Aspinall Unit operations update May 18, 2023: Black Canyon peak flow target is equal to 6,400 cfs for a duration of 24 hours #GunnisonRiver #ColoradoRiver #COriver #aridification

Black Canyon July 2020. Photo credit: Cari Bischoff

From email from Reclamation (Erik Knight):

The May 15th forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 830,000 acre-feet. This is 131% of the 30 year average. Blue Mesa Reservoir current content is 468,000 acre-feet which is 57% of full. Current elevation is 7475.3 ft. Maximum content at Blue Mesa Reservoir is 828,000 acre-feet at an elevation of 7519.4 ft. 

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

Black Canyon Water Right 

The peak flow target is equal to 6,400 cfs for a duration of 24 hours.  

The shoulder flow target is 810 cfs, for the period between May 1 and July 25.  

Aspinall Unit Operations ROD 

The year type is currently classified as Average Wet. 

The peak flow target will be 14,300 cfs and the duration target at this flow will be 2 days. 

The half bankfull target will be 8,070 cfs and the duration target at this flow will be 20 days. 

The ramp up for the spring peak operation has been paused as flows on the Gunnison River at Whitewater are already above the spring peak target flow. Flows on the Gunnison River at Delta are close to the flow level that could impact the Delta Wastewater Treatment Plant. Currently Crystal Reservoir is spilling with a total release of 5,300 cfs. Flows in the Gunnison River through the Black Canyon are 4,600 cfs.  

With the projected increase in flows on the North Fork of the Gunnison River, releases at Morrow Pt Dam (which is now controlling the spill at Crystal Dam), will be reduced by a total of 1,400 cfs by tomorrow, May 19th. This should bring flows in the Gunnison River through the Black Canyon down to around 3,200 cfs. This release rate will be maintained through the weekend and may possibly continue well into next week.  

This adjustment to the release plan is based on the latest forecast for river flows in the Gunnison Basin. Adjustments in Aspinall Unit release rates may be made in either direction to achieve downstream target flows or if water gets too high at points along the Gunnison River through Delta.

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