Ballast Water
Many cities and states must toughen disappointing new rules intended to stop more destructive invasive species from devastating the Great Lakes.
Regulations introduced this summer continue to put the lakes at significant risk from invaders that damage the underwater and shoreline environment and cost billions of dollars to control. The new rules are aimed at stopping invaders from entering the lakes in ballast water ocean-going freighters carry.
Ships carry ballast to remain stable when sailing without cargo. It often contains species ranging from microscopic organisms to small fish.
The few vessels that enter the Great Lakes empty of cargo and with full ballast tanks are fine. They are required to dump their ballast at least 200 miles offshore and replace it with saltwater, which kills invaders. Most ships are weighed down with cargo and don't require ballast but their tanks are never totally empty. A bit of any ballast they held previously is left behind; there's usually enough residue to keep any invaders alive.
A freighter unloads cargo at a Great Lakes port. To replace the weight, ballast is pumped into the tanks, where it mixes with the residual water. The ship travels to a second port where the ballast and invaders it contains are released as the ship takes on new cargo.
That's how many of the 180 foreign species now in the lakes arrived. A new one is found every 28 weeks. Most don't gain a foothold in the lakes, but some that do are wiping out native species, fouling beaches and ruining recreation. Notably, zebra and quagga mussels multiply by the billions and clog intake pipes for municipal drinking-water systems and power plants.
August 21, 2006 7:09 AM | Category: Boats