Urban runoff kills salmon

Update July 18, 2016: Please refer to the comment below by Nat. There is a link to the original study.

Here is a very good reason to set up rain barrels, and slow sand filters. Urban runoff is killing salmon.  It has been known for a long time that urban runoff contains lots of nasty stuff. Common sense tells us that just about anything can be in rain water once it hits the ground. Petroleum, weed killers, herbicides, drugs, chemicals, fertilizers, and anything that people use outdoors will wash off impervious surfaces and will be in urban runoff. That water then runs to the nearest drain and from there right into rivers, creeks, streams, lakes and oceans. If every house had a rain barrel at each downspout, urban runoff during heavy rain events would be reduced, and the water could slowly filter through the soil.  Add to that a slow sand filter, and the water would be cleaned up even more. The article states:

“scientists have mentioned a relatively easy fix that is the filtration through a simple, soil-based system.”

A simple soil based system is essentially a slow sand water filter. We’ve been shouting this out for the past 7 years: slow sand filters clean up water nicely. Others have been saying the same thing.

A copy of the study can be found here

Another article about the same thing is here.



Update October 11, 2015:

Today this article showed up suggesting that 55 gallon barrels filled with, gravel, soil, and compost cleans up the water:

Update October 27, 2015 The link above is no good. 

Here is another link to the same article, captured by another site.

Update February 2016: the above two links are now dead. I cannot find the information they had written. I guess information about urban runoff  poisoning salmon is not very important to some people.


“However regardless of the perpetrator is, the researchers have already got an answer—filter runoff via a fifty five-gallon drum barrel stuffed with gravel, soil, and compost, and the fish survive.” In this quote the author, David Bryan, must mean “regardless of who the perpetrator is”.  The article goes on to state:

“After researchers filtered the water by a 3-foot-excessive soil column containing gravel, sand, compost and bark layers, all the coho survived in addition to they did in clear water.  Exams confirmed the filtration columns lowered heavy metals by fifty eight p.c and polyaromatic hydrocarbons, that are byproducts of gasoline combustion, by ninety four %.”


Update February 19, 2016:  Here is another link to a similar article  regarding urban runoff and salmon; hopefully this one won’t disappear in a few weeks.


I think the author means Polycyclic aromatic hydrocarbons, although they are also referred to as polyaromatic hydrocarbons, but they are most commonly called PAH’s. We tested for hydrocarbons in January of 2010 nearly 6 years ago in one of our slow sand filters. A slow sand filter takes out hydrocarbons. The filter we tested isn’t even 3 feet deep, and it still took out hydrocarbons and harmful bacteria.  Here is another site with information on slow sand filters, (the biosand filter is essentially a slow sand filter with a slightly different design and name, the same principle of operation is used).  There is another site here. Both of these sites have been around longer than ours, and they have plenty of information about slow sand filtration. In fact, this technology has been around for over 100 years. Read about it here.

This is serious stuff. Really! Its just not making national news. This runoff kills salmon in hours. We are continuously allowing toxic water to pollute everywhere. We remove forests, and replace them with blacktop and other types of impervious surfaces, shopping malls, and houses without any thought of the consequences. Now we’re all paying for it. In our neighborhood here,  its not uncommon to see people out in the street at the edge of their front yards with a can spraying the “weeds”. The next week its all brown dead stuff there. Then it rains and all that crap, mixed with tire dust, PAH’s, and oil, runs right down into bear creek, which then runs into Lake Washington. These people should think about it the next time they want a drink of water, or go to that fancy restaurant and order salmon.

This entry was posted in slow sand water filter study and construction. Bookmark the permalink.

5 Responses to Urban runoff kills salmon

  1. Doug says:


    Thanks for the guide on sand filters. I am going to build one.

    I would also like to list your guide on my site. I will link directly to your site. I supply DYI guides and I think this one is a perfect compliment.

    Let me know if this is okay.

    Please check out my site.

    All the best,


  2. filter_guy says:

    Yes, that would be ok. I’ve sent you an email reply also.

    Dave T

  3. nat says:

    The original scientific publication can be found at wiley onlinelibrary. Unlike many scientific papers this is not the heavy going read you might expect. And unlike the secondary reports, it’s not going to disappear.

  4. filter_guy says:

    Thank you for posting the link to the study.

  5. Manoj Kumar says:

    Thanks for sharing this wonderful post,Here is Rainwater Harvesting website for India.Rainwater harvesting very helpful criteria to save natural water. It’s good investment for future.

Leave a Reply

Your email address will not be published. Required fields are marked *

This blog is kept spam free by WP-SpamFree.