Federal biologists say endangered species would be affected while emissions from diesel-powered heavy equipment could foul already polluted air, and dozens of rivers, canals and wetlands fed from the Sierra Nevada would have to be crossed with possible impacts on aquatic life.
California's rail authority wants to start construction of a 130-mile segment of the proposed bullet train route from Madera to Bakersfield as early as December but must gain approval from a number of state and federal agencies, the Los Angeles Times reported Monday.
Environmental lawsuits brought by the powerful California agriculture industry threaten to further delay work.
The rail authority has said it would work closely with regulatory agencies, protect the public health and comply with all environmental laws.
But local officials and activists say their health concerns are discounted.
"These high-speed rail people just blow through everything," said Harold Hanson, a board member of the San Joaquin Valley Air Pollution Control District and a Bakersfield city councilman.
"I am not sure they know how much dust and pollution they will cause. Their environmental homework has been shoddy."