Abstract: The Tar Creek Superfund Site is a portion of the abandoned lead and zinc mining area known as the Tri-State Mining District (OK, KS and MO) and includes over 100 square kilometers of disturbed land surface and contaminated water resources in extreme northeastern Oklahoma. Underground mining from the 1890s through the 1960s degraded over 1000 surface hectares, and left nearly 50 km of tunnels, 165 million tons of processed mine waste materials (chat), 300 hectares of tailings impoundments and over 2600 open shafts and boreholes. Approximately 94 million cubic meters of contaminated water currently exist in underground voids. In 1979, metal-rich waters began to discharge into surface waters from natural springs, bore holes and mine shafts. Six communities are located within the boundaries of the Superfund site. Approximately 70% of the site is Native American owned. Subsidence and surface collapse hazards are of significant concern. The Tar Creek site was listed on the National Priorities List (NPL) in 1983 and currently receives a Hazard Ranking System score of 58.15, making Tar Creek the nation's number one NPL site. A 1993 Indian Health Service study demonstrated that 35% of children had blood lead levels above thresholds dangerous to human health. Recent remediation efforts have focused on excavation and replacement of contaminated residential areas. In January 2000, Governor Frank Keating's Tar Creek Task Force was created to take a “vital leadership role in identifying solutions and resources available to address” the myriad environmental problems. The principle final recommendation was the creation of a massive wetland and wildlife refuge to ecologically address health, safety, environmental, and aesthetic concerns. Additional interim measures included continuing the Task Force and subcommittees; study of mine drainage discharge and chat quality; construction of pilot treatment wetlands; mine shaft plugging; investigations of bioaccumulation issues; establishment of an authority to market and export chat, a local steering committee, and a GIS committee; and development of effective federal, state, tribal, and local partnerships.

Abstract: An experimental diversion of acid mine drainage was set up near an abandoned mine in Saint Kevin Gulch, Colorado. A mass-balance approach using natural tracers was used to estimate flows into Saint Kevin Gulch. The diversion system collected about 85 percent of the mine water during its first year of operation (1994). In the first 2 months after the diversion, benthic algae in an experimental reach (stream reach around which mine drainage was diverted) became more abundant as water quality improved (increase in pH, decrease in zinc concentrations) and substrate quality changed (decrease in rate of metal hydroxide deposition). Further increases in pH to levels above 4.6, however, led to lower algal biomass in subsequent years (1995-97). An increase in deposition of aluminum precipitates at pH greater than 4.6 may account for the suppression of algal biomass. The pH in the experimental reach was lower in 1998 and algal biomass increased. Mine drainage presents a complex, interactive set of stresses on stream ecosystems. These interactions need to be considered in remediation goals and plans.