Around here
Around Lower South Branch Thunder Bay River
Data Source: Recreation.gov · Public land: USGS PAD-US
About this river
Lower South Branch Thunder Bay River is a 31.7 mile river. Streamflow is measured at the USGS gauge Thunder Bay River at Herron Road near Bolton, MI (site 04133501). The National Hydrography Dataset places it at stream order 5. Reach geometry comes from the USGS National Hydrography Dataset.
Typical flow by month
1945 to 2026
Lower South Branch Thunder Bay River typically runs highest in April, at a median 732 cfs, and lowest in August, at 301 cfs. The highest flow on record for any single day is 5,270 cfs, in 2026.
Show the numbers
| Month | Typical (cfs) | Usual range (cfs) |
|---|---|---|
| January | 390 | 320 to 480 |
| February | 370 | 310 to 469 |
| March | 464 | 370 to 727 |
| April | 732 | 499 to 1,255 |
| May | 493 | 370 to 657 |
| June | 374 | 290 to 507 |
| July | 318 | 242 to 408 |
| August | 301 | 238 to 375 |
| September | 302 | 244 to 373 |
| October | 345 | 285 to 435 |
| November | 441 | 354 to 556 |
| December | 445 | 350 to 535 |
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 59 years of record. Statistics published by the US Geological Survey for Thunder Bay River at Herron Road near Bolton, MI (site 04133501). Conditions on any given day can fall well outside the usual range. Check the current reading before you go.
Boat access nearby
2 mapped launches sit in the mapped area of Lower South Branch Thunder Bay River, all of them public access. Ramp data comes from the USGS national boat-ramp inventory.
- Hubbard Lake South BayHubbard LakePublic
- Hubbard Lake North BayHubbard LakePublic
Made to print
Put Lower South Branch Thunder Bay 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 Lower South Branch Thunder Bay 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.
