While California lawmakers approved $8 billion in funds Friday to start construction for the nation's first high-speed rail line connecting Los Angeles and San Francisco, the rail still faces a number of challenges including environmental concerns, clashes with local leaders over land use, a $68 billion overall price tag with no funding guarantees, and an increasingly disenchanted public.

The bill, which passed 21-16, authorizes the state to begin selling $4.5 billion in voter-approved bonds, including the $2.6 billion needed to build the initial 130-mile stretch of the high-speed rail line from Madera to Bakersfield. By passing the bill, the state can also collect $3.2 billion in federal funding - a larger sum than expected since Florida, Ohio, and Wisconsin turned down the rail money.

Gov. Jerry Brown and other officials pushed for the project to accommodate expected growth and create jobs in the state with the most people - 37 million - and the third highest unemployment rate.

"No economy can grow faster than its transportation network allows," U.S. Transportation Secretary Ray LaHood said in a statement supporting the vote. "With highways between California cities congested and airspace at a premium, Californians desperately need an alternative."

But farmers in the Central Valley are upset. The Madera and Merced County farm bureaus have filed a lawsuit to halt the project on grounds that the state has not done enough environmental vetting. The plaintiffs say the train would render 1,500 acres of fertile land unfarmable and disrupt 500 agricultural businesses. More lawsuits are expected in the coming months.

"We are going to protect our property," said Frank Oliveira, a farmer who actively opposes the plan.

Many more oppose the plan for its enormous cost to the state. Private companies - including bullet train operators from France and Japan - had initially shown interested in the project, but after learning of the train's route they backed out, leaving the state to deal with the rail's $68 billion price tag.

"It's unfortunate that the majority would rather spend billions of dollars that we don't have for a train to nowhere than keep schools open and harmless from budget cuts." said Sen. Tom Harman, R-Huntington, in a statement. "We cannot afford this current project and across the state, public opinion polls have clearly shown that the Californians no longer want it."

A recent USC Dornsife and LA Times poll conducted in May shows that 59 percent of voters would oppose the bullet train proposition if they could vote on it again, and only one-third of Californians would use the train regularly.

One dissenter, Sen. Joe Simitian, D-Palo Alto, said public support had waned for the project, and there were too many questions about financing to complete it.

"Is there additional commitment of federal funds? There is not. Is there additional commitment of private funding? There is not. Is there a dedicated funding source that we can look to in the coming years? There is not," Simitian said.

The Associated Press contributed to this report.