Hydrohistorian
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Oso Diversion near Chromo
Transbasin diversion gage · OSODIVCO · Division 7 · Water District 77 · Archuleta County
Live gage at DWR ↗ · Download daily record (CSV)
Source DWR administrative record · verify at DWR station ↗ Source Our computation, no independent reference · computed here from the screened record
What this gage meters
This is not a natural stream record. The Azotea Tunnel (San Juan-Chama Project) moves water from Navajo, Little Navajo and Rio Blanco headwaters (Div 7) into Rio Grande basin at Chama, New Mexico, operated by USBR — so this record is a ledger of those deliveries. Trends here reflect operational and demand decisions, not the basin's hydrology, and the basin trends page marks it accordingly (⇆). All of Colorado's curated transbasin diversions are collected at /transbasin.
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 Oso Diversion near Chromo, water years 1991 to 2026. The measured record is no trend at -6.55 cubic feet per second per decade. The underlying yearly values are available as a CSV download linked at the top of this page.
This gage measures the Azotea Tunnel (San Juan-Chama Project), water carried across the Continental Divide. It is taken from Navajo, Little Navajo and Rio Blanco headwaters (Div 7) and delivered to Rio Grande basin at Chama, New Mexico — so what this gage reads leaves one river basin for good and arrives in another.
The two ends: Usbr Navajo Diversion (source, on Navajo River); Usbr Little Navajo Divr (source, on Little Navajo River); Usbr Blanco R Diversion (source, on Rio Blanco)
The ditch’s mapped channel is drawn on the map below where the USGS has surveyed it. Every crossing →
Where it sits
Location as DWR records it (5).
Provenance
DWR station abbreviation OSODIVCO; recorded station name “OSO DIVERSION NEAR CHROMO,CO.”; 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.