The Killebrew Lake beavers mean business.

They diligently work on their dam every night, from 11 p.m. to 4:30 a.m., and there’s always a sentry posted, ready to alert the construction crew to danger with an emphatic slap of his scaly tail.

Joel Mietzner and his 5th grade daughter Joanne should know. They discovered the beaver colony while working on Joanne’s science project to calculate the lake’s surface area. They have spent months tracking down the beavers’ elusive, well-concealed den, setting up game cameras and capturing images of the beavers.

Joanne, who learned that beavers live in dens, not their dams, said the den is made up of two structures connected by a tunnel. It’s also extremely well built.

“I jumped on it, and it didn’t collapse,” she laughed.

She’s named one of the beavers “Justin Beaver,” after the teen pop singer and heartthrob Justin Bieber.

“One of the things people don’t realize is how many beavers we actually have on this island – probably in the neighborhood of 15-20 beavers,” said Joel, who believes the Killebrew Lake colony is the offspring of beavers on LaPorte Road.

While beavers were almost wiped out in the fur-trapping heyday of the 1800’s, he said they’ve made a solid comeback.

San Juan County Public Works has been compelled to study the beavers as well, but for a different reason. The Killebrew Lake beavers are so hardworking, they have completely blocked the drainage culvert, flooded the road, and submerged a nearby CenturyLink utility pedestal that routes 911 calls.

“They can only take so much moisture,” said public works project engineer Guard Sundstrom. “That’s pretty threatening and serious. If the phone system goes out, they can’t patch it underwater.”

He said this is the first time in his tenure that public works has encountered beaver issues.

“I don’t know much about beavers, but they are busy and they don’t like running water,” said Sundstrom. “We took it down four or five days ago, and today it is built back up.”

Another potential hazard worries Sundstrom: if the dam held back a large amount of water, and then somehow broke loose, it could unleash a torrent on downstream homes or facilities.

Beavers are protected in Washington state, and though it’s possible to get a rare kill permit, San Juan County public works is working hard to co-exist with them. So they’ve opted to go with a “beaver deceiver,” a cage-like device built around the culvert that allows beavers to do what beavers do best while still allowing water to flow and protecting the road.

Since the device is best installed during dry August days, the department is currently keeping busy dismantling the dam as the beavers build it.

In harsher climates, beavers will store a cache of food at the bottom of their pond, making it essential that they keep the pond at a sufficient depth so that it does not freeze to the bottom, which would cut off access to their food.

With the lake at sufficient depth, a beaver deceiver would allow both the beavers, public works, and the utility pedestal to thrive.

The deceptive devices are currently used throughout King and Skagit counties, and Sundstrom said the department has been considering various designs.

Brendan Brokes, a biologist at the Washington Department of Fish and Wildlife, applauds the county’s efforts.

“The county has really done a nice job in my opinion,” he said. “They could have trapped these beavers …  but as you remove beavers from an area, the females become more fecund and reproduce at a greater rate … In the short run it gets rid of the animals, but in the long run you get a big boom of beavers coming back.”

“We like beavers because they often help the fish habitat,” Brokes said, their activity creating excellent rearing habitat for juvenile fish, as well as habitat for bats, migratory birds, herons and more. Flooded trees become snags for raptors and woodpeckers.  The semi-aquatic animals feast on the roots of skunk cabbage, the leaves, inner bark and twigs of deciduous trees, and other aquatic plants.

“The lake was really overgrown with plants and debris,” said Joel. “The beavers have just really cleaned this lake up tremendously [and] created a much healthier environment; the water clarity has really improved.” He said the beavers have already greatly reduced the amount of invasive milfoil in Killebrew Lake by eating the plants to which the milfoil normally attaches.

“They alter their environment more than any other species of animal on the planet,” added Brokes.