"Fieldnotes," August 18th & 19th, 2013: "Beaver Dams," by Elizabeth Ann Straub. http://www.montananaturalist.org/
"The headline of a Stony Point, NY newspaper could have read: "Beavers Save Town" when, during the New England Hurricane of 1938, the town's sixty colonies of beavers worked through the night to repair their overflowing dams. Made of mud, sticks, stone and plant debris, the dams held like cement. When the hurricane was over, the local beavers were credited with saving three main highways from serious flooding, preventing the destruction of at least one bridge, and keeping acres of soil from eroding."