Aquatic Life Water Quality Standards Technical Support Document for Cadmium

From the Minnesota State Register, Volume 33 (35), March 2, 2009: Cadmium has numerous municipal and industrial sources that may be discharged into surface waters. The EPA revised surface water aquatic life criteria values for cadmium in 2001 (Update of Aquatic Life AWQC – Cadmium 2001 (EPA822R01001)). Changes to the current Minnesota acute and chronic WQSs for cadmium would involve compiling, reviewing and developing a value for the short-term (acute) and long-term (chronic) protection of aquatic life communities (e.g. fish, invertebrates, aquatic plants, etc.). Efforts to revise the existing Minnesota standard will require reviewing existing toxicity data from the published literature and other sources. The Minnesota Pollution Control Agency (MPCA) has reviewed the U.S. Environmental Protection Agency (EPA) Ambient Water Quality Criteria (AWQC) for Cadmium. The AWQC provides technical review of current or new criteria for pollutants in surface waters that may affect beneficial uses of surface water. In the case of the cadmium AWQC the beneficial use is a healthy, viable aquatic life community. Based on aquatic toxicity-based methods in EPA's criteria document, MPCA is proposing to revise the current water quality standards (WQSs) for cadmium in Minn. R. chs. 7050 and 7052. The WQSs for cadmium continue to be dependent on total hardness. Parameters for the equations to calculate the WQSs have been updated to reflect additional toxicity data. The changes will result in lower cadmium concentrations for the WQSs.