The Oregon state water quality standard provides that a single sample shall not exceed 406 E.coli colonies/100 mL of water and the geometric mean of 5 samples within 30 days shall not exceed 126 colonies/100 mL. The EPA recommended standard is more protective and provides that a single sample shall not exceed 235 colonies/100mL and the geometric mean of 5 samples within 30 days shall not exceed 126 colonies/100mL. The Swim Guide will utilize the EPA standard for Oregon beaches.

There is currently very limited water quality monitoring of Oregon's inland swim beaches. The federal Beach Act does not cover freshwater or riverine beaches, and the state of Oregon does not monitor swim beaches or recreation sites on the Columbia. Columbia Riverkeeper monitors recreation sites in the Columbia River Gorge through their Volunteer Water Quality Monitoring Program. Most sites are sampled monthly and high priority sites are sampled weekly from June-September.

The Swim Guide's safety ratings are based solely on E.coli levels. While E.coli concentration is a useful indicator of fecal contamination, there are many other potential sources of pollution that are not reflected in the Swim Guide. These include other bacteria, heavy metals, pharmaceuticals, and pesticides that may harm aquatic life. On the Columbia and other salmon rivers, high temperatures threaten fish that need cold water. If you are interested in getting involved or learning more about the Columbia River, visit <A HREF="http://www.columbiariverkeeper.org">www.columbiariverkeeper.org</A>.