Section R. 325.10604c - MCL for inorganic chemicalsRule 604c.
(1) Except as specified, the maximum contaminant levels and effective dates for inorganic chemicals in table 1 of this rule apply to community and nontransient noncommunity water supplies. These public water supplies are considered "water supplies" or "supplies" in this rule. Table 1 MCLs for inorganic chemicals
| Contaminant | Maximum Contaminant Level in mg/l | Effective Date |
| Antimony | 0.006 | January 17, 1994. |
| Arsenic | 0.010 | April 6, 2005. |
| Asbestos | 7 million fibers per liter (longer than 10 um) | July 30, 1992. |
| Barium | 2 | January 1, 1993. |
| Beryllium | 0.004 | January 17, 1994. |
| Cadmium | 0.005 | July 30, 1992. |
| Chromium | 0.1 | July 30, 1992. |
| Cyanide (as free | 0.2 | January 17, 1994. |
| cyanide) |
| Fluoride1 | 4.0 | [effective date of this rule] |
| Mercury | 0.002 | July 30, 1992. |
| Nickel | MCL withdrawn | May 30, 2002 |
| Nitrate (as | 10 | July 30, 1992. |
| Nitrogen)2 |
| Nitrite (as | 1 | July 30, 1992. |
| Nitrogen)2 |
| Total Nitrate and | 10 | July 30, 1992. |
| Nitrite (as Nitrogen)3 |
| Selenium | 0.05 | July 30, 1992. |
| Thallium | 0.002 | January 17, 1994. |
1 The MCL and effective date apply to only community water supplies.
2 The MCLs and effective dates apply to community and noncommunity water supplies.
(2) Compliance with the MCL requirements of this rule shall be determined based on the analytical results that are obtained at each sampling point as specified in R 325.10710. If 1 sampling point is in violation of an MCL, then the water supply is in violation of the MCL. All of the following provisions apply:(a) For supplies monitoring more than once per year, compliance with the MCL for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium, or thallium is determined by a running annual average at each sampling point.(b) Supplies monitoring annually or less frequently whose sample result exceeds the MCL for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium, or thallium shall begin quarterly sampling. Compliance with the MCL shall be based on the running annual average. For the purpose of calculating the running annual average, the initial exceedance shall be considered the result for the first quarter. If the department requires a confirmation sample under R 325.10710(9), then the average of the initial exceedance and the confirmation sample shall be considered the result for the first quarter. The supply shall not be considered in violation of the MCL until it has completed 1 year of quarterly sampling.(c) If any sample result causes the running annual average to exceed the MCL at any sampling point, then the supply is out of compliance with the MCL immediately.(d) If a supply fails to collect the required number of samples, then compliance shall be based on the total number of samples collected.(e) If a sample result is less than the detection limit, then zero shall be used to calculate the annual average.(f) Compliance with the MCLs for nitrate and nitrite is determined based on 1 sample if the levels of these contaminants are below the MCLs. If the level of nitrate or nitrite or the combination of nitrate and nitrite is more than the MCLs in the initial sample, then a confirmation sample is required under R 325.10710 (9) (b) and (c), and compliance shall be determined based on the average of the initial and confirmation samples. (3) The department may allow nitrate levels above 10 milligrams per liter but not more than 20 milligrams per liter in a noncommunity water supply if the supply demonstrates, to the satisfaction of the department, all of the following: (a) A permanent alternate source of water meeting state drinking water standards can not be obtained.(b) The water will not be available to children under 6 months of age.(c) Water meeting state drinking water standards, such as bottled water, will be provided to those who request it.(d) There is continuous posting at all drinking water outlets available to the public that nitrate levels exceed 10 mg/l and the potential health effects of exposure as specified in part 4 of these rules.(e) Adverse health effects are not documented.Mich. Admin. Code R. 325.10604c
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