Primary injury: Loss of Chinook salmon and steelhead habitat.

The Blackbird Mine is an inactive mine site located in the Panther Creek drainage, a major tributary of the Salmon River in east-central Idaho. Active mining, primarily of copper and cobalt, first began in the 1890s and continued intermittently until the late 1960s. The mine site includes approximately 10 miles of underground workings on 12 different levels, an 11-acre open pit, 2 million cubic yards of mill tailings, and 4.8 million cubic yards of waste rock.

Studies from the last 25 years documented releases of hazardous substances from the mine site, including cobalt, copper, nickel, and zinc. The Panther Creek drainage contains approximately 400 miles of perennial streams, including nearly 100 miles of streams suitable for anadromous fishes. Highly contaminated discharge from the mine directly affected habitat in the lower 25 miles of Panther Creek and presented a barrier to fish passage that blocked access to upstream habitat.

Injury Assessment

In support of litigation, the Trustees conducted an injury assessment to evaluate the biological impact of releases from the Blackbird Mine. Injury was quantified by comparing the quality and quantity of the resources relative to baseline, where baseline is defined as the condition of the resource but for the discharge. Field sampling showed that acute and chronic federal ambient water quality criteria were exceeded for concentrations of copper, and the federal ambient water quality advisory for cobalt concentrations was also exceeded. Sediments and streambed fauna downstream of the mine releases contained higher concentrations of arsenic, cobalt, and copper than upstream reference areas. Stations downstream of the mine showed dramatic reductions in biomass and species composition of streambed fauna, indicative of impacts due to metals exposure.

Laboratory bioassay studies determined that copper and cobalt are acutely lethal to trout at concentrations less than those concentrations measured in Panther Creek; that copper concentrations lower than those measured in the creek caused significantly reduced growth in rainbow trout fry; that copper bioaccumulated in rainbow trout fry at concentrations lower than those measured in the creek; and that rainbow trout fry avoided copper concentrations lower than those measured in the creek.

Overall, the studies showed that salmonids in the Panther Creek drainage are injured by hazardous substances released from the Blackbird Mine site. Copper concentrations in Blackbird, Big Deer, and Panther Creeks continually exceeded concentrations shown to cause harmful effects in the toxicity studies.

Remedial Process

NOAA, in association with the other Trustees, is working closely with EPA to ensure a coordinated, cost effective remediation strategy. Successes over the past several years include:

• the water treatment plant has been upgraded
• mine tailings have been removed or sequestered
• water diversions have been completed
• contaminated sediments were removed from streams
• sediment retention dams were constructed

Studies have been conducted to identify and determine appropriate treatment for previously undetected contaminant sources, and to determine water quality objectives for cobalt concentrations that will be protective of aquatic life.