Local environmentalists are sharply divided over whether to support a plan to extend a half-cent sales tax for transportation projects.

Many say they worry that the plan to spend the $14 billion in revenue from the tax won't go far enough to ease congestion on the roads, provide better public transportation and smarter growth.

Others say that the tax extension will provide critical money to protect animals and wildlife.

Proposition A will ask voters on Nov. 2 for a 40-year extension of the tax, which is known as TransNet. The current tax, first levied in 1988, will expire in 2008.

"It will be a disservice for the environment if we don't get this funding," said Michael Beck, the San Diego director for the Endangered Habitat League, a southern California group aimed at preserving open space.

Unlike the tax passed nearly 20 years ago, the extension won't build any new highways, Beck said. It will just expand existing ones. That means less pristine habitat will be destroyed, he said.

The new plan sets aside $850 million to be used to safeguard gnatcatchers, protect wetlands and preserve open space -- among other things. If TransNet doesn't pass, Beck said, many of the projects will still be built but the environmental safeguards will be scrapped.

"The risks are unacceptable," Beck said. "Plants and animals will die if we don't get this funding."

With other supporters, he believes the plan needs to go to voters this year. They say the higher turnout from a presidential election will boost the chances of getting the 66 2/3 percent needed to pass the measure.

But many environmentalists have deemed the current TransNet tax a failure, pointing to the area's congested roads. They say there is time to get a new plan to voters in 2006, and that the last two decades are proof that a better plan is needed.

"If you think the last 20 years has been good for the quality of life and the environment, you'd want to support this (extension)," said Carolyn Chase, chairwoman of the political committee for the local chapter of the Sierra Club, which voted to oppose the extension. Not everyone in the club opposed the plan, and one executive board member resigned in protest.

Chase, who is also a San Diego city planning commissioner, said she doesn't think the last 20 years have been good to the region's quality of life or the environment.

Chase is also the spokesman of new group called Taxpayers for Better Transportation Planning, which opposes the extension.

A number of environmental groups are on board with the group, including San Diego Audubon, San Diego Baykeeper, Surfrider Foundation, Center for Biological Diversity and Save Our Forests and Ranchlands.

The TransNet plan is flawed because it doesn't require developers to contribute enough to road improvements, Chase said. There's a $2,000 impact fee for residential units, but commercial and industrial developers won't have to pay such a fee.

Chase also said that the transit system needs to be redesigned so that it appeals to more commuters.

"We should have a plan that works better, and we will," she said.

Duncan McFetridge, the president of Save Our Forests and Ranchlands, worries that TransNet will perpetuate the status quo, overpriced housing, congested roads and poorly planned communities.

There's little consideration given to smart growth, the idea that housing and jobs should be located near transportation corridors, he added.

What's more, he said, public transportation in San Diego offers too few choices and that more money should be directed to it.

"For 30 years, we've been pouring money into freeways," he said. "We've got to reverse the flow."

Regional planners who drafted the TransNet measure have reached out to environmentalists, said Gary Gallegos, executive director of the San Diego Association of Governments. The association is the region's transportation agency and is backing the measure.

In addition to the money for environmental safeguards, $280 million in the plan is set aside for transportation projects that embody "smart growth" principles, putting jobs and homes near transportation corridors, he said.

A number of environmental groups support the measure, including the Buena Vista Audubon Society, Nature Conservancy, Trust for Public Lands and the Endangered Habitats League, Gallegos said. But he acknowledged that there are many environmental groups that aren't on board.

"The difficulty in creating one of these measures is no one's ever happy," he said. "You have all these competing interests. We believe the proposition is balanced."

He cites the creation of a bus rapid-transit system as one such example. The bus system will speed commuters from Sorrento Mesa or San Diego using lanes in the center of the freeway that are also used by car-pools and paying solo drivers.

Gallegos said that the plan won't solve all the region's traffic problems, but it is a critical piece of the equation.

"I don't know that we're ever going to totally solve traffic congestion," Gallegos said.

Contact staff writer Katherine Marks at (760) 740-3529 or kmarks@nctimes.com.