The spring sunlight that delighted so many across the Puget Sound region this weekend may have been responsible for setting a deck on fire...

The spring sunlight that delighted so many across the Puget Sound region this weekend may have been responsible for setting a deck on fire Sunday.

After ruling out other possible causes, investigators for the Bellevue Fire Department blamed the blaze in the 17100 block of Northeast Fifth Street on the dogs’ glass water bowl. The partially-filled bowl apparently concentrated the sun’s rays like a magnifying glass, said Lt. Eric Keenan, the department’s community liaison officer.

“It’s very unusual, but it’s not unheard of,” he said.

The 11-inch-diameter bowl was elevated above the wooden deck in a wire stand, Keenan said. “There was nothing else in that area that could be identified as a fire source — no smokers, no electrical devices.”

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No one was home when the fire started just before 3 p.m. Neighbors called in the alarm when they noticed flames and smoke.

The deck was destroyed and the adjacent kitchen badly burned. Total damage was estimated at about $215,000.

The family’s two dogs were both apparently unhurt, Keenan said.

Every youngster knows that a magnifying glass can be used to start a fire, and the Internet is replete with tales of other lens-like devices doing the same thing, from partially filled water bottles to a broken light bulb filled with water.

Keenan said he’s heard of another case where curved glass in a door sparked a fire at a construction site.

University of Washington atmospheric scientist Steve Warren says the dog-bowl theory sounds far-fetched, but not impossible. “The shape, the height and the angle of the sun would have to be just right,” said Warren, whose research involves measurement of solar radiation.

Bellevue’s investigation is complete, but now the insurance company will examine the case.

“It’s causing a lot of discussion … as to whether or not this can actually happen,” Keenan said. “Who knows what they will come up with.”

Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com