What is Stormwater Management? What are Stormwater BMPs for?
We hear a lot about stormwater BMPs and stormwater management these days, and they seem to be some of the most-used buzzwords in the environmental and development industries. So, the million dollar question is, what is stormwater management?
Stormwater management is both simple and complex. Let’s handle the simple first.
What is stormwater management?
Simply put, stormwater management is the way that stormwater – the runoff from rain events – is handled, both in terms of the overall quantity of runoff, and of the water quality of that runoff.
Why do we care about the quantity, or volume, of stormwater runoff? Because, in today’s built environment, we created a lot of impervious surfaces, like concrete and asphalt pavements, that don’t allow stormwater to infiltrate, or soak into the ground, the way that it did pre-development. Therefore, we have a much higher volume of runoff quickly being discharged across land and into our waterways. This can result in negative consequences such as soil erosion and flooding. So, what is stormwater management for? Stormwater management is designed to reduce or eliminate the negative consequences, through strategies (stormwater best management practices, or stormwater BMPs) to slow down the runoff, allow additional infiltration, or keep runoff in developed areas at or near what they might have been before the development occurred.
Stormwater management is also important when considering water quality. It’s long been known that there is a direct link between the water quality of streams, lakes, rivers and other water bodies and when it rains. Water quality usually gets much worse after a heavy storm event because the runoff, particularly in urban and developed areas, picks up all the pollutants that are available to be washed away, including chemicals, oils, sediments, litter, floating materials, and more. So careful stormwater management through the use of stormwater BMPs can be a useful way to reduce or eliminate this runoff pollution, and so aid in keeping our natural waterways clean.
This all sounds pretty easy, right? If someone asked what is stormwater management, you should be able to give them a simple explanation. Remember, stormwater management, through the use of various types of stormwater BMPs can be used to reduce the undesirable impacts associated with uncontrolled runoff volume and runoff water quality. How can it be any more difficult?
The ideas remain the same, but it does get a bit more complicated. For starters, there is a whole science behind the engineering aspects of stormwater management, such as managing stormwater flow, which can get pretty complicated. But unfortunately, it’s needed in order to properly design a program to reduce stormwater volume and intensity, design, and implement stormwater BMPs, and to comply with environmental regulations such as site construction and development codes and standards.
Water quality is further complicated through a complex regulatory program here in the United States (mandated by the Federal Clean Water Act), known as the NPDES or National Pollutant Discharge Elimination System permitting program. The NPDES permitting program requires, among other things, that all stormwater discharges from industrial activities, construction activities, and municipal separate storm sewer systems (MS4s) all obtain a permit from an applicable delegated government agency for their stormwater discharge, as well as prepare implement a program of stormwater BMPs to reduce the potential for pollutants in the stormwater that is discharged. The plan for choosing and implementing the stormwater BMPs is the Stormwater Pollution Prevention Plan or SWPPP. The NPDES stormwater discharge permit program can be a pretty effective tool towards enhancing and preserving runoff water quality.
So for those wondering just what is stormwater management, I hope this cleared it up. There’s a lot to stormwater management, but most of it is directed towards either handling runoff volume and intensity, or addressing runoff water quality. In almost all cases, the end result is intended to be a system that more closely mimics a natural state by reducing man’s impacts on the environment, and results in clean water for all of us.