2007 Assessment Macroinvertebrates Communities of the Tualatin River Basin, September 2008

Clean Water Services (District) is committed to protecting water resources of the Tualatin River basin. As part of this commitment, the District periodically performs assessments of the status of macroinvertebrate communities in rivers and streams of the watershed to better inform water quality planning and management decision making. In 2007, the District began performing bi-annual macroinvertebrate assessments at approximately 20 monitoring stations. 

This monitoring is in support of the District ’s efforts to track long-term trends in benthic community conditions in more than 60 stream and river reaches that have been monitored since 2001 (Clean Water Services 2006). The objective of the present study was to determine the current condition of macroinvertebrate communities in 20 stream reaches within the Tualatin River basin and compare these present conditions to those measured in previous investigations of these reaches. Study sites included 12 low-gradient reaches and 8 high-gradient reaches.