Abstract Historical production of metals in the western United States has left a legacy of acidic drainage and toxic metals in many mountain watersheds that are a potential threat to human and ecosystem health. Studies of the effects of historical mining on surface water chemistry and riparian habitat in the Animas River watershed have shown that cost-effective remediation of mine sites must be carefully planned. of the more than 5400 mine, mill, and prospect sites in the watershed, ∼80 sites account for more than 90% of the metal loads to the surface drainages. Much of the low pH water and some of the metal loads are the result of weathering of hydrothermally altered rock that has not been disturbed by historical mining. Some stream reaches in areas underlain by hydrothermally altered rock contained no aquatic life prior to mining. Scientific studies of the processes and metal-release pathways are necessary to develop effective remediation strategies, particularly in watersheds where there is little land available to build mine-waste repositories. Characterization of mine waste, development of runoff profiles, and evaluation of ground-water pathways all require rigorous study and are expensive upfront costs that land managers find difficult to justify. Tracer studies of water quality provide a detailed spatial analysis of processes affecting surface- and ground-water chemistry. Reactive transport models were used in conjunction with the best state-of-the-art engineering solutions to make informed and cost-effective remediation decisions. Remediation of 23% of the high-priority sites identified in the watershed has resulted in steady improvement in water quality. More than $12 million, most contributed by private entities, has been spent on remediation in the Animas River watershed. The recovery curve for aquatic life in the Animas River system will require further documentation and long-term monitoring to evaluate the effectiveness of remediation projects implemented.

Abstract The Vermont copper belt includes the Elizabeth mine in South Strafford, the Ely Mine in Vershire, and the Pike Hill mines in Corinth. Of these the Elizabeth mine operated over the longest period of time, produced the highest tonnage of copper and left the largest and most complex collection of historic resources. The Elizabeth mine site is complex and represents approximately 160 years of industrial activity from 1809 to 1958. It was the site of a major 19th century U.S. copperas manufacturing plant, and several important firsts in American copper smelting. It was the site of no less than nine copper ore smelting campaigns and multiple ore concentration milling phases. The extent of industrial operations encompassed hundreds of acres. The Elizabeth mine produced an estimated 4,726,800 kg (10,500,000 lbs) of copper before its World War II revival. During the subsequent campaign the mine became the largest and most productive copper mine in New England, and yielded another 41,502,495 kg (91,495,800 lbs) of copper. Briefly during the 1950s it was one of the top 20 U.S. copper producers. The unique copperas works remains and the World War II-era remains constitute one of the largest and least disturbed historic mining sites in New England. This landscape includes the only intact cluster of historic hard-rock metal-mine plant buildings in the region. The Ely mine orebody was discovered in 1813 and explored during the 1830s, but it was most active between the mid-1850s and about 1905. Mining began seriously in 1853 with the incorporation of the Vermont Copper Mining Company. For the next 13 years the ore was shipped to east coast smelters. The mine eventually came under the control of Smith Ely, for which it is named. In 1867 the company built its own smelter on the mine site. This plant was periodically expanded to become a massive mid-19th century nonferrous metallurgical works, more than 122 m (700 ft) long with 24 smelting furnaces. By the mid-1870s the town of Ely had become a mining boomtown and in 1883, the town was the site of the “Ely War” labor conflict. The Ely mine was the only copper mine in Vermont where all technological aspects of refined copper production, from mining of raw ore to smelting of refined ingot copper, were successfully integrated on a large scale. The site geography at the Ely mine dictated a confined, straight-line flow of materials and processes, and today the historic landscape expresses copper production in a linear, understandable way. Total copper output for the Vermont copper belt mines between 1793 and 1958 has been estimated at about 65.8 million kg (145 million lbs), with about 25 million kg (100 million lbs) from the Elizabeth mine, about 16 million kg (35 million lbs) from Ely and under 4.5 million kg (10 million lbs) from Pike Hill ( Abbott, 1964 ; Howard, 1969 ). In addition to their economic contribution, the Vermont copper belt mines also contributed to the historic legacy and landscape of New England. They have left unusual stories and sites that convey the drama and impact of hard rock mining, an industry not usually associated with New England.

Abstract The Gold King mine water release that occurred on 5 August 2015 near the historical mining community of Silverton, Colorado, highlights the environmental legacy that abandoned mines have on the environment. During reclamation efforts, a breach of collapsed workings at the Gold King mine sent 3 million gallons of acidic and metal-rich mine water into the upper Animas River, a tributary to the Colorado River basin. The Gold King mine is located in the scenic, western San Juan Mountains, a region renowned for its volcano-tectonic and gold-silver-base metal mineralization history. Prior to mining, acidic drainage from hydrothermally altered areas was a major source of metals and acidity to streams, and it continues to be so. In addition to abandoned hard rock metal mines, uranium mine waste poses a long-term storage and immobilization challenge in this area. Uranium resources are mined in the Colorado Plateau, which borders the San Juan Mountains on the west. Uranium processing and repository sites along the Animas River near Durango, Colorado, are a prime example of how the legacy of mining must be managed for the health and well-being of future generations. The San Juan Mountains are part of a geoenvironmental nexus where geology, mining, agriculture, recreation, and community issues converge. This trip will explore the geology, mining, and mine cleanup history in which a community-driven, watershed-based stakeholder process is an integral part. Research tools and historical data useful for understanding complex watersheds impacted by natural sources of metals and acidity overprinted by mining will also be discussed.