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Discussion Starter #1
I'll do my best to update you monthly or so with the most recent forecast for the spring peak release. It will likely change with evolving snowpack. Call if you have questions.

Susan
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Susan Novak Behery, P.E.
Hydraulic Engineer
Reclamation
Western Colorado Area Office
Durango, CO
[email protected]
970-385-6560



BUREAU OF RECLAMATION

NAVAJO UNIT FORECAST FOR SPRING OPERATIONS

February 10, 2016


The February most probable forecast for the April – July modified unregulated inflow volume to Navajo Reservoir is 735,000 acre-feet. This is 100% of the 30 year average. Snow pack above Navajo is currently 114% of average. Navajo reservoir current content is 1,396,000 acre-feet, which is 82% full (71% of active storage). Current reservoir elevation is 6063.7 ft.

As per the 2016 Interim Operations at Navajo Reservoir, releases will be made to target the San Juan River Basin Recovery Implementation Program's (SJRIP) recommended base flows of between 500 cubic feet per second (cfs) and 1,000 cfs through the critical habitat area. The target base flow is calculated as the weekly average of gaged flows throughout the critical habitat area. The reservoir will be operated to target an end of year storage level between 6050 feet and 6063 feet. Water over this target will be made available for a spring peak release.

The most probable forecast results in a Type 4 spring peak release. This release would most likely begin in late April with a long 4-week long ramp up to 5,000 cfs, 3 weeks at 5,000 cfs, followed by a 2-week ramp back down to the base release. The shape and timing of the hydrograph may change and will be coordinated with the SJRIP to balance recovery program benefits with potential flood control and operational safety. During spring operations, releases from the Navajo Unit will be made in an attempt to match the peak flow of the Animas River to maximize the peak at the San Juan at Four Corners gage while remaining below the US Army Corps of Engineers safe channel capacity of 5,000 cfs between Navajo and the confluence with the Animas in Farmington, and 12,000 cfs downstream of Farmington.

Projected spring operations will be updated with revisions to the forecast and are highly dependent on tributary flows throughout the San Juan River Basin.

If you have any questions, please contact Susan Behery at 970-385-6560 or [email protected].
 

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Thanks. What an interesting year for the SW, including SW Colorado. Our snowpack in Utah was decimated this month and it seems to be the trend throughout our region. Fingers crossed the "El Nino" kicks in again and we get a spike in spring snowpack.

We launch in 10 days which is a little early for this forecast but who cares. I get to soak up the desert scenery after 4 months in a windowless, concrete office at 10,000 feet. Woohoo!

Phillip
 

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Discussion Starter #5
Here's the update for March. The spring peak release is currently forecast to be approximately the same volume, but it has been reshaped with a very short (3-day) ramp up, thus maximizing the total number of 5,000 cfs days. The goal is to maximize the peak downstream, so during the peak we are hoping to reach at least 10,000 cfs in the rafting reach for several days. Most likely we will start in early May (timing will depend entirely on Animas runoff timing). The total number of days at peak may change as new forecasts come in. Call or email if you have questions or concerns.

Susan Novak Behery, P.E.
Hydraulic Engineer
Reclamation
Western Colorado Area Office
Durango, CO
[email protected]
970-385-6560

----------------------------

BUREAU OF RECLAMATION

NAVAJO UNIT FORECAST FOR SPRING OPERATIONS

March 7, 2016

The February most probable forecast for the April – July modified unregulated inflow volume to Navajo Reservoir is 650,000 acre-feet. This is 88% of the 30 year average. Snowpack above Navajo is currently 93% of average. Navajo reservoir current content is 1,408,000 acre-feet, which is 83% full (72% of active storage). Current reservoir elevation is 6064.7 feet (ft).

As per the 2016 Interim Operations at Navajo Reservoir, releases will be made to target the San Juan River Basin Recovery Implementation Program's (SJRIP) recommended base flows of between 500 cubic-feet per second (cfs) and 1,000 cfs through the critical habitat area. The target base flow is calculated as the weekly average of gaged flows throughout the critical habitat area. The reservoir will be operated to target an end of year storage level between 6050 ft and 6063 ft. Water over this target will be made available for a spring peak release.

The most probable forecast results in a 40-day spring peak release. This release would most likely begin in early May with a short 3-day ramp up to 5,000 cfs, 40 days at 5,000 cfs, followed by a 2-week ramp back down to the base release. The shape and timing of the hydrograph may change and will be coordinated with the SJRIP to balance recovery program benefits with potential flood control and operational safety. During spring operations, releases from the Navajo Unit will be made in an attempt to match the peak flow of the Animas River to maximize the peak at the San Juan at Four Corners gage while remaining below the US Army Corps of Engineers safe channel capacity of 5,000 cfs between Navajo and the confluence with the Animas in Farmington, and 12,000 cfs downstream of Farmington.

Projected spring operations will be updated with revisions to the forecast and are highly dependent on tributary flows throughout the San Juan River Basin. If you have any questions, please contact Susan Behery at 970-385-6560 or [email protected].
 

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Discussion Starter #6
And obviously I left a typo in there, it's based on the MARCH forecast, not the February forecast.

Thanks-
Susan
 

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Discussion Starter #7
An update to the spring peak release forecast-

Based on the most recent forecast, the release has been decreased to a total of 36 days at peak. My guess is the April 1st forecast will also decrease because we haven't been getting any of that snow that's going on up north. We'll see what April and May bring, hopefully more precipitation!

Susan Novak Behery, P.E.
Hydraulic Engineer
Reclamation
Western Colorado Area Office
Durango, CO
[email protected]
970-385-6560
--------------------------------------------

BUREAU OF RECLAMATION

NAVAJO UNIT FORECAST FOR SPRING OPERATIONS

March 17, 2016


The Mid-March update to the most probable forecast for the April – July modified unregulated inflow volume to Navajo Reservoir is 570,000 acre-feet (af), a decrease of 80,000 af since the last forecast. This is 77% of the 30 year average. Snowpack above Navajo is currently 88% of average. Navajo reservoir current content is 1,420,000 acre-feet, which is 84% full (75% of active storage). Current reservoir elevation is 6065.8 ft. A dry March has contributed to the falling forecast.

As per the 2016 Interim Operations at Navajo Reservoir, releases will be made to target the San Juan River Basin Recovery Implementation Program's (SJRIP) recommended base flows of between 500 cubic feet per second (cfs) and 1,000 cfs through the critical habitat area. The target base flow is calculated as the weekly average of gaged flows throughout the critical habitat area. The reservoir will be operated to target an end of year storage level between 6050 ft and 6063 ft. Water over this target will be made available for a spring peak release.

The most probable forecast results in spring peak release beginning in early May with a short 3-day ramp up to 5,000 cfs, 36 days at 5,000 cfs, followed by a 2-week ramp back down to the base release. The shape and timing of the hydrograph may change and will be coordinated with the SJRIP to balance recovery program benefits with potential flood control and operational safety. During spring operations, releases from the Navajo Unit will be made in an attempt to match the peak timing of the Animas River to maximize the peak at the San Juan at Four Corners gage while remaining below the US Army Corps of Engineers safe channel capacity of 5,000 cfs between Navajo and the confluence with the Animas River in Farmington, and 12,000 cfs downstream of Farmington.

Projected spring operations will be updated with revisions to the forecast and are highly dependent on tributary flows throughout the San Juan River Basin. If you have any questions, please contact Susan Behery at 970-385-6560 or [email protected].
 
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