The State Pollutant Discharge Elimination System (SPDES) General Permit for Stormwater Discharges from Municipal Separate Storm Sewer Systems (MS4) rules are currently in the modification process. The SPDES General Permit was originally issued in April 2015; this is the second modification proposed. The proposed rulemaking draft (draft GP-0-22-002) and Fact Sheet released by the New York State Department of Environmental Conservation (NYSDEC) are available for public comment.

What is a Municipal Separate Storm Sewer System?

Storm sewers redirect runoff formed during rain or snow events into a system of catch basins and pipes. An MS4 is a publicly-owned conveyance or system of conveyances (including but not limited to streets, ditches, catch basins, curbs, gutters, and storm drains) that is designed or used for collecting or conveying stormwater. MS4 systems discharge directly to surface waters of the State without going through a wastewater treatment plant. MS4s rely on catch basins and other infrastructure to filter out large pieces of litter, sediment, and oils to reduce the risk of large amounts of non-stormwater contaminants from entering the surface water. MS4s only function well if they are cleaned, maintained, and understood by the public. By implementing a robust MS4 program in compliance with the MS4 General Permit, municipalities work towards protecting surface water quality.


What are the Proposed Changes?

The proposed General Permit changes involve requiring electronic submissions for all forms (unless meeting the requirements of a waiver) and extended time frames for compliance. Draft GP-0-22-002 identifies areas where additional clarity or specificity is needed, building on the previous permit by providing specific requirements, timeframes, and methodologies. The proposed changes include the removal of the table summarizing permit requirements and timeframes. The draft contains timeframes for the completion of permit requirements embedded throughout the draft general permit.


Draft GP-0-22-002 redefines the annual reporting period as of March 1st of the current year to February 28th (February 29 if on a leap year) of the following year and requires that MS4 Operators do the following to meet MEP rules:

  • Track information collected through the implementation of the Best Management Practices (BMPs);
  • Analyze tracked information by identifying trends, patterns, and common problems; and
  • Adjust the BMPs in the Stormwater Management Program (SWMP) accordingly to improve the SWMP effectiveness in protecting water quality.


Total maximum daily load (TMDL) is the calculation of the maximum amount of a pollutant allowed to enter a waterbody. The majority of the provisions pertaining to TMDL implementation progress reporting remain the same except that any plans to implement additional BMPs and applicable retrofitting are required to be submitted as an attachment by MS4 Operators located within the watersheds identified in the permit.


Another proposed change to the Stormwater Management Program required by the permit is the requirement that the MS4 Operator designates, in writing, a Stormwater Program Coordinator. The Operator shall identify the individual (by name and title) and ensure that the individual receives four hours of Department endorsed training once per permit term and meets other minimum qualifications.


Public Comment Information

The public is invited to submit written comments on the proposed rulemaking through March 7, 2022, by close of business. Written comments can be submitted as follows:

  • By mail to NYSDEC – Division of Environmental Remediation: 625 Broadway, Albany, NY 12233-7012, attention: Jenn Dawson; or
  • By Email to with the subject line “Comments on the Draft SPDES General Permit for Stormwater Discharges from Municipal Separate Storm Sewer Systems (GP-0-22-002)”

Walden’s engineers and environmental scientists have considerable experience in helping municipal clients manage their MS4s and comply with SPDES General Permit requirements. We will continue to track NYSDEC’s proposed General Permit revisions and how they might impact our clients. Contact us today at 516-588-6859 with any questions about MS4 operations and requirements.