Aspinall Unit operations update: Releases to turn down 50 CFS on August 17, 2020 #ColoradoRiver #COriver #aridification

Looking downstream from Chasm View, Painted Wall on right. Photo credit: NPS\Lisa Lynch

From email from Reclamation (Erik Knight):

Releases from the Aspinall Unit will be decreased from 1650 cfs to 1600 cfs on Monday, August 17th. Releases are being adjusted to bring flows closer to the baseflow target in the lower Gunnison River. The actual April-July runoff volume for Blue Mesa Reservoir came in at 57% of average.

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 650 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 600 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

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