Hydrohistorian
Roberts Tunnel at East Portal near Grant
Transbasin diversion gage · ROBTUNCO · USGS 09050590 · Division 1 · Water District 80 · Park County
Live gage at DWR ↗ · USGS monitoring location ↗ · Download daily record (CSV)
What this gage meters
This is not a natural stream record. The Harold D. Roberts Tunnel moves water from Blue River at Dillon Reservoir (Div 5) into North Fork South Platte River near Grant (Div 1), operated by Denver Water — 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
Where it sits
Location as DWR records it (digitized off map).
Provenance
DWR station abbreviation ROBTUNCO; recorded station name “ROBERTS TUNNEL AT EAST PORTAL NEAR GRANT”; 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.