2005-2006 Assessment of Fish and Macroinvertebrates Communities of the Tualatin River Basin, August 2006

Biological monitoring with fish and macroinvertebrate communities is widely used to determine the ecological integrity of surface waters. Such surveys directly assess the status of surface waters relative to the primary goal of the Clean Water Act and provide information valuable to water quality planning and management. As such, fish and macroinvertebrate communities are periodically assessed by Clean Water Services to assist with water quality management in the Tualatin River basin. 

Fish and macroinvertebrate communities, physical habitat, and water chemistry were sampled in streams throughout the Tualatin River basin in fall 2005 to determine current ecological conditions of streams within the watershed. Fish communities were sampled again in spring 2006 to examine seasonal changes in fish community conditions. Sampling sites were selected to correspond with sites sampled in previous fish and macroinvertebrate surveys performed between 1999 and 2001. In fall 2005, fish communities were assessed in 64 stream reaches, while macroinvertebrate communities were assessed in 63 reaches. Fish and macroinvertebrate sampling occurred in the same reach at 29 locations.