Rivermatics

3 USGS Streamgages · Columbia River system

Sf Boise River flows and levels

Sf Boise River is gauged at 3 USGS streamgages in Idaho, each tracked by Rivermatics. It feeds the South Fork Boise River. It drains into the Columbia River system. Drainage area at the gauges ranges from 641 square miles at SF Boise River near Featherville, ID up to 1,172 at SF Boise River at Neal Bridge near Arrowrock Dam, ID. Rivermatics issues a daily machine-learned 14-day flow outlook at 2 of them.

Gauges on this river, upstream to downstream

Ordered by drainage area, which is how far down the river each gauge sits. April and July figures are long-term median daily flows for that month from the USGS record — historical normals, not a forecast and not today's reading.

USGS streamgages on this river, ordered upstream to downstream
Gauge State Drainage sq mi Elevation ft April p50 cfs July p50 cfs Forecast
SF Boise River near Featherville, ID ID 641 — 1,071.2 601.2 14-day
SF Boise River at Anderson Ranch Dam, ID ID 978 — 770.1 1,514.2 14-day + temp
SF Boise River at Neal Bridge near Arrowrock Dam, ID ID 1,172 — 1,242 1,759 —

Typical flow by month at SF Boise River at Neal Bridge near Arrowrock Dam, ID

The furthest-downstream gauge on this river, so the fullest flow it carries here. Long-term daily discharge percentiles from the USGS record (up to 9 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 — 373.9 —
February — 425.4 —
March — 523.5 —
April — 1,242 —
May 410.3 2,699 6,385.6
June 749.6 1,970.7 5,071
July 1,520.1 1,759 2,063.5
August 736.2 1,380.7 2,002.9
September 476.8 528.2 1,320.6
October — 354.6 —
November — 355.8 —
December — 365.4 —

All values in cubic feet per second (cfs).

Common questions

When does the Sf Boise River run highest?
May, on the long-term record at SF Boise River at Neal Bridge near Arrowrock Dam, ID — the furthest-downstream gauge Rivermatics tracks on this river. Median daily flow there is about 2,699 cfs that month, against 354.6 cfs in October, the lowest. Upstream gauges peak on their own schedule; the table on this page gives April and July for each.
How many gauges are on the Sf Boise River?
Rivermatics tracks 3 USGS streamgages on the Sf Boise River, across Idaho. Each has its own page with the site's full flow record and monthly normals. The river may carry other gauges that publish neither daily values nor discharge statistics; those are not tracked here.
Is there a flow forecast for the Sf Boise River?
Yes, at 2 of the 3 gauges. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on each basin's observed flows, weather and snowpack, and issues a daily 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 each gauge's live screen.
What river system is the Sf Boise River part of?
The Sf Boise River drains into the Columbia River system — it is a tributary somewhere in that chain, following the flowpath down to its terminal river. Rivermatics builds this from the USGS/geoconnex reference-mainstem network rather than from names.
Can I use Sf Boise River 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 rivers in the Columbia River system

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