The lawsuit comes after the U.S. Department of Interior signed off on a $17.5 million water treatment plan last month for the Northwest Area Water Supply project. The project first was authorized by Congress more than two decades ago but is still a long way from completion.
It would use pipes to redirect about 15,000 acre feet of water annually - the equivalent of 15,000 football fields covered with 1 foot of water - from Lake Sakakawea, a reservoir created by a dam on the Missouri River.
The pipeline would carry the water about 45 miles northwest where it would be distributed as tap water to an estimated 81,000 North Dakotans, according to the federal Bureau of Reclamation. In the process, the water would leave the Missouri River basin and enter the Hudson Bay basin.
The Canadian province of Manitoba sued in federal court in Washington, D.C., in 2002 citing fears that the water diversion project would transfer harmful materials such as bacteria into its waters. A federal judge in 2005 ordered the Bureau of Reclamation to do an environmental assessment. That led to the development of the water treatment plan approved in January by the federal agency.
The lawsuit by Missouri Attorney General Chris Koster contends the environmental assessment never considered alternatives to the water diversion project, nor how it would affect people in downstream states. It asserts that the Missouri River supplies water for about half of Missouri's 5.9 million residents while also supporting the state's shipping and agricultural industries.
The Missouri lawsuit was filed in U.S. District Court in Washington, D.C., against both the Bureau of Reclamation and the U.S. Army Corps of Engineers, which manages the Missouri River's dams and navigation system.
"Under the Corps plan, Missouri stands to lose water at a time of year when it's direly needed for a multitude of uses, including navigation and drinking water supplies," Koster said.
Officials for the federal government and North Dakota denied downstream states would be harmed by the diversion of Missouri River water.
"We believe the Northwest Area Water Supply project is a sound, well-designed and necessary project, and we are disappointed by the news of the lawsuit," said Mike Odle, a Helena, Mont.-based regional spokesman for the Bureau of Reclamation.
A spokesman for North Dakota Gov. John Hoeven called Missouri's lawsuit "unfortunate."
"This is an important project for northwestern North Dakota, and we've worked very hard to do it right," said Hoeven spokesman Don Canton. "We've complied with all environmental reviews, and we'll work in order to answer all their concerns. But according to our engineers, the amount of water diverted by NAWS is not even measurable downstream. This is a negligible amount of water."