Aspinall Unit operations update: Releases increasing to meet Black Canyon Water Right peak flow target of 2,054 cfs

May 8, 2015
Aspinall Unit

Aspinall Unit

From email from Reclamation (Erik Knight):

Significant rainfall in the North Fork of the Gunnison basin has changed things considerably over the last 24 hours. What was predicted to be a 1,500 cfs peak at the Somerset gage turned into a 2,600 cfs peak last night, with over 4,000 cfs in the North Fork at the confluence gage. This resulted in flows reaching 5,800 cfs on the Gunnison River at the Whitewater gage, above the peak flow target of 4,991 cfs.

Currently flows in the Gunnison River through the Black Canyon are 1,050 cfs so release at Crystal Dam will continue to be increased in order to reach the Black Canyon Water Right peak flow target of 2,054 cfs. The peak release for the Black Canyon Water Right will be maintained for 24 hours before releases are ramped down, starting late Saturday night, May 9th. The updated release schedule is shown below:

aspinallunitreleaseschedule0507thru05132015


Aspinall Unit operations update

April 29, 2015
Gunnison Tunnel via the National Park Service

Gunnison Tunnel via the National Park Service

From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be increased from 1150 cfs to 1250 cfs on Wednesday, April 29th at 9:00 AM. This release increase is in response to an increase in diversion to the Gunnison Tunnel. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 450,000 acre-feet which is 67% of average.

Flows in the lower Gunnison River are currently above the baseflow target of 890 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 890 cfs for April and May.

Currently, diversions into the Gunnison Tunnel are 800 cfs and flows in the Gunnison River through the Black Canyon are around 350 cfs. After this release change Gunnison Tunnel diversions will be around 900 cfs and flows in the Gunnison River through the Black Canyon should be around 350 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

More Aspinall Unit coverage here.


Aspinall Unit operations meeting Thursday #ColoradoRiver

April 21, 2015
Aspinall Unit dams

Aspinall Unit dams

From email from Reclamation (Erik Knight):

The next Aspinall Unit Operations meeting will be held this Thursday, April 23rd, at the Western Colorado Area Office in Grand Junction, starting at 1 PM.

The address of the WCAO is 445 West Gunnison Ave, Suite #221

More Aspinall Unit coverage here.


Aspinall Unit operations update: Current forecast for inflow into Blue Mesa = 71% of avg

April 15, 2015

Blue Mesa Reservoir

Blue Mesa Reservoir


From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be increased from 1050 cfs to 1150 cfs on Wednesday, April 15th at 9:00 AM. This release increase is in response to an increase in diversion to the Gunnison Tunnel. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 480,000 acre-feet which is 71% of average.

Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for April.

Currently, diversions into the Gunnison Tunnel are 700 cfs and flows in the Gunnison River through the Black Canyon are around 350 cfs. After this release change Gunnison Tunnel diversions will be around 800 cfs and flows in the Gunnison River through the Black Canyon should be around 350 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.


Aspinall Unit operations update

April 8, 2015

Crystal dam spilling May 2009

Crystal dam spilling May 2009


From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be increased from 600 cfs to 750 cfs on Wednesday, April 8th at 8:00 AM. This release increase is in response to an increase in diversion to the Gunnison Tunnel. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 480,000 acre-feet which is 71% of average.

Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for April.

Currently, diversions into the Gunnison Tunnel are 300 cfs and flows in the Gunnison River through the Black Canyon are around 300 cfs. After this release change Gunnison Tunnel diversions will be around 400 cfs and flows in the Gunnison River through the Black Canyon should be around 350 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

More Aspinall Unit coverage here.


Aspinall Unit update: The Gunnison Tunnel to turn on Tuesday

March 30, 2015
Gunnison Tunnel via the National Park Service

Gunnison Tunnel via the National Park Service

From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be increased from 500 cfs to 600 cfs on Tuesday, March 31st at 9:00 AM. This release increase is in response to the start of diversions into the Gunnison Tunnel. On Tuesday morning, the Gunnison Tunnel will begin diverting 200 cfs. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 590,000 acre-feet which is 87% of average.

Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for March and April.

Currently, diversions into the Gunnison Tunnel are zero and flows in the Gunnison River through the Black Canyon are around 500 cfs. After this release change Gunnison Tunnel diversions will be around 200 cfs and flows in the Gunnison River through the Black Canyon should be around 400 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

More Aspinall Unit coverage here.


Aspinall Unit forecast for spring operations

March 24, 2015
Aspinall Unit

Aspinall Unit

From email from Reclamation (Erik Knight):

The March 15th forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 590,000 acre-feet. This is 87% of the 30 year average. Snowpack in the Gunnison Basin is currently at 78% of average. Blue Mesa Reservoir current content is 551,800 acre-feet which is 67% of full. Current elevation is 7486.2 ft. Maximum content at Blue Mesa Reservoir is 829,500 acre-feet at an elevation of 7519.4 ft.

Black Canyon Water Right
The peak flow and shoulder flow components of the Black Canyon Water Right will be determined by the May 1 forecast of the April – July unregulated inflow volume to Blue Mesa Reservoir. If the May 1 forecast is equal to the current forecast of 590,000 acre-feet of runoff volume, the peak flow target will be equal to 4,340 cfs for a duration of 24 hours. The shoulder flow target will be 381 cfs, for the period between May 1 and July 25. The point of measurement of flows to satisfy the Black Canyon Water Right is the Gunnison River below Gunnison Tunnel streamgage at the upstream boundary of Black Canyon of the Gunnison National Park.

Aspinall Unit Operations ROD
Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the peak flow and duration flow targets in the lower Gunnison River, as measured at the Whitewater gage, will be determined by the forecast of the April – July unregulated inflow volume to Blue Mesa Reservoir and the hydrologic year type. At the time of the spring operation, if the forecast is equal to the current forecast of 590,000 acre-feet of runoff volume, the hydrologic year type will be set as Average Dry. Under an Average Dry year the peak flow target will be 8,070 cfs and the duration target at this flow will be 10 days.

Projected Spring Operations
During spring operations, 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 magnitude of release necessary to meet the desired peak at the Whitewater gage will be dependent on the flow contribution from the North Fork of the Gunnison River and other tributaries downstream from the Aspinall Unit. Current projections for spring peak operations show that flows in the Gunnison River through the Black Canyon could be 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 7508.2 feet with an approximate peak content of 730,000 acre-feet.

Downstream flow targets and the projected spring operations to meet them will change with revisions to the forecast and are highly dependent on tributary flows throughout the Gunnison Basin.

More Aspinall Unite coverage here.


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