Any proposed new or expanded treatment facility in the Lake Lyndon B. Johnson or Lake Marble Falls Watersheds but outside the Lake Lyndon B. Johnson and Lake Marble Falls Water Quality Areas may be permitted only if it provides disposal without discharge in accordance with §311.53 of this title (relating to Wastewater Disposal) or if the applicant establishes that any alternative proposed wastewater treatment and disposal will consistently protect and maintain the existing water quality of Lake Lyndon B. Johnson and Lake Marble Falls.