Crews will start constructing a road for the drill rig across the face of the southern embankment, followed this summer with the drilling of a series of holes to pull small samples from the dam’s foundation.

A focus of the exploration is to determine how the embankment could perform under a variety of conditions. According to USBR, the dam has been performing well for 30 years, and the upcoming work will help assure that the dam remains safe.

USBR’s regular agency-wide Safety of Dams programme provides an ongoing assessment of its dams and dikes in the 17 western US states. In addition to continual monitoring through inspections, drill sampling is conducted to allow USBR engineers to evaluate potential hazards using contemporary design and construction standards.