The Tongue River Dam impounds a  tributary that is approximately how many miles long?
Tongue River Dam: The Tongue River Dam (National ID # MT00002) is a dam in Big Horn County, Montana, a few miles north of the Wyoming state border. Tongue River (Montana): The Tongue River is a tributary of the Yellowstone River, approximately 265 mi (426 km) long, in the U.S. states of Wyoming and Montana.
i don't know