Site-specific criteria differ from site-specific water quality standards. Site-specific criteria (SSC) may be developed when a toxic pollutant in surface water lacks a numeric standard in Minn. R. 7050.0220, 7050.0222, 7050.0227 or 7052.0100. The MPCA is authorized to develop a numeric SSC that applies specifically to the water body or region where the pollutant is found, using data from that water body or region. The methods for developing SSC are in Minn. R. 7050.0217, 7050.0218 and 7052.0110. SSC can be used to determine the status of surface waters (impaired or not) and can be applied in permits and at remediation sites following the procedures in Minn. R. 7050.0218, Subp. 2.
The time to develop and implement a SSC is less than developing a water quality standard (WQS) that applies statewide. A SSC is developed using a smaller dataset specific to the water body or region where the SSC will be applied, and the public review requirements are less involved than for statewide WQS, which must be adopted and promulgated into Minnesota Rule following Minnesota’s Administrative Procedures Act. In addition, a SSC does not require EPA approval.
SSC are typically developed when a pollutant is identified in surface water that is of local or regional concern, or in situations where a regulatory limit is needed for permitting or at remediation sites. For example, the MPCA developed SSC for PFOS and PFOA, two perfluorinated chemicals that were released in the eastern part of the Twin Cities Metropolitan Area (TCMA) and found in groundwater, drinking water, and the Mississippi River.