Four distinct types of cool-water areas were located during this midsummer survey of Thrash Creek, Washington, a warm, fifth-order stream. These areas were termed lateral seeps, pool bottom seeps, cold tributary mouths and flow through the bed, depending upon the entry point and source of the cool water. These types differed with respect to average size, depth and location in the stream channel. Temperatures in the cool water areas averaged 4.7°C lower than ambient streamwater on warm afternoons. Thirty-nine such spots were found on a 3.5 km reach of the study stream. They accounted for 1.6% of the surface area and 2.9% of the water volume on this stretch of stream.