What options are available when treatment technology does not exist to enable dischargers to meet the WQBEL?
This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. If dischargers cannot meet the WQBEL based on existing water quality standards, states have the option of changing the water quality standards through variances or changes to designated uses, which would result in a different WQBEL that could be met. In other instances, dischargers may be able to meet the WQBELs based on existing water quality standards through options such as offsets from point and nonpoint sources (e.g., land based BMPs) and water quality trading, and watershed analysis. For information on variances, refer to EPA’s Water Quality Standards Handbook. For information on changing designated uses, please refer to 40 CFR 131.10(g) . For information on offsets, trading, and watershed analysis, refer to the Watershed-Based Permitting website and the Water Quality Trading website.
