Bighorn River level at Fort Smith
Montana · Fishing & wading
Measured at USGS 06287000 — Bighorn R bl Yellowtail Afterbay Dam nr St. Xavier · NWS forecast point STXM8
Reading taken · as of 13 min ago
Below normal — good wading, low and clear
At 1,830 CFS, this gauge is in the lowest quarter of the 91 years USGS has recorded for this date (1935–2026), at 70% of the 2,610 CFS median.
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Flow history at Fort Smith
Daily values from USGS 06287000, updated every 15 to 60 minutes; NWS forecast for STXM8 reissued through the day. Provisional.
Highest crests on record at Fort Smith
12 on record
| Stage | Flow | Date |
|---|---|---|
| 65.60 ft | 15,700 CFS | Jun 20, 2011 |
| 65.60 ft | 16,300 CFS | Jun 25, 2023 |
| 65.15 ft | 14,200 CFS | Jun 22, 2018 |
| 65.12 ft | 14,100 CFS | May 26, 2017 |
| 65.04 ft | 14,500 CFS | Jun 10, 2015 |
| 64.78 ft | 13,300 CFS | Jun 23, 2009 |
| 64.04 ft | 11,000 CFS | Jun 22, 2019 |
| 63.93 ft | 10,800 CFS | Jun 18, 2010 |
| 63.63 ft | 9,530 CFS | Jul 15, 1975 |
| 63.60 ft | 10,000 CFS | Jun 18, 2008 |
Crests published by the National Weather Service.
About Bighorn River at Fort Smith
USGS names this station Bighorn River below Yellowtail Afterbay Dam near St. Xavier. It is the afterbay release gauge, and the number on this page is the volume Yellowtail is letting out rather than anything the weather has done upstream.
The clearest evidence of that is the record low. A basin of 19,670 square miles recorded a daily mean of 112 CFS on 2 April 1967. No drought produces that on a drainage that size. At the other end, 37,400 CFS on 16 June 1935 is the highest daily mean in a series that begins in October 1934. Between those two the published monthly medians sit in a narrow band, roughly 2,450 to 2,930 CFS for nine months of the year, lifting only for June at 5,900 and July at 4,390.
Bighorn River at Fort Smith — common questions
5 questions
Is this number a natural flow or a dam release?
A dam release. The station is below the Yellowtail Afterbay Dam, so what it measures is the discharge being made rather than runoff arriving. That is why the record low of 112 CFS on 2 April 1967 is possible on a 19,670 square mile basin, and why the percent of normal figure on this page should be read as how this release compares with past releases on the same calendar day.
When is this gauge normally highest?
June, by a clear margin. The published median for June is 5,900 CFS and July is 4,390, against roughly 2,450 to 2,930 for the rest of the year. The statistics cover 1935 to 2026, so that pattern is drawn from about 92 years of record.
What makes the flow change on Bighorn River at Fort Smith?
Rain upstream, plus seasonal baseflow. The 12-month chart shows how it behaves through the year.
Is Bighorn River at Fort Smith high or low for this time of year?
The USGS median flow for late September here is 2,610 CFS, from 91 years of record (1935–2026). Today sits in the lowest quarter of those years, at 70% of the median. The comparison is what makes the raw number mean anything: the same reading is a drought on one river and a flood on another.
How often does this reading update?
USGS transmits from gauge 06287000 every 15 to 60 minutes, and the National Weather Service reissues the flood forecast for STXM8 a few times a day — more often when the river is rising. This page refreshes from both when you open it. The timestamp is in the gauge's local time.