Wis. Admin. Code Department of Natural Resources NR 119.04

Current through September 30, 2024

Section NR 119.04 - More stringent SSC

A waterbody or segment is eligible for a more stringent SSC if the requestor demonstrates and the department determines that the statewide phosphorus criterion is not sufficiently protective of the waterbody's designated uses. A more stringent SSC may be appropriate if a waterbody is in one of the following categories:

(1) BIOLOGICAL METRICS NOT ATTAINED. A more stringent SSC may be appropriate if a waterbody attains its statewide phosphorus criterion but does not attain one or more of its phosphorus response indicators or biological assessment thresholds. However, a more stringent SSC is not appropriate under this subsection if a biological assessment threshold or phosphorus response indicator is not attained due to factors other than phosphorus, and the department determines that phosphorus is not contributing to the nonattainment.

Note: Because flowing waters may transport algae downstream from where it is produced, an SSC should only be established on the segment of the waterbody where the impairment is being generated. For example, if a river directly downstream of an impoundment attains its phosphorus criterion but receives high algae concentrations passed through from the impounded area, a more stringent SSC for the river segment downstream from the dam may not be appropriate since the source of the algae is upstream. Establishing an SSC downstream from the dam is not likely to achieve attainment of the phosphorus response indicator.

(2) BIOLOGICAL METRICS ATTAINED. A more stringent SSC may be appropriate even if a waterbody is below its statewide phosphorus criterion and it attains its phosphorus response indicators and biological assessment thresholds if it is demonstrated that a more stringent SSC than the statewide phosphorus criterion is necessary to maintain attainment of any of these indicators and the level necessary can be demonstrated through modeling.

Wis. Admin. Code Department of Natural Resources NR 119.04

Adopted by, CR 19-093: cr. Register September 2022 No. 801, eff. 10/1/2022

For example, certain impounded flowing waters with a statewide phosphorus criterion of 100 ug/L may fit in this category if the ambient concentration of the waterbody is below the statewide criterion but concentrations approaching 100 ug/L would be too high to support recreation and aquatic life.