T15 Upper Feather River Dams Fault Exploration, Indian Creek Fault (ICF)

A geologic investigation is planned at T-15, a trench site on the Indian Creek Fault near Antelope Lake in the Mt. Hough Ranger District of California, to assess historical tectonic activity that may impact the long-term safety of Antelope Dam. The study aims to define the location and past behavior of the Indian Creek Fault approximately six miles upstream of the dam along Indian Creek through controlled excavation and subsurface analysis. Prior to trenching, preliminary subsurface exploration will be conducted using hand augers or post-hole tools to gather stratigraphic data, with all removed soil carefully retained on tarps and subsequently backfilled to restore the original ground conditions. The project is led by the California Department of Water Resources, with Leah Feigelson serving as the primary point of contact for engineering geology matters. The initiative is scheduled for execution in 2026, with the goal of informing dam safety evaluations based on refined understanding of regional fault history.