Changes Being Proposed to Washington’s Industrial Stormwater Permit

On May 1, 2019, the Washington State Department of Ecology published a draft of the new Industrial Stormwater General Permit (New Permit), asking for all public comments by June 29. The New Permit is scheduled to go into effect on January 1, 2020.

While the New Permit maintains the same water quality parameters and benchmark values, it includes some changes that permittees (and potential permittees) will want to keep in mind. For one, it adds two new industrial activities to the list of activities requiring coverage: Marine Construction; and Construction, Transportation, Mining and Forestry Machinery, and Equipment Rental and Leasing. The New Permit also moves up the sampling date for the first fall storm event from on or after October 1st to on or after September 1st. This is an important sampling event because the first fall storm usually picks up pollutants that have accumulated during the drier summer months. Moving the sampling event from the year’s 4th quarter to the 3rd quarter also means permittees are likely to see more 3rd quarter benchmark exceedances, thereby increasing the chances of having multiple exceedances during a calendar year and having to take corrective action.

Finally, the New Permit changes sampling suspension requirements for permitees consistently attaining levels below benchmark values. The current permit allows permittees to suspend sampling for one or more water quality parameters when they have demonstrated consistent attainment with applicable benchmark values. The New Permit instead requires permittees to continue to collect one sample of the “consistently attained” water quality parameter in the 4th quarter of each year. If the sample is above benchmark, the permittee must resume quarterly sampling for that parameter.

These are just a few of the changes in the New Permit. Anyone wanting a deeper dive into these changes and Ecology’s process should see a more complete synopsis prepared by Owen Reese of Aspect Consulting.