I spent much of this morning listening in on the Department of Ecology’s latest Delegates’ Table meeting regarding the ongoing efforts to revise Washington’s Water Quality Standards to account for higher fish consumption rates. The meeting included an update on where Ecology is in the process, Ecology’s current thinking on where the rule making may be going, and a discussion of feedback provided by stakeholders. Here are some of the discussion points I highlighted in my notes:
Ecology is still expecting a draft of the rule to be circulated in March, with the possibility of an additional delegate meeting between now and then. That rule is anticipated to include both draft Human Health Criteria and Implementation Tools. There was some discussion at today’s meeting about whether these two components would be done at the same time or as separate rules, and Ecology provided clarification that it intends to do both components in one rulemaking process.
When Ecology last held a public meeting on the subject (on November 6, 2013), Ecology provided some chemical-specific scenarios for arsenic, PCBs, and mercury that may be carried forward in the rule making. Today, Ecology provided some direction on where it may go with the rule for the following substances (the entire presentation from today is available here). Those specific toxics present unique challenges–you can review current thinking on them starting on page four of the presentation. I noted a few interesting points…
Arsenic: Arsenic presents a number of challenges. One is that it is naturally occurring, and that natural presence alone exceeds risk-based criteria for surface waters. The second is that it is dispersed broadly throughout Western Washington as a legacy pollutant from past smelter operations, including both past atmospheric emissions, and being present in soils and sediments through the past use of smelter slag as fill or sandblast grit. At the November meeting, Ecology proposed two different alternatives to account for the ubiquitous nature of arsenic and the fact that it is also a human influence pollutant, contemplating either (a) using the Safe Drinking Water Act Maximum Contaminant Level (MCL); or (b) calculating a criteria at a different risk level. For a number of reasons, including the outdated nature of the cancer potency factor for arsenic (necessary to calculate a risk based criteria), Ecology is leaning towards setting the new arsenic criterion at the MCL, 10 micrograms per liter for freshwater. Because the MCL doesn’t apply to marine or estuarine waters, Ecology is considering whether to promulgate the 10 microgram per liter MCL for those waters or not have a numeric criterion for those waters.
Mercury: This element presents unique regulatory challenges because (a) the form found in fish (methylmercury) is largely created by bacterial communities living in sediment–so what is found in fish is not what is being discharged by entities regulated under the Clean Water Act; and (b) a substantial amount of mercury in waterbodies is from atmospheric deposition and that deposition is influenced by regional to global scale processes. Ecology proposed three alternatives to address these challenges back in November, including adopting a statewide variance, calculating a specific methylmercury criterion, or adopting new criteria at a later date when a solid implementation plan is ready, including how to develop permit limits. At today’s meeting, Ecology looks to be leaning towards this latter approach and would, in the meantime, continue to apply the aquatic life criteria found in the National Toxics Rule (NTR), the default toxics water quality criteria currently used by Washington.
PCBs: The challenges associated with PCBs are similar to mercury inasmuch as there is a current atmospheric deposition component, there are uncontrolled historic sources of PCBs in sediment and soils, and PCBs are present in fish in nearly all areas in Washington, even undeveloped areas that are considered “clean” and lack industrial sources. In November, Ecology outlined three possible approaches to setting PCB water quality criteria as part of this process, one involving waterbody or statewide variances, another using a PCB-specific additional lifetime cancer risk level, and the third basing the criteria for PCBs on non-cancer effects. Today, Ecology indicated it is leaning towards this third option, and is considering basing the new toxics criteria for PCBs on the Washington Department of Health’s non-cancer toxicity reference dose that WDOH uses to determine if fish advisories are needed. Curiously, if you take that reference dose and calculate additional lifetime cancer risk from that dose, you end up with an excess cancer risk of 4.0e-5, within the range of acceptable cancer risk (10-4 to 10-6) under the Clean Water Act, but higher than the excess cancer risk used in the NTR. Ecology combined a range (125 to 225 grams per day) of fish consumption rates with this excess cancer risk to come up with a calculated Human Health Criterion for PCBs that ranged from 230 to 410 parts per quadrillion (or 0.00023 to 0.00041 micrograms per liter). Interestingly, this range is higher than the current National Toxics Rule criterion (170 parts per quadrillion or 0.00017 micrograms per liter) because the NTR is based on a much lower fish consumption rate. This makes sense given the the higher excess cancer risk Ecology derived using the WDOH reference dose. That being said, the resulting criteria is still exceedingly low, and will likely cause compliance issues for dischargers.
What are the takeaways? It sounds like we’re getting close to seeing a draft rule. The number of chemical-specific issues associated with just three toxics (arsenic, mercury and PCBs) shows how complex of a problem Ecology is wrestling with from a science, law, and policy standpoint. This complexity also highlights the difficulties of addressing low levels of toxics in surface waters using the Clean Water Act–particularly when the sources of those toxics are not the end-of-pipe sources subject to NPDES permits. Up until now, in Washington, the one-in-a-million excess cancer risk level has been something of a sacred cow, and is incorporated in state statutes like the Model Toxics Control Act and the Sediment Quality Standards as the “default” excess cancer risk for individual substances. The Clean Water Act allows for a broader risk range, but it will be interesting to see if the higher excess cancer risk ends up being politically acceptable to all stakeholders. Ecology may be setting itself up for litigation because it is on the path–at least with respect to PCBs–of promulgating a rule that accounts for higher fish consumption rates, but leads to a water quality criteria for PCBs that is higher than the one in the NTR. Although this approach may be justified under the Clean Water Act, I am certain it isn’t what some stakeholders had in mind when the push for this rulemaking started years ago.