Around here
Around St. Mary River
Data Source: Recreation.gov · Public land: USGS PAD-US
About this river
St. Mary River is a 35.3 mile river. Streamflow is measured at the USGS gauge St. Mary River at International Boundary (site 05020500). The National Hydrography Dataset places it at stream order 6. Reach geometry comes from the USGS National Hydrography Dataset.
Typical flow by month
1902 to 2026
St. Mary River typically runs highest in June, at a median 2,190 cfs, and lowest in February, at 126 cfs. The highest flow on record for any single day is 28,000 cfs, in 1908.
Show the numbers
| Month | Typical (cfs) | Usual range (cfs) |
|---|---|---|
| January | 135 | 100 to 175 |
| February | 126 | 95 to 178 |
| March | 140 | 111 to 200 |
| April | 360 | 238 to 572 |
| May | 1,430 | 975 to 2,110 |
| June | 2,190 | 1,535 to 3,240 |
| July | 1,050 | 710 to 1,620 |
| August | 496 | 388 to 649 |
| September | 373 | 271 to 512 |
| October | 335 | 217 to 538 |
| November | 268 | 177 to 416 |
| December | 171 | 120 to 244 |
Typical is the median of each month’s daily median values, and the usual range runs from the median 25th to the median 75th percentile, across about 123 years of record. Statistics published by the US Geological Survey for St. Mary River at International Boundary (site 05020500). Conditions on any given day can fall well outside the usual range. Check the current reading before you go.
Made to print
Put St. Mary River on your wall
This river section as an art print, drawn over the real terrain with its miles, plus the trails, roads and peaks around it. Pick the colors and the size, and see the finished print before you buy. From $39, shipping included.
Embed this gauge on your site
Paste this snippet anywhere, an outfitter page, a club site, a trip report, to show St. Mary River's live streamflow, water level and 7-day trend. It reads the USGS gauge directly, updates itself, and links back here.
See every free widget you can put on your site, including live conditions and a 7 day forecast.
