George Bush lashed out Thursday at Michael Dukakis' environmental record in his Democratic rival's home state, charging that the governor has repeatedly fought efforts to make Boston Harbor cleaner. Dukakis called the Republican nominee a member of the Reagan administration's "environmental wrecking crew."

While the two presidential candidates traded rhetorical salvos over the environment, former contender Jesse Jackson denied reports that aides to Dukakis had told him not to campaign in several states.The Democratic nominee, upon ariving in California Wednesday night, said that he will be meeting with leaders of the Jackson campaign, "who are already becoming a very important part of our campaign in California."

"The Democratic Party has never been so united as it is this year," Dukakis said.

Bush, who took an early morning boat tour of the polluted harbor in Dukakis' hometown, said Dukakis had sought permission from former Environmental Protection Agency administrator William Ruckelshaus to delay a ban on dumping wastes in the harbor. Dukakis' first administration prepared the papers to do so, but it was his successor, Ed King, who actually filed the EPA request.

"Two hundred years ago tea was spilled in the Boston harbor in the name of liberty," the vice president said. "If tea were spilled in the Boston harbor today it would dissolve in the residue of my opponent's neglect and delay."

While campaigning in his opponent's back yard, Bush was greeted by about 70 Dukakis supporters who chanted, "Where was George?" - a refrain questioning Bush's role in the Reagan administration.

A new national poll, meanwhile, shows Bush and Dukakis in a dead heat, but shows a 2-to-1 sentiment that the Democratic vice presidential nominee, Sen. Lloyd Bentsen of Texas, is more qualified than Sen. Dan Quayle of Indiana, the Republican nominee for the No. 2 slot.

Another poll found Dukakis running even against Bush in Massachusetts, two months after the governor led the Republican nominee by 14 percentage points in a similar survey.

In the Boston Herald poll of 400 likely Massachusetts voters conducted Wednesday, Dukakis and Bush were tied at 42 percent each with 15 percent undecided and 1 percent favoring other candidates.

"I can't believe it - in Massachusetts?" a pleased Bush responded when shown the newspaper headline.

Promising swift action on acid rain if elected, Bush also said he would convene a global conference during his first year in office to address the problem of the warming of the atmosphere. He further called for wetlands protection and pledged a policy of "zero tolerance" for polluters.