New Jersey environmental advocates are fighting bitterly over a surprising issue: whether the state should borrow $600 million to preserve open space, farmland, and historic sites over the next three years.

An alliance of more than 100 groups, the Keep It Green Coalition, wants voters to decide, and believes residents would approve selling bonds to raise the money, even in a depressed economy.

A bill in the Legislature must be approved in the next few weeks for the question to appear on November ballots. This month, several lawmakers from both parties signed on as cosponsors. The bills have been approved by the environment committees in both houses and await discussion in budget committees.

But a handful of environmental groups vehemently oppose the bill. Instead of borrowing money for a short-term fix, the leaders of those groups say, the state should adopt a permanent source of funding for open space. Among the suggested sources are new or higher fees on sport-utility vehicles or water.

Both sides agree money is needed to preserve open space in the most densely populated state. The Garden State Preservation Trust, which provides the funding, has committed nearly all of the $200 million that state voters approved borrowing in 2007 to replenish it. That bond issue was intended as a one-year stopgap measure until there was more stable funding.

Supporters of the bond referendum proposed for November say that with the trust about to run out of money, potential land-preservation projects could evaporate.

Kelly Mooj, coordinator of the Keep It Green Coalition, said this could be the first time in two decades that the state's coffers for open-space preservation run dry.

"There are lots of needs that will go unmet because there's no new money for new projects," she said.

Tom Gilbert of the Trust for Public Land said negotiations with owners to preserve land could take months or years, making uninterrupted funding doubly important.

"Without any predictability that there's funding beyond what's just been allocated, that whole process shuts down," he said.

Supporters also argue that with real estate prices and interest rates low, now is a good time to buy.

Among the loudest critics of the proposed referendum is Jeff Tittel, director of the state chapter of the Sierra Club. He pointed out that many of the groups in the Keep It Green Coalition worked in land preservation, meaning they may benefit directly from approval of a ballot question.

Among Tittel's arguments is that bonds are an expensive way to pay for open space. The $600 million issue would cost the state $170 million a year in debt service, he said. He argued much of that money would come out of the Department of Environmental Protection's budget, which has already been cut significantly during the last several administrations.

According to state Treasury spokesman Tom Bell, the state will spend $59 million in debt service for open space this fiscal year. The Treasury cannot predict what the increase would be as a result of the referendum because the bonds would not be sold until they were needed, Bell said.

Given the deep cuts in the state budget because of the recession, Tittel added, "it makes no sense to spend so much on open space when we don't even know how we're going to pay for it."

The Sierra Club reluctantly supported the $200 million bond referendum in 2007 only after efforts to find permanent funding failed, he said.

The New Jersey Environmental Federation also opposes the bond measure. Campaign director David Pringle said one concern was the damage that could be done to long-term efforts to preserve open space if the ballot question failed, which he called a real possibility in this economy.

An April poll commissioned by some members of the Keep It Green Coalition found strong support for the open-space bonds among likely voters.

Pringle also noted the state hadn't sold the bonds from the 2007 effort, which means there is time to work for a longer-term funding source.

Keep It Green Coalition members said that they, too, preferred a permanent source, but that with no such option on the table, bonds would provide the money to continue preserving land, they say.

Since 1961, New Jersey voters have approved 12 consecutive statewide bond measures for open space.

In 1998, they approved dedicating $98 million each year from the sales tax to open space. Today, that money is used to pay down debt service.

But with the arrival of the recession and the Assembly up for reelection in November, lawmakers are wary of setting a new tax or raising an existing one, even for a cause popular with voters.

Sen. Robert Smith (D., Middlesex), chairman of the Senate Environment Committee, has said he favors a stable, permanent funding source. But he said that was not an option in the current economic and political climate.

By supporting a ballot question, though, lawmakers can say they support the environment and the voters' right to decide - without being held directly responsible for the costs.

Conspicuously absent in the debate has been Gov. Corzine, who has said he supports a ballot measure for open space but has not committed to a dollar amount.

Contact staff writer Adrienne Lu at 609-989-8990 or alu@phillynews.com.