Stormwater Permitting Requirements for Phase II (Small) MS4s

Authorization options, control measures required, annual reporting requirements, and links to best management practices for operators of Phase II MS4s.

Stormwater Management Program
Annual Report

Stormwater Management Program

Regulated municipal separate storm sewer systems (MS4s) are required to reduce the discharge of pollutants from its MS4 to the maximum extent practicable (MEP), to protect water quality, and to meet the appropriate water quality requirements of the Clean Water Act. U.S. EPA refers to these requirements collectively as “the MS4 permit standard.” MS4 permits implement this standard through requirements to develop and implement stormwater management programs (SWMPs) that covers the duration of the general permit term.

If you operate a regulated small MS4, then you must develop and implement a SWMP that includes at least the following seven minimum control measures (MCMs):

MCM 1: Public Education and Outreach
MCM 2: Public Involvement/Participation
MCM 3: Illicit Discharge Detection and Elimination (IDDE)
MCM 4: Construction Site Stormwater Runoff Control
MCM 5: Post-construction Stormwater Management in New Development and Redevelopment
MCM 6: Pollution Prevention and Good Housekeeping for Municipal Operations
MCM 7: Industrial Stormwater Sources (only for Level 4 small MS4s that serve a population of 100,000 or more)
MCM 8 (optional): Authorization for Construction Activities Where the MS4 is the Site Operator

The minimum seven MCMs, and the optional eight MCM if selected, must be developed by identifying and applying the best management practices (BMPs) in the 2024 Phase II MS4 General Permit, effective August 15, 2024, for the applicable small MS4 level. The 2024 general permit is a Comprehensive General Permit that includes specific BMPs and measurable goals for each MCM to specify the “clear, specific, and measurable”: activities, goals, and deadlines that must be implemented by small MS4s in their SWMPs based on their MS4 level. Complete implementation of the SWMP is required within five years from the date of issuance of the 2024 general permit.

Small MS4s must develop a SWMP, according to the provisions of the general permit, to the extent allowable under state and local law, to address the portions of the small MS4 that are either located within the urban area with a population of at least 50,000 people or that are designated by the TCEQ, with discharges that reach Waters of the U.S. as defined in 40 CFR §122.2 .

Although a SWMP must be developed and implemented, with a Comprehensive General Permit option, small MS4s are not required to submit the SWMP to TCEQ for review and approval. Additionally, small MS4s are not required to provide public notice of their application or for changes to the SWMP since the 2024 Phase II MS4 General Permit provides the required public notice of the defined terms and conditions for each small MS4 by specifying the required controls and schedules.

Small MS4s having a public website are required to post their SWMP on their website, no later than 30 days after the NOI or NOC approval date, to share information with the public.

Annual Report

2024 Phase II MS4 General Permit

Under the 2024 Phase II MS4 General Permit, the small MS4 operator is required to submit a concise annual report to TCEQ within 90 days of the end of each calendar year (i.e., March 31). The first annual report for the 2024 general permit must address the period beginning on the day that authorization is obtained and ending on December 31 of that same calendar year.

The annual report must be signed (in accordance with 30 TAC §305.128 relating to Signatories to Reports) and submitted using the online electronic reporting system, NeT-MS4 , unless the permittee requests and obtains an Electronic Reporting Waiver.

If the small MS4 obtains an Electronic Reporting Waiver, the annual report must be submitted with the appropriate paper annual report form provided by the executive director and submitted to the following locations:

Original – TCEQ Austin Headquarters Office c/o the Stormwater Team (MC-148), and
Copy – TCEQ Regional Office that serves the area of the regulated small MS4.

2019 Phase II MS4 General Permit

Existing small MS4 operators authorized under the 2019 Phase II MS4 General Permit, are required to continue to submit an annual report to TCEQ until a renewal authorization under the 2024 general permit is obtained. The concise annual report is due to TCEQ within 90 days of the end of the reporting year selected by the small MS4 (permit year, calendar year, or fiscal year).

The annual report must describe the activities conducted during thesmall MS4’s reporting year. The annual report must be signed (in accordance with 30 TAC § 305.128 relating to Signatories to Re ports) and must be submitted on TCEQ Form 20561 available for the 2019 general permit.

Small MS4s having a public website are required to post their annual report on their website, no later than 30 days after the due date, to share information with the public.