Extended record — reconstructed, not measured

This gage's own record starts in 1965. A retired gage nearby, ARKANSAS RIVER NEAR PUEBLO, CO., ran earlier and overlapped it, so its measurements can be translated onto this gage's scale to extend the picture back roughly 71.0 years. The result before 1965 is a reconstruction. It is not what this gage measured, because this gage did not exist.

Donor gage	ARKANSAS RIVER NEAR PUEBLO, CO., 4.2 km away
Overlap used to fit	3,652 days, 1965-10-01 to 1975-09-30
Agreement (held out)	r² 0.974
Typical error (held out)	8.1%, bias -4.2%
Grade	strong

How this was built, and what it cannot tell you

• The two gages had to overlap. Without shared days there is nothing to measure the relationship against, and no extension is offered at all — that rule rejected the overwhelming majority of candidate pairs.
• The relationship is fitted in log space, because the ratio between two gages changes with flow. On Clear Creek the downstream gage reads 95% of the upstream one at low flow but 88% at high flow, because ditches in between take more when there is more to take. A single scale factor would get both ends wrong.
• It is scored out of sample: fitted on half the overlap, tested on the other half. The numbers above are from the half it never saw.
• Reconstruction never replaces a real observation. Every day in the series is labelled measured or reconstructed, and the overlap itself stays measured.
• The trends published on this site still use the measured record only. This extension is offered for reading the longer shape, not as an input to the statistics.
• DWR's published record is the authority. A reconstruction is an estimate of what this location would have read, not a measurement of it.

What the longer record says

Record used	Years	Trend	p	Change / decade
Measured only (what the site publishes)	61 1966–2026	decreasing	0.01603	-42.233 cfs
ARKPUNCO alone (measured, no reconstruction)	81 1895–1975	no trend	0.05692	-22.343 cfs
Extended (with reconstruction)	132 1895–2026	decreasing	0.00484	-14.962 cfs

Both records reach the same conclusion, over 71 more years.

Extending changes the conclusion for roughly half the gages that have a reconstruction — which is why both rows are here and neither replaces the other. Every trend published elsewhere on this site uses the measured record only.

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.

The water itself

USGS keeps a sensor here. Latest readings, with the last 30 days of daily means beside each. Provisional: not yet reviewed by USGS, and revised when it is.

Fetched 2026-10-13 18:22 UTC from USGS NWIS (site 07099400). The USGS page has the full sensor record; every Colorado sensor site is listed on one page.

Seasonal runoff outlook

NRCS calls it even odds that this gage carries at least 118 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 — 42% of a normal season; almost certainly at least 60, probably not more than 176. 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
60 kAF	94 kAF	118 kAF	142 kAF	176 kAF	280 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.

Record-adjusted April benchmark: re-anchoring NRCS’s April number (170 kAF) on this river’s own history moves it to 87 kAF; the river delivered 48. Computed by this site, shown only where it beats NRCS in replay (33% → 27% typical miss over 71 seasons). Method →

Provenance

DWR station abbreviation ARKPUECO; recorded station name “ARKANSAS RIVER ABOVE PUEBLO”; operated by DWR. 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.