Federal rail regulators Thursday lifted a 10-year-old embargo on freight traffic over the Northwestern Pacific Railroad in Sonoma, Napa and Marin counties, setting the stage for a return of cargo trains later this year.

The Federal Railroad Administration said the railroad south of Windsor meets U.S. safety standards following a $68 million repair project.

"FRA's decision is great news," said Hal Wagenet, chairman of the North Coast Railroad Authority, the public agency responsible for cargo service. "It makes it possible to re-start train service from Napa to Windsor by mid-June."

NCRA has contracted with a private operator, NWP Co., to provide the freight service. The company's president, John Williams, said Thursday his crews are training for a possible start of operations next month.

Under his plan, service would begin with three round trips a week between Windsor and a rail junction south of Napa where the NWP connects to the national rail system.

NCRA officials said the service will provide a lower-cost alternative for shippers and take trucks off Highway 101.

But there are still several hurdles to be overcome before trains roll again. NCRA needs to finalize a joint operating agreement with Sonoma-Marin Area Rail Transit, the commuter rail agency that owns the tracks south of Healdsburg.

NCRA also must adopt an environmental report on the project and a final agreement with Novato, which sued the authority in 2007.

Those issues could be settled by mid-June, said Mitch Stogner, NCRA's executive director.

But environmentalists have threatened to sue NCRA, alleging the agency hasn't considered all environmental impacts.