AUGUSTA – State election officials predict a strong turnout when Mainers go to the polls today for an off-year election that features a referendum on whether to repeal or keep on the books the state’s law to bar discrimination against gays.

Both sides say a heavy turnout will benefit them.

Also on the statewide ballot are five state borrowing questions totaling $83 million, and a constitutional amendment on whether to allow special tax treatment of waterfront land to help preserve Maine’s fishing industry.

Voters in many towns and cities across Maine also will elect local officials and decide a range of ballot questions, such as Biddeford and Saco’s proposals on whether each should borrow $10 million for a possible buyout of the Maine Energy Recovery Co. incinerator in Biddeford.

An enticing statewide question and state laws designed to encourage people to vote will combine to draw 45 percent to 50 percent turnout, Maine’s top election official predicted. That’s high for a year in which no major statewide races are on the ballot.

“And I wouldn’t be surprised if it is higher than that,” added Secretary of State Matthew Dunlap. Maine allows Election Day voter registration and requires no special reason for choosing to vote absentee.

Opponents of the proposal at the top of the ballot, which seeks to repeal Maine’s anti-discrimination law, said Monday they would benefit from a heavier turnout on Election Day.

“We’re excited about prospects for a heavy turnout,” said Jesse Connolly of the group Maine Won’t Discriminate. “The more people who turn out, the more people understand what this is really about.”

Connolly said his side, which pushed for a no vote, leaned heavily on personal contacts – encouraging friends to talk to friends and relatives, and door-to-door campaigning – to get its message through.

That approach is also so basic to the opposing side that one of the groups driving the people’s veto question is called the Maine Grassroots Coalition. Paul Madore of Maine Grassroots also said that those who want the gay rights law off the books will benefit from a heavy turnout.

“No question; if it’s a heavy turnout, it’s ours,” said Madore, adding that his side is relying on support from a base of Christian church members and hopes to see results from 150,000 leaflets that have been distributed.

Madore also noted that his side has won in two previous gay rights votes in 1998 and 2000 – the first with a light turnout and second with a heavy turnout.

The last time Maine had an off-year referendum on a similar issue was 1995, when voters rejected a proposal to pre-emptively ban municipal gay rights laws. Turnout in that election was 44 percent, Dunlap said.

The last off-year referendum featured a highly contentious Indian casino question in 2003 and turnout – for an off year – was a record 51 percent.

Tuesday’s ballot also features the five bond issue questions and the constitutional amendment, which prompted quiet campaigns and little if any opposition. A spokesman for the constitutional amendment predicted a turnout of 40 percent, somewhat lower than Dunlap’s figure.

“I hope I’m wrong and will be pleasantly surprised if I am,” said Dennis Bailey of the Campaign to Save Working Waterfront Jobs.

The bonds include $33.1 million for transportation projects, $8.9 million for clean water improvements, $20 million for research and development, $12 million for land conservation, and $9 million for renovations at state university and community college campuses.