Jesuit mission time capsule for Silver Valley

A Jesuit mission built in 1848 on the banks of the Coeur d’Alene River in northern Idaho is helping scientists understand what the natural levels of lead and zinc were prior to mining.

The discovery of the Cataldo mission is being viewed with interest because the U.S. Environmental Protection Agency (EPA) is in the process of setting up clean-up stands for the area as part of a basin-wide Superfund effort.

The Coeur d’Alene district was an active mining camp for much of this century, with silver being the main commodity of interest, though the deposits also contained appreciable amounts of lead and zinc.

The discovery of the old mission is also of interest to the last four mining companies active in the region. The federal government had previously filed suit against these companies under the Natural Resources Damage Assessment (NRDA). The amount of damages sought is about US$600 million; however, if the concerns of local native groups are taken into account, this could rise to US$1 billion. One of the companies obtained core samples from the original adobe brick, which were tested at an independent lab. The lead content in the pre-mining mud was found to be 1,490 parts per million (ppm). The EPA currently takes action at levels above 1,000 ppm and prefers lead levels to be under 400 ppm in soils in residential areas.

The discovery sparked controversy in mining circles because the EPA has ignored the new information and continues to reaffirm its official position that natural background levels of metals were very low. However, Idaho’s Department of Environment has since initiated a follow-up study.