On any given morning over the past few weeks, sunrise along the western bank of the Willamette River meant Mother Nature's wakeup call for dozens of homeless people who spent the night sleeping on public property.

Some had simply unrolled a sleeping bag or folded themselves up on the park benches along Tom McCall Waterfront Park. Others parked all their worldly possessions -- shopping carts, bikes, suitcases and filled-to-bursting garbage bags -- in increasingly large, impromptu settlements beneath the Hawthorne, Morrison and Burnside bridges.

To a certain degree, this is expected. Summer brings people who've been hidden, in cars and abandoned buildings or on friend's couches, out into the sunshine. The end of the rainy season also coincides with the arrival of a different, usually younger population of homeless travelers.

But this year's boom feels more intense, advocates and actual homeless people say, particularly in downtown Portland and along the western bank of the Willamette River. It's a reminder of a troubling fundamental truth in the effort to end homelessness: Portland, like most major U.S. cities, forbids public camping -- and also has no feasible means of consistently enforcing that ban.

And it's adding to a slow, ongoing thaw in how civic leaders talk and think about a concept that would have seemed outlandish -- and out of the political question -- just a few years ago: Legalized, if limited, camping. Government-authorized tent cities.

"I know the general public doesn't want to hear it," said Israel Bayer, an advocate for homeless Portlanders and executive director of Street Roots, the alternative weekly paper sold by homeless vendors. "No, it's not popular. No, it's not an answer. But at some point, the gap between places to sleep and people needing them is too great. We're overwhelmed."

We're also not the first.

A camping ban we can't enforce

Camping, or in technical terms "establishing or maintaining a temporary place to live," is illegal in Portland, along with most other Oregon communities.

As a general rule, Portland Police enforce that law, as well as one that forbids erecting temporary structures on public property, on a complaint-driven basis unless camps grow so large or so obvious that they pose a public health or safety danger.

"Our primary complaints are about garbage and human waste," said Assistant Chief Bob Day. "It really isn't about the people so much as it's about the stuff."

"We try to operate in a very restrained fashion in terms of understanding that we have almost 2,000 people outside every night, and even if all 2,000 were ready to be housed today, we couldn't do it."

Put more plainly: If you stay out of sight, out of trouble and away from large groups, officers will usually leave you alone.

"We are not interested in the unsheltered man or woman who is sleeping in a doorway and picks up after themselves and is just looking for a safe place for the night," said Sgt. Nate Voeller, of Central Precinct's neighborhood response team. "We know as well as anybody that people need a place to sleep, and that we don't have enough options in Portland."

Earlier this summer, officers spent three weeks working to reduce the number of people sleeping outside along the Eastbank Esplanade and on the streets near OMSI and under the eastern end of the Fremont Bridge. They were responding to complaints from neighbors and to camps that had grown too sprawling to control or ignore, officers said.

By the numbers

Seattle

10,047 total counted

3,772 on the streets

3,282 in shelters

2,993 in transitional housing

Portland

3,801 total counted

1,887 on the streets

872 in shelters

1.042 in transitional housing

Note: These are from the biennial point-in-time count, which does not include people couch surfing. Experts say the total number of homeless is likely three to four times the point-in-time results.

Advocates for the homeless decried the effort as abusive and unnecessary. Officers object to that characterization -- they don't like the frequently used term "homeless sweeps" -- and stress that most people left voluntarily. Police made 896 "contacts" during the three-week operation but only arrested 12 people, six on outstanding warrants.

The problem: In the inner city, the number of places to hide is shrinking. Development in the Central Eastside Industrial District and inner southeast, including the redevelopment of Washington High School and St. Francis Park, longtime refuges for homeless men and women, have resulted in more calls to police and other authorities. So the crackdown on camping along the inner eastside helps explain the apparent, anecdotal jump on the number of people sleeping in the inner westside.

"Historically, a complaint-driven system resulted in, for the most part, people being OK," Bayer said. "The problem is a complaint-driven system when there's really nowhere safe and secluded for people to go."

Seattle embraces tent cities

In the United States, tent cities -- semi-permanent communities built of temporary shelters -- date back at least to the Great Depression. Rising numbers of homeless men and women have prompted a few communities to reconsider.

Usually, that's a last-ditch approach, as in Phoenix, where community leaders allowed an overflowing shelter to expand into an adjacent parking lot for almost two years. Or it's grudging: San Jose leaders, facing overwhelmed shelters and drops in federal affordable-housing money, allowed a 68-acre shantytown dubbed "the Jungle" to grow to almost 300 people -- large enough that it appeared on Google Maps -- before shutting it down in 2014.

In Seattle, Portland's northern neighbor and sister city in government-led, politically liberal approaches to social problems, legal camping has been a small but accepted part of the approach to homelessness for more than a decade.

Churches and other religious institutions were giving the right to host homeless camps several years ago. This spring, the Seattle City Council went even further and OK'd three new tent cities that will be permitted and regulated by the city, for as many as 100 residents each. The expansion was Mayor Ed Murray's response to a spike in homelessness and the number of illegal camps in hard-to-miss places such as along highways, in public parks and under bridges.

The longtime homeless camp known as Nickelsville, after former Mayor Greg Nickels, opened in Seattle in 2008. Since 2004, the city has allowed churches to host homeless camps.

"The impact those illegal camps have on our community are huge in terms of public health, sometimes in terms of the general public but even more than that in terms of the safety of individuals living outside on their own without the protection of a community," said Sola Plumacher, who works in Seattle's Human Services Department and is helping coordinate location and establishment of the three new settlements. "We're calling this an interim survival mechanism."

Seattle's new camps will not be allowed in public parks, must be within a half-mile of a transit stop and must move at least once a year. Social-service providers will run the camp, and the city will pay for basic services such as trash collection and portable toilet rentals at the encampments, expected to cost taxpayers as much as $200,000 annually. That's far less than it would cost to build or rent and operate a traditional indoor shelter.

"Obviously, we cannot stop there," said Seattle City Councilmember Kshama Sawant, a socialist whose election two years ago helped spur Seattle's shift toward government-permitted tent cities. "We have to be moving to a broader, more comprehensive solution, toward a time when people do not suffer from homelessness. This is a way to make people's day-to-day lives a little easier."

In Portland, advocates for the poor have pushed legalized camping for more than two decades. Those calls have grown louder in the past few years as homelessness jumped -- a result of both the recession and Portland's hot rental market, which has driven up prices, driven down vacancy rates and driven out many poorer residents.

Civic leaders' opposition to some form of legalized camping is beginning to loosen. "I think in a limited way that's an option that has some merit," Mayor Charlie Hales said when asked about tent cities this spring. A committee of government officials, elected leaders and service providers that's been studying solutions to homelessness has included tent cities -- in this case, called "transitional campgrounds" -- in early conversations about what form additional shelter space should take.

According to the Home for Everyone committee, the ultimate answer to Portland's homeless crisis is better access to mental health care, more low-skill jobs and higher wages for the ones that already exist, more options for people fighting addiction and, above all else, more permanent affordable housing.

But Portland also needs more emergency places for homeless people to sleep right now.

"We have an ordinance that prohibits camping. We also have upwards of 1,800 people who are going to have to sleep somewhere," said Marc Jolin, director of the city-county A Home for Everyone initiative "We do not have enough lawful places to sleep right now, no question. The question is how we use our resources."

Tent cities: The cons

- They're unsightly.

- They take up public space and resources that could be used for more permanent solutions.

- They're hard to manage.

- They're not a long-term answer to homelessness.

The arguments against tent cities are easy to list: They're unattractive. They take up public space. They're not a long-term answer for people trying to reach self-sufficiency. They can, done with little thought or placed in out-of-the-way places, look and feel less like small towns and more like internment camps for the extreme poor. In Honolulu, where the City Council has passed multiple laws aimed at criminalizing loitering and camping, Mayor Kirk Caldwell is building a small, legal homeless camp made of shipping containers at Sand Island Recreation Area -- a World War II internment camp for Japanese-Americans.

"The risk is that you're just pushing homelessness out of the public eye but not actually doing anything to help homeless people," said Eric Tars, senior attorney with the National Law Center on Homelessness and Poverty. "If you put a camp in the middle of nowhere, away from any services, the only thing they accomplish is making the people you're trying to help feel even more ostracized and isolated."

Tent cities: The pros

- They give homeless people a place to store their belongings while they look for work.

- They give social-service providers a centralized spot to help people get housing or medical care.

- They're safer for women, seniors and other frequently victimized subpopulations.

- They remove the stress a homeless person feels at having to look for a new place to sleep each night.

- They give police more leeway to enforce the ban on illegal camping elsewhere.

- They are a political hard sell, and very hard to place.

The pros are subtler: Tent cities allow residents who want to look for work or go to the doctor a place to store their belongings during the day without worry and freedom from the stress of trying to find a new safe place to sleep every night. They can, depending on location, give social service providers, who often must search for clients or patients, a centralized location to do good work. They offer, if well run, a safer option for women and seniors living outdoors.

"I'm of the opinion that a sheltered place to go might reduce the victimization of some of our more vulnerable unsheltered population," Voeller said.

And they give police and policymakers more leeway to enforce anti-camping and loitering laws elsewhere in a city: it's hard for officers to crack down on camping with lasting results when there is nowhere for them to go besides "not here."

Portland's two legal homeless camps

Right now, there are two legal camps in Portland. Dignity Village, in far North Portland, grew out of a protest and into a permanent government-approved city-within-a-city run by and for homeless people.

Downtown, the Right 2 Dream Too rest area has drawn complaints from some nearby business owners, who say it's an eyesore that scares away out-of-town visitors. Last week, a developer who hoped to convert a former motel that catered to down-on-their-luck men into a trendy youth hostel sued the city, saying the nearby homeless camp made it impossible for him to find investors.

City leaders, after initially trying to fine the community out of existence, have come to accept the Old Town rest area's usefulness, if not its location. They're currently negotiating with Right 2 Dream Too organizers to move near the southeast end of the new Tilikum Crossing bridge.

Yet Right 2 Dream only has room for 100 people, and routinely turns away 100 or more on cold, wet winter nights. The rest area's potential new home isn't big enough to solve that problem.

"Of course we need more legal camps, unless we're suddenly going to come up with houses for everyone," said Ibrahim Mubarak, a homeless man who helped found both Dignity Village and Right 2 Dream Too. "Look at it this way: You have a two-year waiting list to get housing in this city. If you're trying to stop doing drugs, get a handle on a mental-health problem, stay away from somebody who abused you, two years is a very, very long time.

"A lot of bad things can happen in two years."

-- Anna Griffin

(503) 412-7053; @annagriff