THE OPERATOR WAS PULLING A SKI TUBE BEHIND HIS BOAT ON MARINA BAY ON CLEAR LAKE.  THE SKI TUBE WAS OCCUPIED BY THE VICTIM AND HER 3 SISTERS.  AS THE BOAT DID A LEFT HAND TURN THE TUBE WENT OUT TO THE RIGHT AND HIT THE BOAT'S WAKE.  THIS CAUSED THE TUBE TO OVERTURN AND THE VICTIM WAS INJURED WHEN SHE HIT THE WATER.  THE VICTIM COMPLAINED OF LOWER BACK PAIN AND WAS TRANSPORTED BY STEUBEN COUNTY EMS TO CAMERON HOSPITAL IN ANGOLA IN.  AT CAMERON X-RAYS REVEILED A FRACTURED LOWER BACK AT THE L-1 LOCATION.  THE VICTIM WAS TRANSFERRED TO LUTHERN HOSPITAL IN FORT WAYNE IN. FOR FURTHER TREATMENT.