Stormwater Action Monitoring — source identification

Illicit discharge detection and elimination (IDDE) incidents are recorded by Western Washington municipal stormwater permittees in many formats. The first SAM source identification project compiled the IDDE incidents reported to Ecology from 2014 into a dataset of almost 3,000 incidents. This represents a first step in capturing the breadth and scale of incident investigation work.

• IDDE Final Report
• SAM Fact Sheet #005

Key findings

• A wide variety of methods are used by permittees to report IDDE efforts to Ecology, requiring a significant effort to compile and learn about local efforts, resource needs, and common solutions. Standardization of reporting is recommended; for example, by spreadsheet.
• Municipal stormwater staff invest a substantial amount of time investigating and addressing potential incidents. Response is quick, usually within one to three days.
• The most common stormwater problems were:
  • Petroleum hydrocarbons and other vehicle fluids — often from accidents
  • Sediment from construction sites
  • Chemicals from industrial activities
  • Sewage from illicit connections
• Most incidents were reported to local governments via hotlines or citizen calls. A significant number of incidents investigated were not illicit discharges, but allowable discharges. Permittees will continue to spend time and effort on such calls.

In 2016-17 the Stormwater Work Group's Source Identification Subgroup revised the illicit discharge detection and elimination (IDDE) recommendations for which fields should be in the form for consideration by Ecology's permit managers. This revision should help standardize data collection for the next permit cycle.

King County and subconsultants led this 2020 update to the Illicit Connection and Illicit Discharge (IC-ID) Field Screening and Source Tracing Guidance Manual (IC-ID Manual), which was originally published in 2013.

Scope of work, Amendment 1

Study findings

The updated IC-ID Manual provides municipal stormwater professionals across the region with widely-used information in an accessible format for screening, identifying, and tracing the sources of stormwater pollution. Trainings on the updated IC-ID Manual provided a refresher for existing personnel, and new additional training resources (five short videos showing techniques) will to help train future personnel on the updated manual. 

Key project deliverables

• Presentation to SWG June 2020
• Final updated IC/ID manual and examples forms in appendix B and on the Washington Stormwater Center ICID website.
• SAM Fact Sheet #21 2020 Update to the IC-ID field screening manual

Visit the IC-ID videos at the Washington Stormwater Center's YouTube Channel for staff training and techniques on MS4 screening and pollution source identification.