Aspinall Unit Spring 2016 forecast #ColoradoRiver

Aspinall Unit
Aspinall Unit

From email from Reclamation (Erik Knight):

The February 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 640,000 acre-feet. This is 95% of the 30 year average. Snowpack in the Upper Gunnison Basin is currently 110% of average. Blue Mesa Reservoir current content is 582,000 acre-feet which is 70% of full. Current elevation is 7490.1 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 640,000 acre-feet of runoff volume, the peak flow target will be equal to 5,102 cfs for a duration of 24 hours. The shoulder flow target will be 515 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 640,000 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 7517.5 feet with an approximate peak content of 812,000 acre-feet.

Aspinall Unit operations update: Gunnison River through Black Canyon streamflow to increase to 1100 cfs

From email from Reclamation Erik Knight:

Releases from Crystal Dam will be increased from 600 cfs to 1100 cfs on Monday, November 16th. The purpose of this increase is to lower Blue Mesa Reservoir down towards the winter icing target. The current content of Blue Mesa Reservoir is 673,000 acre-feet which is 81% full.

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 the remainder of the year.

Currently, there are no diversions into the Gunnison Tunnel and flows in the Gunnison River through the Black Canyon are 600 cfs. After this release change Gunnison Tunnel diversions will still be at 0 cfs and flows in the Gunnison River through the Black Canyon should be around 1100 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

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

#ColoradoRiver Basin: Aspinall Unit operations update

From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be decreased from 1300 cfs to 600 cfs on Friday, October 30th. This reduction coincides with the shutdown of the Gunnison Tunnel. River flows may fluctuate by up to 200 cfs during the day of the diversion shutdown, but will return to the current level afterwards. The current content of Blue Mesa Reservoir is 676,000 acre-feet which is 81% full.

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 the remainder of the year.

Currently, diversions into the Gunnison Tunnel are around 700 cfs and flows in the Gunnison River through the Black Canyon are 600 cfs. After this release change Gunnison Tunnel diversions will be down to 0 cfs and flows in the Gunnison River through the Black Canyon should still be around 600 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

This scheduled release change is subject to changes in river flows and weather conditions. For questions or concerns regarding these operations contact Erik Knight at (970) 248-0629 or e-mail at eknight@usbr.gov

Aspinall Unit operations update: Current inflow forecast for Blue Mesa = 105% of avg

Black Canyon via the National Park Service
Black Canyon via the National Park Service

From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be decreased from 3000 cfs to 2000 cfs, over the next 3 days. Releases will be decreased by 400 cfs on Wednesday, July 22nd, by 350 cfs on Thursday, July 23rd, and by 250 cfs on Friday, July 24th. This reduction is in response to the declining inflows to Blue Mesa Reservoir which have allowed the reservoir elevation to drop to 2 feet below the maximum water surface elevation. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 710,000 acre-feet which is 105% of average.

Flows in the lower Gunnison River are currently above the baseflow target of 1500 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 1500 cfs for July and 1050 cfs for August.

Currently, diversions into the Gunnison Tunnel are around 1050 cfs and flows in the Gunnison River through the Black Canyon are 2000 cfs. After this release change Gunnison Tunnel diversions will be around 1050 cfs and flows in the Gunnison River through the Black Canyon should be around 1000 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

More Aspinall Unit coverage here.

Aspinall Unit operations update: Releases from Crystal to be lowered to 2000 cfs #ColoradoRiver

Aspinall Unit
Aspinall Unit

From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be decreased from 3700 cfs to 2000 cfs between July 2nd and July 6th. Releases will be decreased by 200 cfs today, and then by 400 cfs each day over the next 3 days, with a final decrease of 300 cfs on the morning of July 6th. This reduction is in response to the continuing decline in runoff to the Aspinall Unit reservoirs. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is now 700,000 acre-feet which is 104% of average.

Flows in the lower Gunnison River are currently above the baseflow target of 1500 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 1500 cfs for July.

Currently, diversions into the Gunnison Tunnel are around 1000 cfs and flows in the Gunnison River through the Black Canyon are 2800 cfs. After this release change Gunnison Tunnel diversions will be around 1000 cfs and flows in the Gunnison River through the Black Canyon should be around 1100 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

More Aspinall Unit coverage here.

UGRWCD: Morrow Dam spilling — beautiful

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

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