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.


       City of Sunnyside: Ordinance 2207 (PDF)
  1. City of Sunnyside: Ordinance 2009-17 (PDF)
  2. City of Sunnyside: Ordinance 2010 - 5 (PDF)
  3. City of Union Gap: Ordinance 2624 (PDF)
  4. Yakima County: Ordinance 4-2009 (PDF)