Environmentalism is a popular cause in New Jersey, and no aspect of it has broader support than preserving open space. With the wisdom gained from their intimate experience of overdevelopment, the state's residents have again and again been willing to vote for taxes and borrowing to save what little unspoiled land they have left.

But now a few of the state's oddly under-occupied environmental lobbyists are seeing if they can fix something that's not broken. They are opposing the latest bid to seek voter approval of a bond issue for preserving open space, farmland, and historic sites. Tellingly, they are at odds with much of their own movement.

The dissenters' impractical and ill-timed argument is essentially that their cause is too righteous to rely on borrowed funds and the will of the people. They demand a "dedicated" funding source - that is, a new tax.

One opponent of the $600 million bond measure, David Pringle of the New Jersey Environmental Federation, said he fears it will be defeated at the polls in November. He pointed out that the economic downturn makes this a bad time to ask the voters to borrow money.

That may be true, but it makes for an even worse time to call for more taxes that aren't totally necessary. And if the voters decide the government shouldn't borrow the money, so be it. That's the whole point of asking them, after all.

A rejection would not, as the critics have darkly warned, threaten the end of environmentalism as we know it. There's simply no evidence that voting against open space is habit-forming.

Another opponent of the bond measure, Jeff Tittel of the state Sierra Club, has noted that borrowing costs more than paying outright. Well, yes, as a matter of fundamental economics, one pays more to spread costs over time. But that's no argument against assuming any debt whatsoever.

Although New Jersey has engaged in plenty of stupid borrowing schemes over the years, open-space bonds should not be confused with them. Real-estate purchases are among the most appropriate purposes for government borrowing. Moreover, these bonds - also unlike much of New Jersey's debt - would have the imprimatur of voter approval.

History suggests the voters will approve them. On the local level, Garden State residents are generally willing to raise their already burdensome property taxes to buy open space. On the state level, they have voted for 12 out of 12 bond issues for land preservation since 1961.

They even backed $200 million for open space in 2007, when they were in a rotten enough mood to reject other ballot questions - one of which was for the generally popular cause of stem-cell research.

If the Legislature is content to let the voters decide this matter, New Jersey's environmentalists should be, too. Those leading the quixotic quest against this measure should find themselves a real environmental problem to shout about. The state certainly has plenty of them.