Maryland Department of the Environment
Industrial and General Permits Division
Water Management Administration
1800 Washington Boulevard
Baltimore, MD 21230

General Discharge Permit No. 12-SW (NPDES No. MDR00) General Permit For Stormwater Discharges Associated With Industrial Activity

Sampling is not required in the current permit.

effective January 1, 2014 through December 31, 2018

Measurable Storm Events All required monitoring must be performed on a storm event that results in an actual discharge from your site (“measurable storm event”) that follows the preceding measurable storm event by at least 72 hours (3 days). The 72-hour (3-day) storm interval does not apply if you are able to document that less than a 72-hour (3-day) interval is representative for local storm events during the sampling period. In the case of snowmelt, the monitoring must be performed at a time when a measurable discharge occurs at your site.

Magnitude: results in actual discharge

Interval Between Storms: 72 hours, unless less than that is representative

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