Ask the Expert: The DEQ's New Fish Consumption Rate

What Does the Higher Fish Consumption Rate Mean?

by Brett Moore, P.E., Senior Engineer

The Oregon Department of Environmental Quality has recently approved the use of a higher fish consumption rate for determining water quality parameters in the state of Oregon. The new fish consumption rate is on the order of about 10 times higher than the rate that has been used in the past. This dramatic change in the fish consumption rate is important to note for all cities and organizations that have National Pollution Discharge Elimination System (NPDES) permits for discharging treated waters into receiving waters that contain fish.

Many of the pollutant parameters identified in NPDES permits are based on the level of pollutants that would be consumed by fish and then stored in the flesh and the tissues of the fish. These pollutants would then be passed on to humans through the consumption of the fish. The increase in the fish consumption rate to about 10 times the previous limit means that many pollutants that are currently discharged into receiving streams may require increased treatment to reduce the presence of pollutants down to as much as 10 percent of their current levels. The implications of this requirement are that some facilities will be required to increase treatment levels for pollutants such as copper, zinc, arsenic, mercury, and other metals that bio-accumulate in the tissues of fish.

When this fish consumption rate is adopted by the DEQ, an evaluation will be completed on the receiving streams to determine the mass loads that are acceptable in these waters. Then, testing of the pollutants of concern will need to be completed for the receiving waters, and all dischargers and discharge limits will be established. In receiving waters where pollutants approach levels that are of concern, testing for these pollutants may be added to NPDES permit requirements and, in some cases, new additional treatment of the effluent may be required in order to reduce pollutant levels.

Although many organizations may have seen news items and other reports about this topic during recent months, the potential implications and impacts of the increased fish consumption rate for organizations that discharge waters under an NPDES permit have not been explicitly explained and, therefore, are not well understood by those whom the change will affect. If you have any questions regarding how this may affect you and your organization specifically, please do not hesitate to call me or Troy Baker at (541) 963-8309. I can be reached by email at bmoore@andersonperry.com, and Troy’s email address is tbaker@andersonperry.com.