They have survived ice ages, asteroid collisions and what the 19th century naturalist George Perkins Marsh called the "destructive agency of man," but turtles need a hand every now and then.

The Blanding's turtle is a case in point, particularly around this time of year when the highly mobile critters emerge from wetlands surrounding Big Marine Lake in northern May Township, where they overwinter and head for the upland areas to nest and lay eggs. To get there, they have to cross a lonely, perilous two-lane stretch of County Highway 4 (also known as 170th Street) that cuts through their watery home.

To help the increasingly rare turtles, the Washington Conservation District — in partnership with the county, the University of Minnesota, Department of Natural Resources and Minnesota Herpetological Society — installed a 20-by-25 inch "turtle tunnel" in June under a "hot spot" on the road where turtle-vehicle collisions are frequent. The hope is that it will reduce the number of turtle fatalities.

"That's why the DNR and the University of Minnesota are involved: because if it does prove to be something that works, other areas that are having issues with saving other endangered species, this could be a solution," said Don Theisen, the county's public works director.

The medium-size turtles, named for the 19th century Philadelphia doctor who discovered them, are distinguished by a long neck and a bright yellow throat.

Although there are no accurate figures of how many turtles are killed each year while crossing the road (some estimates say it's in the hundreds of thousands nationwide), local volunteers have been tracking the number of flattened carcasses found on the road every week using an app called HerpMapper.

Officials hope the “turtle tunnel” in May Township will allow Blanding’s turtles to make their way to and from wetlands on either side of the road.

"We've actually had some people who've seen quite a high rate of turtles up there being killed on the road, and other animals," Thiesen said.

The $50,000 project was funded through grants from the DNR and the University of Minnesota, Thiesen said, adding that the passageway could also solve the problem of motorists stopping and getting out of their cars to help the turtles across the road.

The Big Marine Park Reserve, home to one of the state's largest colonies of Blanding's turtles, sits along the highway, where traffic zips along at 55 miles per hour.

Before the road was built in 1961, the turtle had an easy trip. Now, the speeding cars can make it treacherous. Officials said that has contributed to the animals' dwindling numbers (along with loss of habitat), landing them on the state's threatened species list.

"Adult turtle mortality, which is naturally pretty low, increased a lot," said Christopher Smith, president of the Herpetological Society.

It's not the first time wildlife officials have tried to spare the reptiles from becoming roadkill, but it is the first such passageway in the state, Smith said.

"Going forward," he said, "I really hope that a lot of transportation departments will really start considering these types of things as they're considering redoing some of these roads."

Libor Jany • 651-925-5033 • Twitter:@StribJany