Navajo Unit Forecast for Spring Operations- April Update

alertIf you are planning a trip to the San Juan River in May be award.
Bulletin: Information related to the San Juan River.

Hi All-

I’m looking at a pretty similar forecast as March right now, a 3-day ramp up starting in mid-May, 33 days at 5,000 cfs, and a 2-week ramp back down. The start date is still up in the air, just waiting to see what the Animas does, but I’m still guessing mid-May is a good bet. I’ll update in a couple weeks…..
Susan

by
Susan Novak Behery, P.E.
Hydraulic Engineer
Reclamation
Western Colorado Area Office
Durango, CO

BUREAU OF RECLAMATION
NAVAJO UNIT FORECAST FOR SPRING OPERATIONS
April 7, 2016

The April update to the most probable forecast for the April – July modified unregulated inflow volume to Navajo Reservoir is 530,000 acre-feet, a decrease of 40,000 af since the last forecast. This is 72% of the 30 year average. Snowpack above Navajo is currently 82% of average. Navajo reservoir current content is 1,445,000 acre-feet, which is 85% full (75% of active storage). Current reservoir elevation is 6067.4 ft. A dry spring 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 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 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 mid-May with a short 3-day ramp up to 5,000 cfs, 33 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 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 sbehery@usbr.gov.