Environmental

Reclamation takes steps to support Lake Powell hydropower generation

The U.S. Department of Interior’s Bureau of Reclamation has announced two drought response actions to help prop up water stored in Lake Powell by nearly 1 million acre-feet (maf) over the next 12 months (from May 2022 through April 2023).

As of May 3, Lake Powell’s water surface elevation was at 3,522 feet, its lowest level since original filling in the 1960s. Lake Powell’s critical elevation, the lowest point at which the associated 1,312 MW hydro powerhouse at Glen Canyon Dam can generate electricity, is 3,490 feet. This elevation introduces new uncertainties for reservoir operations and water deliveries because the facility has never operated under such conditions for an extended period of time.

Given extraordinary circumstances, Reclamation said it is invoking its authority for the first time to change annual operations at Glen Canyon Dam. The measure is intended to protect hydropower generation, the facility’s key infrastructure, and water supply for the city of Page, Ariz., and the LeChee Chapter of the Navajo Nation.

“Today’s decision reflects the truly unprecedented challenges facing the Colorado River Basin and will provide operational certainty for the next year. Everyone who relies on the Colorado River must continue to work together to reduce uses and think of additional proactive measure we can take in the months and years ahead to rebuild our reservoirs,” said Tanya Trujillo, Interior’s assistant secretary of Water and Science.

The two measures that are designed to allow more water to flow into the lake from upstream reservoirs release less water downstream, are:

  • Under a Drought Contingency Plan adopted in 2019, about 500 thousand acre-feet (kaf) of water will come from Flaming Gorge Reservoir, located some 455 river miles upstream of Lake Powell.
  • Another 480 kaf will be left in Lake Powell by reducing Glen Canyon Dam’s annual release volume from 7.48 maf to 7.0 maf, as outlined in the 2007 Interim Guidelines that control operations of Glen Canyon Dam and Hoover Dam.

Together, these two actions equate to a roughly 16-foot elevation increase for the lake.

In addition to the release from Flaming Gorge Reservoir, included in the 2022 Drought Response Operations Agreement (DROA), Reclamation could release water from the Blue Mesa and Navajo reservoirs through a modified plan if those reservoirs meet their water contract obligations and have water available. A determination is expected later this year.

Flaming Gorge Reservoir in Utah and Wyoming currently holds about 3 maf of water and is at 78% of its storage capacity. Under the 2022 DROA, operators are expected to begin sending additional water to Lake Powell in May. In addition to normal monthly releases, about 81 kaf of supplemental water is planned to be released through May. Additional supplemental releases are planned to fulfill the 500 kaf total by the end of April 2023. Flaming Gorge’s contribution of 500 kaf of water is expected to drop the reservoir’s water surface elevation by about 9 feet and could impact some recreational uses.

To reduce the amount of water released from Glen Canyon Dam, Reclamation said it will keep the 350 kaf of water that was held back earlier this year and along with 130 kaf before the end of the water year (Sept. 30, 2022). Reclamation said it would account for this reduction so that it does not penalize either basin by triggering a new series of required releases or shortage determinations.

Water users in the Lower Basin are implementing the shortage provisions in the 2007 Interim Guidelines and 2019 Drought Contingency Plan and are creating additional programs, such as efforts designed to conserve an additional 500 kaf in Lake Mead in 2022 and 2023. Complementary actions are also under consideration with Mexico, pursuant to Minute No. 323 to the 1944 U.S. Mexico Water Treaty.