The attack was the fourth time such an incident has happened on or near the trail in the past three years. The trail looks peaceful and serene, but now some residents are concerned about using it.
"I'll walk usually just like on the street, but not on the path because I've heard that there was an attack before. So I try to stay away from it," said Alysia Houser of Livermore.
At around 6 p.m. on Tuesday, police said a 29-year-old Livermore woman was sexually assaulted here on the trail. They added the victim is being treated for her injuries.
"The police woman came last night to the door, and we didn't know what happened. She just [asked] had I seen anything," said area resident Lin Tobin. She told police that she saw nothing unusual.
Police report there have also been three other attacks in the past three years on or near the trail. One happened in May 2012, another in May 2013, and one last August.
"It kind of scares me, 'cause I live really close to this bridge. I live just down the street from it. And my mom, just last night she came home and she said 'There's a lot of cops.' And I'm like, 'Oh my gosh, somebody must have been attacked or murdered or something,'" said Houser.
Investigators won't say what the woman was doing there, whether she was walking or running, or where exactly the attack happened.
But authorities warned people to be vigilant and aware of their surroundings, stay out of poorly lit or secluded areas, avoid using headphones, and never come here alone.
Whenever possible, residents should walk with another person, and carry a cell phone programmed with the direct number for Livermore police dispatch, (925) 371-4987. Any suspicious behavior or persons should be reported to the police.
One woman who didn't want to give her name warned people: "You should never be out here after dark."
Anyone who witnessed Tuesday's assault should call police at (925) 371-4777.