Rivermatics

3 USGS Streamgages · Mississippi River system

Ruby River flows and levels

Ruby River is gauged at 3 USGS streamgages in Montana, each tracked by Rivermatics. The mainstem runs about 102 miles (165 km) from headwaters to outlet. It drains into the Mississippi River system. Drainage area at the gauges ranges from 534 square miles at Ruby River above reservoir near Alder, MT up to 970 at Ruby River near Twin Bridges, MT. The gauged reach falls about 735 feet, from 5,412 feet down to 4,676. 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
Ruby River above reservoir near Alder, MT MT 534 5,412 148.3 173.7 14-day
Ruby River below reservoir near Alder, MT MT 595 5,294 69.4 319.9 14-day
Ruby River near Twin Bridges, MT MT 970 4,676 146.7 183.8 14-day

Typical flow by month at Ruby River near Twin Bridges, MT

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 85 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 99.2 138.4 199.7
February 102.9 136 203.7
March 101.7 137.2 254.8
April 91.3 146.7 340.6
May 30.8 155.6 474.4
June 43.2 304.1 916.5
July 60.5 183.8 445.1
August 51.4 117.2 207.2
September 102.9 175.7 291.7
October 135.1 204 280.8
November 152.8 215.4 294.7
December 126.3 171.1 259.1

All values in cubic feet per second (cfs).

Common questions

When does the Ruby River run highest?
June, on the long-term record at Ruby River near Twin Bridges, MT — the furthest-downstream gauge Rivermatics tracks on this river. Median daily flow there is about 304.1 cfs that month, against 117.2 cfs in August, 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 Ruby River?
Rivermatics tracks 3 USGS streamgages on the Ruby River, across Montana. 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 Ruby River?
Yes, at 3 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 Ruby River part of?
The Ruby River drains into the Mississippi 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 Ruby 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 Mississippi River system

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