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State Development of Numeric Criteria for Nitrogen and Phosphorus Pollution

Numeric nutrient criteria are a critical tool for protecting and restoring a waterbody's designated uses related to nitrogen and phosphorus pollution. These criteria enable effective monitoring of a waterbody for attaining its designated uses; facilitate formulation of NPDES discharge permits; and simplify development of total maximum daily loads (TMDLs) for restoring waters not attaining their designated uses (i.e., impaired waters).

The interactive maps and tables below describe progress states are making towards the development of numeric nutrient criteria, the criteria they've developed, and specific details about Clean Water Act adopted criteria, including values and parameters.

States and territories are also conducting additional activities to control nutrient pollution including watershed prioritization, setting goals to reduce nutrient loads, and other work as described in the EPA memo "Working in Partnership with States to Address Phosphorus and Nitrogen Pollution through Use of a Framework for State Nutrient Reductions". However, this particular work is not reflected on this webpage.

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