Twenty-five years ago, logger Johnny Davis knew of one beaver hutch in Dorchester County. One. Today, he can hardly step into the bottoms without wading up to one.

The beaver

Largest rodent in North America. Strict vegetarian.

24-year approximate life span.

Builds dams of sticks, logs and mud to protect hutches, or lodges, from predators.

Causes conflicts with humans by flooding timber and agricultural land but creates excellent habitat for raccoons, muskrats, otters and mink, wood ducks and other waterfowl.

Wiped out in South Carolina the late 1800s by trapping. Reintroduced to the Pee Dee region in 1940 by the U.S. Fish and Wildlife Service, and recolonized the Savannah River drainage basin. The two populations rapidly expanded across the state

Controlled by licensed trapping and fur hunting.

Sources: S.C. Department of Natural Resources, Beavers: Wetlands and Wildlife

“Now they're are in every stream. It's just amazing what they've done,” he said.

What the saw-toothed rodents have done is lay waste to hundreds of hardwood forest acres by backing up creeks and drowning trees that are only supposed to be submerged part of the time.

Their dams flood low-lying roads and undermine bridges along drainage in areas as populated as Rumphs Hill Creek outside Summerville. They have backed up Polk Swamp near St. George far enough to help threaten a key sewer outfall for upper Dorchester County.

They are ubiquitous and toothy enough that the county has a dedicated beaver crew to clean up their messes. But with the recent deluges, the ponding has only gotten worse.

Now the county is bringing out the cavalry to clear those streams: a Caterpillar 305 Amphibious Excavator. Or, as Councilman George Bailey called it, “the Beaver Buster.”

The $167,000 excavator is an economy-sized mechanical shovel whose tracks double as pontoons. It can work its way into the bottoms and then float its way to the problem.

The equipment is an all-round necessity for public works crews in a county defined by its bottoms, a place where “just about every drop of water that falls ends up in swamp somewhere,” as county engineer Matt Halter said. The excavator can clear all sorts of debris in flooded spots other shovels can't, and there are drainages in the county that have been debris-snarled since Hurricane Hugo dropped trees in 1989.

But make no mistake, this piece will pick away at the beavers' haunts. When Halter was hired recently, he thought the beaver crew was a joke. He has since redirected some $700,000 in scheduled projects that would have had only limited benefits. But not the crew.

“My goal is to do projects that impact the most residents,” he said.

Less than a generation ago, most people outdoors in the Lowcountry had never seen a beaver. Now, S.C. Department of Natural Resources gets a steady stream of complaints.

In the water-logged coastal plain, where a foot-high mud dam can flood 100 acres, the critter has made itself way too at home.

Berkeley County has one paid beaver crewman and contracts with the S.C. Transportation Department. Charleston County crews remove dams as problems a rise.

Dorchester County is so laced with swamps — Polk, Indian Fields, Four Holes, Cypress and others — that nearly every major road crosses two or more.

Beavers “are a major problem,” said Davis, the logger. “If there's water flowing, there's a good chance there's a beaver in it.”

Reach Bo Petersen at 937-5744, @bopete on twitter or Bo Petersen Reporting on Facebook.