RedactedNarrative: V1 was pulling his granddaughters on 2 tubes in Swift Slough. V1 turned the boat to the right & 1 on the tubers were swung into a down tree (snag).  The victim was impaled on a branch from the tree in her left arm. Operator of V1 swam out & pulled the girl to safety.  All individuals were wearing life jackets. Operator of V1 was given a BWI breath test & registered .0000.