Aspinall Unit operations update: Black Canyon peak flow target 5,000+ cfs over 10 days

Sunrise Black Canyon via Bob Berwyn
Sunrise Black Canyon via Bob Berwyn

From email from Reclamation (Erik Knight):

The May 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 525,000 acre-feet. This is 78% of the 30 year average. 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 3,349 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 Average Dry

The peak flow target will be 8,070 cfs and the duration target at this flow will be 10 days.

Pursuant to the Aspinall Unit Operations ROD, releases from the Aspinall Unit will be made in an attempt to match the peak flow of the North Fork of the Gunnison River to maximize the potential of meeting the desired peak at the Whitewater gage, while simultaneously meeting the Black Canyon Water Right peak flow amount. The latest forecast for flows on the North Fork of the Gunnison River shows a peak of around 2,000 cfs occurring this weekend. This peak is followed by a couple days of lower flows and then higher flows are expected to return by the next weekend. If the forecast for flows on the North Fork of the Gunnison River continues to show a rise, the start of the ramp up towards the peak release may begin next week.

It is expected that the ramp up to the peak release will take 8 days. The current projection for spring peak operations shows flows in the Gunnison River through the Black Canyon in the 5,000 to 5,500 cfs range for 10 days in order to achieve the desired peak flow and duration at Whitewater. If actual flows on the North Fork of the Gunnison River are less than currently projected, flows through the Black Canyon could be even higher.

With this runoff forecast and corresponding downstream targets, Blue Mesa Reservoir is currently projected to fill to an elevation of around 7499.0 feet with an approximate peak content of 654,000 acre-feet.

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