Complete Your Semiannual Stormwater Sampling By 6/30!

The deadline for quarterly and/or semiannual stormwater monitoring and sampling is June 30, 2026! These requirements are set forth by your facility’s New York State Pollutant Discharge Elimination System (SPDES) permit. Facilities that must comply with these requirements include those covered under the New York State Department of Environmental Conservation’s (NYSDEC’s) Multi-Sector General Permit (MSGP) for Stormwater Discharges Associated with Industrial Activity (GP-0-23-001), as well as certain other facilities that hold individual SPDES permits.

Monitoring

Stormwater monitoring is performed during a qualifying storm event, in which at least 0.1 inches of rain falls. It consists of a visual inspection, where a site walkthrough is performed to check for signs of pollution in runoff from all stormwater outfalls. Any obvious signs of pollution at the facility (i.e., spills) will also be flagged.

Sampling

Stormwater sampling involves collecting a measure of stormwater from each outfall at the facility. The samples are sent to a lab, where tests are performed to check for the presence of pollution. Some sites are required to perform monitoring but not sampling; this depends on the specific conditions of your permit.

Reporting

Results from your stormwater monitoring and sampling must be reported to NYSDEC at periodic intervals. Discharge Monitoring Reports (DMRs) are due to the state by July 28, and must be electronically submitted through the Environmental Protection Agency’s (EPA’s) NetDMR platform.

How Walden Can Help

If you need assistance interpreting New York’s stormwater regulations (or similar SPDES requirements, if you are located in another state), Walden’s experts are here to help. We can take care of any and all of your semiannual stormwater compliance needs.

We provide a wide array of stormwater-related services to many of our industrial, municipal, and construction clients, including:

• Stormwater Pollution Prevention Plan (SWPPP) development and implementation
• Stormwater Management Program (SWMP) development and implementation
• National Pollutant Discharge Elimination System (NPDES) and SPDES permitting and compliance
• Municipal Separate Storm Sewer System (MS4) program coordination and mapping
• Erosion and Sediment Control (ESC) plan development, inspections, and training
• Stormwater management system design
• Stormwater-related grant writing and management of awarded funds

Contact us at 516-980-5508 or download our stormwater management guide to learn more!