Aspinall Unit operations update: 1050 CFS through the Gunnison Tunnel #ColoradoRiver #COriver #aridification

From email from Reclamation (Erik Knight):

Releases from the Aspinall Unit will be decreased from 1550 cfs to 1450 cfs on Tuesday, July 21st. Releases are being adjusted to maintain flows near the baseflow target in the lower Gunnison River. The July 15th runoff forecast for Blue Mesa Reservoir predicts 57% of average for April-July inflows.

There is a drought rule in the Aspinall Unit Operations EIS which has changed the baseflow target at the Whitewater gage. The rule states that during Dry or Moderately Dry years, when the content of Blue Mesa Reservoir drops below 600,000 AF the baseflow target is reduced from 1050 cfs to 900 cfs. Therefore, the baseflow target for July and August will now be 900 cfs.

Flows in the lower Gunnison River are currently above the baseflow target of 900 cfs. River flows are expected to stay at levels above the baseflow target after the release decrease has arrived at the Whitewater gage.

Currently, Gunnison Tunnel diversions are 1050 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 1050 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.

Grand opening of the Gunnison Tunnel in Colorado 1909. Photo credit USBR.

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