What is an illicit discharge detection and elimination (IDDE) program and what are its key components?

• A. A program that focuses on routine maintenance of stormwater BMPs.
• B. A program to locate and eliminate non-stormwater discharges to the storm drainage system; components include mapping, reporting, inspections, source tracing, sampling, and enforcement.
• C. A plan to replace all outfalls with sealed piping.
• D. A safety program for workers on the site.

Answer: (B)

An illicit discharge detection and elimination (IDDE) program is a structured approach to find and stop discharges of non-stormwater into the storm drainage system, with the goal of protecting water quality by ensuring the system carries only stormwater. The program relies on knowing where flows enter the system and who or what is responsible for discharges, so it typically includes mapping of the drainage network and all outfalls, procedures for reporting suspected illicit discharges, regular inspections of outfalls and related infrastructure, tracing the source of discharges to their origin, sampling and analyzing discharges to verify non-stormwater conditions and identify pollutants, and enforcement actions to halt the discharges and remediate the source.

This focus is different from routine maintenance of stormwater BMPs, which concentrates on keeping practices functioning rather than locating and eliminating non-stormwater inputs. It’s also not about replacing outfalls with sealed piping or a safety program for workers. The essence is a proactive, organized effort to detect and remove illegal discharges through mapping, reporting, inspections, source tracing, sampling, and enforcement.