During December 1983 and early January 1984, about 200 Canada geese (Branta canadensis) died of lead poisoning at Parker River National Wildlife Refuge on Plum Island, Massachusetts. In an effort to determine the source of lead, 100 bottom samples were taken from a refuge impoundment where much of the mortality/morbidity occurred. An average of 157,150 pellets/ha was found with a range of 64,582 to 322,910 pellets/ha. Water levels in this impoundment were low when Canada geese arrived, making shot more readily available to the geese and contributing to the outbreak. To minimize the risk of Canada geese being exposed to lead shot poisoning at this location in the future, we recommend several corrective manipulations of habitat.