Last Tuesday, EPA published its draft of the latest update to the National Recommended Water Quality Criteria for the Protection of Human Health. These recommended criteria are developed under Section 304(a)(1) of the Clean Water Act, and provide guidance to states and tribes that promulgate criteria under delegated programs. Importantly, they are not binding requirements on states or tribes, and do not go through the formal rulemaking process. The publication of the draft updated criteria is intended to solicit scientific comments on those criteria. Once finalized, states and tribes are free to adopt these criteria, modify these criteria to reflect site-specific conditions, or adopt different criteria based on scientifically-defensible information.
The central purpose of these criteria is to translate impacts to human health into numeric values in the form of acceptable concentrations of pollutants in water. This is done by considering various exposure factors, including body weight, exposure duration, and intake rates (daily water intake or fish consumption rates). These parameters are coupled with pollutant-specific toxicological information to provide pollutant-specific numeric criteria for waters.
EPA updated the exposure parameters it uses in calculating the recommended criteria to reflect the latest science. Notably, the body weight used in the exposure model increased by 22 pounds (reflective of a heavier overall population); the daily intake of drinking water went up (from 2 to 3 liters); and fish consumption increased from 6.5 grams per day (about a meal per month) to 22 grams per day (3-4 meals per month). In short, people are heavier, drink more water, and eat more fish as compared to the last time the criteria were updated. Because the toxicological information for individual compounds changed as well, these exposure parameter updates did not lead to a uniform change in the numeric values of the recommended criteria. Some criteria went up, some went down, and some stayed similar to the last recommended values.
So, what can Washington learn, if anything from EPA’s proposed updated criteria? I’ve written a fair amount on the topic of fish consumption and the efforts to update Washington’s Water Quality Standards to incorporate dramatically higher consumption rates over the past few years. These recommended criteria contain a hierarchy and guidance on the issue of consumption rate, summarized nicely in EPA’s fact sheet published with the Federal Register Notice:
As described in EPA’s human health criteria methodology (USEPA 2000), the level of fish intake in highly exposed populations varies by geographical location. Therefore, EPA suggests a four preference hierarchy for states and authorized tribes that encourages use of the best local, state, or regional data available to derive fish consumption rates. EPA recommends that states and authorized tribes consider developing criteria to protect highly exposed population groups and use local or regional data over the default values as more representative of their target population group(s). The four preference hierarchy is: (1) use of local data; (2) use of data reflecting similar geography/ population groups; (3) use of data from national surveys; and (4) use of EPA’s default intake rates.
Reportedly, Washington State Department of Ecology (Ecology) is soon going to publish its long-awaited draft rule revising its water quality standards. At February’s Delegate’s Table Meeting, Ecology mentioned it would release a draft rule by the end of March—although I’m not surprised the draft rule is taking more time given the political turmoil it is causing. It will be interesting to see if Ecology applies the recommended hierarchy suggested by EPA. It provides a spectrum of trade-offs, with the use of local data arguably the most defensible and scientifically accurate way to set consumption rates (but also the most costly) at one of end of the spectrum, and the use of EPA’s default intake rate of 22 grams per day at the other end. This would involve the least amount of regulatory effort because of the lack of a need to collect site-specific consumption data. If I had to guess, Ecology will use some combination of the first two parts of EPA’s suggested hierarchy, as it will find data from national surveys or the new default rate publish by EPA to not be reflective of fish consumption rates in Washington. We should see the draft rule from Ecology soon, I’ll be sure to provide an update when that is released for public comment.