Illicit Discharge

Illicit discharges are the introduction of non-stormwater runoff, sewage, or hazardous materials into the public stormwater system. Studies have shown that dry weather illicit discharges into stormwater systems can exceed the total pollutants from storm event flows. Stormwater systems typically flow untreated to water bodies thus the Department of Ecology places a significant emphasis on illicit discharge detection to protect water quality.

Illicit Discharge Requirements & Conditions

Illicit discharges are:

Hazardous waste
Liquid or solid wastes
Operational wash water
Septic or sewer connections

Under certain conditions, the following are not illicit discharges:

Dust control water
Lawn water
Permitted discharges covered under another permit
Street/sidewalk wash water
Swimming pool discharge - dechlorinated pool water only at undetectable levels (0.1mg/L).
Water line or hydrant flush water

Illicit discharges are not:

Air conditioning condensate
Uncontaminated crawl space pump discharge
Footing drains
Foundation drains
Ground water
Irrigation water from agricultural sources

Detection & Elimination

Permittees are required to develop and implement an ongoing program to detect and address non-stormwater discharges to the stormwater system including spills, illicit connections, and illegal dumping. The Illicit Discharge Detection and Elimination Procedures (PDF) guide provides permittees with guidance to implement this program.

Reporting Discharges

To report a suspected illicit discharge in Selah, Sunnyside, Union Gap, or the County, call 509-574-2300 or email.

Illicit Discharge