Critical review of US Environmental Protection Agency numerical nutrient criteria with respect to Culturally Significant Waters as a designated use

Abstract

The Cherokee Nation, a Federally-recognized Tribal government in Northeastern Oklahoma lacks Tribal water quality standards for numerical nutrient standards based on baseline conditions in the Cherokee Nation. Lotic waters are of special significance in Cherokee Nation culture and ceremonies. Three water quality standard priorities within the Tribe include defining Culturally Significant Waters as a designated use, identifying Culturally Significant Waterbodies and determining applicable numerical nutrient standards. Culturally Significant Water as a designated use was defined based on community surveys. Twelve rivers and streams were identified as a portion of the Culturally Significant Waters of the Cherokee Nation based on a tribal community survey using a Use Attainability Analysis. To address excess nutrients in the Cherokee Nation, a total phosphorus numerical nutrient criterion was determined using data for Culturally Significant Water bodies, literature guidance and the US Environmental Protection Agency recommended nutrient criteria process for the respective Aggregate Nutrient Ecoregion. The Oklahoma Scenic Rivers criterion of 0.037 mg/L total phosphorus for a 90-day geometric mean was evaluated and determined not to be protective of Cherokee Nation's Culturally Significant Waters. A total phosphorus criterion of 0.016 mg/L was recommended to protect Cherokee Nation Culturally Significant Waters from benthic algae greater than 100 mg/m2 Chlorophyll a.