BISMARCK, N.D. (AP) — Much of the Upper Midwest on Saturday was dealing with swaths of unhealthy air because of drifting smoke from Canadian wildfires, covering the northern region of the U.S. at a time when people want to be enjoying lakes, trails and the great outdoors.

Most of Minnesota and parts of Montana, North Dakota and Wisconsin were ranked “unhealthy” for air quality on a U.S. Environmental Protection Agency map. Part of North Dakota that is home to Theodore Roosevelt National Park and other tourist attractions was ranked “very unhealthy,” some of the worst air quality in the nation.

In Minnesota, “If you have a nice pork loin you can hang from a tree, it’ll turn into ham,” quipped Al Chirpich, owner of the Hideaway Resort near Detroit Lakes, where people come to enjoy tree-lined Island Lake for fishing and other water activities.

Normally there would be boats and jet skis all over, but on Saturday he couldn’t see a boat on the lake, where the smoke impaired visibility and curtailed his camper business. None of his 18 RV sites was occupied. His seven rental cabins drew a handful of customers.

“I suspect when the weather clears, we’ll be swamped again. Fourth of July, I had probably 20 boats here lined up at my docks, and today my boat is the only one,” Chirpich said.

The conditions started Friday, dragging smoke from the Canadian wildfires down to the surface, said National Weather Service Meteorologist Jennifer Ritterling, in Grand Forks. Periods of bad air quality are expected to last through the weekend in the region, she said.

Limiting time outdoors, keeping windows closed and running air purifiers are good ideas for people with lung conditions such as asthma and chronic obstructive pulmonary disease, and even healthy people, Ritterling said.

“Our summers up here are fairly short and so everyone wants to get out and enjoy them, and it’s a little frustrating when there’s this smoke in the air,” she said.

Fires in Canada prompt state of emergency for some

All of Manitoba is under a state of emergency because of the wildfires, which have led to 12,600 people evacuating their homes in the province. The fires in the central Canadian province have burned over 3,861 square miles (10,000 square kilometers), the most land burned in 30 years of electronic record-keeping.

Under 1,000 people have evacuated their homes in Saskatchewan, where wildfires also continue to burn.

North Rim in Grand Canyon still closed

In Arizona, the North Rim in Grand Canyon National Park is still closed because of a 2.3 square-mile (6.1 square-kilometer) wildfire and another fire nearby on Bureau of Land Management land that has burned nearly 17 square miles (44 square kilometers).

More than 200 firefighters and support personnel worked to halt the uncontained fire Saturday as it burned across a high-altitude plateau between the communities of Lonesome, White Sage and Jacob Lake.

In Colorado, Black Canyon of the Gunnison National Park remains closed because of a 4.4-square-mile (11.3-square-kilometer) wildfire burning on the South Rim of the park, known for its dramatic, steep cliffs. A few miles from the fire, an evacuation was ordered for the community of Bostwick Park, and a nearby highway also was shut.

The fires in and near both national parks led to evacuations of hundreds of people.

Chirpich, the Minnesota resort owner, said he has plans to go to Black Canyon of the Gunnison National Park on Thursday and is “a bit pensive about how that’s going to be there.”

“I’m going to leave one smokehouse for another, I guess,” he said.