Arizona Governor Katie Hobbs announced Friday that the state has intervened in Nevada's lawsuit against the Trump administration's Colorado River water allocation plan.

The move comes two months after the Bureau of Reclamation released its operating guidelines in August. Those guidelines require the Lower Basin states of Arizona, California, and Nevada to reduce their Colorado River withdrawals substantially over the next two years, with the possibility of deeper mandatory cuts later.

Under the plan, Arizona faces an annual reduction of 760,000 acre-feet, roughly 27 percent of its full allocation. Nevada would lose about 210,000 acre-feet yearly, and California a smaller share. The three states together committed to conserving more than 3.2 million acre-feet through 2028 under their own Lower Basin Agreement.

Upper Basin states Colorado, Utah, New Mexico, and Wyoming face no mandatory reductions, even though Arizona and Nevada argue the 1922 Colorado River Compact requires them to deliver water to Lake Mead.

Nevada filed suit on August 24, claiming the federal plan unfairly shifts the entire burden to the Lower Basin and fails to enforce upstream delivery obligations. Arizona's intervention seeks to preserve the short-term voluntary conservation deal while challenging elements of the federal environmental review that do not compel Upper Basin deliveries.

“ Arizona has always been willing to do our part to protect the Colorado River, but we will not accept a forced federal plan that solves this crisis on the backs of our families, farmers, and businesses,” Hobbs said in a statement. “We are drawing a line in the sand.”

Arizona Department of Water Resources Director Tom Buschatzke said intervention protects the state's legal rights and keeps open a path for collaboration with California and Nevada.

Nevada Governor Joe Lombardo welcomed the development, calling it an important step against a framework that places Southern Nevada at risk of losing more than 70 percent of its allocation in future years.

The Central Arizona Project, which supplies water to Phoenix, Tucson, and agricultural users, stands to absorb a large portion of the state's reductions. Officials have warned that deeper cuts could threaten communities and farms across the state.

The lawsuit remains pending in federal court. Arizona and Nevada continue to urge the Interior Department to enforce compact obligations across the entire basin.