The purpose of this study is to document the depth and thickness of the White River Ash in lakes across the southwest Yukon for use in paleoenvironmental impact studies. Sediment cores were sampled from seven lakes located within the plume of the eastern lobe of the White River Ash (1147 cal. years BP). Site locations are between 92 and 254 km from Mount Churchill, Alaska, the probable source for the White River Ash. Based on magnetic susceptibility measurements, the depth of the sediment above the ash layer in the lakes ranges between 38 and 98 cm; these differences are due to factors associated with sedimentation rates. The thickness of the ash ranges between 0.1 and 32 cm and typically increases with proximity to the source vent. These results can be used in paleoenvironmental studies to assist in the interpretation of the impact of volcanic ash events.