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.
- 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.