Aspinall unit operations update: Blue Mesa inflow forecast = 52% of 30 year average

Blue Mesa Reservoir

From email from Reclamation (Erik Knight):

The May 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 350,000 acre-feet. This is 52% of the 30 year average. Snowpack in the Upper Gunnison Basin peaked at 69% of average. Blue Mesa Reservoir current content is 496,000 acre-feet which is 60% of full. Current elevation is 7478.7 ft. Maximum content at Blue Mesa Reservoir is 829,500 acre-feet at an elevation of 7519.4 ft.

Based on the May 1st forecast, the Black Canyon Water Right and Aspinall Unit ROD peak flow targets are listed below:

Black Canyon Water Right
The peak flow target will be equal to 987 cfs for a duration of 24 hours.
The shoulder flow target will be 300 cfs, for the period between May 1 and July 25.

Aspinall Unit Operations ROD
The year type is currently classified as Dry.
There is no peak flow target in a Dry year category
Baseflow targets will continue to be met throughout the year.

Releases from the Aspinall Unit will be increased by 400 cfs on Monday, May 14th in order to allow the Black Canyon water right to be met. Flows on the North Fork of the Gunnison River are also predicted to be near peak levels at this time. The resulting flow on the lower Gunnison River at the Whitewater gage is estimated to be around 2500 cfs. On Tuesday, May 15th, releases from the Aspinall Unit will be decreased by 400 cfs to return river flow to the pre-peak level.

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 May and 1050 cfs for June.

Currently, diversions into the Gunnison Tunnel are 1000 cfs and flows in the Gunnison River through the Black Canyon are 600 cfs. During the 1 day peak flow Gunnison Tunnel diversions will still be 1000 cfs and flows in the Gunnison River through the Black Canyon will be around 1000 cfs. River flows will return to 600 cfs the day after the peak flow. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

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