Proposed Phase II Rule Clarification Related to Census Bureau Urban Area Designation Criteria

On December 2, 2022, EPA published a proposed rule (pdf) (282 KB) to clarify its NPDES Stormwater Phase II regulations due to the Census Bureau’s recent changes (pdf) (288.8 KB) to discontinue its practice of defining and publishing the location of “urbanized areas” along with the 2020 Census and future censuses. The changes would be limited to one clarification. Under the proposal, EPA would clarify that the designation criteria for small MS4s, which have relied on the Census Bureau’s identification in every decennial census of “urbanized areas” and have been used since the promulgation of the Phase II regulations in 1999, would remain the same. These rule text changes would allow NPDES permitting authorities to use 2020 Census and future Census data in a manner that is consistent with existing longstanding regulatory practice.

What Phase II rule text changes are proposed: Under the proposed rule, EPA would replace references in the Phase II regulations to “urbanized area” with “urban areas with a population of at least 50,000,” which is the Census Bureau’s longstanding definition of the term urbanized areas. 

Withdrawal of direct final rule/status of proposed rule: EPA had also published on December 2, 2022 a direct final rule (pdf) (292 KB) with the same clarifications to the Phase II regulations. As EPA explained in the direct final rule, “…if EPA receives adverse comment in response to either publication, the Agency will publish a timely withdrawal of the direct final rule in the Federal Register informing the public that the direct final rule will not take effect. EPA would then address public comments as required as part of any subsequent final rule based on the proposed rulemaking.” EPA received two public comments, one of which was an adverse comment, and has therefore withdrawn the direct final rule (pdf) (213 KB). EPA will respond to the adverse comment received as part of any final action it takes on the parallel proposed rule.

Interim Guidance: Earlier this year, EPA published an Interim Guidance on Census Elimination of “Urbanized Area” Definition, providing interim guidance on the effect of the Census Bureau’s revised designation criteria. EPA intended this as interim guidance prior to the Agency taking more formal action to revise its regulations. For this reason, upon the effective date of any final rule clarifying the regulations to account for the Census Bureau's changes, the interim guidance will no longer be necessary and will be rescinded.