Geology topics

David Lawler

Publications and source records attributed to David Lawler.

2 recordsLinked to original sources

USGS2009

Environmental Impact of the Contact and Sonoma Mercury Mines on Water, Sediment, and Biota in Anna Belcher and Little Sulphur Creek Watersheds, Sonoma County, California

The Contact and Sonoma mercury (Hg) deposits are among the youngest Hg deposits in the Coast Range Hg mineral belt and are located in the western part of the Clear Lake volcanic field in Sonoma County, California. The mine workings and tailings are located in the headwaters of Anna Belcher Creek, which is a tributary to Little Sulphur Creek. The Contact Hg mine produced about 1,000 flasks of Hg, and the Sonoma mine produced considerably less. Waste rock and tailings eroded from the Contact and Sonoma mines have contributed Hg-enriched mine waste material to the headwaters of Anna Belcher Creek. The mines are located on federal land managed by the U.S. Bureau of Land Management (USBLM). The USBLM requested that the U.S. Geological Survey (USGS) measure and characterize Hg and other geochemical constituents in tailings, sediment, water, and biota at the Contact and Sonoma mines and in Anna Belcher and Little Sulphur Creeks. This report is made in response to the USBLM request, the lead agency mandated to conduct a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) - Removal Site Investigation (RSI). The RSI applies to removal of Hg-contaminated mine waste from the Contact and Sonoma mines as a means of reducing Hg transport to Anna Belcher and Little Sulphur Creeks. This report summarizes data obtained from field sampling of mine tailings, waste rock, sediment, and water at the Contact and Sonoma mines that was initiated on April 20 during a storm event, and on June 19, 2001. Further sampling of water, sediment, and biota in a pond and tributaries that drain from the mine area was completed on April 1, 2003. Our results permit a preliminary assessment of the mining sources of Hg and associated chemical constituents that could elevate levels of monomethyl Hg (MMeHg) in tributaries and biota that are impacted by historic mining.

Open-File Report↗

USGS2009

Environmental Impact of the Helen, Research, and Chicago Mercury Mines on Water, Sediment, and Biota in the Upper Dry Creek Watershed, Lake County, California

The Helen, Research, and Chicago mercury (Hg) deposits are among the youngest Hg deposits in the Coast Range Hg mineral belt and are located in the southwestern part of the Clear Lake volcanic field in Lake County, California. The mine workings and tailings are located in the headwaters of Dry Creek. The Helen Hg mine is the largest mine in the watershed having produced about 7,600 flasks of Hg. The Chicago and Research Hg mines produced only a small amount of Hg, less than 30 flasks. Waste rock and tailings have eroded from the mines, and mine drainage from the Helen and Research mines contributes Hg-enriched mine wastes to the headwaters of Dry Creek and contaminate the creek further downstream. The mines are located on federal land managed by the U.S. Bureau of Land Management (USBLM). The USBLM requested that the U.S. Geological Survey (USGS) measure and characterize Hg and geochemical constituents in tailings, sediment, water, and biota at the Helen, Research, and Chicago mines and in Dry Creek. This report is made in response to the USBLM request to conduct a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA - Removal Site Investigation (RSI). The RSI applies to removal of Hg-contaminated mine waste from the Helen, Research, and Chicago mines as a means of reducing Hg transport to Dry Creek. This report summarizes data obtained from field sampling of mine tailings, waste rock, sediment, and water at the Helen, Research, and Chicago mines on April 19, 2001, during a storm event. Further sampling of water, sediment, and biota at the Helen mine area and the upper part of Dry Creek was completed on July 15, 2003, during low-flow conditions. Our results permit a preliminary assessment of the mining sources of Hg and associated chemical constituents that could elevate levels of monomethyl Hg (MMeHg) in the water, sediment, and biota that are impacted by historic mining.

Open-File Report↗