Washington ? The Supreme Court refused Monday to hear North Dakota’s arguments that the Army Corps of Engineers has violated state water pollution laws in managing the Missouri River’s water flows.

An appeals court ruled in August that North Dakota could not use its anti-pollution laws to force the agency to keep more cold water in Lake Sakakawea’s lower depths and help the state’s fishing and recreation industries.

The states of Montana, South Dakota, Nevada and South Carolina had also asked the justices to consider North Dakota’s appeal. The Supreme Court declined Monday to hear the case. No reason was given.

Atty. Gen. Wayne Stenehjem speculated that the court decided against hearing the dispute because similar arguments have not arisen in other appeals courts.

“Sometimes, the Supreme Court declines to hear a case because there are not sufficient circuits that have different rulings on a question, and that could well be the reason that they determined not to take this case, at this time,” Stenehjem said.

The 8th U.S. Circuit Court of Appeals court ruled earlier that North Dakota could not enforce its anti-pollution laws against the corps if doing so would hamper its ability to manage Missouri River navigation.

A federal law called the Clean Water Act shields the corps from lawsuits over its Missouri River management decisions, the appeals ruling said.

A second case, brought by North Dakota and South Dakota, is still awaiting the Supreme Court’s decision on whether it will consider it.

In that dispute, the two states are challenging the same appeals court’s ruling that Missouri River navigation trumps other water interests when the corps makes decisions on managing river flows.

The decision said recreation and other water uses on the Missouri’s upstream reservoirs are of lesser value than maintaining navigation traffic along the river’s shipping channel, which runs from Sioux City, Iowa, to St. Louis.

“That’s a more serious issue for us,” Stenehjem said. “I’m hopeful we’ll be able to get the Supreme Court to take the case and to determine that all of the (water) uses are to be given equal consideration.”

Lake Sakakawea is the largest of the six Missouri River reservoirs in Montana, North Dakota and South Dakota.

All three states have been pushing the corps to store more water in the reservoirs, while downstream states resist the idea. They rely on the water to maintain Missouri River barge shipping and satisfy other needs, including water supplies to some cities.