The National Academy of Sciences will review the water quality conditions of Lake Coeur d’Alene over the next year and a half.

The NAS was contracted by the Idaho Department of Environmental Quality to analyze the available data and information on the lake’s water quality. From there the NAS plans to determine future water quality conditions of the lake.

The Kootenai County Board of Commissioners contributed $200,000 last year to the NAS with the hopes of identifying areas of concern within the lake.

The study has also been endorsed by the Coeur d’Alene Tribe and the EPA has suggested at potentially financially supporting the study.

The study will not include recommended remedial action. The study will overview the impacts of historical mining operations in the Coeur d’Alene River basin. The operations deposited an estimated seventy-five million tons of metals-contaminated sediment. This includes zinc, cadmium and lead which has been deposited into Lake Coeur d’Alene and its tributaries.

The toxic metals are currently settled on the lakebed but they metals could be release under hypoxic conditions according to a press release from the IDEQ. Hypoxic conditions could be a result of a water environment being low in dissolved oxygen.

It has been determined that oxygen levels in the lake may be altered due to the increase nutrients loads related to development and land use changes around the lake.

The NAS plans to evaluate the water quality of the lake and its lower rivers with a focus on trends in nutrient loading and metal concentrations. They plan to also consider how those trends can be affected by the change in temperature, precipitation and streamflow.

NAS will also examine the impacts of current summer time anoxia on the fates of the metals and nutrients and whether the reduced levels of zinc entering the lake as the result of the upgrade to the Central Treatment Plant are removing important control of algal growth.

NAS will discuss if the metals found in the lake sediments will continue to be released into the lake if current trends continue.

If sufficient data is not available as a result of the studies, the NAS will identify additional data required to achieve an appropriate level of confidence in the study.

The NAS will also discuss the relevance of the materials in the lake and how they impact human health as well as the ecological health of the lake.

In 1983 the areas of the Coeur d’Alene basin that were affected by the historic mining operations were listed as a priority Superfund Site by the EPA.

Prior to the NAS study, the basic strategy to prevent metals from releasing from the lakebed was to limit basin-wide nutrient inputs to the lake as well as the acceleration of the eutrophication process which occurs due to human activity and land use.

For more information on the NAS study, contact IDEQ Coeur d’Alene Lake Management Supervisor, Jamie Brunner at 208-946-0174.

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