The San Diego County Water Authority’s General Manager notified the region’s water board on Wednesday that she is retiring. Maureen Stapleton has held the top job at the agency for more than two decades. She led the Water Authority through the complicated settlement negotiations surrounding the Colorado River. That deal cleared the way for a huge water transfer with the Imperial Valley that provides a significant chunk of local drinking water. Stapleton also encouraged projects like the Carlsbad Desalination plant as a way to diversify the region’s water supply.