THE LETTER landed all over the city in mid-April, as Portland prepared to celebrate its first-ever 4/20 with legal pot on the horizon.

It was a short four-paragraph missive—polite in the officious way of landlords—reminding residents of buildings run by Income Property Management (IPM) that the era of legal weed wasn't quite created equal.

"As many of you know," IPM's director of affordable housing wrote, "Measure 91 passed, which will effectively legalize possession for personal use of marijuana in Oregon for persons over the age of 21.... However, we would like to remind residents and guests that the building in which they reside is a no-smoking property, and smoking of marijuana will be considered a lease violation."

In one of the property group's Southeast Portland buildings, residents bristled.

"It's basically like, 'Have a bag of weed in your house, it's legal, but in no way shape or form can you use it,'" says one resident who didn't want to be identified for fear of retribution at a time when Portland's rental market is bowstring-tight and growing more expensive by the day. "So what do I do? Go outside and get a ticket?"

It's a question likely to come up more and more once recreational pot officially becomes legal on July 1.

The Portland area has tens of thousands of apartment dwellers, with tens of thousands more expected to show up in coming years. And Portland, like housing markets throughout the country, has embraced smoking bans in many of these buildings. Casual industry group surveys suggest more than 30 percent of apartment buildings (in some parts of town) have non-smoking apartments, but experts guess the amount is far higher.

"I can tell you that the vast majority of rental properties restrict smoking to be done outside the unit only," says Christian Bryant, a Portland property manager and board president of the Portland Area Rental Owners Association.

Another local industry watcher, apartment appraiser Patrick Barry, says he inspects more than 100 complexes a year, and estimates an average of five of those allow smoking in the units.

Allowing smoking is "a pain for property owners because they typically have to replace the carpet, paint the walls, and complete a deep cleaning before turning over the unit," Barry says.

That situation works fine for tobacco, which can be used openly on the street. It poses a trickier scenario for the pot smoker who wants to follow the rules. Smoking in public is illegal under Measure 91, which specifically included "hallways, lobbies, and other parts of apartment houses and hotels not constituting rooms or apartments designed for actual residence" in its definition of that term.

And since landlords also sometimes include use of vaporizers—which heat cannabis at a lower temperature than combustion and don't produce actual smoke—in their definition of smoking, the apartment-dwelling marijuana user in Oregon might be left with a couple of choices: Flout the rules and risk eviction or a police citation, eat or drink their weed, or find a friend whose living situation isn't so restrictive.

"It is something that needs to be addressed because we need people to stay out of public view to comply with the law," says Anthony Johnson, the chief petitioner behind Measure 91. "But where can they use cannabis or medical cannabis?"

The answer, he thinks, lies in better educating property management—who are typically most concerned about the value of their rentals being harmed—about vaporizers. And Johnson thinks Oregon will see legislation allowing adults-only membership clubs where smoking's allowed.

Measure 91 "didn't say we couldn't create cannabis lounges," he says.

As Johnson hints, the situation that recreational cannabis users are about to face has been the case for years for medical pot patients. The Oregon Bureau of Labor and Industries (BOLI) used to press cases on behalf of patients who were prohibited from using medical marijuana by their jobs or landlords. That ended when a 2010 Oregon Supreme Court decision found employers have every right to prohibit medical pot use for employees.

BOLI doesn't plan to weigh in on recreational smokers' housing rights, a spokesman says.

But the dilemma posed by legal pot could affect hundreds of thousands of Portlanders. It's hard to track down the exact number of rental properties in the Portland area, but US Census Bureau figures show that, as of 2013, the metro area had more than 250,000 dwelling units in buildings containing two units or more—roughly one-third of housing stock. That number's expected to go up at a near record clip in coming years.

A recent analysis published by local trade group Multifamily NW found there are 13,200 apartments planned or in construction in the Portland area. Roughly half of those will be finished within three years.

The crazy growth, the analysis found, "is something that our market has not seen since the late 1990s."

It's unclear just how hard landlords will press their anti-smoking policies in a pot-positive world—obviously stoners have been living in apartments for decades, long before the age of legal weed. The Mercury reached out to a half dozen of the city's largest apartment management companies. None of them, including IPM, responded meaningfully to our inquiry by press time.

But the letter sent out to some IPM residents earlier this month suggests that company, at least, is willing to force the issue.

"Any consumption, use, production, or sale of marijuana anywhere on the premises that could be seen at any time by anyone is both against the law and a lease violation," the letter said. "Those found using or smoking anything that produces smoke in their unit or on premises will be in violation of the rental agreement."

Which struck that anonymous IPM resident quoted earlier as sort of funny.

"The thing about it," he says, "is everyone's smoked weed in this place for years."