The Environmental Protection Agency (EPA) is taking direct final action to clarify its National Pollutant Discharge Elimination System (NPDES) Stormwater Phase II regulations due to recent changes made by the Census Bureau. The changes to EPA's regulations are limited to clarifying that the designation criteria for small municipal separate storm sewer systems (MS4s), which have been used since the promulgation of the regulations in 1999, will remain the same. These clarifications are necessary due to the Census Bureau's recent decision to discontinue its practice of publishing the location of "urbanized areas" along with the 2020 Census and future censuses. The clarification in this direct final rule replaces the term "urbanized area" in the Phase II regulations with the phrase "urban areas with a population of at least 50,000," which is the Census Bureau's longstanding definition of the term urbanized areas. This change will allow NPDES permitting authorities to use 2020 Census and future Census data in a manner that is consistent with existing longstanding regulatory practice. Because this clarification maintains the current scope of which entities are regulated as small MS4s, it is not expected to generate opposition, and EPA is publishing the clarification in the Federal Register as a direct final rule. As is EPA's practice for direct final rules, EPA is also publishing a parallel proposed rulemaking with the same changes included in this direct final rule if the Agency receives adverse comments.