BISMARCK (AP) — Attorneys for North Dakota and the federal government are asking an appeals court to reject the state of Missouri’s challenge to a massive upstream Missouri River water project.

The $244 million Northwest Area Water Supply project aims to bring Missouri River water to as many as 82,000 people in northwestern North Dakota, giving them a reliable source of quality water. The state of Missouri worries that the project it describes as “monumental in scope” will diminish its own water supplies as well as harm its farming and shipping industries — and possibly even alter its state borders.

U.S. Department of Justice attorney Anna Katselas and Special Assistant North Dakota Attorney General Nessa Horewitch Coppinger argue in court documents filed this month that Missouri doesn’t have a legal case and is exaggerating its claims.

The larger issue is a technical matter of whether Missouri has legal standing to sue the federal government on behalf of its residents. But the underlying dispute centers around how much water NAWS will actually use.

Missouri maintains it will deplete the river by 3.5 billion gallons each year, an amount Solicitor General John Sauer says would cause “manifold injuries to Missouri’s sovereign and proprietary interests.”

Those include drinking water for 3 million people, the fertility of over 1 million acres of farmland, a multimillion-dollar shipping industry, state wildlife habitat and recreational facilities, and even the state’s water borders with Kansas and Illinois, he said.

Horewitch Coppinger countered that Missouri doesn’t own the river and said the state “wildly overstates the size and potential impacts of the project” to a river system that has the capacity for more than 23 trillion gallons of water.

“If the reservoir system capacity were scaled down to one gallon of water, the annual NAWS withdrawal would represent less than three drops,” she said.

Congress first authorized the NAWS project in 1986. It ran into a big snag in 2002 when the Canadian province of Manitoba sued over concerns about the possible transfer of harmful bacteria or other agents from the Missouri River Basin to the Hudson Bay Basin.

The international dispute was resolved in June when the U.S. Bureau of Reclamation and the Manitoba government reached an agreement giving Canada a say in water treatment and monitoring.

Missouri sued in 2009 over its fears of water depletion. U.S. District Judge Rosemary Collyer in Washington, D.C., has never ruled on the claims because she ruled last year that the state had no authority to sue the federal government over the matter. The state appealed.

Missouri acknowledges that the Supreme Court has decided in many instances that states typically lack standing in such matters but argues there are exceptions in case law under which its claim fits. Katselas, the Justice Department attorney, disputes that.

There’s no guarantee that NAWS will ever be fully built. A combined $129 million in federal, state and local money has been spent so far on more than 225 miles of pipeline and other infrastructure, and the system currently serves about 25,000 people. But future state and federal funding is not guaranteed.