A federal judge Tuesday denied an environmental coalition's request to stop work on the Highway 101 widening project at the Petaluma River bridge. The ruling clears the way for work to continue on the project.

The environmental groups said that work on the bridge is harming a federally-protected bird species.

In the 27-page ruling, U.S. District Judge Jon S. Tigar said the environmental groups did not show enough evidence that continuing work on the project would cause "likely future harms" to a colony of cliff swallows.

The bridge work, which began in December, is part of a $130 million Caltrans project to alleviate traffic on Highway 101 through Petaluma.

Environmental groups said that netting installed under the bridge to keep cliff swallows away actually entangled and killed the birds.

Caltrans said they had fixed the netting and that no birds have been killed in three months.

The suit, which was argued Friday in U.S. District Court in San Francisco, was brought by Veronica Bowers and her Sebastopol bird care center, Native Songbird Care and Conservation, together with Madrone Audubon Society, Center for Biological Diversity, Marin Audubon Society and Golden Gate Audubon Society. The defendants are Caltrans and the Federal Highway Administration.

You can reach Staff Writer Matt Brown at 521-5206 or matt.brown@pressdemocrat.com.