42 U.S.C. § 300g–7 — Monitoring of contaminants

(a) Interim monitoring relief authority (1) A state with primary enforcement responsibility can loosen the testing rules for regulated or unregulated contaminants — except microbial contaminants (or their indicators), disinfectants, disinfection byproducts, or corrosion byproducts — for a temporary period. During that period, a water system serving 10,000 people or fewer doesn't have to do the usual extra quarterly testing for a covered contaminant if (A) a test done at the start of the period, and certified to the state by the system, finds no trace of the contaminant in the ground or surface water supplying the system; and (B) the state, after weighing local geology and other relevant factors, decides in writing that further testing is unlikely to find the contaminant. (2) This interim relief period ends when a state adopts permanent monitoring relief, or 36 months after August 6, 1996 — whichever happens first. The starting test that qualifies a system for relief must happen at the time the state believes the system is most vulnerable to that contaminant showing up in its source water. For pesticides, the state must account for application timing and how long the pesticide takes to reach the source water. For other contaminants, the state must account for rainfall patterns and how long contamination takes to travel. (b) Permanent monitoring relief authority (1) A state with primary enforcement responsibility and an approved source-water assessment program can adopt, following the Administrator's guidance, tailored alternative testing rules for chemical contaminants — replacing the usual national testing rules — if the state concludes, based on data about risk, use, occurrence, or its own source-water assessments, that the alternative plan still meets the Administrator's guidelines. The state's overall program must still be strong enough to ensure real compliance with, and enforcement of, national drinking water rules. This alternative testing cannot apply to regulated microbial contaminants (or their indicators), disinfectants, disinfection byproducts, or corrosion byproducts. None of this limits any other authority the Administrator has to grant monitoring flexibility. (2)(A) The Administrator must issue guidelines — after notice and comment, and at the same time as the source-water assessment guidelines required under section 300j–13 — telling states how to propose alternative monitoring for chemical contaminants under paragraph (1). The Administrator must publish these guidelines in the Federal Register. They must protect public health, apply contaminant-by-contaminant, and require a system to show the state either that the contaminant isn't present in its drinking water supply, or that it's reliably and consistently below the maximum contaminant level, to qualify. (2)(B) "Reliably and consistently below the maximum contaminant level" means that, even though the contaminant has been detected, the state knows enough about where the contamination came from and how far it spreads to predict the legal limit won't be crossed. In deciding this, states must weigh the quality and completeness of the data, how long a time period the data covers, how stable or volatile the results are over that time, and how close the results run to the legal limit. Results that swing widely, or that sit close to the limit, don't count as reliably and consistently below it. (3) The guidelines must require that, once an alternative monitoring program is up and running, if a covered contaminant is later found at or above the maximum contaminant level, or is no longer reliably and consistently below it, the system must either (A) prove that the contamination source has been removed or otherwise fixed, or (B) go back to testing for that contaminant under the regular national rule. (4) The governor of a state that didn't have primary enforcement responsibility as of August 6, 1996, can ask the Administrator to modify that state's monitoring requirements. After consulting the governor, the Administrator must modify the requirements if the governor's request meets every part of this subsection that applies to states with primary enforcement responsibility. Any approval the Administrator gives under this paragraph lasts 3 years, and can later be extended in 5-year blocks. (c) Treatment as NPDWR Any monitoring relief a state grants to a system for a regulated contaminant under (a) or (b) is treated as part of that contaminant's national primary drinking water regulation. (d) Other monitoring relief Nothing in this section limits states' existing authority, under applicable national drinking water rules, to change monitoring requirements through waivers or other existing tools. The Administrator must periodically review those other authorities and revise them as appropriate.