Missouri Water Science Center
Study Area Locations. Image links to larger photo.
Study Area Locations.Image links to larger photo.
Exploration study area and location of the approximately 300 lead-zinc exploration boreholes near Winona, Missouri
In response to diminishing economic ore reserves in the Viburnum Trend, exploration for new sources of lead-zinc ore began in an area south of Winona, Missouri, and north of the Eleven Point River. Much of the exploration drilling is in the Mark Twain National Forest, which is managed by the U.S. Department of Agriculture, Forest Service (FS) and U.S. Department of Interior, Bureau of Land Management (BLM).
The exploration area is within a region highly valued for its scenic beauty and recreational opportunities, including two federally designated scenic rivers that are visited annually by more than 2 million people: the Ozark National Scenic Riverways (ONSR) administered by the National Park Service (NPS); and the Eleven Point National Scenic River (EPNSR) administered by the FS.
Photograph of Big Spring, the largest spring in Missouri.
There is concern that mine dewatering in the exploration area could substantially lower ground-water levels and, thereby, decrease the discharge of the many springs in the area. Also, mining-related support activities could potentially degrade the quality of ground and surface water in the area and threaten aquatic biota by introducing lead and other heavy metals into stream and spring sediments. Of particular concern is the possibility that lead-zinc mining in the new exploration area could adversely affect the flow and quality of water at Big Spring and Greer Spring. Dye-trace data indicate the recharge area of Big Spring (the largest spring in Missouri and part of the ONSR) encompasses much of the exploration area. Greer Spring (the second largest spring in Missouri and part of the EPNSR) is only a few miles south of the area of most intense exploration drilling.
Because of the many environmental concerns associated with potential lead-zinc mining in the new exploration area, the FS, BLM, and U.S. Geological Survey (USGS) have supported several investigations since 1988 designed to quantify background physical and chemical characteristics of ground, surface, and spring water and sediment; assess aquifer and confining unit hydraulic properties; study background concentrations of trace elements in aquatic biota; and provide geological mapping to establish a geohydrologic framework in the exploration area. Additional financial support has been provided by the U.S. Congress since 2000 to conduct more thorough investigations of the potential effects of mining on the environment of the exploration area, and the effect of current mining and mining-related activities on the environment in the Viburnum Trend area.
For more information contact:
David C. Smith, Hydrologist
U.S. Geological Survey
Missouri Water Science Center
1400 Independence Rd., MS 100
Rolla, MO 65401
Telephone: (573) 308-3675