Although mineral hazards are generally not well established in the public consciousness compared to other natural hazards, they can adversely affect public health and safety and the environment. The term “mineral hazards,” as used here, includes certain naturally occurring earth materials and sites of man-made activities related to them, such as mining and oil drilling. Since the 1990s, the California Geological Survey has conducted many studies of mineral hazards in California in response to an increasing number of requests from government agencies, private industry, and the public. These studies have focused mostly on naturally occurring asbestos, radon, and various metals, such as mercury and cadmium. The mineral-hazard maps and companion reports produced from these studies are typically at statewide and regional scales. They are designed for use by nongeoscientists and geoscientists alike in an effort to educate these groups about mineral hazards and to help in mitigation of those hazards. These products indicate the likelihood of the occurrence of a mineral hazard at a given location, but not the associated health risk. Geographic information systems (GIS) are used to manage and analyze data, and to design the maps. The variety of products developed ranges from traditional paper maps to thematic digital layers for use in a GIS. This range of products increases the likelihood that a greater number of people will use the information. The maps and reports have been used in many applications, and additional applications await development as awareness of mineral hazards and the need for mitigation of them increase.

Abstract Vulnerability assessments of the potential for asbestos contamination in public water supplies provide a basis for states to grant waivers from compliance monitoring requirements of public water supply systems if they can demonstrate they are not vulnerable under final U.S. Environmental Protection Agency (EPA) rulings published in the Federal Register. Land area of geologic units of North Carolina as represented on the 1:500,000-scale state geologic map in digital format and published geologic maps provide the technical basis for waivers for compliance monitoring and associated expensive analytical laboratory testing. These data show that only 3.68% of North Carolina’s land area of 18,790 square km (48,666 square mi) is underlain by rocks that are potentially hosts for asbestiform minerals. We assumed the EPA would follow the initiative of the Occupational Safety and Health Administration (OSHA) and remove nonasbestiform anthophyllite, tremolite, and actinolite from inclusion in the definition of asbestos. We concluded that the portion of North Carolina likely to contain any chrysotile asbestos would be reduced to 0.77% of land area. Ultramafic rocks that have a higher probability of chrysotile occurrences comprise only 0.07%, or 33.8 square mi of land surface in North Carolina. With additional investigation to delineate watersheds in which chrysotile susceptible rocks occur, the regulatory agency exempted 73 of North Carolina’s 100 counties from asbestos testing of surface water supply intakes. Sixty-eight percent (3,493) of the state’s surface water supply intakes were exempted from unnecessary testing, saving taxpayers at least $368,000; this is about one-third of the North Carolina Geological Survey’s annual appropriated budget. Author staff time to perform the work leading to the conclusion was about two person-weeks at a taxpayer cost of about $2,000.