Jonathan Gonzalez

Jonathan Gonzalez is good at hiding. At 31, he’s already been living outside for 10 years, and he wants nothing to do with big cities. It’s hard to stay out of sight there, especially when you smoke pot and meth and need to do that often to balance them out, he said.

So his latest camp is underneath Interstate 580 in suburban Castro Valley, in a steep canyon studded by bushes and trees with a stream gurgling at the bottom. Sometimes he winds up in a hospital, and that’s a nice change of pace, he said. A recent trip to the John George Psychiatric Hospital after a mental episode netted Gonzalez a followup stay in a shelter and a free pair of thin blue hospital pants — but it wasn’t long before he headed back outside.

“I can leave my stuff here and nobody takes it, and I don’t even need a tent because I sleep under the overpass,” he said. “I think that virus that people talk about was invented to keep people from communicating, but I’m not going to catch it out here. This is nice. I feel safe.”

A few other people have built ramshackle shanties in the gully, and dozens of battered shopping carts line the slopes, flung there along with so much trash the debris forms retaining walls for thin trails winding down to the stream. Last year, neighbors complained so bitterly about a 60person camp in a nearby gully that police swarmed it. They shot two dogs and arrested four people before it was cleared.

Gonzalez and the others under I580 don’t want a repeat of that, so they’re trying to keep their group small. But Michael Kusiak, a community activist who tried to ease tensions between last year’s camp and its neighbors, fears that the cratering economy means people like Gonzalez soon will have a lot more company in the gullies and forests of suburbia.

“Some people are surprised we have homeless people out here, under freeways and in RVs,” he said. “But we do. And up ahead, I see more people falling through the cracks. It’s going to get worse.”

Kevin Fagan is a San Francisco Chronicle staff writer. Email: kfagan@sfchronicle.com Twitter: @KevinChron