About this river
Lemhi River is an 18.6 mile river near Helfrich River Outfitters in Idaho. Streamflow is measured at the USGS gauge Lemhi River near Lemhi ID (site 13305000). The National Hydrography Dataset places it at stream order 6. Reach geometry comes from the USGS National Hydrography Dataset.
Typical flow by month
1939 to 2025
Lemhi River typically runs highest in June, at a median 458 cfs, and lowest in August, at 116 cfs. The highest flow on record for any single day is 2,100 cfs, in 1984.
| Month | Typical (cfs) | Usual range (cfs) | Relative level |
|---|---|---|---|
| January | 217 | 185 to 252 | |
| February | 225 | 196 to 259 | |
| March | 253 | 210 to 282 | |
| April | 253 | 198 to 300 | |
| May | 228 | 161 to 324 | |
| June | 458 | 280 to 707 | |
| July | 190 | 128 to 322 | |
| August | 116 | 93 to 163 | |
| September | 126 | 96 to 177 | |
| October | 243 | 200 to 298 | |
| November | 265 | 229 to 308 | |
| December | 218 | 190 to 251 |
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 66 years of record. Statistics published by the US Geological Survey for Lemhi River near Lemhi ID (site 13305000). Conditions on any given day can fall well outside the usual range. Check the current reading before you go.
Embed this gauge on your site
Paste this snippet anywhere, an outfitter page, a club site, a trip report, to show Lemhi River's live streamflow, water level and 7-day trend. It reads the USGS gauge directly, updates itself, and links back here.
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