Oregon has 2,500 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 52 largest municipal water systems serve 80% of the population, yet 85% 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 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 OHA to analyze their drinking water samples, and the water supplier must report the results of their required samples to OHA. Oregon water systems submit 150,000 or more compliance sample results to OHA each year.
The
2020 Oregon Annual Compliance Report summary table shown below presents violation data for key contaminant groups that have MCLs. "Water Quality Violation" means that the drinking water at a water system exceeded the MCL or did not properly treat the water (Treatment Technique) for a specific monitoring period. "Monitoring violation" means that sample results were not received at all or not received on time from a water supplier as required for a specific monitoring period. For each type of violation, the total number of individual violations is listed, along with the total number of water systems that committed those violations. For detailed and current information on the drinking water quality at specific public water systems, see
Drinking Water Data Online.
Most Oregon public water systems test their drinking water as required, submit the results on time, and demonstrate that their drinking water meets the maximum contaminant levels. We continue to work with all water suppliers to assure that drinking water quality problems are identified and corrected to protect public health.
Table 1. Oregon Drinking Water Services 2020 EPA Annual Compliance Report Summary
Key
Contaminant
Group | Water Quality Violations
| Monitoring Violations |
|---|
Number of
Violations | Number of
Water Systems
with Violations | Number of
Violations | Number of
Water Systems
with Violations |
|---|
|
Volatile Organic Chemicals: This is a group of 21 chemicals, such as degreasers and solvents. Water systems must monitor from quarterly to every 6 years. |
|
Synthetic Organic Chemicals: This is a group of 30 chemicals, such as pesticides. Water systems must monitor from quarterly to every 9 years. |
|
Inorganic Contaminants: This is a group of 16 contaminants, usually naturally occurring due to geology but also including nitrate from fertilizer use. Water systems must monitor from quarterly to every 9 years. |
|
Coliform Bacteria: Frequent bacteria monitoring is required of every water system as ongoing assurance that drinking water is free of microbes that can cause waterborne disease. Monitoring is required from every month to every quarter, with the number of samples based on the number of people served. |
|
Treatment Technique: EPA has established treatment techniques (TTs) to control unacceptable levels of turbidity and levels of contaminants, including viruses and some bacteria. Ten systems violated a treatment technique for groundwater sources at some point during 2015, and 11 systems violated a treatment technique for surface water at some point during 2015. 71 surface water systems failed to submit as required a monthly operating report during 2015, and 43 groundwater systems failed to submit as required a monthly operating report during 2015. |
|
Lead and Copper: EPA has established an action value for lead and copper in drinking water. Excess lead in drinking water poses adverse health effects, especially to infants and children. The most common source of lead in drinking water is from leaching household plumbing. Community and Non-Transient-Non-Community water systems must monitor every six months to one year to three years for lead and copper. System that have installed treatment must also report monthly to demonstrate compliance to adjust the corrosiveness of the water. |
|
Disinfection By-Products: Disinfection of drinking water, usually with chlorine, is the key means to assure that water is safe from microbes. Disinfection of drinking water can produce by-products that must be limited to protect health. |
Radiologicals: The three contaminants of this group, gross alpha, combined radium and uranium, are usually naturally occurring due to geology. Water systems must monitor from quarterly to nine years.
|
| Volatile Organic Chemicals | 0 | 0 | 263
| 18
|
| Synthetic Organic Chemicals | 0 | 0 | 248
| 9
|
| Inorganic Contaminants | 0 | 0 | 12
| 2
|
| Nitrates | 7
| 5
| 101
| 89
|
| Arsenic | 27
| 11
| 15
| 11
|
| Coliform Bacteria | 31
| 29
| 948
| 478
|
| Surface Water Treatment Rule | 7
| 5
| 90
| 32
|
| Groundwater Rule | 12
| 10 | 220
| 146
|
| Lead and Copper Rule | 7
| 6
| 277
| 154
|
| Disinfection By-Products | 30
| 9
| 109
| 48
|
| Radiologicals | 0 | 0 | 32
| 9
|