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Bighorn Lake Yellowtail water level

Reservoir, Montana, United States

Directions

Normal for mid-October

Surface elevation

3,626.18ft Up 1.70 ft over the last 7 days

Water stored
862,893 acre‑ft
3,610 3,620 3,630 3,640

History

3,6103,6203,6303,640ftOct 13Oct 14Oct 15Oct 16Oct 173,6103,6203,6303,640ftOct 13Oct 15Oct 17
3,6203,640ftSep 20Sep 26Oct 3Oct 10Oct 173,6203,640ftSep 20Oct 3Oct 17
3,6003,6203,640ftOct 2025Jan 2026Apr 2026Jul 2026Oct 20263,6003,6203,640ftOct 2025Apr 2026Oct 2026
3,6003,6203,640ftOct 2016Apr 2019Oct 2021Apr 2024Oct 20263,6003,6203,640ftOct 2016Oct 2021Oct 2026
3,6003,6203,640ftJanMarMayJulSepNov20263,6003,6203,640ftJanAprJulOct2026

202120222023202420252026

Surface elevation Normal range (10–90 %)

What this means

Nothing unusual at Bighorn Lake Yellowtail right now: the lake level of 3,626.18 ft is in the normal range for mid-October.

That puts it 8.47 ft below the median of 3,634.65 ft for mid-October, based on 36 years of readings. A year ago it stood at 3,632.81 ft (−6.63 ft).

The water is rising: up 1.70 ft over the past week. Over the past 30 days it has moved between 3,623.36 ft and 3,626.18 ft.

Many reservoirs are drawn down through summer and fall; most of the refill comes later, with winter rain or spring snowmelt.

Compared with 36 years of daily readings for this time of year. How to read levels

Key numbers

Median for this date
3,634.65 ft8.47 ft below the median for this date
Normal for this date
3,608.16 ft – 3,639.95 ft8 years in 10 fall in this range (36 years of records)
Same day last year
3,632.81 ft−6.63 ft
Lowest and highest in 30 days
3,623.36 ft – 3,626.18 ft
Lowest and highest in 12 months
3,613.78 ft – 3,633.38 ft

Swimming and boating at Bighorn Lake Yellowtail

At a normal level, ramps and marinas generally run as usual, and fishing tends to follow the season more than the water level.

If you swim, pick a spot with an easy way out, and remember that drop-offs move as the level changes.

Weather at the gauge

No rain in the last 3 days.

18 Sun 64° 47° – Wind 16 mph
19 Mon 71° 42° – Wind 7 mph
20 Tue 69° 50° – Wind 11 mph
21 Wed 71° 46° – Wind 6 mph
22 Thu 76° 57° – Wind 7 mph
23 Fri 63° 40° 0.36 in, 70% Wind 13 mph
24 Sat 49° 37° 0.03 in, 70% Wind 7 mph

Forecast: Open-Meteo

Sunrise 07:34 AM Sunset 06:21 PM Daylight 10 hr, 47 min First quarter 57%

Map

Nearby gauges

Gauge Level Compared with normal 24 hours Distance
Bighorn R below Yellowtail Afterbay Dam near St. XavierRiver gauge, Bighorn R 1,590 cfs Low ±0 2.0 mi
Bighorn River and BIA Canal near St. XavierReservoir 3,188.24 ft High 2.0 mi
Bighorn River at bridge, at St. XavierRiver gauge, Bighorn River 1,720 cfs Very low −30.0 cfs 15 mi
Little Bighorn River at State Line near Wyola MTRiver gauge, Little Bighorn River 69.5 cfs Low −1.7 cfs 27 mi
Bighorn River at Two Leggins Bridge, near HardinRiver gauge, Bighorn River 1,780 cfs Very low ±0 27 mi
Little Bighorn River near Crow Agency MTRiver gauge, Little Bighorn River 115 cfs Normal +2.0 cfs 30 mi
Agency Canal Tailwaste near Hardin MTCanal gauge, Agency Canal Tailwaste 3.9 cfs Normal −0.1 cfs 35 mi
Little Bighorn River near Hardin MTRiver gauge, Little Bighorn River 2.67 ft Below flood stage +0.06 ft 35 mi

Questions and answers

How does Bighorn Lake Yellowtail compare with last year?

It is 6.63 ft lower than on the same day last year, when the reading was 3,632.81 ft.

What is a normal level for Bighorn Lake Yellowtail in mid-October?

The median for mid-October is 3,634.65 ft. In 8 years out of 10 the reading falls between 3,608.16 ft and 3,639.95 ft, based on 36 years of records.

Is Bighorn Lake Yellowtail really 3,626.18 ft deep?

No. 3,626.18 ft is the height of the water surface above sea level (or the agency's vertical datum), not the depth of the water.

What is the water level of Bighorn Lake Yellowtail today?

On Oct 17, 2026, the surface elevation was 3,626.18 ft. Up 1.70 ft over the last 7 days.

Is Bighorn Lake Yellowtail rising or falling?

Up 1.70 ft over the last 7 days.

Is the level of Bighorn Lake Yellowtail normal?

Normal for mid-October. Compared with 36 years of daily readings for this time of year.

How often is this data updated?

The U.S. Bureau of Reclamation publishes a new reading once a day. This page refreshes within minutes of each update.

For specialists

Station codes, datum, parameters, data quality and downloads
Operator
U.S. Bureau of Reclamation
Station code
usbr:275 (Agency page)
Coordinates
45.30720, -107.95690 (WGS84)
Update interval
once a day
Licence
Public domain. Data: U.S. Bureau of Reclamation (RISE), provisional data subject to revision

Published series

ParameterLast valueTime (UTC)Quality
Surface elevation 3,626.18 ft 2026-10-17 06:00 Provisional
Water stored 862,893 acre‑ft 2026-10-17 06:00 Provisional

Download

Embed this gauge

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How to cite

U.S. Bureau of Reclamation: Bighorn Lake Yellowtail (usbr:275). Accessed October 19, 2026 via Nivelmap, https://nivelmap.com/en/united-states/montana/bighorn-lake-yellowtail

How we check values

Each reading is stored as published. We hold back values that jump faster than physically plausible and show the measurement time with every value.

Readings are provisional, can be delayed or wrong and are not a flood warning. Read the disclaimer