The purpose of this January 1976 rule is to prevent the potential adverse effects of radionuclide exposure (primarily cancer). To comply, all water systems must measure gross alpha activity. Large surface water systems, such as Bull Run, must also monitor gross beta, strontium-90, and tritium. Every four years, the water system must report the annual composite of four consecutive quarterly samples or the average of four quarterly samples. Additional analyses are required if trigger levels are exceeded or the system is downstream of a nuclear facility. The Portland Water Bureau's surface and ground water sources comply with the regulation.
The Phase I, II, IIB, and V rules establish monitoring and reporting and maximum contaminant level (MCL) or treatment technique requirements for 69 contaminants in drinking water. Contaminants include volatile organic chemicals (VOCs), agricultural chemicals, chemicals used by some water systems in the water treatment process, inorganic chemicals, and pesticides. These regulations also establish monitoring and reporting requirements for unregulated contaminants.
The 9-year compliance cycle contains three 3-year compliance periods. Systems must complete base monitoring and increase monitoring based on trigger levels. An assessment can reduce monitoring requirements.
Effective February 2002, the Arsenic Rule sets a new standard of 0.010 mg/L or 10 parts per billion (ppb) for arsenic. Although systems don't have to comply to the new standard until January 2006, arsenic levels greater than 5 ppb have to be reported in the water system's Consumer Confidence Reports effective immediately.