This spring, when we relaunch our Healthy Virginia Lawns and Healthy Landscape programs, the Piedmont Master Gardeners will advise households on how they can reduce the environmental footprint of their yards and gardens. This includes pet waste, particularly dog poop and urine, which adds a significant amount of nitrogen and phosphorus to our lawns and stormwater, contributing to nutrient overloading of our streams and rivers.
The 2017-2018 U.S. Pet Ownership & Demographics Sourcebook calculates there were 76,811,305 dogs and 58,385,725 cats in American households, not including feral dogs and cats. According to the American Veterinary Medical Association, 38.4% of U.S. households own dogs and 25.4% own cats. Each pet household on average owns 1.6 dogs and 1.8 cats. Charlottesville and Albemarle County respectively have 19,312 and 43,066 households, so it’s fair to assume we have about 11,865 dogs and 8,829 cats in Charlottesville, and around 26,460 dogs and 19,690 cats in Albemarle County.
Most studies detailing pet waste’s impacts on the environment concern dogs, since most cats are now confined indoors and only a small population is allowed to roam part-time. A recent study conducted in Belgium and published last February in the British Ecological Society journal, Ecological Solutions and Evidence, found that dogs contribute 24 pounds of nitrogen and 11 pounds of phosphorus per hectare, or about 2.5 acres, per year.
While picking up dog poop is a relatively common practice in urban environments, dogs in the country typically have free rein to relieve themselves where they please. It would seem to make sense that keeping dogs on a leash and picking up after them would reduce nutrient loading. And it does. Picking up after your dog reduces nutrient levels 97% for phosphorus and 56% for nitrogen. Urine has a high concentration of nitrogen, due to higher protein feed levels for pets, so removing fecal material does not reduce nitrogen as significantly.
Interestingly, this same Belgium study revealed that nutrient pollution reached levels of 385 pounds for nitrogen and 160 pounds for phosphorus per hectare (2.5 acres) in areas adjacent to paths and in other areas reachable by dogs on a leash in nature preserves, a reflection of the high numbers of pets out with their owners.
Nitrogen and phosphorus are the most common nutrients polluting our waterways and the chief source of degradation downstream in the Chesapeake Bay. The EPA lists five major sources of nitrogen and phosphorus pollution:
- agriculture
- stormwater runoff
- wastewater
- fossil fuels
- in and around the home.
The EPA specifically mentions impervious surface runoff, overfertilization of the landscape (a target of our Healthy Virginia Lawns program), and pet waste.
Nitrogen and phosphorus are essential for plants—nitrogen for leaf development and phosphorus, a mineral, for root development and production of seeds, fruits, and flowers. In excess, nitrogen and phosphorus not utilized by plants runs off and enters our waterways, leading to algal blooms and oxygen-deprived dead zones in a process known as eutrophication. Harmful algal blooms, or HAB’s, secondary to nutrient pollution can also occur.
Virginia in recent years has been no stranger to HAB from blue green algae. These algae, also known as cyanobacteria, produce toxins. When pets or humans come in contact, ingest, inhale, or eat food contaminated by these toxins, a multitude of bad things can happen, including vomiting, diarrhea, neurologic symptoms, seizures, liver failure, and even death. Other mammals, birds, fish, and other aquatic animals can also be affected. In 2019 blue green algae blooms broke out in Albemarle, Orange, Louisa, and Spotsylvania counties. In recent years, Chris Green Lake in Earlysville and Mint Springs Lake in Crozet have had warnings from the county and the state about cyanobacteria overloads. These waters were placed off-limits to people and pets.
We all have a direct role to play in preventing nutrient pollution. Simply choosing phosphate-free detergents and soaps, judicious fertilizer use, septic tank/field management, and picking up pet waste will greatly reduce phosphorus overloading. Follow these simple tips to minimize the environmental and health risks of pet waste:
- Always clean up after your pet. Don’t employ the “stick and flick” method of flinging poop off the trail, over the bank, or where someone can’t see it.
- Never dispose of pet waste down a storm drain where it washes directly into waterways
- Bag dog waste and place it in the trash or take it home and flush it down a toilet.
Also, encourage other pet owners to be responsible and inform and educate them on why proper disposal of pet waste is good for the environment. It’s their “dooty.”
Sources
American Veterinary Medical Association – US Pet Ownership and Demographic Sourcebook
United State Census, Charlottesville
United States Census, Albemarle County
Nutrient fertilization by dogs in per-urban ecosystems
