 Thermographs at several locations on Johnson Creek in 1992 recorded maximum average weekly water temperatures higher than in June, July, and August, and an absolute maximum temperature of .Studies conducted by DEQ, USGS, the City of Gresham, and other public agencies have identified DDT (dichloro-diphenyl-trichloroethane), dieldrin, polychlorinated biphenyls (PCB), chlordane, and polycyclic aromatic hydrocarbons (PAH) as carcinogenic pollutants of Johnson Creek.The creek has been classified as a "waterbody of concern" by the DEQ because of elevated levels of copper, chromium, and nickel in water and sediments.