A comprehensive plan for cleaning up the Great Lakes is still years from completion, despite the federal government's pledge this year to move more aggressively against toxic pollution in the world's largest fresh-water system.

Cuts in federal research programs during the Reagan administration are one reason for the slow progress on developing a cleanup strategy for the lakes, environmentalists say.The complex nature of the "toxic soup" in the Great Lakes - with more than 350 different chemicals interacting through air, water and contaminated soils - also has made it harder to determine the best ways to tackle toxic pollutants, say scientists and government officials.

"You can't expect to quickly solve a problem that took 30 to 50 years to develop," says Dr. John Hartig, coordinator of remedial action plans for the International Joint Commission, the U.S. and Canadian agency overseeing Great Lakes cleanup efforts.