If you are a regular user of the Black Canyon or Gunny Gorge you may want to send a quick email to Erik Knight at Reclamation and ask to get on his Aspinall Release update email list. His email is eknight at usbr dot gov or phone (970) 248-0629
. He sends an email anytime something changes with a little info about operating parameters, inflow to blue mesa, and target flows on the USGS Gunnison at Whitewater Gage.
His most recent update was this morning:
Releases from Crystal Dam will be decreased from 1300 cfs to 1200 cfs on Wednesday, May 27th at 10:00 AM. This release decrease is in response to a decrease in diversion to the Gunnison Tunnel. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 520,000 acre-feet which is 77% of average. A little primer about how Gunnison flows work:
Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.
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 1050 cfs for May.
Currently, diversions into the Gunnison Tunnel are 950 cfs and flows in the Gunnison River through the Black Canyon are near 400 cfs. After this release change Gunnison Tunnel diversions should be around 850 cfs and flows in the Gunnison River through the Black Canyon should be near 400 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.
- Based on Blue Mesa pool level and projected inflow a monthly baseflow target is set.
- downstream flow is measured at this gage: USGS Current Conditions for USGS 09152500 GUNNISON RIVER NEAR GRAND JUNCTION, CO.
- Basically, Flows in the Black Canyon and Gunny Gorge crank up as the flow at the Whitewater Gage drop below the baseflow target
- More rain and/or snowmelt in the basin = more flow in the North Fork, Uncompaghre, Roubideau, etc and less water in the Gunny Gorge. Dry conditions equals higher gunny flows.
The takeaway, Don't hold your breath for anything more than 400cfs. Even if the June baseflow target increases to 1500cfs, we are still well above that at 4000cfs. There is no need to increase above the current 400cfs to meet the baseflow target.