Red Flag Warning
2026-04-13T20:00:00-06:00

* AFFECTED AREA...Fire Weather Zones 214, 216, 238, 241, 242, 246 and 247. * TIMING...From 11 AM this morning to 8 PM MDT this evening. * WINDS...Southwest 10 to 20 mph with gusts around 30 mph. * RELATIVE HUMIDITY...As low as 10 percent. * IMPACTS...Conditions will be favorable for rapid fire spread. Avoid outdoor burning and any activity that may produce a spark and start a wildfire.

Marias River

Last Updated: April 13, 2026

Total streamflow across the Marias River was last observed at 757 cfs, and is expected to yield approximately 1,501 acre-ft of water today; about 47% of normal. River levels are low and may signify a drought. Average streamflow for this time of year is 1,603 cfs, with recent peaks last observed on 2011-06-10 when daily discharge volume was observed at 18,600 cfs.

Maximum discharge along the river is currently at the Marias River Near Shelby Mt reporting a streamflow rate of 757 cfs. This is also the highest stage along the Marias River, with a gauge stage of 3.71 ft at this location. This river is monitored from 3 different streamgauging stations along the Marias River, the highest being situated at an altitude of 3,099 ft, the Marias River Near Shelby Mt.

The Marias River is a tributary of the Missouri River, spanning a length of approximately 210 miles in Montana.


15-Day Long Term Forecast


River Details

Last Updated 2026-04-13
Discharge Volume 1,501 ACRE-FT
Streamflow 757.0 cfs
Past 24 Hours: +30.0 cfs (+4.13%)
Percent of Normal 47.24%
Maximum 18,600.0 cfs
2011-06-10
Seasonal Avg 1,603 cfs
       
River Streamflow Levels
Streamgauge Streamflow Gauge Stage 24hr Change (%) % Normal Minimum (cfs) Maximum (cfs) Air Temp Elevation
Marias River Near Shelby Mt
USGS 06099500
757 cfs 3.71 ft 4.13
Marias River Near Chester Mt
USGS 06101500
412 cfs 3.22 ft 0
Marias River Near Loma Mt
USGS 06102050
401 cfs 1.09 ft 1.78
Seasonal Discharge Comparison
Maximum Streamflow Discharge
Streamflow Elevation Profile

The Marias River is a tributary of the Missouri River, approximately 210 mi (338 km) long, in the U.S. state of Montana. It is formed in Glacier County, in northwestern Montana, by the confluence of the Cut Bank Creek and the Two Medicine River. It flows east, through Lake Elwell, formed by the Tiber Dam, then southeast, receiving the Teton River at Loma, 2 mi. (3.2 km) above its confluence with the Missouri.
The river was explored in 1805 by the Lewis and Clark Expedition. Some of the men on the expedition mistook it for the main branch of the Missouri until their subsequent discovery of the Great Falls of the Missouri near Great Falls, Montana. The river was named by Meriwether Lewis after his cousin, Maria Wood. Lewis led a small detachment of men to further explore the Marias River on the Expedition's return trip in 1806 to determine if the river ventured north above the Canada border, and he killed a young Blackfeet warrior trying to steal horses and a gun from the small detachment.
The river was the scene of the 1870 Marias Massacre.The Marias is a Class I river from Tiber Dam to its confluence with the Missouri River for public access for recreational purposes.The Montana Watershed Coordination Council is an advocate for the river.The Marias River Bridge was listed on the National Register of Historic Places in 2012.