It’s the water. Of all the features that combine to make the Metolius unique – the ponderosa and tamarack forest, the wildlife, the surrounding mountains, the region’s history, the quiet – it is the spring fed clarity and beauty of the river itself that ultimately defines the region. Working to maintain the quality of the water is at the heart of Friends’ mission.

Water Quality Analysis

Invertebrate Study

The goal of this study was to collect benthic macroinvertebrate samples from multiple sites on the Metolius River and tributaries to gather data that describe the ecological condition (structure and function) of the macroinvertebrate community.
 
The condition of the macroinvertebrate community will contribute to an understanding of the overall health of the Metolius River and provide baseline data that can be valuable in identifying future changes in water quality and/or habitat quality that could occur from natural changes like climate change and wildfires or from human impacts like increased recreational use, population growth or other activities within the watershed.
 
The full report can be found here, and the detailed Excel spreadsheet that includes granular data from the study can be found here.

Friends completed a multi-year study, analysis, and report on Metolius River water quality in 2014. Bottom line – the water is second in terms of overall quality in Oregon only to stretches of the Grand Ronde River in the northeast corner of the state.

Friends contracted with  Geosyntec Associates  in Portland to analyze and report on water quality data gathered over the last two decades by groups including:

Friends of the Metolius
Friends in collaboration with US Forest Service
Oregon Department of Environmental Quality
The Confederated Tribes of Warm Springs
US Geological Survey
Portland General Electric
US Department of Agriculture

Analysis of data was across multiple sites along the length of the river, over two decades, and looked at a variety of water quality factors including levels of E. coli, nitrates, phosphorous, pH, turbidity, and dissolved oxygen. No critical trends were discovered, although levels of phosphorous and nitrates did occasionally rise above regional standard levels – likely attributable to local geology.

The database on which the analysis was done excluding precipitation data and recent Oregon DEQ data has been available online and updated over the past years via an interactive map on this site (below). We are excited to add to our website a summary version of the report completed by Geosyntec and, for those with the technical background in water quality analysis and the related statistics, a complete copy of the report and related spreadsheet data. Public agencies with an interest in maintaining the pristine quality of the river will find this an invaluable baseline tool going forward.

Summary of Geosyntec Report
Complete Geosyntec Report

(12 mb – includes report, appendices, and maps
in a zipped file)
Spreadsheet file on which Geosyntec analysis is based

(1 mb – in a zipped file)
Interactive Metolius Basin Map – Water Testing

(updated January, 2026)