Caltrans announced Wednesday it has awarded $107 million in construction contracts for the first phase of the contentious Highway 101 Willits bypass.

"Awarding the construction contract is a huge milestone," Caltrans District 1 Director Charlie Fielder said in a written release.

The contract was awarded to a partnership of DeSilva Gates Construction of Dublin and Flatiron West Inc., a Denver-based company with offices in Benicia.

Caltrans hopes to begin construction by late fall, but environmentalists said they would be seeking a court order to block the planned work.

"We will likely be filing an injunction at the end of this week," said Aruna Prabhala, an attorney for the Center for Biological Diversity, one of four environmental groups that in May sued in federal court to challenge the bypass project on environmental grounds. The California Farm Bureau Federation in July joined the lawsuit, which was filed in San Francisco federal district court.

Environmentalists contend the bypass is unnecessary and will harm wetlands, salmon-bearing streams and endangered plants. The lawsuit targets Caltrans, the Federal Highway Administration and the Army Corps of Engineers, alleging they violated the National Environmental Policy Act and Clean Water Act when they approved the project.

The bypass has been delayed by funding issues and opposition for decades. News articles about a proposed bypass date back to the 1950s.

The bypass is intended to alleviate traffic congestion through Willits, where Highway 101 narrows and often backs up. The bypass would skirt Willits to the east and eliminate the only traffic light on Highway 101 between San Francisco and Eureka.

As currently planned, the 5.9-mile, two-lane bypass would cost about $210 million, including land purchase, impact reports and mitigation measures. The overall plan calls for four lanes, but there was insufficient funding available so it was downsized. Caltrans hopes to widen the bypass at a future date.

You can reach Staff Writer Glenda Anderson at 462-6473 or