"Ships entering the Great Lakes should be made to kill all the creatures that hitch a ride in their ballast tanks, environmental groups said on Tuesday, challenging as too lax a proposed government standard to combat invasive species."
"Zebra mussels, spiny water fleas, round gobies and other invaders brought into the lakes in ships' ballast water have damaged the Great Lakes' $7 billion fishery and allowed algae - some that produce toxins that foul the world's largest body of fresh surface water - to flourish.
Researchers at the University of Notre Dame put the annual cost of dealing with invasive species such as clearing mussels from clogged water intakes at $200 million. The mussels and other invaders have filtered out plankton at the base of the food web, hurting lake fish species and allowing more sunlight to fuel algae growth.
Environmental groups said they may go to court for a fourth time since the 1990s to get the U.S. Environmental Protection Agency to tighten its restrictions on ballast discharge."