Pick it Up: How Dog Poop is Ruining Our Waterways

We’ve all been there at least once: no one is looking and you forgot a poop bag so you just walk away from your dog poop and hope no one sees you.

Most people probably would’t feel guilty doing it once in a while. I mean, how is one dog poop pile going to hurt anything?

Then, there is me. I worked in the field of water quality protection for 10 years.

Someone like me loses sleep for several nights over leaving dog poop on the ground (kidding. kind of).

But why? What’s the big deal?

Well, you may not know it, but dog poop is ruining our waterways.

UPDATED: Originally published November 19, 2023

Do People Really Leave Their Dog Poop on the Ground?

In my former career as a surface water quality specialist, I did a lot of research on people’s attitudes about pet waste.

Did you now that a 1999 study by the Center for Watershed Protection found that 41% of bay-area dog-owners rarely or never pick up after their pets?

Yes, we would hope that number would have improved since then.

While more people probably pick up their dog’s poop today due to the prevalence of educational campaigns, the percent of dog-owning households has in creased since 1999.

That means that the number of owners not picking up after their dog might be the same or similar.

I found that a big factor in people’s unwillingness to pick up their dog’s poop the perception that poop is natural – that it doesn’t hurt anything by leaving in on the ground and “letting it go back to nature.”

The truth is there are a lot of issues with leaving pet waste on the ground.

Is Dog Poop Natural?

Many people believe that dog poop is natural.

While pooping is natural, the effects dog poop can have on people and the environment is not.

First, dog poop contains a lot of bacteria. Bacteria that can make people sick.

One gram of dog waste can contain 23 million fecal coliform bacteria, which can cause illnesses in humans.

Dog poop left on the ground can be stepped on and bacteria from it can contaminate people’s vehicles and homes.

Bacteria from dog poop can also contaminate the soil.

Children crawl on floors, and eat dirt, so this bacteria can make them sick.

Second, people and dogs are concentrated to certain urban areas, surburban areas, and trails.

The volume of dog poop left in these areas from the hundreds of dogs that pass by is not natural.

While the environment might be able to degrade one pile of dog poop on occasion, it’s not able to handle the unnatural amount of dog poop left on the ground in most places.

How Long Does Dog Poop Take to Decompose?

How fast dog poop decomposes and breaks down depends on several different factors, including your dog’s diet, climate, exposure to sunlight, and the surface it’s resting on.

Dog poop left on dirt in the woods will break down faster than dog poop left on a lawn.

This is because there is less good bacteria in urban, chemically-treated lawns to help break it down.

Dog poop left on any kind of soil will decompose faster than if it’s left on concrete.

Dog poop exposed to cold temperatures will decompose slower than the piles exposed to warm temperatures.

Dog poop that remains most will decompose faster than poop that dries out (because when it dries out, the bacteria that can break it down also dies).

If a dog eats a high protien diet, it’s more work for bacteria to break it down.

For these reasons, dog poop can decompose in as little as 9 weeks or take 12+ months.

Does Dog Poop Disappear When it Rains?

While it may look like a pile of dog poop dissolves after a few rains, it doesn’t actually go away.

In reality, it breaks down into a million microscopic piles and washes away only to end up somewhere else.

Those microscopic poop piles take a float trip when it rains and can end up in the nearest waterway.

In urban areas, dog poop particles wash into storm drains and flow, unfiltered, straight into lakes and streams.

This bacteria can multiply.

It can also feed, and cause excessive overgrowh, of aqualtic plants that can rob life-sustaining oxygen from the water.

I’ve had to close down public swimming beaches because there is too much dangerous fecal coliform, or toxins released by decaying blue-green algae, in the water.

Pet waste is one of the most common contributors to making water unsafe to drink or swim in.

Check out this infographic from Earth Rated Poop Bags for a more a visual explanation.

What About Dog Poop in My Yard?

Now you might say, “But I don’t live or walk in an urban environment?

I know for sure that when I leave poop in my back yard, it doesn’t wash into streams or other waterways. This information doesn’t apply to my situation.”

Here is the potential problem with leaving dog poop in your yard.

In your back yard, it may look like the poo dissolved but the bacteria is still in the soil.

Now imagine your kid, or your neighbor’s kid, is playing in your yard. Their toys get dirt on them, then their hands get dirty, and then they stick their fingers in their mouth like kids do.

Now they have just eaten bacteria from dog poop. Yuck!

Eating contaminated dirt can make kids sick.

I will admit that it’s rare but it happens. Taking that risk is up to you.

Final Thoughts

The bottom line is scoop the poop using a bag or shovel and put it in the trash.

Sending masses of poop to the landfill is not the perfect solution but it’s the best there is right now to keep the earth clean and keep everyone safe and happy.

About the Author

Hi, I’m Jessica. I’m a Dachshund sitter, President of the largest social Dachshund club in Washington State, a dog trainer in training, and I’ve been a Dachshund owner for 20 years. I have over 150,000 hours of experience with the breed. When I’m not working, you can find me hiking, camping, and traveling with my adventurous wiener dogs.


  1. I admit, I don’t scoop in my yard (at least not all the time) but I definitely do on our walks, even in the woods. We live in a very hilly area and the park is at the top of the street. There are streams in the park and their waters eventually makes their way down the hill to the sewer system. I just wish more people were aware of this, because I have to constantly keep my head down on walks, just to make sure I don’t step in anything.

    1. Does water in your area actually go in a sewer? Geeky semantics I know but I ask because in most areas of the country, rainwater that goes down the drain flows untreated into streams. In the old days, rainwater and toilet water used to flow in the same system (called combined sewer systems). There are some areas like that in Seattle because they are so old. That water goes to treatment plants. It’s been a law for decades now that two separate systems be constructed so the sewage treatment plants aren’t flooded with rainwater. Just curious how it is in your neighborhood.

    2. Let’s look at the big picture. Bacteria which is a natural form of life vs. Plastic which is man-made.

      How else do you pick up poop?

      The plastic ends up in landfills (when picking up poop in our backyards) or in the streams and oceans (when we leave it on the side of the trail with no garbage cans in sight). Landfills – out of sight, out of mind?

    1. Yeah, it is frustrating that there is not a better solution at this point. I’ve heard of some people flushing it (from their yard or bringing it home and doing that) but when flushable poop bags first came to market I called our local sewage treatment plant for their opinion. They said they absolutely don’t want people putting pet waste into toilets. There are so many reasons. I won’t bore you but the main reason is that treatment plants wouldn’t be able to handle the additional influx of “sewage” and the plants aren’t designed to destroy all of the bacteria and pathogens in dog poop (some are different than in humans).

  2. I am SO sharing this. I am a pick it up person too. I actually read up on the effects dog feces has on the environment a fe years back and was surprised at how little we can do with it in terms of the environment. I know one community in Great Britain tried using it to generate electricity for the dog park lights, but that was a one-off circumstance and not all that effective. Dogs carry a lot of bacteria in their poop, so leaving it is not an option for me. Great piece.

    1. I think I saw a waste digester in the states like that too – ran the lights for a dog park. I can’t remember where it was though.

  3. That’s interesting, because when I looked into it a while ago, Metro was recommending putting dog waste into toilets because they could handle it and it was a better option than landfills. I’ll have to go back and check again. I just use a shovel in the yard and take to to a toilet in my studio that is used infrequently and flush it. I figure it’s good for the toilet to have some use, and the poop goes where poop goes.

    1. I worked in Shoreline and talked directly to my contact at the sewer treatment plant. That was over 5 years ago though so they might have changed their tune. I still keep up on all of the regional messaging though (helped start the coalition in the Puget Sound about stormwater education) and I haven’t heard their primary message change. Let me know if you find where you saw that. I would be interested to check it out.

  4. This is a link to an article linked to on the King County Sewage Treatment website. http://your.kingcounty.gov/solidwaste/ecoconsumer/documents/SeattleTimes_2015-04-04.pdf
    In one section it says that dog poop can go in the sewage system, but not cat litter. They also don’t recommend burying it at home anymore as it can leach into the ground water. Bag and toss is also recommended, but not in the yard waste, and also that the bio bags are a waste in solid waste because they won’t bio degrade quickly in a landfill.

    1. Thanks. Unless I am missing something, that article says that bagging dog poop and placing it in the trash is the best way to go (the in the bag section). Specifically, “For now, most health- and waste-related government agencies recommend pet waste be put in a plastic bag and placed in the garbage. Although not ideal environmentally, it’s considered the most practical and safest approach.”

      It does say “Flushing small amounts of dog waste down the toilet is fine, if you’re so disposed” (in the cat litter quandary section) but does not promote that as a primary way of disposal. One person doing it is probably not a big deal. They certainly wouldn’t want every dog owner in the are doing it on a regular basis though.

  5. As a water quality protection specialist, I can attest to the fact that dog poop left on the ground is a serious problem. Not only is it unsightly, but it can also contaminate our waterways and harm aquatic life. That’s why it’s crucial for dog owners to always have a pooper scooper on hand when walking their furry friends. Even one missed pile can make a difference! And if you forget your pooper scooper, don’t just walk away and hope no one sees. Instead, make an effort to come back with a bag and clean up the mess. Let’s all do our part to protect our waterways and keep our neighborhoods clean.

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