The Semi-Annual Stormwater Sampling Deadline Is Imminent!

For facilities covered under the Multi-Sector General Permit (MSGP) for Stormwater Discharges Associated with Industrial Activity (GP-0-23-001), the semi-annual stormwater sampling deadline is rapidly approaching! The New York State Department of Environmental Conservation (NYSDEC) enforces compliance with this permit to protect water quality conditions relating to stormwater discharges. Facilities covered under the MSGP include various industrial facilities that discharge stormwater to surface waters of NYS.

Important Deadlines

Semi-annual stormwater sampling and monitoring must be completed by June 30, 2025. Additionally, Discharge Monitoring Reports (DMRs) for the first monitoring period of 2025 must be submitted to the NYSDEC by July 28, 2025. These deadlines are critical, as non-compliance may result in penalties enforced by the NYSDEC.

Compliance Obligations

Compliance obligations are included within site-specific Stormwater Pollution Prevention Plans (SWPPPs), which are required to receive authorization under the MSGP. SWPPPs outline measures to limit pollutants discharged into stormwater from industrial sites, and are dependent on how a site is configured. Compliance typically includes:

• Submittal of semi-annual and discharge monitoring reports.
• Numeric effluent limitations monitoring (sector dependent).
• Benchmark monitoring (sector dependent).
• Corrective actions, including implementation and documentation of any changes to a facility’s stormwater management system.

Benchmark monitoring, numeric effluent limitations monitoring, and DMRs must be submitted electronically through the United States Environmental Protection Agency’s (USEPA’s) “NetDMR” system. Walden’s staff of stormwater compliance experts can help you navigate these complex reporting requirements for your facility and avoid costly penalties.

How Walden Can Help

If you need assistance interpreting stormwater sampling requirements for your facility, Walden’s team of experts in water quality management and regulatory program compliance can help you. Contact us today at 516-980-5508.