North Dakota's Health Department is allowing a Devils Lake water outlet to divert more sulfates into the Sheyenne River, a prospect that has raised alarm in Minnesota and Canada.

A top Manitoba official called the decision "unfathomable" and said the U.S. federal government should strip North Dakota of its environmental regulatory authority for the project.

North Dakota officials said the changes would not allow the outlet to begin operating soon. Sparse rainfall has left the Sheyenne as a stagnant ditch where the outlet channel meets the river, and water from Devils Lake's west bay is too salty to dump it directly into the riverbed.

"We'd need one, and probably more than one, big rainfall to be able to operate the outlet," said Bruce Engelhardt, a Water Commission engineer. "Right now, we have zero flow in the Sheyenne River."

The Health Department on Thursday issued a revised Devils Lake discharge permit that raises the maximum sulfate amount to 450 milligrams per liter of water over seven days. The limit is now 300 milligrams per liter.

The Sheyenne's sulfate level was recently measured at 790 milligrams per liter, said Dave Glatt, the Health Department's environmental section chief. Water in Devils Lake's west bay usually has about 600 milligrams per liter.

Steve Ashton, minister of Manitoba's Water Stewardship agency, said the province was reviewing its legal options.

"We do not believe North Dakota provided sufficient new evidence to support a relaxing of the environmental standards that governed the Devils Lake outlet," Ashton said.

The Sheyenne is a tributary of the Red River, which forms most of the North Dakota-Minnesota border and flows into Lake Winnipeg, in Manitoba.

Opponents of the revised permit may ask the Health Department to hold an administrative hearing on its decision, and they have the option of appealing any result to state court.

The water's quality will be measured near Bremen, several miles downstream from the spot where the outlet's 14-mile channel empties into the Sheyenne River.

The $28 million channel, which includes a series of pipes, pumps and open ditches, is meant to divert excess water from Devils Lake, which has tripled in size in recent years and flooded thousands of acres of land.

Glatt said the permit change would have a negligible effect on the river system.

"You need to take a look at the water quality in Devils Lake, the water quality in the Sheyenne, and also how the river responds to changes in water quality as the water moves downstream," Glatt said. "We felt that this permit … would be protective of the downstream beneficial (water) uses, and it would not adversely impact the stream itself."

Sulfates occur naturally in the soil and leach into water as it washes through rocks and soil. High sulfate levels can make water taste bitter and act as a laxative on people who drink it. Federal Environmental Protection Agency guidelines set a maximum of 250 milligrams per liter for drinking water.