WASHINGTON — The Supreme Court ruled against the Navajo Nation on Thursday in a dispute involving water from the drought-stricken Colorado River.

States that draw water from the river — Arizona, Nevada and Colorado — and water districts in California that are also involved in the case had urged the court to decide for them, which the justices did in a 5-4 ruling. Colorado had argued that the court siding with the Navajo Nation would undermine the “Law of the River” — the 1922 Colorado River Compact and subsequent agreements reached in the last 100 years.

Colorado’s brief asserted: “The predictable and effective management of the Colorado River system that the Law of the River provides is critical for Colorado to benefit from and protect its apportionments of Colorado River water.”

Foundational to the “Law of the River,” Colorado’s brief said, is a 1964 Supreme Court decision contained in Arizona v. California. The decision granted the court exclusive jurisdiction that also “finalized water apportionments in the mainstream of the Lower Colorado River Basin to the Lower Basin States and provided the exclusive mechanism for adjusting the distribution of water in accordance with those apportionments going forward.”

The Navajo Nation lawsuit violates settled law and undermine the court’s jurisdiction, the brief added. But, the brief noted, failure to follow settled law would affect Colorado’s Ute Mountain Ute and Southern Ute tribes, which rely on agreements with the state that also rely on the 1922 compact and subsequent agreements.

“Colorado must fulfill the Tribes’ reserved water rights from its apportionments under the compacts,” the brief said.

That was also part of the argument from the Biden administration, which had said that, if the court were to come down in favor of the Navajo Nation, the federal government could face lawsuits from many other tribes.

Colorado Attorney General Phil Weiser was unavailable for comment.

The Native American Rights Fund, based in Boulder, was included in a friend of the court brief supporting the Navajo Nation’s claims. That brief also represented 37 tribal governments, although the Colorado tribes were not among them.

“The U.S. government excluded Navajo tribal citizens from receiving a share of water when the original apportioning occurred and today’s Supreme Court decision for Arizona v. Navajo Nation condoned this lack of accountability,” said Native American Rights Fund Executive Director John Echohawk. “Despite today’s ruling, tribal nations will continue to assert their water rights and NARF remains committed to that fight.”

Lawyers for the Navajo Nation had characterized the tribe’s request as modest, saying they simply were seeking an assessment of the tribe’s water needs and a plan to meet them.

The facts of the case go back to treaties that the tribe and the federal government signed in 1849 and 1868. The second treaty established the reservation as the tribe’s “permanent home” — a promise the Navajo Nation says includes a sufficient supply of water. In 2003, the tribe sued the federal government, arguing it had failed to consider or protect the Navajo Nation’s water rights to the lower portion of the Colorado River.

Writing for a majority made up of conservative justices, Justice Brett Kavanaugh explained that “the Navajos contend that the treaty requires the United States to take affirmative steps to secure water for the Navajos — for example, by assessing the Tribe’s water needs, developing a plan to secure the needed water, and potentially building pipelines, pumps, wells, or other water infrastructure.”

But, Kavanaugh said, “in light of the treaty’s text and history, we conclude that the treaty does not require the United States to take those affirmative steps.”

Kavanaugh acknowledged that water issues are difficult ones.

“Allocating water in the arid regions of the American West is often a zero-sum situation,” he wrote.

It is important, he said, for courts to leave “to Congress and the President the responsibility to enact appropriations laws and to otherwise update federal law as they see fit in light of the competing contemporary needs for water.”

A federal trial court initially dismissed the lawsuit, but an appeals court allowed it to go forward. The Supreme Court’s decision reverses that ruling from the appeals court.

In a dissent, Justice Neil Gorsuch wrote that he would have allowed the case to go forward and he characterized the Navajo’s position as a “simple ask.”

“Where do the Navajo go from here?” he wrote. “To date, their efforts to find out what water rights the United States holds for them have produced an experience familiar to any American who has spent time at the Department of Motor Vehicles. The Navajo have waited patiently for someone, anyone, to help them, only to be told (repeatedly) that they have been standing in the wrong line and must try another.”

Gorsuch said one “silver lining” of the case may be that his colleagues in the majority recognized that the tribe may still be able to “assert the interests they claim in water rights litigation, including by seeking to intervene in cases that affect their claimed interests.”

Gorsuch, a conservative, was joined by the court’s three liberals in Justices Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson.

During arguments in the case in March, Justice Samuel Alito pointed out that the Navajo Nation’s original reservation was hundreds of miles away from the section of the Colorado River it now seeks water from.

Today, the Colorado River flows along what is now the northwestern border of the tribe’s reservation, which extends into New Mexico, Utah and Arizona. Two of the river’s tributaries, the San Juan River and the Little Colorado River, also pass alongside and through the reservation. Still, one-third of the some 175,000 people who live on the reservation, the largest in the country, do not have running water in their homes.

The government argued that it has helped the tribe secure water from the Colorado River’s tributaries and provided money for infrastructure, including pipelines, pumping plants and water treatment facilities. But it said no law or treaty required the government to assess and address the tribe’s general water needs. The states involved in the case argued that the Navajo Nation was attempting to make an end run around a Supreme Court decree that divvied up water in the Colorado River’s Lower Basin.

Colorado Politics reporter Marianne Goodland contributed to this report.