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.

Grand Junction: Aspinall Unit operations meeting, April 28 #ColoradoRiver #COriver

Aspinall Unit
Aspinall Unit

From email from Reclamation (Erik Knight):

The next Aspinall Operations meeting will be on Thursday, April 28th at 1PM.

Location is at the Western Colorado Area Office in Grand Junction at 445 West Gunnison Ave #221.

Topics of discussion will include:

  • summary of the snow season
  • discussion of runoff forecasts
  • projected spring operations
  • spring/summer weather outlook
  • #ColoradoRiver: Aspinall Unit operations update #COriver

    Blue Mesa Reservoir
    Blue Mesa Reservoir

    From email from Reclamation (Erik Knight):

    The April 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 515,000 acre-feet. This is 76% of the 30 year average. Snowpack in the Upper Gunnison Basin is currently 87% of average. Blue Mesa Reservoir current content is 558,000 acre-feet which is 67% of full. Current elevation is 7487.0 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 515,000 acre-feet of runoff volume, the peak flow target will be equal to 3,197 cfs for a duration of 24 hours. The shoulder flow target will be 300 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 515,000 acre-feet of runoff volume, the hydrologic year type will be set as Moderately Dry. Under a Moderately Dry year the peak flow target will be 8,029 cfs and the duration target at this flow will be 1 day.

    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 between 5,000 cfs and 5,500 cfs for 1 day 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 7508.5 feet with an approximate peak content of 733,000 acre-feet.

    Fog-filled Black Canyon via the National Park Service
    Fog-filled Black Canyon via the National Park Service

    Aspinall Unit operations update: Gunnison Tunnel deliveries to start March 28

    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 600 cfs to 700 cfs on Monday, March 28th. Irrigation diversions to the Gunnison Tunnel will begin on Monday, March 28th. The latest runoff forecast is now at 79% of average. The current content of Blue Mesa Reservoir is 563,000 acre-feet which is 68% 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 March and April.

    Currently, there are no diversions into the Gunnison Tunnel and flows in the Gunnison River through the Black Canyon are around 600 cfs. After this release change Gunnison Tunnel diversions will be at 200 cfs and flows in the Gunnison River through the Black Canyon should be around 500 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

    Aspinall Unit spring operations forecast

    Aspinall Unit dams
    Aspinall Unit dams

    From email from Reclamation (Erik Knight):

    The March 15th forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 530,000 acre-feet. This is 79% of the 30 year average. Snowpack in the Upper Gunnison Basin is currently 92% of average. Blue Mesa Reservoir current content is 560,000 acre-feet which is 68% of full. Current elevation is 7487.3 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 530,000 acre-feet of runoff volume, the peak flow target will be equal to 3,426 cfs for a duration of 24 hours. The shoulder flow target will be 300 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 530,000 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 7507 feet with an approximate peak content of 720,000 acre-feet.

    #Colorado River — Aspinall Unit operations update: Blue Mesa storage = 67% of capacity

    From email from Reclamation (Erik Knight):

    Releases from Crystal Dam will be decreased from 800 cfs to 600 cfs on Tuesday, March 8th. Dry conditions in February resulted in another reduction in the runoff forecast. The latest runoff forecast is now at 86% of average. The current content of Blue Mesa Reservoir is 557,000 acre-feet which is 67% 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 March.

    Currently, there are no diversions into the Gunnison Tunnel and flows in the Gunnison River through the Black Canyon are around 800 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 600 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

    Aspinall Unit dams
    Aspinall Unit dams

    Aspinall Unit Spring operations update #ColoradoRiver #COriver

    Fog-filled Black Canyon via the National Park Service
    Fog-filled Black Canyon via the National Park Service

    From email from Reclamation (Erik Knight):

    The March 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 580,000 acre-feet. This is 86% of the 30 year average. Snowpack in the Upper Gunnison Basin is currently 94% of average. Blue Mesa Reservoir current content is 557,000 acre-feet which is 67% of full. Current elevation is 7487 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 580,000 acre-feet of runoff volume, the peak flow target will be equal to 4,188 cfs for a duration of 24 hours. The shoulder flow target will be 354 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 580,000 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 7513.0 feet with an approximate peak content of 772,000 acre-feet.