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.


The Aspinall Unit operations meeting minutes are hot off the presses #ColoradoRiver

February 25, 2015

Aspinall Unit dams

Aspinall Unit dams


Click here to read the minutes from the recent Aspinall Unit Operations meeting.


Aspinall Unit operations update: Releases from Crystal Dam to decrease today

February 5, 2015
Aspinall Unit

Aspinall Unit

From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be decreased from 800 cfs to 600 cfs on Thursday, February 5th at 9:00 AM. This release decrease is in response to the declining runoff forecast for Blue Mesa Reservoir. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 620,000 acre-feet which is 92% 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 February.

Currently, diversions into the Gunnison Tunnel are zero and flows in the Gunnison River through the Black Canyon are around 850 cfs. After this release change Gunnison Tunnel diversions will still be zero and flows in the Gunnison River through the Black Canyon should be around 650 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.


Aspinall Unit operations update

January 23, 2015


From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be decreased from 1100 cfs to 800 cfs on the morning of Monday, January 26th. This release decrease is in response to the declining runoff forecast for Blue Mesa Reservoir. The current forecast for April-July unregulated inflow to Blue Mesa Reservoir is 660,000 acre-feet which is 98% 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 January through March.

Currently, diversions into the Gunnison Tunnel are zero and flows in the Gunnison River through the Black Canyon are around 1150 cfs. After this release change Gunnison Tunnel diversions will still be zero and flows in the Gunnison River through the Black Canyon should be around 850 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

More Aspinall Unit coverage here.


Blue Mesa Reservoir water bank study #ColoradoRiver

December 14, 2014

Aspinall Modeling Memo coverviaarkansasbasinroundtable122014
Click here to read the report.

From The Pueblo Chieftain (Chris Woodka):

Another piece of the Colorado River shortage puzzle has been put in place with the completion of a Blue Mesa Reservoir water bank study. The study was a joint effort by the Arkansas Basin Roundtable, Gunnison Basin Roundtable and Colorado Water Conservation Board. It looked at whether water could be stored in Blue Mesa Reservoir near Gunnison to be released during a drought when Colorado might owe water to downstream states.

“There are benefits to the environment during low-flow periods,” said Mark McCloskey, of CDM-Smith, consultants for the study, as he explained the study to the Arkansas Basin Roundtable this week.

Under the 1922 Colorado River Compact, upper basin states (Colorado, New Mexico, Utah and Wyoming) are required to deliver 75 million acre-feet to Lake Powell under a 10-year rolling average. If that fails to happen, downstream states (Arizona, California and Nevada) could issue a call on the river. Colorado’s share is 51.25 percent of the deficit.

Another 1.5 million acre-feet annually must be delivered to Mexico.

While there has never been a shortfall of deliveries, there are indications from tree-ring studies that decades-long dry spells are possible.

The study used the worst-case scenarios from the Bureau of Reclamation’s Colorado River Basin study — high demand in very dry years — to develop models of optimum timing and levels of storage in a water bank in Blue Mesa. It projected water that would be needed if levels fell to 80-98 percent of minimum levels. The study also determined how much water would be lost to evaporation or to stream banks along the way to Lake Powell.

Replacement water likely would be purchased by Front Range or statewide interests from ranchers, and it’s not known how those purchases would affect high-altitude hay meadows, McCloskey acknowledged.

It’s important to the Front Range, because a call on the Colorado River could mean curtailment of diversions across the Continental Divide.

A curtailment could mean less water for Pueblo, the Fryingpan- Arkansas Project, Colorado Springs, Denver, Aurora and the Colorado-Big Thompson Project.

All of those have water rights that were established after the 1922 compact.

The study showed the optimum time to store water would begin when deliveries fell to 85 million acre-feet in a 10-year period. The optimum amount to keep in storage would be about 300,000 acre-feet. Some benefit was also seen in deficit irrigation below Blue Mesa in dry years to preserve river flows.

The compact was drawn up by the states and approved by Congress because down­stream development was already occurring in Arizona and California. While it was known that drought impacts the basin, most thought the average flows in the 1920s could be used as a yardstick.

The flows at that time actually were higher than they have been in the ensuing decades. Record low flows were recorded during the 2000s.

More Colorado River Basin coverage here.


Aspinall Unit update: 1150 cfs in Black Canyon

December 9, 2014
Fog-filled Black Canyon via the National Park Service

Fog-filled Black Canyon via the National Park Service

From email from Reclamation (Erik Knight):

Releases from Crystal Dam will be increased from 800 cfs to 1100 cfs on Thursday, December 11th at 8:00 AM. This release increase is intended to lower the elevation in Blue Mesa Reservoir to the winter target of 7490 feet by December 31st. 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 September through December.

Currently, diversions into the Gunnison Tunnel are zero and flows in the Gunnison River through the Black Canyon are around 850 cfs. After this release change Gunnison Tunnel diversions will still be zero and flows in the Gunnison River through the Black Canyon should be around 1150 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

More Aspinall Unit coverage here.


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