"This is an important milestone and a significant win for aquatic species, wildlife species, and humans that depend on water from Railroad Creek and Lake Chelan," Wier said Monday.
The Holden Mine operated from 1938 to 1957, extracting copper, zinc, gold and silver. It was abandoned in 1957, but continued to contaminate the environment with toxic metals including aluminum, cadmium, copper, iron and zinc.
The metals also created a hazardous, hard orange coating on the creek's streambed. Unstable waste rock and tailings piles from about 10 million tons of mined ore further compounded the problem, the U.S. Forest Service said.
The cleanup took five years and was paid for by the Australian-British Rio Tinto Group mining company. No taxpayer funds were used, the Forest Service said.
As part of the project, a 30-to-90 foot (9-to-27 meters) concrete barrier wall was erected between toxic mine tailings piles and Railroad Creek to prevent runoff. Thousands of gallons of contaminated ground water are also treated daily at a plant on the site.
Pollution from the mine is now "controlled for future generations," said Mike Steele, a Republican state lawmaker from the resort community of Chelan alongside the lake.
The cleanup spending sent about $240 million into the local economies because much of the work was performed by people and businesses in the area, the Forest Service said.
Native trees and shrubs will be planted this year atop former mine waste rock and tailing piles.
by: NICHOLAS K. GERANIOS, Associated Press Updated: May 2, 2017