THE DIRT: EPA conducting waterfowl survey

The Environmental Protection Agency, in collaboration with wildlife management staff from state, federal and tribal organizations, is conducting a study to develop tools for monitoring waterfowl health and exposure to lead contamination in the Lower Coeur d’Alene River Basin. The team includes scientists from the U.S. Fish and Wildlife Service, the Coeur d’Alene Tribe, Idaho Fish and Game, the U.S. Geological Survey and EPA. The study aims to assess the effectiveness of remediation and restoration efforts by tracking changes with new biomonitoring tools.

Tundra swans migrating between California and Alaska stop in the Coeur d’Alene Basin each spring. While foraging in contaminated wetlands for food buried in the sediment, they incidentally ingest toxic levels of lead from the sediment. Wood ducks, a species that nests in the Basin, are also vulnerable to lead ingestion while foraging for insects and submerged plants. Lead exposure results from the ingestion of sediments contaminated by historic mine tailings that were once discharged directly into waterways by mining companies operating in the Silver Valley. This practice spread contaminants throughout the Lower Basin of the Coeur d’Alene River. Despite changes in mining practices, previously discharged toxic sediments remain accessible to waterfowl throughout most of their habitat.

The number of tundra swan deaths fluctuates annually. In 2022, 388 swans were found dead, likely due to lead exposure from prolonged stays in the contaminated Basin. The swans may have been more vulnerable to exposure than in previous years due to a greater need for food after encountering limited feeding habitats in California from drought. Furthermore, feeding habitats in the Basin were also limited due to ice, forcing them to feed in areas with heightened risks for exposure to contaminated sediments. While the continental swan population remains stable, ongoing efforts aim to reduce lead exposure to improve swan health.

Field teams are collecting and testing blood and feces from trapped birds while also monitoring exposure by placing GPS or radio collars on swans and wood ducks. Scientists will also collect and analyze samples from additional waterfowl, invertebrates, sediment and water across wetlands, ranging from clean areas in the St. Joe River watershed to heavily contaminated sites in the Coeur d’Alene River Basin. Sampling will continue through mid-March 2025 for swans and from late March through June for wood ducks.

A key goal of the study is to develop noninvasive biomonitoring methods to measure lead exposure. Rather than relying on expensive traditional blood sample measurements, which require specialized experience and extensive permitting, researchers are testing the use of fecal material and eggshells to assess aquatic waterfowl exposure to metals and track changes over time as remediation and restoration work create a clean habitat in the Lower Coeur d’Alene Basin. The study may also provide information to aid in future wetland cleanup efforts, ensuring that waterfowl are attracted to clean habitats rather than toxic ones. EPA and the Restoration Partnership are already working on projects such as Gray’s Meadow, where soil cleanup and habitat restoration are underway, with completion expected by the end of 2025.

Public involvement is encouraged. If individuals encounter a dead tundra swan or a wood duck with a neck collar or satellite transmitter, they are asked to report sightings to Idaho Fish and Game at 208-769-1414. The study findings will be made available to the public by the EPA when complete.

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The Dirt is a series of informative articles focused on all aspects of cleanup efforts associated with the Bunker Hill Superfund Site. Our goal is to promote community awareness of contamination issues, to provide tools for protecting public health, and to keep the community informed of current and future cleanup projects. The Dirt is a group of committed and local experts from multiple agencies, including the Basin Environmental Improvement Project Commission, Panhandle Health District, Shoshone County, Silver Valley Economic Development Corporation and the Idaho Department of Environmental Quality.