
December 17.1 23.3 32.1

All values in cubic feet per second (cfs).

Common questions

When does NF Big Lost River at Wild Horse near Chilly, ID normally run highest?
June, on the long-term record. The median daily flow that month is about 354.5 cfs, against 20.2 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 NF Big Lost River at Wild Horse near Chilly, ID?
It depends on the month. In January, half of days historically fall near 21.8 cfs, with the middle 80% of days between 16.6 and 29.8 cfs. The month-by-month table on this page gives the full range.
How long has NF Big Lost River at Wild Horse near Chilly, ID been measured?
Discharge records at USGS site 13120000 begin in 1944, about 82 years, covering roughly 9,200 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for NF Big Lost River at Wild Horse near Chilly, ID?
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 NF Big Lost River at Wild Horse near Chilly, ID?
The gauge sits at 43.93278, -114.11389, in Idaho, in hydrologic subbasin 17040218, draining roughly 115 square miles.
Can I use NF Big Lost River at Wild Horse near Chilly, ID 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.

Other gauges in this subbasin