OAR 340-040-0080: Numerical Groundwater Quality Reference Levels and Guidance Levels

(1) The numerical groundwater quality reference levels and guidance levels contained in Tables 1 through 3 of this Division are to be considered by the Department and the public in weighing the significance of a particular chemical concentration, and in determining the level of remedial action necessary to restore contaminated groundwater for human consumption. They are not to be construed as acceptable groundwater quality management goals. They are to be used by the Director and the EQC in establishing permit-specific and remedial action concentration limits according to the requirements of OAR 340-040-0030 through 340-040-0060. [Note: View a PDF of the tables by clicking on the "Tables" link at the end of OAR 340-040-0020.] (2) The Department shall periodically review information as it becomes available for establishing new numerical groundwater quality reference levels and guidance levels, and to ensure consistency with other statutorily mandated standards. (3) Human consumption is recognized as the highest and best use of groundwater, and the use which usually requires the highest level of water quality. The numerical groundwater quality reference levels listed in Tables 1 and 2 of this Division reflect the suitability of groundwater for human consumption. [Note: View a PDF of the tables by clicking on the "Tables" link at the end of OAR 340-040-0020.] (4) The numerical groundwater quality guidance levels listed in Table 3 of this Division are for contaminants which do not adversely impact human health at the given concentrations. At considerably higher concentrations, human health implications may exist. These guidance levels are for contaminants that primarily affect the aesthetic qualities relating to the public acceptance of drinking water. The aesthetic degradation of groundwater may impair its beneficial use. [Note: View a PDF of the tables by clicking on the "Tables" link at the end of OAR 340-040-0020.] (5) For pollutant parameters for which numerical groundwater quality reference levels or guidance levels have not been established and listed in Tables 1 through 3, or for evaluating adverse impacts on beneficial uses other than human consumption, the Department shall make use of the most current and scientifically valid information available in determining at what levels pollutants may affect present or potential beneficial uses. Such information shall include, but not be limited to, values set forth in OAR 340-041-0033. [Note: View a PDF of the tables by clicking on the "Tables" link at the end of OAR 340-040-0020.]