RedactedNarrative: Boat tubing near Ross Point on the Spokane River headed west down stream. A larger vessel throwing a very large wake was traveling east up stream passed by. The operator observed the wake and started to slow the vessel. The operator was unable to get the vessel slowed in time. When the two tubers impacted the first wave of the wake they remained on the tube but were separated. Upon impacting the secondary wave of the wake the girls were thrown together smashing heads but still remaining on the tube. TUBER 1 impacted Tuber 2's forehead with the back of her head. Tuber 2 was transported for her injuries. Tuber 1 was check at the scene by medical and cleared.