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U.S. Geological Survey U.S., Department of the Interior, House Committee on Natural Resources Subcommittee on Energy and Mineral Resources—Legislative Hearing

July 19, 2022

Chair Lowenthal and Ranking Member Stauber, thank you for this opportunity to provide the views of the U.S. Geological Survey (USGS) on H.R. 3681, the Sinkhole Mapping Act. The USGS has previously conducted sinkhole research via several projects, drawing on expertise from variety of programs within our Natural Hazards, Water, and Core Science Systems mission areas.

For example, in 2020 at the Sinkhole Conference at the University of South Florida, the USGS announced the publication of a comprehensive map of the karst topography of the conterminous United States, which are geologic regions that feature limestone and can be susceptible to sinkhole formation.1 This was a first-of-its-kind effort to map these structures at a nationwide scale. The USGS is undertaking limited research and mapping activities on sinkhole processes and hazards and the requirements of this bill are much more expansive. Development of reliable and routinely updated sinkhole hazard maps and assessments at the scales required in this bill to inform hazard avoidance and risk reduction would require the USGS to undertake a more expanded and sustained effort and would need to be achieved using existing resources that are currently committed for other purposes.


H.R. 3681, Sinkhole Mapping Act

H.R. 3681 directs the USGS to study the short- and long-term mechanisms of sinkholes and develop maps of sinkhole risk. These maps would be published online and updated at least once every five years.

As noted above, the USGS does have the expertise required to conduct this analysis related to sinkhole processes and hazards. For instance, the USGS is establishing Integrated Water Availability Assessments in select basins, which could contribute to improved understanding of sinkhole formation. However, the ability to develop maps, especially on five-year schedules, at the scales required to inform hazard avoidance and risk reduction would require a substantially expanded and sustained effort. Furthermore, unlike the national scale karst topography map produced in 2020, an operational program assessing hazards across the country would require many local scale efforts. Sinkholes are highly localized geologic processes, meaning that, while they can happen in many places, the triggers and dynamics in a particular area depend very much on aspects of the local geology. State geologists provide this local expertise. Some of this local scale work is already undertaken by state geologists, but the maps contemplated by H.R. 3681 would require substantial additional work.

The USGS appreciates the intent of the bill and recognizes the need to address sinkhole hazards. The program as envisioned in H.R. 3681 would, however, impact other priorities, including those authorized by the Energy of Act of 2020 and the Infrastructure Investment and Jobs Act of 2021. We would like to work with the bill’s sponsors to address these priorities without impacting other critical USGS work.


1 Daniel H. Doctor et. al, Progress Toward a Preliminary Karst Depression Density Map for the Conterminous United States, 16TH SINKHOLE CONFERENCE, UNIV. OF S. FLA., (May 2020),