May 8, 2023 — The federal government’s decision to release additional water from Lake Powell into Lake Mead this year signifies the conclusion of an unofficial accounting method sometimes called “shadow accounting.” The method was previously utilized in the Colorado River watershed’s records, reports Circle of Blue.

To maintain Lake Powell’s water levels and preserve its hydroelectric power capabilities, the Bureau of Reclamation kept an additional 480,000 acre-feet of water in the reservoir during the previous year. This led to Lake Mead’s water levels dropping lower than intended, potentially causing even more severe restrictions in Arizona and Nevada. To avoid this, the Bureau acted as if the water had been transferred to Mead when determining shortage conditions, a water accounting practice referred to as “operational neutrality.”

Thanks to the abnormally high snowpack this winter, the Bureau of Reclamation plans to release an extra 2.5 million acre-feet of water from Lake Powell, exceeding earlier projections. This additional release will effectively put an end to the operational neutrality accounting method, as explained by the Bureau of Reclamation.