Main MenuAspinall Unit and Gunnison Tunnel Operations
September 23, 2020 Report from Erik Knight – USBR, Grand Junction, CO
Releases from the Aspinall Unit will be decreased from 1450 cfs to 1350 cfs on Wednesday, September 23rd. Releases are being lowered while the Crystal powerplant is offline for maintenance. The actual April-July runoff volume for Blue Mesa Reservoir came in at 57% of average.
Flows in the lower Gunnison River are currently above the baseflow target of 890 cfs. River flows are expected to stay at levels above the baseflow target after the release change has arrived at the Whitewater gage.
Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 890 cfs for September.
Currently, Gunnison Tunnel diversions are 950 cfs and flows in the Gunnison River through the Black Canyon are around 550 cfs. After this release change Gunnison Tunnel diversions will still be around 950 cfs and flows in the Gunnison River through the Black Canyon will be around 450 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.
This scheduled release change is subject to changes in river flows and weather conditions. For questions or concerns regarding these operations contact:
For questions or concerns regarding these operations contact:
Erik Knight at (970) 248-0629, e-mail [email protected]
Ryan Christianson at (970) 248-0652, email [email protected]
April – July unregulated inflow volume to Blue Mesa Reservoir
387,000 AF (57% of average)
Blue Mesa Reservoir current conditions
Content = 487,000 AF (59% full)
Elevation = 7477 ft
Inflow = 350 cfs
Crystal Release = 1450 cfs
Gunnison Tunnel diversion = 1050 cfs
Gunnison River flow = 450 cfs
Spring Operations Summary
Aspinall Unit Operations ROD
Hydrologic Category = Moderately Dry
Peak Flow = 4510 cfs
Duration at Peak Flow = 1 day
Baseflow Target: September = 890 cfs
(Point of measurement is the Gunnison River near Grand Junction streamgage, commonly called the Gunnison River at Whitewater)
Black Canyon Water Right
Peak Flow = 2840 cfs (24 hour duration)
Shoulder Flow Target = 300 cfs (May 1 – July 25)
(Point of measurement is the Gunnison River below Gunnison Tunnel streamgage at the upstream boundary of Black Canyon of the Gunnison National Park)
Projected Operations
Gunnison River flows (Black Canyon/Gunnison Gorge)
Currently around 450 cfs, expected to remain at 450 cfs for September/October
Blue Mesa Reservoir maximum fill = 604,000 AF at 7492.9 ft elevation
Projected Blue Mesa Reservoir conditions on Dec 31 = 402,000 AF at 7465 ft elevation
Useful information from previous operational updates:
Downstream Flow Targets
Downstream flow targets are finalized based on the May runoff forecast for unregulated inflow to Blue Mesa Reservoir
Aspinall Unit Operations ROD
Hydrologic Category = Moderately Dry
Peak Flow Target = 3200 cfs
Duration at Peak Flow Target = 1 day
Baseflow Target: May = 890 cfs | June/July/Aug = 1050 cfs
(Point of measurement is the Gunnison River near Grand Junction streamgage, commonly called the Gunnison River at Whitewater)
Black Canyon Water Right
Peak Flow Target = 2200 cfs (24 hour duration)
Shoulder Flow Target = 300 cfs (May 1 – July 25)
(Point of measurement is the Gunnison River below Gunnison Tunnel streamgage at the upstream boundary of Black Canyon of the Gunnison National Park)
Blue Mesa Dam (looking east, upstream)