Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
USGS Oklahoma Water Science Center Hydrologic Technicians Kyle Davis and Jim Wellman take water-quality measurements in a sinkhole in the abandoned Picher mining district of northeastern Oklahoma.
Public Domain.
