As promised here's the official language update. Not much has changed since mid-April, now we are ramping up over 5 days, holding 31 days at peak (5,000 cfs) followed by a 12-day ramp down. The start date is either May 16th (30% chance) or May 23rd (70% chance). Once our release combines with the Animas River we are still expecting peak flows between 8,000 cfs and 10,000 cfs down near Mexican Hat, it will just depend on what shape the Animas runoff takes.
Let me know if you have questions.
Susan Novak Behery, P.E.
Western Colorado Area Office
BUREAU OF RECLAMATION
NAVAJO UNIT FORECAST FOR SPRING OPERATIONS
May 3, 2016
The May update to the most probable forecast for the April – July modified unregulated inflow volume to Navajo Reservoir is 520,000 acre-feet, an increase of 5,000 acre-feet since the last forecast. This is 71% of the 30 year average. Snowpack above Navajo is currently 76% of average. Navajo reservoir current content is 1,496,000 acre-feet, which is 88% full (80% of active storage). Current reservoir elevation is 6070.1 feet.
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 baseflows of between 500 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 spring peak release consisting of a 5-day ramp up to 5,000 cfs, up to 31 days at 5,000 cfs, followed by a 12-day ramp back down to the base release. The ramp-up date is dependent on weather, and will most likely be either May 16th (30% chance) or May 23 (70% chance). The final date will be decided one week before ramp-up begins.
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 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 firstname.lastname@example.org