Due to health concerns, Washington state prohibits pet waste in curbside compost and drop-off collection systems.

Why is this an important issue?

Pet waste (cats and dogs) contains pathogens that may cause infectious diseases (e.g. roundworms, E.coli, toxoplasmosis).¹ In order to kill these pathogens, one must maintain a compost temperature of 165 F for several days.²

It is still important to dispose of pet waste in the garbage. When left alone, dog waste can pollute ground and surface water. Thus, it is important to pick up after your pet and dispose of its waste in the garbage.

The same is true for cat litter: it does not belong in the compost. Commercial cat litter (particularly scented brands) contain chemicals that don’t break down when you compost cat waste.³

Biodegradable and Compostable bags

Companies advertise pet waste bags as biodegradable and compostable. Unfortunately, pet waste still does not belong in the compost. Above all, pet waste in compost continues to be a health risk regardless of the bag material.

Personal Actions

Continue to clean up pet waste and properly dispose of it in the garbage.

Policy Options

Different cities in Washington have different laws about pet waste disposal. Thus, it’s important to check with your city’s laws to make sure you’re getting rid of your pet’s waste correctly.

Successful pet poop composting projects

Woodland Park Zoo Doo

Woodland Park Zoo’s Zoo Doo is the most exotic compost available in the Pacific Northwest. Zoo Doo is a fully composted blend of select animal manures mixed with bedding materials such as straw and wood chips from around the grounds of the zoo.

All the non-primate herbivore (plant-eating) animals are happy to doo their part. These animals include rhinos, giraffe, hippos, mountain goats, zebras, and many more! Woodland Park Zoo composts approximately 625 tons of animal waste each year saving around $90,000 per year in disposal costs.

The process begins when fresh manure and bedding materials are collected from animal enclosures. Next, the materials are taken to the Zoo Doo yard for composting. The active composting phase lasts 30 days and the piles maintain temperatures between 135°F and 160°F, which allows for the optimal decomposition of organic materials as well as destroying weed seeds and potential pathogens.

Active composting is followed by secondary composting, or curing, which is the decomposition process slowing down as the microbes finish breaking down the materials. During this phase, temperatures in the pile decrease, and the compost matures into dark and crumby humus. After this 30 or more day process, the material looks and smells like rich organic soil or mulch, bearing little resemblance to its original components and is ready for use in home gardens!

All of our material is composted through the same process, but piles have slightly different materials to begin with, which is how we end up with Zoo Doo (hay and straw blend) and Bedspread (woodchip blend).⁴

Denali National Park Service composts its sled dogs' poo

The dogs in the Denali National Park kennels produce up to 50 pounds of poo a day. In 1980, the kennels staff decided that launching all that poo down the hill behind the kennels building probably wasn’t the greatest idea. To minimize the build up of waste and keep our kennels area clean, a composting program was established. We built a four bin system in which the waste (nitrogen) is mixed with sawdust (carbon) and water and rotated regularly until it transforms into a soil that is jam-packed with nutrients.

The mixture of waste, sawdust, and water is carefully concocted to give us a carbon: nitrogen ratio of 20 or 30:1, with the consistency of a worn out sponge. Once the texture and ratio are adequate, we’ll start monitoring the temperature of the pile. As the pile sits, microorganisms digest the nitrogen and carbon of the waste mixture and heat is produced. The temperature of the pile tells you the level of microbial activity within it. In Denali, we wait for a pile to heat up to 145° F before we turn it.

When the microorganisms have broken down all the organic material, the pile is done “cooking”. This process can take anywhere from 4-8 weeks. The odorless, nutrient-rich material that is produced is called humus. It increases the nutrient content of soils and helps retain moisture. Composting also reduces the volume of waste by over 50%!

We use this compost in flowerbeds and gardens in the Denali area. By composting our dogs’ waste, we are being resourceful and sustainable. We are reducing the need for fertilizers and pesticides, cutting out the need for big trucks to transport all that poo, and making our park even more beautiful. [4]

  1. http://www.tilthalliance.org/learn/resources-1/city-chickens/compostingchickenmanure
  2. https://www.cdc.gov/parasites/transmission/index.html#tabs-1-1
  3. https://www.zoo.org/zoodoo
  4. https://www.nps.gov/dena/blogs/the-scoop-on-poop.htm