The South Coast Water District may have room for a larger well system for its proposed desalination facility in Dana Point, meaning that more potable water could be produced for customers. At a meeting last week, consultant Mark Donovan, a senior engineer with GHD, Inc., told South Coast’s board that an ancient river channel topped with younger sediment — known as a paleo channel — at the mouth of San Juan Creek is larger than “orginally anticipated.” “These are positive preliminary findings,” Donovan said. Geophysicists used sonar to map the area in October.