Rivermatics

6 USGS Streamgages · Columbia River system

Portneuf River flows and levels

Portneuf River is gauged at 6 USGS streamgages in Idaho, each tracked by Rivermatics. The mainstem runs about 116 miles (187 km) from headwaters to outlet. It drains into the Columbia River system. Drainage area at the gauges ranges from 92 square miles at Portneuf River. above Toponce Rd, near Chesterfield, ID up to 1,305 at Portneuf River near Tyhee, ID. Rivermatics issues a daily machine-learned 14-day flow outlook for every one 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
Portneuf River. above Toponce Rd, near Chesterfield, ID ID 92 — — — 14-day
Portneuf River at Pebble, ID ID 261 — — 129.2 14-day
Portneuf River at Topaz, ID ID 576 — 215 196.5 14-day
Portneuf River. at Inkom, ID ID 1,065 — 753.8 76.2 14-day
Portneuf River at Pocatello, ID ID 1,256 — 451.3 72.7 14-day
Portneuf River near Tyhee, ID ID 1,305 — 577.1 163.9 14-day

Typical flow by month at Portneuf River near Tyhee, 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 41 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 372.1 440.9 575.5
February 374.1 465.9 672.8
March 417 545.7 769.5
April 383.8 577.1 1,103.2
May 155.7 401.3 1,180.2
June 76.9 195.2 686.2
July 98.5 163.9 263.2
August 149 211.3 311.2
September 191.8 268.1 414.6
October 317 413.9 536.1
November 376.2 445.9 547.3
December 374.9 446.5 550

All values in cubic feet per second (cfs).

Common questions

When does the Portneuf River run highest?
April, on the long-term record at Portneuf River near Tyhee, ID — the furthest-downstream gauge Rivermatics tracks on this river. Median daily flow there is about 577.1 cfs that month, against 163.9 cfs in July, 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 Portneuf River?
Rivermatics tracks 6 USGS streamgages on the Portneuf 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 Portneuf River?
Yes, at 6 of the 6 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 Portneuf River part of?
The Portneuf 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 Portneuf 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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