The Manitoba government is appealing a U.S. court ruling that could lead to a controversial water-diversion project going ahead.

Sustainable Development Minister Rochelle Squires says the Northwest Area Water Supply project could bring harmful or invasive plants and animals into Manitoba waters.

Squires says the biggest concern is whirling disease, which can be fatal to many fish species.

The $244-million project would transfer water from the Missouri River to northwestern North Dakota, where rivers flow into Manitoba.

Manitoba and Missouri have fought the project for more than a decade, but a U.S. federal judge ruled in August the project follows U.S. environmental laws.

A court date has not been set for Manitoba's appeal.