To date, the Laboratory's Environmental Restoration Project has not collected samples from the canyon itself, although monitoring wells have been or will be installed as part of the groundwater management and protection program. After the fire, samples of sediments, surface water, and groundwater were collected to establish a baseline prior to any potential flood events. Although no sources of contamination originate within Water Canyon itself, contaminants are known to have been transported from mesa-top TAs through discharges and surface erosion. Most contaminants released into the canyon were retained in sediments deposited in geomorphic locations in the active and inactive channels and floodplains. These contaminants will remain in place for varying time periods, depending on their locations and surface water flow patterns.
Sediment transport decreases the contaminant concentrations as the canyon extends downstream.
Laboratory environmental surveillance reports show that contaminant concentrations from samples collected at the point where State Highway 4 crosses Water Canyon are not elevated. Current knowledge of contaminants in Water Canyon is limited. TA-16 that enter Water Canyon were characterized during investigation activities and none of these is highly contaminated. None of these PRSs is a major source of contamination for Water Canyon. Very few PRSs drain directly into Water Canyon.