Sunday, February 7, 2021

What Is Stormwater and Why Does It Matter?

This first installment is your basic refresher course on what stormwater is and why it is important to think about. Over the past 50 years, stormwater has evolved as a science and profession. It is a complex issue that impacts all of us and the environment. Let's begin!

The Water Cycle

Let's start with water. You remember the water cycle from grade school, right? Have you thought about it much since then? Below is an image depicting the natural water cycle, without human interference. Notice the precipitation which can become natural runoff, recharges groundwater through infiltration, and streams and lakes which are fed by both. 

Where Stormwater Begins and Ends

Although the water cycle has no beginning and no end, stormwater for our purposes certainly does. It begins as precipitation and ends in local waterbodies. We hear it on the rooftop, collect it in gutters and pipes, and generally try to drain it away as quickly as we can. Out of sight, out of mind. Good riddance, right? Not so fast! This is the crux of the issue.

In the urban landscape, rain can no longer slowly infiltrate into the soil or transpire through natural vegetation. We built our homes, manicured our lawns, and paved driveways and roads so we can live in this beautiful place that drains to the Puget Sound. The water that once filtered through the forest or infiltrated through the ground runs off as stormwater in larger amounts. Below is a good approximation of the amounts of runoff and groundwater recharge from a typical suburban development in the Puget Sound lowlands (Low Impact Development Technical Guidance Manual for Puget Sound, December 2012). 

Stormwater Where You Live

When you walk around your neighborhood, have you ever noticed the storm drains in the street? Is there a stormwater facility collecting the water from your street? Do you have any creeks nearby? Maybe even a lake? Do you know where the creek goes, and if that goes to the lake, where does the lake drain? How does it get to Puget Sound and what is the water collecting along the way? 

If you don't know, or haven't thought much about it before, the next time you go out I challenge you to look at the drains and stormwater in your neighborhood. Think about where it came from and where it is going to. To help you out, there is an easy to use map! Using the link below, you can enter your address and it will show you the watershed you live in and how it drains.

Open the map! (opens the U.S. EPA's, How's My Waterway? tool in a new page)

Why Does It Matter? It's About Quality and Quantity.

Stormwater is the biggest source of pollution in Puget Sound. It gathers pollutants when it runs across manmade surfaces. It collects excess nutrients from fertilizer used on your lawn and metals deposited on the road from vehicles. I will write a more detailed post going into water quality, but what you should know right now, is that these pollutants cause many problems like reducing habitat diversity, harming wildlife, and infringing on recreational opportunities.

Another issue of stormwater is the volume of runoff we generate. The figure above points out that stormwater runs off in a greater amount after our homes have replaced forested land. Instead of being captured by the forest and slowly put into the ground and streams, impervious surfaces (hard surfaces that impede the ability of water to infiltrate) cause water to runoff quickly. This increases the amount of water entering the creeks for a short period of time. The increased runoff causes stream levels to rise above normal which causes erosion. And when a stream is overwhelmed, we see localized urban flooding.

Share Your Stormwater Story!

So, tell me, do you already think about stormwater? What kind of experiences do you have with stormwater? Please share what you learn about your neighborhood. What brought you here to this post and what are you interested to learning about? 

Are you implementing ways to reduce your runoff and improve water quality where you live? 
Or, has stormwater and how you affect it, not really crossed your mind before?

Already wondering what you can do to help? There are so many things we can do, from simple to advanced, that allow all of us to do our part to help recover and restore the watersheds we live in.

5 Easy Things You Can Do Today! 

  1. Maintain your vehicle. Never dump anything down a storm drain. Always recycle used oil, antifreeze, and other fluids. Fix oil leaks.
  2. Wash your car at a commercial car wash. If you wash your car at home, wash it on your lawn.
  3. Cut down on fertilizers, pesticides and herbicides. Use them sparingly. Don't fertilize before a rainstorm. Consider using organic fertilizers. 
  4. Replace part of your lawn with native, drought-resistant plants.
  5. Pick up after your pets and keep animals out of streams. If you have farm animals, compost manure in a designated area so that it doesn't wash off into nearby waterways.
For the full list see King County's webpage Stormwater runoff pollution and how to reduce it - King County


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