Should WQBELs apply only if a water is determined to be impaired by nutrients (nitrogen and phosphorus)?
This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. The permitting authority must include a WQBEL in a permit if nutrients or any pollutant cause, contribute to, or have the reasonable potential to cause or contribute to an excursion of a water quality standard. In other words, even if a waterbody is not currently impaired for nutrients, a permit writer must include a WQBEL if a discharge has the reasonable potential to cause or contribute to an excursion of the nutrient criteria. For more information on WQBELs, please refer to 40 CFR 122.44(d) .
