Hydrohistorian
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Big Thompson River at Mouth of Canyon near Drake
River gage · BTCANYCO · USGS 06738000 · Division 1 · Water District 4 · Larimer County
Live gage at DWR ↗ · USGS monitoring location ↗ · Download daily record (CSV)
Source DWR administrative record · verify at DWR station ↗ Source Independent agency measurement · verify at USGS ↗ Source Our computation, no independent reference · computed here from the screened record
The record
Readings come from the weekly-refreshed cache, never fetched live — the date beside the value says exactly how fresh it is. The live gage is one click up.
Annual flow & trend
Chart: annual mean flow at Big Thompson River at Mouth of Canyon near Drake, water years 1927 to 2013. The measured record is decreasing at -15.56 cubic feet per second per decade. A Pettitt changepoint is detected around 1958. The underlying yearly values are available as a CSV download linked at the top of this page.
Where it sits
Location as DWR records it (5.0).
Seasonal runoff outlook
NRCS calls it even odds that this gage carries at least 48 thousand acre-feetA volume: one acre covered a foot deep, about 326,000 gallons -- roughly a suburban household's outdoor use for a year. over 06-01 to 09-30 — 61% of a normal season; almost certainly at least 38, probably not more than 62. Issued 2026-06-01 — the season’s final; new forecasts begin in January.
| 90% chance of at least | 70% chance of at least | 50% chance of at least | 30% chance of at least | 10% chance of at least | Normal |
|---|---|---|---|---|---|
| 38 kAF | 43 kAF | 48 kAF | 53 kAF | 62 kAF | 79 kAF |
The row is one season as a range of odds (exceedanceA forecast stated as odds of AT LEAST this much: the 90% exceedance value is a near-floor the river beats nine years in ten, the 10% value a near-ceiling it reaches one year in ten, and 50% is even odds -- as likely to come in above as below. values): the left end is a near-floor the river beats nine years in ten, the right a near-ceiling. How to read these numbers → Forecast by the NRCS National Water and Climate Center; shown beside the gage’s own record, which is what it is verified against on the report card.
Provenance
DWR station abbreviation BTCANYCO; recorded station name “BIG THOMPSON RIVER AT MOUTH OF CANYON NEAR DRAKE”; operated by NWBOR. Daily flows from the DWR HydroBase snapshot plus CDSS REST updates, refreshed on the weekly cycle. Trend statistics are Mann-Kendall (Hamed-Rao corrected) with Sen's slope in native cfs, the same numbers as the basin Trends tab.