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.

Statutory/Other Authority

ORS 468B.165

Statutes/Other Implemented

ORS 468B.165

History

DEQ 32-2018, minor correction filed 04/02/2018, effective 04/02/2018
DEQ 4-1996, F. & cert. ef. 3-7-96
DEQ 38-1990, f. & cert. ef. 9-17-90
DEQ 26-1989(Temp), f. & cert. ef. 10-27-89