TULALIP — Bonnie Puhrmann paid $130,000 in November for a home with an airy main floor, a large deck and windows that stretch wide enough to offer a view of every boat in Tulalip Bay.

She knew she wouldn’t find that price for a waterfront home anywhere else, so she wasn’t deterred by the fact that the Hermosa Beach home is on land leased out by the Tulalip Tribes.

“You know how you find that place that you want to stay forever?” she said.

But it wasn’t long after Puhrmann, a 61-year-old technical writer, hung glitter-dusted paintings of angels on the walls and smoothed the wrinkles from her handmade quilts that she discovered the forever home won’t be forever at all.

Her current lease ends in 2012. If tribal leaders offer her a 15-year extension, she’ll have the house until 2027, when she will be 81 years old.

But a recent property assessment has Puhrmann nervous that she may be unable to afford her home long before then.

The official value of the home when Puhrmann purchased it was $79,200. This year’s assessment lists the home’s value at $124,800 — an increase of 57.5 percent.

“I thought it was a mistake,” Puhrmann said.

It wasn’t, said Stephen Lightle, a residential appraisal manager in the Snohomish County Assessor’s Office. In fact, a spike in this year’s assessments on many of the 274 homes on leased land on the reservation is a reversal of a mistake Lightle said the assessor’s office made two years ago.

That’s when tribal leaders announced that they would not indefinitely renew leases, he said.

“We believed (the announcement) would have a significant impact on the values,” Lightle said. “We thought, ‘Would a person want to buy a property with such a short-term lease?’ “

So Lightle’s office dramatically reduced the assessed values of the homes.

That’s where Lightle said his team went wrong.

Instead of tapering off, home sales on leased land have continued as before, Lightle said.

“It appears we adjusted the values a little too much,” he said.

This year, the assessments were raised to more closely match the selling prices of the homes, he said.

Norm Petterson has lived with his wife at Hermosa Beach for 16 years. Two years ago, the assessed value of their home dropped, from $78,400 to $59,400.

“I thought, ‘Holy smokes! I didn’t tear any part of this house down,’ ” Petterson said. “I called the assessor, and they said, ‘The house value is not as good as we thought it was.’ “

This year, the value went up, to $92,300.

The Pettersons pay just over $300 each month to lease the land their home sits on, but they’re ready to sell and move somewhere smaller. They hope to get about $130,000 out of their home before their lease ends in 2012.

Puhrmann worries that her home’s higher assessment will cost her $200 or more each month in property taxes. She also worries about a widespread rumor that the price tag of a 15-year extension will be based on the increased value. If she can’t afford the new lease, she’s not sure she could sell the home. It’s unlikely that a potential buyer could get a mortgage on a home that will be returned to the tribes within 20 years, she said.

“How can a house have an appraised value if you have to surrender it?” she said.

Puhrmann’s house payments under her mortgage are poised to increase, from about $1,000 to about $1,800, she said. She assumed she’d be able to refinance to lower the payment, but now she’s not sure she’ll be able to secure a loan with less than 20 years left — at best — on her lease.

“The thought of those kinds of payments over my head, that scares the daylights out of me,” Puhrmann said. “I’m stuck.”

Reporter Krista J. Kapralos: 425-339-3422 or kkapralos@heraldnet.com.