Nothing surprises the officers in Portland's East Precinct anymore.

Not buckets of human waste left by the side of the Springwater Corridor. Not a snake slithering mere feet from a homeless man's campsite. Not reports of people being robbed or even assaulted along the idyllic isolated bike and pedestrian trail.

Officers Robert Brown and Matthew Nilsen were responding to a report of a robbery on the Springwater Corridor early Thursday when 23-year-old transient Nicholas Glendon Davis swung a three-foot-long crowbar at them, police said. The officers began backing away, but Brown fell. When Davis continued to advance, Brown shot him in the chest.

Portland Police officers looking for homeless camps on the Springwater Corridor, where high grass and shrubbery and frequent curves make for peaceful riding -- and easy hiding.

It's the latest and highest profile reminder of something police and an increasing number of East Portlanders already knew: When city and county leaders pushed to annex large swaths of east Multnomah County almost three decades ago, they promised residents all the perks of city living. But as poverty spreads east from gentrifying neighborhoods closer to downtown, east Portland is getting the worst of urban life.

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Scientific studies and anecdotal evidence show homelessness, along with other forms of extreme poverty, moving east from downtown Portland into communities beyond 82nd Avenue. The Springwater Corridor is a focal point.

The bike and pedestrian path, 21 miles from the central city to Boring, cuts a gentle, sloping path through some of the noisiest and ugliest stretches of the city. The attributes that make it so appealing – the sense of seclusion and privacy created by surrounding shrubs, trees, tall grass and blackberry bushes – also make it a magnet for homeless people seeking campsites.

Greg Sargent, who owns a business near the corridor, called it a "thief's getaway route," on Thursday. Police say it's a "homelessness highway." Mike Davis, a pastor who ministers to homeless men and women and lives near the trail, says it's an escape route for people who, for various reasons, do not want to stay in a shelter or get a free meal at one of downtown's many charities.

A close look at a homeless person's campsite near the Springwater Corridor.

"People go downtown first and realize that it's crazy. Most shelters won't let you keep a dog, they won't let you drink, and if you're traveling with someone of the opposite sex, they'll make you separate," said Davis, who has worked along the corridor for seven years. "It's easy to see why this area is attractive: You take a bike up the Springwater or you ride MAX out, and you're just a few footsteps from the middle of nowhere."

The problem is that the trail – along with Rocky Butte, the Johnson Creek watershed and other bits of quasi-suburban green space that have become popular camping spots – merely feels like the middle of nowhere. It's actually quite close to homes and businesses. From most spots on the trail, getting basic supplies is as easy as walking out of the woods to the closest Plaid Pantry, Taco Bell ... or residential neighborhood.

"Homelessness equals car prowls, graffiti, vandalism, all those little petty crimes that make a lot of people feel unsafe. That's why you can't just leave people alone to camp," said Officer Jason Lemons, part of the East Precinct neighborhood response team. "Everyone who camps isn't an issue. Probably most people aren't. But the more people you have out here doing that, the more likely you are to have neighbors notice problems."

On any given night, it's hard to tell how many people are sleeping outdoors in East Portland and East County. In the 2013 point-in-time homelessness count, 11 percent of the people surveyed in Multnomah County planned to spend the night east of 82nd Avenue. But the count is voluntary and only calculates people actually contacted by census-takers.

One or two people occupy most of the illegal or unauthorized campsites police find. But officers have cleared out tent villages that were home to as many as 50 people. One Johnson Creek camp had a vegetable garden. At another, on Kelly Butte, clean-up crews needed almost 1,000 trash bags to pack up all the personal belongings and garbage they carted away, officers said.

On a recent spring morning, Lemons and several colleagues took a reporter and photographer on patrol. Finding campsites wasn't difficult.

Portland Police officers surveyed an unauthorized campsite just off the Springwater Corridor in east Portland in late April.

Lemons parked his police SUV in the back of an industrial park off Foster Road near Southeast 111th Avenue, half a mile from Thursday's shooting scene. The Springwater Corridor runs just behind the industrial park, and from it, officers saw a flash of blue tarp amid some blackberry bushes. They ducked under the limb of a small tree, rounded the bush and spotted a campsite: A wooden pallet served as a front porch, a tent and a tarp draped over it as a front door. Next to the tent were a collection of camping-sized propane bottles, a few pots, a disassembled shopping cart, a few full trash bags and two painters' buckets filled with something that didn't look or smell like paint.

"There's the toilet," Lemons said.

An officer shouted out identification-- "Anybody in there? This is the Portland Police." -- and three people emerged from the tent, squinting in the sunlight.

A man and a woman -- the man, who identified himself as Derrick, came out with his sweatshirt open to reveal a chest covered in tattoos -- travel together and shared the tent together. They had a guest, 31-year-old Loren Kurth, who had set up his own camp about 15 yards away under a small patch of trees. As officers examined Kurth's campsite a snake slithered by a few feet away.

"I don't really think I'm doing anything wrong out here," Kurth said. "I'm just trying to save up some money and maybe buy a house."

Loren Kurth, 31, took his bike and headed back to the Springwater Corridor trail after officers cleared outside his campsite this spring.

Derrick and Kruth's shelters were situated on a low, marshy stretch of open space just east of Beggars Tick Wildlife Refuge and on public property, where camping is not allowed. Officers found three more abandoned campsites within a 50-yard radius. Several had flooded during spring rains – soggy, mildew-smelling clothes and blankets rested atop the remains of one ripped tent. At another spot, the previous occupant had left behind a twisted bike wheel, more empty propane bottles, an assortment of fast-food wrappers and a child's sleeping bag bearing the face of actor Zac Efron and the logo from the movie "High School Musical."

"Imagine that you're here with your kids on a nice sunny summer day, you're having a nice bike ride, and you run into somebody like Derrick?" Lemons said.

Neither officers nor activists have an answer. Park rangers, who patrol the trail itself, have taken to writing more exclusions barring people caught camping from the trail. And agencies that own land along it are doing more regular grooming of the shrubs and trees that block views. The Police Bureau has increased its enforcement of camping – officers use ATVs to patrol harder-to-reach spots, and this summer will use airplane surveillance to look for larger camps.

Few shelters or services exist for homeless men, a bulk of the population of campers, in east Multnomah County. When officers force campers to move, they're shifting the problem rather than solving it.

They know that.

"Usually when we interact with campers, all we're trying to do is see if they want to get into services, if there's some way we can help them, just build a relationship. We could arrest them, but they'd be back here in maybe a few hours," said Officer Robert Brown, another member of the neighborhood response team who shares the same name with the night-shift officer involved in Thursday's shooting.

"It's frustrating for us, because it's this big, complicated, messy issue that we can't solve. It's frustrating because you have kids out here who are growing up thinking this is normal: people living in a tent off a trail in a swamp."