Over the next couple of weeks flows through the Black Canyon and Gunnison Gorge could reach 11,000 cfs. This is higher water than what we've seen since the mid-1980s.
Update from the Bureau of Reclamation:
BUREAU OF RECLAMATION
ASPINALL UNIT SPRING OPERATIONS
May 11, 2017
The May 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 850,000 acre-feet. This is 126% of the 30 year average. Snowpack in the Upper Gunnison Basin peaked at 138% of average. Blue Mesa Reservoir current content is 679,000 acre-feet which is 82% of full. Current elevation is 7502.1 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 6,427 cfs for a duration of 24 hours.
The shoulder flow target will be 831 cfs, for the period between May 1 and July 25.
Aspinall Unit Operations ROD
The year type is currently classified as Moderately Wet.
The peak flow target will be 14,350 cfs and the duration target at this flow will be 10 days.
The half bankfull target will be 8,070 cfs and the duration target at this flow will be 40 days.
Projected Operations
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 keeps river flows below their projected peak flow level for the 10 day forecast period. Warmer weather and higher flows are forecast to return by the weekend of May 20th.
Therefore, ramp up for the spring peak operation will begin on Sunday, May 14th, with the intent of timing releases with this potential higher flow period on the North Fork of the Gunnison River. Releases from Crystal Dam will be ramped up according to the guidelines specified in the EIS, with 2 release changes per day, until Crystal begins to spill. The daily release schedule for Crystal Dam is:
Inline image 1 (see attachment)
Crystal Dam will be at full powerplant and bypass release by May 17. Crystal Reservoir will begin spilling by May 18, and the peak release from Crystal Dam should be reached on May 23. The flows in the Gunnison River after that date will be dependent on the timing of the spill and the level of tributary flow contribution. Estimates of those numbers will be determined in the upcoming days.
The current projection for spring peak operations shows flows in the Gunnison River through the Black Canyon between 10,800 cfs and 11,200 cfs for 10 days in order to achieve the target peak flow and duration at Whitewater. Actual flows will be dependent on the downstream contribution of the North Fork of the Gunnison River and other tributaries. Higher tributary flows will lead to lower releases from the Aspinall Unit and vice versa.
Crystal Dam releases and Gunnison River flows after May 23rd will be determined when the mid-May inflow forecast is issued. There is a possibility that the mid-May inflow forecast will result in a change to the Aspinall Unit ROD targets, if the forecast drops into the Average Wet category. Once the official mid-month forecast is released, the ROD targets will be adjusted as necessary, and the releases from Crystal Dam and the flows in the Gunnison River will be determined.
Update from the Bureau of Reclamation:
BUREAU OF RECLAMATION
ASPINALL UNIT SPRING OPERATIONS
May 11, 2017
The May 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 850,000 acre-feet. This is 126% of the 30 year average. Snowpack in the Upper Gunnison Basin peaked at 138% of average. Blue Mesa Reservoir current content is 679,000 acre-feet which is 82% of full. Current elevation is 7502.1 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 6,427 cfs for a duration of 24 hours.
The shoulder flow target will be 831 cfs, for the period between May 1 and July 25.
Aspinall Unit Operations ROD
The year type is currently classified as Moderately Wet.
The peak flow target will be 14,350 cfs and the duration target at this flow will be 10 days.
The half bankfull target will be 8,070 cfs and the duration target at this flow will be 40 days.
Projected Operations
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 keeps river flows below their projected peak flow level for the 10 day forecast period. Warmer weather and higher flows are forecast to return by the weekend of May 20th.
Therefore, ramp up for the spring peak operation will begin on Sunday, May 14th, with the intent of timing releases with this potential higher flow period on the North Fork of the Gunnison River. Releases from Crystal Dam will be ramped up according to the guidelines specified in the EIS, with 2 release changes per day, until Crystal begins to spill. The daily release schedule for Crystal Dam is:
Inline image 1 (see attachment)
Crystal Dam will be at full powerplant and bypass release by May 17. Crystal Reservoir will begin spilling by May 18, and the peak release from Crystal Dam should be reached on May 23. The flows in the Gunnison River after that date will be dependent on the timing of the spill and the level of tributary flow contribution. Estimates of those numbers will be determined in the upcoming days.
The current projection for spring peak operations shows flows in the Gunnison River through the Black Canyon between 10,800 cfs and 11,200 cfs for 10 days in order to achieve the target peak flow and duration at Whitewater. Actual flows will be dependent on the downstream contribution of the North Fork of the Gunnison River and other tributaries. Higher tributary flows will lead to lower releases from the Aspinall Unit and vice versa.
Crystal Dam releases and Gunnison River flows after May 23rd will be determined when the mid-May inflow forecast is issued. There is a possibility that the mid-May inflow forecast will result in a change to the Aspinall Unit ROD targets, if the forecast drops into the Average Wet category. Once the official mid-month forecast is released, the ROD targets will be adjusted as necessary, and the releases from Crystal Dam and the flows in the Gunnison River will be determined.