CABIN JOHN, Md. — Scientists say a bridge expansion project across the Potomac River will threaten a patch of land in Maryland that has been dubbed “the most thoroughly studied island in North America.”

The Washington Post reported Friday that the 12-acres are called Plummers Island. And it has been home to the Washington Biologists’ Field Club for more than a century.

The group says the island’s research value is in danger because of a plan to widen the American Legion Bridge and relieve traffic congestion on the Capital Beltway.

State officials say they’ve worked to reduce the amount of affected land from 1.92 acres to 0.65 acres. But biologists say any impact would cause irreparable harm.