The United States Bureau of Reclamation (Reclamation) has released its August 24 Month Study, which projects Colorado River operations for the next two years. The study projects the operating conditions of the Colorado River system, as well as runoff and reservoir conditions. The Upper Basin experienced around average snowpack (107%) this year, and the April-July inflow into Lake Powell came in at 52% of average. The below-average projection was due to extremely hot and dry conditions in the Upper Basin during the spring and summer of 2020. Consistent with the 2007 Interim Guidelines, Lake Powell will operate under an annual release of 8.23 million acre-feet in water year 2021 with a potential of an April adjustment up to 9.0 million acre-feet.
The August 24 Month Study projects Lake Mead’s January 1, 2021 elevation to be 1085.28 feet, putting Lake Mead in a Tier Zero condition for 2021. The Study also projects a Tier Zero condition for Lake Mead in 2022 with the projected January 1, 2022 elevation of 1086.90 feet. Tier Zero conditions require a 192,000 acre-foot reduction in Arizona’s 2.8 million acre-foot allocation. The Lower Colorado River Basin is in Tier Zero for 2020. The August 24 month study projects that the Lower Colorado River Basin will remain in the Tier Zero condition in 2021.
“This is more evidence that the Drought Contingency Plan that was approved by the Arizona Legislature and signed by Governor Ducey in early 2019 was a success,” said Tom Buschatzke, Director of the Arizona Department of Water Resources.
“Its implementation offsets potentially deeper cuts in Arizona’s Colorado River allocation beyond the 192,000 acre-feet that the State annually has stored in Lake Mead for several years.”
These reductions will fall entirely on Central Arizona Project (CAP) supplies, impacting CAP supplies for water banking, replenishment and agricultural users. The Tier Zero reductions will not impact tribal or municipal CAP water users.
While the Tier Zero reductions are significant, they are part of broader efforts being implemented to reduce the near-term risks of deeper reductions to Arizona’s Colorado River supplies. In addition to the Tier Zero reductions to CAP supplies, other programs to conserve and store water are being implemented in Arizona.
These include programs with the Colorado River Indian Tribes, Gila River Indian Community, the Arizona Department of Water Resources (ADWR), and the Central Arizona Water Conservation District (CAWCD), as well as Reclamation. Including the 192,000 acre-foot allocation reduction, Arizona entities conserved a total of 385,000 acre-feet in Lake Mead in 2020.
The August 24 Month Study shows that in the near term, the programs being implemented in Arizona and across the Colorado River system, along with favorable hydrology, have helped avoid a near-term crisis in the Colorado River system. However, we continue to face significant near-term and long-term risks to Arizona’s Colorado River supplies. We have much more work to do to address our shared risks. ADWR and CAWCD have jointly convened Arizona water stakeholders to address these risks and to prepare for new negotiations regarding the long-term operating rules on the Colorado River.