 I'm Kathy Worzer with Minnesota News Headlines. The Rapidan Dam on the Blue Earth River near Mankato, still standing, but a home that hung precariously from an eroding slope, fell into the raging river last night. The rain-swollen river caused a partial breach of the dam, so with water sweeping around the west end of the dam, the powerful surge of water took out an Xcel Energy substation and now the nearby home.