Responding to concerns about the potential impacts that invasions of aquatic species could have on the Bay, the U.S. Coast Guard instituted a voluntary program more than a year ago to encourage ships to exchange their ballast water before entering the Chesapeake.

The Coast Guard has been handing out pamphlets focusing on ballast water and the Chesapeake, conducted "focus group" meetings with vessel agencies and distributed copies of an informational video and training package.

As a result of their efforts, compliance with the voluntary program has risen from about 25 percent to 30 percent at the beginning of last year, to about 80 percent compliance recently, according to Coast Guard figures.

The inspections do not include any inspection of the tanks to check the salinity of the water -- an indication of whether an exchange took place in the ocean, and how much water was exchanged.

"I don't have any reason to suspect there's a great deal of sandbagging on that questions said Capt. Richard Vlaun, chief of the Marine Safety Division of the 5th Coast Guard District in Portsmouth, Va. "It's not that hard to do if you plan ahead."

"We're trying to do the best we can under the voluntary program," Vlaun added. "Is it good enough? I don't know. The biologists will have to answer that."

Under the National Invasive Species Act of 1996, which was recently introduced in Congress, new record-keeping and sampling techniques would be developed to better measure compliance in the Bay and around the country.