Some conservationists worry that a proposed network of power lines that would stretch from Mt. Lassen and through the Central Valley could endanger wetlands and waterfowl.

Called the Transmission Agency of Northern California Transmission Project, the massive 600-mile network of power lines would connect dozens of utility plants throughout Northern California. The wires would branch off a few miles north of Tracy — westward to Livermore toward San Jose and east toward Modesto.

The proposed project would help ease congestion of California’s power grid much like widening a freeway would speed up traffic, said an agency spokeswoman. Less electrical “traffic,” she said, prevents power failures.

One of the proposed substations would sit just west of Mountain House, connected by wires that would extend across dozens of miles of privately owned Delta island wetlands just north of Tracy.

If built, the wires would cross too much restored wetland and migratory bird paths, say environmental groups Ducks Unlimited and the California Waterfowl Association. The power lines would cut through the Sutter National Wildlife Refuge, Stones Lake National Wildlife refuge and Butte Sink in Sacramento County and Yolo wildlife area. They would also stretch through lots of private, but federally protected wetlands.

Raptors, swans, geese and other large birds could run right into the wires, clip a wing and drop to the ground, said Rudy Rosen of Ducks Unlimited.

“Especially if it’s a foggy day, which you see a lot of in the valley,” he said. “If they’re not killed outright, usually predators will get them after they fall to the ground.

“Sometimes, you’ll see dead birds littering the ground beneath these power poles.”

Transmission Agency officials say they welcome the criticism and will include the feedback in the draft environmental impact review, which should be published sometime within the year. The public comment period ends May 31. If all goes as planned, construction would begin in 2014 at the earliest.

Rosen said he would rather see the wires follow the same paths as some existing utility networks, instead of winding through large swaths of untouched land. Otherwise, he said the proposed routes would mar 250,000 acres of wetlands — a fraction of what’s left from what used to be 5 million acres of undeveloped habitat for Northern California’s water birds.

Many private owners have restored wetland on their property that they placed on federal or state protective status, Rosen said. As planned, the power lines would span many of those easements.

“We’re talking about some of the most valuable wetlands in the state that this project would threaten,” Rosen said. “And for private property owners, it could even devalue their land.”

Rosen’s organization is encouraging people to write letters to the Transmission Agency — which represents 15 public utilities — to demand that officials revise the plan to more carefully consider its effects on wildlife.

About 60 percent of the Pacific Flyway’s waterfowl, and 20 percent of those in all of North America, winter or migrate through the Central Valley, according to Rosen.

He said he’s not opposed to the project itself, just the way it’s mapped out because he believes it could degrade public lands.

More than 1,000 people, including environmentalists, landowners and elected public officials, have commented on the proposed project since the comment period opened a couple of months ago, according to the Transmission Agency.