The State of Edmonds Waters: Part 1 — Stormwater runoff

Part 1 of a 5-part series.

Edmonds is surrounded by water. It falls on us; it runs beside us through streams and gutters, and beneath our feet into puddles and lakes and Puget Sound. It is vital and useful, beautiful, sometimes dangerous, and we cannot take it for granted. A better understanding of water quality, quantity and the condition of aquatic habitat will, I hope, raise awareness, promote discussion of water management issues and help generate solutions.

Introduction and overview

This discussion of stormwater runoff is the first of a series of articles on the state of Edmonds’ waters, including streams, wetlands, the estuary, and marine waters. Subsequent topics will address:

– The state of Edmonds’ streams, including flows, contamination, erosion, and fish blockages.

– The state of the marine waters off Edmonds.

– The Edmonds Marsh and Estuary including issues, history and opportunities.

– Possible solutions to improve our aquatic resources, and how to finance the necessary improvements for stormwater management and habitat restoration.

Stormwater affects the quality of all our waters and will feature in each of these.

Stormwater and water quality

Graphics from Kitsap County with permission from Chris May.

“Stormwater” is rainfall that runs off impervious surfaces. Stormwater is the largest source of pollutants to Puget Sound and to our streams.

When Edmonds was covered with old-growth forests, there was less runoff. Only 70% of the water dropped by clouds actually reaches the ground; the rest stays on trees and evaporates. In the natural environment, roughly half of the rainfall that reaches the ground infiltrates shallow soils and slowly flows through the soils to streams. The remainder reaches deep soils and recharges aquifers. Large storms may drop more water than can be absorbed resulting in surface runoff into streams or wetlands but they are infrequent events, occurring less than once every two years.

As forests are removed and replaced with roads, parking lots and roof tops, stormwater runoff increases significantly and the impact on our streams is devastating. Peak flows occur more often, eroding stream banks and causing channels to become wider and shallower. Small gravel and salmon eggs are washed away by these higher volumes of fast-moving water and the gravel is replaced with sand and silt. Between storms the widened streams are shallower and unable to support fish populations.

Stormwater from impervious surfaces introduces pollutants that harm salmon and the insects they eat. Pollutants, many from vehicles and pavement wear, include:

– Zinc (toxic) from tire wear

– Copper (toxic) from brake linings

– 6ppd-q (toxic) from tire wear

– Oil and grease

– Detergents from motor oil and residential use

– Phosphorous from motor oil and fertilizers

– Silt from channel erosion

– Pesticides (insects, weeds, rats)

– Bacteria from pets and improper sewer connections

– Phthalates (mimic female hormones) from plastics and cosmetics

– Bark from landscaping

– Trash

– Sand, silt and salt from treating roads during snow events

– Silt from construction sites

– Microplastics

Studies show that as density increases from one house every five acres to one house every two acres, there are significant declines in the diversity of species, in the numbers of salmon, and in the insects that young salmon eat. These populations continue to decline as we increase the density of urban development and, if the impact is ignored, valuable species like salmon can be destroyed.

Houses and roads are essential to our way of life, and our population is growing.  Urban development is ongoing.  However, we can reduce our impact, through thoughtful approaches to building that preserve and protect habitat.

The next article will explain the conditions of Edmonds’ streams in more detail.

— By Bill Derry

Edmonds resident Bill Derry is the president of the Pilchuck Audubon Society and a member of the Edmonds Marsh Estuary Advocates. He previously served six years on the board of directors for People for Puget Sound.

 

  1. Thank you so much for this highly educational article. I will make sure I read the rest of your series!!

  2. Living next to a major source of runoff into Puget Sound, I too am looking forward to the next installment.

    1. Thank you for providing this clear explanation for the increase in storm water run-off and the impact it has on streams. That salmon eggs could be washed away by higher volumes of water is just one of the things I learned. Looking forward to next articles.

  3. Don’t be shy about reporting environmental abuse when you see it. About a month ago I had to call WA EPA to file a complaint on Snohomish County Public Utilities. The street sweeper they sent to my neighborhood dropped a sheen of oil and engine fluids that went for miles and we live on a downward slope to the Sound.. The curbs were clean though. Hopefully they took that sweeper out of service. Maybe they can go electric or issue a broom to every resident and give them a tax break if they clean their curb .

  4. I look forward to your recommendations on how the City Code can be updated and improved to better protect our streams and water quality from increased development in Edmonds.

  5. Wonderful, useful article! I look forward to reading the subsequent ones.

    May I just add a note regarding stormwater – please think twice about installing artificial grass lawns, which inhibit water absorption and kill off the very active things that live in natural soil and are part of the natural life cycle. The same goes for over-paving.

  6. Many thanks, Bill, for this article and the diagrams . Well done! We Love our waterfront and our beautiful location. And sometimes we forget how fragile it all is. Your article reminds us that it is endangered, and I’m looking forward to your next article with more specifics about what we must do. Time is running out.

  7. A very clear and thought provoking message. Thank you Bill. Edmonds is fortunate that you are willing to share your expertise about stormwater.

  8. Thank you this interesting article letting people know how damaging this run-off is to our waters. I hope the Mayor and City Council Members read this and reassess the plans for Zero lot lines, more concrete, more asphalt, removal of trees, removal of grass, and overbuilding our town. They either have no idea of the damage they are doing or they don’t care.

  9. Is it better to have a 1-story home that covers 1,200 sq. ft of ground, or a 4-story home that covers 300?
    Thanks for the article!

  10. Thank you Bill, for getting this conversation going. At some point, I hope you include information about rain gardens and pervious concrete and asphalt.

  11. Oh boy, I don’t want to speculate, but I know where this series of articles is going!

    I appreciate the educational component of this complex topic and I’ll be curious to see in the next installments if there will be detailed reference to our existing, Dept of Ecology required, LID storm water management code and the requirements for BMPs relating to max impervious area, pervious materials, infiltration, onsite treatment, and flow control before discharge and compare the current new development standards to our existing aged developed land where a very high percentage doesn’t incorporate any LID strategies and how each condition overall impacts runoff and our streams.

    Stay tuned!

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