Manitoba has joined nine U.S. states in suing the Bush administration over U.S. federal rules on water dumped from ships.

The states fear that a ruling could allow the transfer of polluted or contaminated water by ship from one body of water to another, where it would do harm.

For example, they say salt water from the ocean could be dumped in the Great Lakes.

The states suing the U.S. Environmental Protection Agency are New York, Connecticut, Delaware, Illinois, Maine, Michigan, Minnesota, Missouri and Washington.

Manitoba has joined because of concerns that a $28-million US Devils Lake outlet in North Dakota sends water into the Sheyenne River, which drains into the Red River. That, in turn, empties into Lake Winnipeg, raising concerns about the transfer of harmful material.

But officials in North Dakota say the Canadian fears are unfounded.

At issue is regulation of water discharges from ballast and other sources on vessels large and small.

State officials said that if the federal action is allowed to stand, ships and boats could carry sediment-laden water into clear drinking water reservoirs.

As well, water containing chemicals could foul sources for farm irrigation and warm water could be pumped into cold-water habitats, threatening trout.

The states' action also targets invasive species contained in ballast that could destroy lakes and rivers.