Tundra swans are arriving by the hundreds at marshes along the Coeur d’Alene River, which provide resting and feeding stops during the swans’ annual migration to Arctic nesting grounds.
A pilot project currently underway south of Rose Lake, Idaho, could help protect the swans from lead poisoning from historic mining waste. The U.S. Environmental Protection Agency is testing a method for capping the heavy metals in the marshes through applications of thin layers of clean dirt. Depositing the dirt over several years allows wetland plants to grow up through the clean layers, said Kim Prestbo, a remedial project manager.
Eight test plots at Lane Marsh will be monitored to evaluate how effective the soil caps are and how they react to spring flooding, Prestbo said.
As tundra swans feed on roots and tubers, they swallow soil polluted with lead and other metals that washed downstream during a century of mining activity in the Coeur d’Alene River’s headwaters. At high enough levels, the lead shuts down the swans’ digestive systems, causing them to starve on full bellies.
Federal and state agencies are working on ways to provide clean feeding areas for the swans and other wildlife along the Coeur d’Alene River.