Half steps not good enough for lakes
Half steps not good enough for lakes
January 28, 2008
Swishing out ballast tanks with salt water is a helpful measure in the fight against foreign species invading the Great Lakes. But it won't deter every menace, and Michigan must keep pressing for more extensive solutions.
The St. Lawrence Seaway Development Corp. announced this month that no ship can enter without a saltwater rinse of its tanks at least 200 miles out into the ocean. The rule is aimed at ships that enter without ballast water but often have puddles of sludge from previous trips lodged in the nooks of the otherwise "empty" tanks. That sludge can contain a potent load of troublesome eggs, larvae and plants just waiting to be revived in freshwater.
A University of Michigan study has shown that saltwater rinses can cut back appreciably on the number of organisms that survive. Ships that contain ballast water already must follow a protocol for exchanging their ballast water at sea before they reach the seaway.
The salt water cuts down considerably on the number of freshwater organisms that survive the trip, and it is freshwater species that pose the danger here. Zebra mussels, initially released here, have now spread as far as California.
As welcome as the Seaway's new rule is, it also poses a danger that Congress will take it as an excuse to slack off on ordering complete water treatment. Shippers may use it to evade the threat of a lawsuit from the National Wildlife Federation, which continues in discussions on the subject.
Another recent study shows some hull-clinging organisms may survive an oceanic voyage, suggesting even ballast water treatment may not suffice. But that is surely a lesser problem. In the fight to get ships to stop dumping foreign species here, Congress has to get beyond every half-measure and distraction.
