Illicit Discharge Detection and Elimination Compliance Tools

NPDES PHASE II
Illicit Discharge Detection and Elimination Compliance Tools

"You must develop, implement and enforce a program to detect and eliminate illicit discharges (as defined at Sec. 122.26(b)(2)) into your small MS4." —USEPA NPDES Illicit Discharge Detection & Elimination Regulatory Text (Storm Water Phase II Final Rule)



According to EPA Storm Water Phase II Final Rule Fact Sheet 2.5—Illicit Discharge Detection and Elimination Control Measure, an operator of a regulated small MS4 is required to develop, implement and enforce an illicit discharge detection and elimination program which must include the following elements:

  • A storm sewer system map, showing the location of all outfalls
  • A plan to detect and address non-storm water discharges, including illegal dumping, into the MS4
  • The determination of appropriate best management practices (BMPs) and measurable goals for this minimum control measure.

offers tools and instrumentation to help meet those compliance goals.


Storm Sewer System Map
The storm sewer system map is meant to demonstrate a basic awareness of the intake and discharge areas of the system. It is needed to help determine the extent of discharged dry weather flows, the possible sources of the dry weather flows, and the particular waterbodies these flows may be affecting.

To aid with compliance, offers a line of Global Positioning System (GPS) instruments.Particularly useful is the Garmin® Global Positioning System (GPS) III, which offers new mapping features that can help you provide a topology survey of the area.


Illicit Discharge Detection
The plan to detect and address illicit discharges is the central component of this minimum control measure. As guidance only, the four steps recommended by the EPA are outlined below:

  • Locate Problem Areas by (among other methods) visual screening and water sampling from manholes and outfalls during dry weather.
  • Find the Source through (among other methods) dye-testing buildings in problem areas, dye- or smoke-testing buildings at the time of sale, and tracing the discharge upstream in the storm sewer.
  • Remove/Correct Illicit Connections by directing the offending discharger to correct the problem.
  • Document Actions Taken (in an annual report), including the number of outfalls screened; any complaints received and corrected; the number of discharges and quantities of flow eliminated; and the number of dye or smoke tests conducted.
To aid with compliance, offers a host of water testing instruments and dyes, including: water quality testing, Dye tracers, multiparameter water-quality meters, colorimeters, water quality analyzers, and water-testing glassware.


Dry Weather Sampling
Dry weather sampling and sample analysis often includes—but is not limited to—testing the following:

  • pH—(Field and lab) pH readings provide a quick and easy way to monitor water quality. offers a full line of OAKTON® pH/mV/C 310, that lets you stamp stored readings and calibration data with date and time.
  • Turbidity—(Field and lab) Turbidity readings provide a good indication of water quality based upon the clarity of the water. offers a full line of Hach® portable turbidity meter, which meets or exceeds design and performance criteria as specified in U.S. EPA method 180.1.
  • COD—(Lab only) Coliform testing requires a sample to be sent back to the lab and incubated in order to monitor bacterial contamination. has two YSI 910 COD Reactor, Test Kits, and Colorimeter to choose from, both of which utilize USEPA-approved COD methodology.
  • BOD—(Lab only) Biological oxygen demand also requires a sample to be sent back to the lab to determine oxygen uptake rates. offers a wide variety of YSI® models 5000 and 5100, which come with built-in software.
  • Oil and Grease—(Lab only) Oil contamination levels must be measured in the lab. For this, offers the Environmental Express Oil and Grease Extraction Disks