The oldest question in environmental law is "how clean is clean?" It's a question that environmental practitioners are tired of discussing, and that quickly leads to glazed eyeballs at any environmental meeting. So I shouldn't be discussing it -- but there is a new development worth notice. Under state law, the Regional Water Quality Control Boards have a two-part cleanup target for contaminated groundwater: clean up to background levels, or to health-based levels, such as the maximum contaminant level (drinking water standard) or public health goal. Which of these goals (background or health) is selected for a particular site is not often an issue of substantial dispute because in practice usually neither of them can be achieved, at least with active remediation in a reasonable time.
In May, however, the State Water Resources Control Board confronted the issue in a context where the issue does have practical consequences: should a "discharger" be required to provide alternate water supplies to persons affected by contamination that is below health standards but higher than the naturally occurring level? The case involved an Olin Corporation site in Morgan Hill, and the chemical was potassium perchlorate, which occurs naturally, if at all, only at undetectable levels. Olin and another discharger were ordered by the Regional Board to provide alternate drinking water supplies to residents whose water contained perchlorate at or above 4 ppb, even when the level of perchlorate was below the new public health goal of 6 ppb established by OEHHA. The PHG is supposed to be a level at which a person may be exposed to a chemical for a lifetime with no deleterious effects.
The State Board decided that in this context the Regional Boards should defer to OEHHA, and should not require a discharger to provide an alternate water supply. The decision includes many caveats, and the State Board expressly limits its opinion to replacement water supply decisions ("This Order applies only to requirements for water replacement and not to groundwater or soil cleanup levels required under State Water Board Resolution 92-49"), but the decision nevertheless seems to mark an important choice. The Board could have required Olin to continue providing alternate drinking water supplies, even without a health-based reason to do so. But it chose instead to conserve societal resources for another day and another threat, a threat supported by scientific evidence.