One of the co-founders of Shelburne Farms died on Thursday while swimming in Shelburne Bay with his grandchildren.Shelburne Police said that Marshall Webb, 74, was swimming with his grandchildren on Lake Champlain near the edge of the Shelburne Farms property when a storm began to roll in. The children told police they continued to play in the water, then the boat they were using began to float away, causing Webb to stop and help put the children inside. Police say Webb was able to successfully get his grandson into the boat, but while helping his granddaughter he went under the water and did not reemerge.Webb was the current Carbon Drawdown Coordinator for Shelburne Farms, according to a release issued by the organization. "Marshall was a passionate believer in the mission of Shelburne Farms, cherished its woodlands and trails, and as our Carbon Drawdown Coordinator, was tirelessly dedicated to addressing global climate change for the future of his children and grandchildren," Shelburne Farms' leadership team said in a statement. "He was a force and a fixture at Shelburne Farms; we will miss him greatly."Police are awaiting the results of an autopsy to determine cause of death, but believe it could have stemmed from a medical emergency.