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Surface and Groundwater Characterization <br /> May Day Idaho Mine Complex <br /> La Plata County, Colorado <br /> January 19, 2017 <br /> 1.0 INTRODUCTION <br /> The May Day Idaho Mine Complex is located in the southern portion of the San Juan Mountain <br /> approximately 15 miles west of Durango, Colorado. The OPERATOR plans to operate a gold <br /> (Au) and silver(Ag)underground mine with the intention of commencing mining in 2017 <br /> pending the receipt of all necessary permits and authorization. One major environmental study <br /> that has been ongoing since 2007 is the baseline characterization of surface and groundwater <br /> resources associated with the 274 acre mine permit boundary. The following provides an <br /> overview of the mining district and a site water resource assessment. <br /> 2.0 BACKGROUND <br /> In 1874, a few cabins of Parrott City, later renamed Mayday, were one of a handful of <br /> scattered settlements in the La Plata Mountains a sub-area of the San Juan Mountains. Mayday <br /> is the entry to the La Plata mining district,also referred to as the California Mining District <br /> (Figure 1). This District is famous for epithermal Au-Ag telluride mineralization,but also has <br /> been mined for base-metal deposits some of which contain platinum-group elements(Eckel, <br /> 1933, 1949; Werle, 1983; Werle and others, 1984). <br /> Metal mining in the La Plata Mountains dates back to the middle of the 18th century when <br /> Escalante's expedition of 1776 discovered workings from earlier Spanish mining efforts (Bancroft, <br /> 1890). The first recorded discovery of ore deposits in the district was in 1873 when placer gold <br /> was discovered in the La Plata River, along with what was named the Comstock Lode. <br /> Gold-placer deposits never yielded significant rewards, but hundreds of lo�Ydl claims were filed <br /> in 1875 with the discovery of silver-gold deposits in the district (Petre, 1898; Eckel, 1949). <br /> Significant metal production in the LaPlata Mountains was realized mostly between 1900 and <br /> 1940 (Eckel, 1949)with the discovery of economic deposits at several mines: the subject May <br /> Day-Idaho as well as the Neglected,Gold King, Incas, and Red Arrow. <br /> It is estimated that the May Day Idaho Mine complex produced over two thirds of the total <br /> production in the district with the May Day Idaho mine complex accounting for about half the <br /> total wealth generated (Eckel, 1949). Total recorded production from the La Plata district <br /> t h r o u g h 19 4 9 was about 213,000 ounces of gold, 2,03 5,000 of silver, 296,000 pounds of <br /> copper, 738,000 pounds of lead, and 8,000 pounds of zinc (Eckel, 1949; Vanderwilt, 1947,Del <br /> Rio, 1960 summarized by Neubert, 1992). Other productive mines were later developed, <br /> May Day Idaho Mine Complex <br /> M-1981-185 <br /> January 19, 2017 <br /> Page I -4- <br />