About this river
Cowlitz River is a 2.7 mile river near St. Helens Marina in Oregon. Streamflow is measured at the USGS gauge Cowlitz River at Castle Rock, WA (site 14243000). The National Hydrography Dataset places it at stream order 8. Reach geometry comes from the USGS National Hydrography Dataset.
Typical flow by month
1927 to 2026
Cowlitz River typically runs highest in December, at a median 12,900 cfs, and lowest in September, at 2,870 cfs. The highest flow on record for any single day is 134,000 cfs, in 1934.
| Month | Typical (cfs) | Usual range (cfs) | Relative level |
|---|---|---|---|
| January | 12,300 | 8,530 to 18,300 | |
| February | 10,800 | 7,860 to 15,200 | |
| March | 9,530 | 7,350 to 13,100 | |
| April | 9,125 | 7,475 to 12,350 | |
| May | 9,680 | 7,070 to 12,800 | |
| June | 8,390 | 6,015 to 11,900 | |
| July | 4,470 | 3,320 to 6,270 | |
| August | 2,990 | 2,400 to 3,700 | |
| September | 2,870 | 2,045 to 3,705 | |
| October | 4,100 | 2,640 to 5,490 | |
| November | 8,845 | 5,220 to 13,100 | |
| December | 12,900 | 8,540 to 18,200 |
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 99 years of record. Statistics published by the US Geological Survey for Cowlitz River at Castle Rock, WA (site 14243000). Conditions on any given day can fall well outside the usual range. Check the current reading before you go.
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Paste this snippet anywhere, an outfitter page, a club site, a trip report, to show Cowlitz 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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