Rivermatics

USGS Streamgage 06038500

Madison River below Hebgen Lake near Grayling, MT

Madison River below Hebgen Lake near Grayling, MT is USGS streamgage 06038500 in Montana, monitoring river discharge in hydrologic subbasin 10020007. It sits on the Madison River, alongside 7 other gauges Rivermatics tracks on the same river. It drains a watershed of about 931 square miles. Discharge records at this site go back to 1938. Typical flow runs near 986.8 cfs in July and 841.8 cfs in April, with the higher of the two arriving in July. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead, alongside daily high and low water-temperature forecasts.

View live conditions & forecast →

Gauge details

State
Montana
Drainage area
931 sq mi
Gauge elevation
6,459 ft
Subbasin (HUC-8)
10020007
Coordinates
44.86639, -111.33878
USGS site number
06038500
Records begin
1938-10-01 (88 years)
Rivermatics forecast
14-day flow outlook + water temperature

14-day flow forecast

Based on observations through for Madison River below Hebgen Lake near Grayling, MT. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.

Forecast daily mean discharge in cubic feet per second, by date
Date Low p10 Expected p50 High p90 Range
746 761 776
747 764 782
744 765 792
742 766 807
736 764 844
729 763 872
727 764 894
722 763 910
720 763 932
715 762 933
713 763 954
710 762 973
706 762 970
702 761 968

All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.

Typical flow by month

Long-term daily discharge percentiles from the USGS record (up to 88 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 712 873.9 1,178.4
February 650.4 824.6 1,113.4
March 499.3 813.3 1,241.6
April 353.6 841.8 1,584
May 223 785 1,714.8
June 297.8 1,098.9 2,360.7
July 690.4 986.8 1,456.1
August 798.9 1,025.5 1,348.4
September 760 1,060.8 1,532
October 693.4 1,064.4 1,986.8
November 689.6 1,098.8 2,042
December 705.1 888.9 1,257.4

All values in cubic feet per second (cfs).

Common questions

When does Madison River below Hebgen Lake near Grayling, MT normally run highest?
June, on the long-term record. The median daily flow that month is about 1,098.9 cfs, against 785 cfs in May, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
What is a normal flow for Madison River below Hebgen Lake near Grayling, MT?
It depends on the month. In January, half of days historically fall near 873.9 cfs, with the middle 80% of days between 712 and 1,178.4 cfs. The month-by-month table on this page gives the full range.
How long has Madison River below Hebgen Lake near Grayling, MT been measured?
Discharge records at USGS site 06038500 begin in 1938, about 88 years, covering roughly 9,200 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for Madison River below Hebgen Lake near Grayling, MT?
Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. A companion model forecasts each day's water-temperature high and low. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
Where is Madison River below Hebgen Lake near Grayling, MT?
The gauge sits at 44.86639, -111.33878, in Montana, in hydrologic subbasin 10020007, at an elevation of about 6,459 feet, draining roughly 931 square miles.
Can I use Madison River below Hebgen Lake near Grayling, MT 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.

Upstream and downstream on the Madison River

Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Madison River in full.

Other gauges in this subbasin