The gold mine had not operated since 1928, and Coeur Alaska obtained a permit in 2005 from the United States Army Corps of Engineers (USACE) to dispose of up to 4.5 million tons of tailings in Lower Slate Lake, which is located in a National Forest.

In March 2009 proposed legislation, the Clean Water Protection Act, was introduced in Congress to remove mining waste from the definition of "fill material".

The permit allowed Coeur Alaska to dispose of 4.5 million tons of tailings from the Kensington gold mine, 45 mi (72 km) north of Juneau, into Lower Slate Lake.

In 2005 Coeur was granted a permit to dispose of tailings into Lower Slate Lake by the USACE under section 404 of the Clean Water Act.

The Circuit Court found in favor of the non-governmental organizations, ruling that discharge of tailings was not permitted under the EPA's New Source Performance Standard.

[3][5] The Supreme Court found in favor of Coeur Alaska by a vote of 6–3, agreeing that the USACE is indeed the appropriate body to issue a permit to discharge mine waste into Lower Slate Lake.

[3] The decision was praised by the National Mining Association, which stated that it would "provide employment and greater economic certainty for all those involved in the project".