Contaminated Wetlands Restoration

The majority of wetland habitat in the lower Coeur d’Alene Basin contains mining related waste materials, including lead at levels known to kill waterfowl. Our office has the primary responsibility for conducting evaluation and restoration at the Mike and Brenda Schlepp farm, which will provide clean/safe feeding habitat for thousands of migrating waterfowl.

As late as the 1880s, the 1,500-square mile Coeur d'Alene Basin was rich with fish and wildlife. The basin had abundant evergreen forests, cottonwoods and silver beeches and was home to a wide range of wildlife, including numerous bird species. During the next 120 years those conditions changed.

Discovery of gold in the Coeur d'Alene River's North Fork in 1883 attracted thousands of prospectors and their families. While the gold rush was short-lived, the upper basin became the largest historic silver, lead and zinc mining district in the world, ultimately producing 7 million metric tons of lead, 30,000 metric tons of silver and 3 million metric tons of zinc. Impacts soon followed: mining wastes, including arsenic, cadmium, lead and zinc, were discharged directly into the river and its tributaries or were deposited on land, migrating into ground and surface water. The Coeur d'Alene River carried these contaminants west into Coeur d'Alene Lake and into adjacent wetlands, and occasional river flooding deposited contaminated sediment throughout the 19,200 acre lower Basin floodplain. More than 100 million tons of soil and sediment were impacted by mining and milling operations. Remaining waste rock, tailings, mine drainage, and contaminated floodplain sediments continue to supply the ecosystem with extremely elevated metals contamination.

Significant numbers of waterfowl deaths have been recorded in the Coeur d’Alene Basin for decades. This project, part of the interim Coeur d’Alene Basin Superfund cleanup plan, will reduce their exposure to toxic levels of heavy metals. It is the first project of its kind in the Basin, and will be a showcase for similar wetland projects through the Superfund and Natural Resource Damage Assessment process throughout the Basin.

Local waterfowl are exposed to lead by ingestion of contaminated sediment while they feed on the roots of wetland vegetation. Biologists have documented this as the cause of death in more than 10 waterfowl species, and the primary cause of death in tundra swans using wetlands in the Basin as feeding habitat. Tundra swan deaths have been documented since 1924, and continue today. Spring migration deaths, due to lead poisoning averaged 150 per year between 1981-2004. A population model developed to convert Basin tundra swan mortality to lost swan-years (based on a life span of 25 years, and lost first-year progeny) estimates that 40,000 swan years were lost between 1981 and 2004, with future mortalities expected to continue.

Many partners cooperated to make the first stage of this project happen. The key partners are the property owners (Mike and Brenda Schlepp) , Environmental Protection Agency, U.S. Fish and Wildlife Service (FWS), and Ducks Unlimited, Inc. The cleanup work is being done under EPA’s 2002 Basin cleanup plan, using an innovative legal agreement. The U.S. Army Corps of Engineers did the construction through a contract with DG&S Company of Kingston, Idaho.

Now that the first stage of the project is complete, the Coeur d'Alene Basin Natural Resource Trustees, led by the FWS in coordination with Ducks Unlimited have begun wetland restoration. FWS and Ducks Unlimited will do the restoration work, and FWS will coordinate maintenance of the site over the long term under the Trustees’ 2007 Coeur d'Alene Basin Final Interim Restoration Plan.

The 2007 construction was done using settlement and Asarco Trust monies. Future restoration work will also use Asarco Trust monies and Natural Resource Damage Assessment settlement funds.