The summary shows the total number of rule violations reported to EPA and the total number of public water systems that had one or more rule violations during 2015 for key groups of regulated contaminants.
Oregon has 2,600 public water systems statewide that are subject to the federal safe drinking water requirements. These include cities, water districts, manufactured housing communities, schools, parks, and campgrounds. The 54 largest municipal water systems serve 70% of the population, yet 90% of the total number of water systems serve fewer than 500 people each. Federal regulations address 91 different drinking water contaminants. For most regulated contaminants, there is a Maximum Contaminant Level (MCL) established by EPA for that contaminant and an associated monitoring requirement.
For a few of the regulated contaminants, EPA established Treatment Technique requirements instead of MCLs. Oregon water systems must monitor for these contaminants on specific schedules or monitoring periods that vary from monthly to every 3-9 years, and must demonstrate that the level of contaminants in the drinking water they supply is lower than the MCLs. The water systems engage private laboratories accredited by the Oregon Health Authority to analyze their drinking water samples, and the water supplier must report the results of their required samples to OHA. Oregon water systems submit a total of about 125,000 compliance sample results to OHA each year.