Although Mr. Harrelson declined to say how much the Mobro's travels have cost him and his partners, a source close to him said the trip had cost almost $1 million.

City and state officials said they were unsure who would pay the $80,000 needed to unload and dump the trash.

Indeed, they disagreed over how much it would cost. Vito A. Turso, a spokesman for the city Department of Sanitation, put the city's costs at $175,000, while state officials said it would involve expenditures of no more than $80,000.

Ever since May 16, when the Break of Dawn, the tugboat that had pulled the Mobro, arrived in New York Harbor, city and state officials have been involved in often contentious negotiations over where to place the garbage.

The Queens Borough President, Claire Shulman, - citing concerns that the trash was toxic and therefore hazardous -went to court to block the city from unloading the barge in Long Island City, Queens. But a State Supreme Court judge declared the trash to be nonhazardous in late May and lifted a restraining order against its unloading.

City officials, however, continued to block the barge from docking until a plan could be approved to remove the trash to a landfill in this South Shore community.

Islip officials, who used the publicity about the barge to win state approval to extend the life of their municipal landfill, said they had not agreed to waive their $40 a ton tipping fee. But since the trash will have been reduced to 400 tons - from 3,100 tons - the tipping fee will be reduced to $16,000, from $124,000. Pleased With Agreement