Is Your Community Ready for 2026 Annual and Interim Stormwater Reporting Requirements?

The current New York State Department of Environmental Conservation (NYSDEC) Municipal Separate Storm Sewer Systems (MS4) General Permit 0-24-001 has been in effect for nearly two years, and this means that the fourth iteration of the Interim Progress Certification and Annual Reporting for Permit Year 2 are both due on April 1, 2026. The Interim Report verifies the permit compliance activities that occurred during the period of July 1, 2025 through January 2, 2026, while the Annual Report captures the compliance activities undertaken during the calendar year from January 3, 2025 through January 2, 2026. Both reports are required to be submitted electronically utilizing the DEC’s electronic submission portal, known as nForm, available at this link.

For clarity, we will be mainly focusing on the general reporting requirements for Traditional Land Use Control MS4 operators, which include operators like municipalities and towns that are able to implement land-use regulations. Listed below are the other MS4 operator types:

• Traditional Non-Land Use Control: Typically a county-level governmental entity, such as a county department of public works, without the authority to directly impose land-use regulations
• Non-Traditional: Includes publicly-owned properties such as state university campuses, military bases, state-owned hospitals, public K-12 schools, etc.

Annual Reporting (January 3, 2025 to January 2, 2026)

The required Annual MS4 Reporting for Permit Year 2 is intended to capture the efforts the MS4 operator(s) have taken to fulfill the required deliverables and recurring items under each Minimum Control Measure (MCM) outlined in the General Permit. A majority of reporting for Permit Year 2 consists of annual tasks, which were included in previous reports under the current permit. However, MS4 operators are required to have developed an inventory of municipal facilities during Permit Year 2.

While we aren’t able to delve into each of the individual reporting requirements for Permit Year 2 and onwards, one of the more substantial upcoming deadlines is the completion of all requirements of Phase 1 comprehensive storm sewer system mapping, which is due at the end of Permit Year 3 in January 2027. The completion of these phased mapping requirements is a component of both Annual and Interim Certification Reporting. You can read about the Phase 1 mapping requirements in-depth in Walden’s recent blog linked here.

Interim Certification Reporting (July 1, 2025 to January 2, 2026)

The required Interim Certification Reporting is intended to verify that the MS4 operator is aware of the compliance activities required under the current MS4 Permit. The Interim Certification Report helps MS4 operators in looking ahead at upcoming and ongoing permit compliance efforts required through the fulfillment of Minimum Control Measures (MCM), continued development and updates to the MS4’s Stormwater Management Plan (SWMP), and stormwater mapping. Interim Certification Reports also provide MS4s with requirements that will be due in the upcoming permit years. For example, the current MS4 Permit has an expansive mapping requirement that is broken up into phases during its term.

Why Is MS4 Reporting Important?

Compliance with both Annual and Interim Reporting requirements is important for several reasons:

• Protection of natural resources, features, and infrastructure
• Protection of public health from adverse effects caused by stormwater contamination
• Avoidance of costly penalization by NYSDEC or other regulatory agencies for non-compliance
• Reporting requirements provide a holistic picture of the current conditions of an MS4 operator’s area and help to quantify the expanse of the operator’s responsibilities

If you or your community need assistance with Annual or Interim Certification Reporting, or would like to explore possible grant funding options for MS4 compliance services, contact Walden’s stormwater team at 516-980-5508 today! If you are interested in learning more about stormwater management, download our guide here.