The Lame Deer Creek watershed of the Northern Cheyenne Reservation in southeastern Montana encompasses about 82 square miles and is home to the community of Lame Deer. Local water resources within the Lame Deer Creek watershed include Lame Deer Creek and groundwater within unconsolidated sediments and bedrock aquifers. In 2017 the U.S. Geological Survey, in cooperation with the Northern Cheyenne Environmental Office, began conducting a multi-phase study. The objectives of this study are to assess the surface-water and groundwater resources within the watershed with an emphasis on the occurrence of water-quality constituents of human-health concern.