OAR 340-040-0090: Interim Standards for Maximum Measurable Levels of Contaminants in Groundwater to be Used in the Designation of a Groundwater Management Area

Interim standards are contained in Tables 4A, 5, and 6 of this division for maximum measurable levels (MMLs) of contaminants in groundwater to be used in the designation of a groundwater management area. Permanent standards for MMLs are found in Table 4B. The permanent or interim levels shall be used in all actions conducted by the Department where the use of maximum measurable levels for contaminants in groundwater is required. Table 4A INTERIM STANDARDS FOR MAXIMUM MEASURABLE LEVELS OF CONTAMINANTS IN GROUNDWATER :1, 2, 3 Inorganic Contaminants — Interim Standard (mg/L) Arsenic — 0.05 Barium — 1.0 Cadmium — 0.010 Chromium — 0.05 Fluoride — 4.0 Lead — 0.05 Mercury — 0.002 Selenium — 0.01 Silver — 0.05 1All reference levels are for total (unfiltered) concentrations unless otherwise specified by the Department. 2The source of all standards listed is 40 CFR Part 141. 3MMLs are used to trigger designation of a groundwater management area when concentrations are detected on an area-wide basis which exceed 70 percent of the nitrate MML or 50 percent of other MMLs. Table 4B PERMANENT STANDARDS FOR MAXIMUM MEASURABLE LEVELS OF CONTAMINANTS IN GROUNDWATER (Continued): 1, 2, 3 Inorganic Contaminants —Standard (mg/L) Nitrate-N — 10 (Nitrate expressed as Nitrogen) 1All reference levels are for total (unfiltered) concentrations unless otherwise specified by the Department. 2The source of all standards listed is 40 CFR Part 141. 3MMLs are used to trigger designation of a groundwater management area when concentrations are detected on an areawide basis which exceed 70 percent of the nitrate MML or 50 percent of other MMLs. Table 5 INTERIM STANDARDS FOR MAXIMUM MEASURABLE LEVELS OF CONTAMINANTS IN GROUNDWATER (Continued): 1, 2, 3 Organic Contaminants — Interim Standard (mg/L) Benzene — 0.005 Carbon Tetrachloride — 0.005 p-Dichlorobenzene — 0.075 1,2-Dichloroethane — 0.005 1,1-Dichloroethylene — 0.007 1,1,1-Trichloroethane — 0.20 Trichloroethylene — 0.005 Total Trihalomethanes — 0.10 (The sum of concentrations bromodichloromethane, dibromochloromethane, tribromomethane (bromoform), and trichloromethane (chloroform)) Vinyl Chloride — 0.002 2,4-D — 0.10 Endrin — 0.0002 Lindane — 0.004 Methoxychlor — 0.10 Toxaphene — 0.005 2,4,5-TP Silvex —0.01 1All reference levels are for total (unfiltered) concentrations unless otherwise specified by the Department. 2The source of all standards listed is 40 CFR Part 141. 3MMLs are used to trigger designation of a groundwater management area when concentrations are detected on an area-wide basis which exceed 70 percent of the nitrate MML or 50 percent of other MMLs. Table 6 INTERIM STANDARDS FOR MAXIMUM MEASURABLE LEVELS OF CONTAMINANTS IN GROUNDWATER: 1, 3 Radioactive Substances, Microbiological and Turbidity Contaminants — Interim Standard Turbidity — 1 T U Coliform Bacteria — < 1/100 ml Radioactive Substances Gross Alpha2 — 15 pCi/1 Combined Radium — 5 pCi/1 226 and 228 Gross Beta — 50 pCi/1 I - 131 — 3 pCi/1 Sr - 90 — 8 pCi/1 Tritium — 20,000 pCi/1 1The source of all standards listed is 40 CFR Part 141. 2Including Radium 225 but excluding Radon and Uranium. 3MMLs are used to trigger designation of a groundwater management area when concentrations are detected on an area-wide basis which exceed 70 percent of the nitrate MML or 50 percent of other MMLs.