Phase I and Phase II MS4s are responsible for the quality of stormwater leaving their municipalities, and to do that effectively, they must develop and follow a Stormwater Management Plan, the main components of which are highlighted below. They’re all important. But let’s take a closer look at Illicit Discharge Detection and Elimination (IDDE).

Obviously, the goal is to prevent illicit discharges in the first place through education and proper management. While that’s a delightful goal, it’s not necessarily 100% achievable. So illicit discharges continue, whether from a poorly managed construction project or Joe down the block dumping his used oil into the storm drain (not cool, Joe. Not cool.). As a result, they wreak havoc on our ecosystems and, depending on what’s in them, our health.

Of course, since they can’t (yet) all be totally prevented, they have to be detected in the first place. Characterized. Traced upstream, and stopped.

Pierce County, home of Tacoma, Washington, identified over 1,000 of these IDDE incidents between 2012 and 2016…and every one of them was reported by a human looking down and seeing something (or, god forbid, smelling something) that’s a bit off, and taking that extra step to call it in.

Which means that we miss thousands upon thousands of these IDDEs simply by the very nature of our ability (or lack thereof) to detect them.

And, of course, so many IDDEs go undetected during drier months simply because an oil spill on pavement in the summer doesn’t exactly create that glorious sheen that you see when it’s raining. So a lot of material builds up over dry periods and causes that particularly nasty “first flush,” aka the first rain after a long dry period that results in nearly instant death for any fish it contacts. (As a slightly relevant aside: driving during that first rain event can be dangerous…all of the buildup of oils and greases makes the roads quite slippery and dangerous for you too, significantly increasing your risk of getting into an accident.)

Overall, what I would like to say is that (1) municipalities have a lot on their hands when it comes to stormwater management, (2) IDDEs are among the more significant and require a great deal of manual labor to identify and track down what is likely a very small percentage of the problem, and (3) it doesn’t have to be this way.

With the development of sensors that can easily detect when something’s off – whether high turbidity, flow where there’s not supposed to be any, or temperature that doesn’t match the surroundings – we have an amazing opportunity to expand not just our data collection capabilities, but our ability to manage what before was a black box, and what can now be identified, opened, and applied to measurably reduce our impacts on our environment and our pocketbooks.


About the author

Erin Rothman

Stormwater Scientist

Talk stormwater with erin@stormsensor.io With more than 15 years of environmental consulting experience, Erin observed so many opportunities for innovation in the stormwater industry. With those in mind, she founded StormSensor to enthusiastically embrace new technology to help solve the problems of an age-old industry.