From email from Reclamation (Susan Novak Behery):
Reclamation’s November 24-Month Study includes a minimum probable (90% chance of being exceeded), a most probable (50% chance of being exceeded) and a maximum probable (10% chance of being exceeded) forecast. While Reclamation operates to the most probable forecast, the range of outcomes in the forecast is tracked on a monthly basis. The latest forecast and projected operations no longer show a shortage to contract deliveries at the Navajo Unit for water year 2022 under the minimum probable forecast. This projection will continue to be updated monthly as the forecast evolves.
Any projected shortage volume is modeled as a proportional distribution to project users (as per PL-87-483 and PL-111-11) and downstream target base flows (pursuant to the Navajo Reservoir’s Record of Decision, 2006).
In anticipation of increasingly severe drought, the Upper Basin states and Reclamation entered into a Drought Response Operations Agreement in 2019. Under this agreement, Reclamation initiated delivery of supplemental water to Lake Powell from the upper CRSP units beginning in July 2021. The delivery from Navajo Reservoir, originally planned for late November through early December, has been postponed and is currently scheduled as a daily release of 1,300 cfs from December 20th to December 30th for a total of 20,000 acre-ft over our regular release. Reclamation will review this release plan after publication of the December 24-Month Study, currently anticipated mid-December.
We will continue to closely monitor conditions and projections as we work with the seven Colorado Basin states on a Drought Response Operations Plan in the coming months.