State of Washington Department of Ecology
Water Quality Program-Industrial Stormwater
PO Box 47696
Olympia, Washington 98504-7696

State of Washington Department of Ecology Industrial Stormwater General Permit, effective January 2, 2015 thru December 31, 2019

S4. General Sampling Requirements

B. Sampling Requirements

1. Sample Timing and Frequency

a. The Permittee shall sample the discharge from each designated location at least once per quarter:

1st Quarter = January, February, and March
2nd Quarter = April, May, and June
3rd Quarter = July, August, and September
4th Quarter = October, November, and December

b. Permittees shall sample the stormwater discharge from the first fall storm event each year. “First fall storm event” means the first time after October 1st of each year that precipitation occurs and results in a stormwater discharge from a facility.

c. Permittees shall collect samples within the first 12 hours of stormwater discharge events. If it is not possible to collect a sample within the first 12 hours of a stormwater discharge event, the Permittee must collect the sample as soon as practicable after the first 12 hours, and keep documentation with the sampling records (Condition S4.B.3) explaining why they could not collect samples within the first 12 hours.

e. Permittees need not sample outside of regular business hours, during unsafe conditions, or during quarters where there is no discharge, but shall submit a Discharge Monitoring Report each reporting period (Condition S9.A).

Magnitude: results in actual discharge

Interval Between Storms: n/a

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