Arkansas River level at Nathrop
Colorado · Paddling & whitewater
Measured at USGS 07091200 — ARKANSAS RIVER NEAR NATHROP, CO
Reading taken · as of 18 min ago
Too low for most boats — rocky and technical
At 153 CFS, this gauge is running 41% of normal for mid-September — below the 370 CFS median USGS has recorded for this date across 55 years of record (1965–2025).
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Flow history at Nathrop
Daily values from USGS 07091200, updated every 15 to 60 minutes. Provisional.
About Arkansas River at Nathrop
Nathrop is the reference gauge for Browns Canyon, which carries more commercial rafting than any other stretch of river in the United States. What keeps it running through a Colorado August is not weather but arrangement: water stored in the upper basin is released under a voluntary flow programme specifically to hold summer boating flows up, then shifted again in late summer for downstream fish habitat.
That makes the seasonal comparison on this page unusually informative. Snowmelt sets the ceiling in June, the managed releases set the floor in July and August, and the difference between a normal year and a thin one is visible here weeks before it is visible on the riverbank.
Arkansas River at Nathrop — common questions
5 questions
Why does the Arkansas at Browns Canyon hold flow all summer?
Because it is managed to. Water stored upstream is released during the boating season under a voluntary flow management arrangement between the water users, the state and the outfitters, which props up flows that would otherwise fall away after runoff. It is why a Colorado river with no dam immediately above it still runs commercially in August.
When does Browns Canyon peak?
With snowmelt, normally late May into June, and the size of that peak is set by the winter snowpack rather than by summer rain. After it passes, the river settles onto the managed summer flows and the character changes from big and pushy to the steadier water most commercial trips run.
How fast can Arkansas River at Nathrop come up?
Fast. It is free-flowing, so rain upstream moves it directly. Several feet in a few hours is normal after a heavy storm.
Is Arkansas River at Nathrop high or low for this time of year?
The USGS median flow for mid-September here is 370 CFS, from 55 years of record (1965–2025). Today is 41% of it. The comparison is what makes the raw number mean anything: the same reading is a drought on one river and a flood on another.
How often does this reading update?
USGS transmits from gauge 07091200 every 15 to 60 minutes. This page refreshes from USGS when you open it, and the reading is provisional until USGS reviews it. The timestamp is in the gauge's local time.