Staring in the faces of a half-million new residents by 2020, Utah County lawmakers say it's time to figure out a way across the lake.

In front of a transportation appropriation subcommittee, Rep. Kenneth Sumsion, R-American Fork, made his case Wednesday for $3 million to cover the cost of an environmental impact study.

A road across the lake ahead of the population boom would save Happy Valley the grief of east-west travel that Salt Lake County struggles with daily. Going across the lake is about 7 miles while going north and around is about 40 miles.

"I realized that if there's some way I could help move that area forward and try and help get ahead of the curve that we've had in Salt Lake County, then I'm here to do that," he said.

Rep. Becky Lockhart, R-Provo, said for years people have speculated about a lake crossing, but it may now actually be time for one.

"I think there are legitimate proposals," she said.

If the environmental impact statement comes back positive, Sumsion said a combination bridge/causeway across the lake would be funded by private money through home fees on the west side of the lake and "a very viable" toll proposal.

One environmental group begs to differ and claims to have federal law on its side.

"It's essentially unimaginable to me that the corps of engineers would ever allow the filling of wetlands," said Mark Clemens, manager of the Utah chapter of the Sierra Club. He added that "it's pretty much a waste of money" to fund an impact study.

He said that building anything that massive across the lake would have a devastating effect on the endangered June sucker and bird life.

The other problem with the idea is that taxpayers shouldn't be "creating a one-way bet for land speculators," Clemens said. Population growth will occur when and where it's feasible. And the idea that part of the money from a toll road could go toward improving the lake? "This is lipstick on a pig. I'm extremely skeptical of that idea," he said.

The $500 million price tag alone is enough to stop the project in its tracks, he said.

But developer David Gardner says a full bridge would probably be more than that, but he can do it for far less using a causeway/bridge combination. Gardner's plan shows a cost of about $150 million paid for via a fee on new homes on the west side of the lake and a $2 or $3 toll each way. The two revenues could produce a combined billion dollars over the life of the road, more than enough to pay for it and pump millions of dollars into lake improvement.

He's not blind to the idea that it may not be environmentally feasible, but says it's "worth studying."

In the appropriations meeting Wednesday, Sen. Carlene Walker, R-Salt Lake City, gave Sumsion a friendly word of advice if the plan ever reaches a building phase: "Have a pot of money for the lawsuit."