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throughline No. 166 August 28, 2026

Interior cuts Lower Basin Colorado River water by 1.25 million acre-feet

Interior fixed only the 1.25 million acre-foot total — the Arizona, California and Nevada figures are expressly conditional on a Lower Basin sharing agreement that has not been executed — and wrapped a two-year rule inside a ten-year Decision Framework that sets an operational range rather than deciding the allocation.

Interior fixed only the 1.25 million acre-foot total — the Arizona, California and Nevada figures are expressly conditional on a Lower Basin sharing agreement that has not been executed — and wrapped a two-year rule inside a ten-year Decision Framework that sets an operational range rather than deciding the allocation.

On August 21, 2026 Interior signed the 2027-2028 Colorado River Operating Guidelines and Record of Decision, cutting Lower Basin deliveries by 1.25 million acre-feet a year for two years with no mandatory reduction for the Upper Basin.

Why it matters: 40 million people, 5.5 million acres of farmland, 30 tribes, and hydropower for seven states, with the cut landing first on junior contracts and agricultural districts rather than on municipal taps.

Date to watch: April 2027, when Reclamation determines the water year release volume from Glen Canyon Dam.

Sources:

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