In turbid wadeable reaches and in nonwadeable reaches, a sample of the substrate is obtained by using an appropriate device such as a shovel, Ponar sampler, or Ekman dredge. In turbid wadeable reaches and in nonwadeable reaches, the presence of boulders and bedrock cannot be determined by sampling. However, in turbid wadeable reaches, the presence of these substrate types can be determined by touch. In nonwadeable reaches where sampling devices cannot yield a substrate sample, acoustic recor ding of the stream bottom along the transect can detect boulders and bedrock.