Changes to the Washington ISGP: Are You in Compliance?

March 27, 2020
By Brian Schefke

The new Industrial Stormwater General Permit (ISGP) for the state of Washington went into effect on January 1, 2020 and contains many changes from the 2015 permit that affect both current permittees and businesses that were previously not covered by the permit. Major changes include:

  • When applying for coverage, applicants must identify their industrial category using North American Industry Classification System (NAICS) codes instead of Standard Industry Classification (SIC) codes.
  • Two new industrial categories are required to obtain permit coverage:
    • Construction; Transportation; Mining; and Forest Machinery and Equipment Rental and Leasing (NAICS codes 53241x)
    • Marine Construction (code ECY003)
  • The date of collection of samples from the first fall rain event is now on or after September 1st.
  • Permittees claiming consistent attainment for one or more parameters must test stormwater discharge for those parameters once annually during the fourth quarter. If the results of testing exceed the benchmark, permittees may no longer claim consistent attainment, the quarterly tally is reset to zero, and permittees must resume quarterly testing. Permittees may collect multiple samples during the quarter and average the results.
  • The requirements for the site map in the Stormwater Pollution Prevention Plan (SWPPP) have expanded.

Whether you’re a current permittee or a business seeking permit coverage for the first time, it’s important to ensure that you’re in compliance with the ISGP’s requirements for Best Management Practices (BMPs), reporting, recordkeeping, training, and more. Compliance not only reduces the risk of fines or costly litigation, but also helps contribute to cleaner waters and a healthier community. If you need guidance with any aspect of stormwater permit compliance, we’re here to help.

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