Approximate Locations of Mills Related to the Comstock Mining Area Click Map To Expand View

The State of Nevada’s Division of Environmental Protection (NDEP), supported by the United States Environmental Protection Agency (EPA), has begun a new phase of the mercury contamination investigation associated with historic Comstock Lode gold and silver mining in the Carson River and Washoe Lake watersheds.

NDEP has contracted with archaeologists to characterize gold and silver millsites that were active during the Comstock (1859-1900). The milling process concentrated naturally-occurring arsenic and lead, and also added mercury to the ore to separate gold and silver from the native rock.

In the intervening century since the mills were active, wind and water have eroded and redistributed these contaminants to soil and water courses, as well as stream, river, lake and floodplain sediments. Original mill site locations are still potential hot spots for mercury, arsenic and lead contamination; therefore, it is important to know exactly where each former mill site was located.

The original Carson River Mercury Superfund Site investigation in the 1990's identified over 130 mill sites and that list has now grown to almost 250. Some of these mill site locations are well established, but the locations of many others are less certain. Since these mill sites are the source for the mercury, arsenic and lead contamination, it is important to know as much about the geographic location, nature, and history of each mill site as possible.

The first step in the process will be a comprehensive archaeological inventory of all Comstock-era mill sites. The inventory will include an accurate description of each mill, the mill’s precise geographic location, physical remains, and processing history. The NDEP has retained the services of archaeologists to review historic records, document mill site histories and ultimately conduct field work to identify the location and what remains of each mill site on the ground surface. Areas to be investigated are shown on the map above.

Read More — Download Carson River Mercury Superfund Site FACT SHEET — Archaeological Studies of Historic Mill Sites.