By Lisa Liotta
As a seasonal park ranger at the only Vermont State Park that allows dogs off-leash in a designated area, I pick up a tremendous amount of doggie doo. Recently, I began thinking seriously about the impact of pet waste on our environment, and started doing some research.
Some common misconceptions that I hear from pet owners are: “It’s completely natural. It just goes away. It’s fertilizer. Leaving it on the ground to decompose is more environmentally responsible than throwing it away and creating more landfill. If it’s not left where someone can step in it, there’s no need to pick it up.”
According to the Environmental Protection Agency, pet waste is 57 percent more toxic than human waste, and, in 1991 it was placed in the same health category as oil and toxic chemicals. The EPA also estimates that in two or three days, 100 dogs can produce enough bacteria to close a small bay with a 20 square mile watershed to swimming and fishing.
Dog feces contains high concentrations of nutrients (nitrogen and phosphorus), and pathogens (bacteria, viruses, worms and parasites) that can cause serious illness in humans and pets. When your dog goes on the ground, it does not just go on the ground. Let’s follow the cycle of poo and see what happens.
Assuming dog feces is NOT picked up, it can take up to a year to break down in the environment, depending on climate, the animal’s diet and other factors. Some bacteria can even become airborne. The deposit site can become toxic to both dogs and people. Some pathogens can survive for years; for instance, roundworms and Giardia survive up to four years, E. coli can live up to four months, and salmonella up to six months. Giardia can survive in lakes, streams, rivers or puddle water at temperatures below 50 degrees F for as long as one to three months, but it can also survive in the soil for approximately seven weeks in soil temperatures as low as 39 degrees F. There are many other harmful pathogens that live in pet feces, these are just a few.
Once on the ground, feces becomes a non-point source (NPS) pollutant. NPS pollution is caused by rainfall or snowmelt running over and through the ground. As the runoff moves, it picks up and carries away the nutrients and pathogens, and deposits them into groundwater, stormwater run-off, streams, rivers and lakes. Non-point source pollutants come in many forms: excess fertilizers from residences and farms; bacteria and nutrients from livestock operations, boat pump-outs and faulty septic systems. Unlike most NPS pollutants, pet feces contains pathogens that make people and/or pets sick.
Feces from yards and urban areas enters stormwater runoff. Stormwater may not be directed to sewage treatment facilities for removal of nutrients and pathogens. Holding ponds remove sand and sediment, but not nitrogen, phosphorus or other disease causing organisms. Feces left in wooded or shoreline areas, such as parks, almost always bypasses stormwater run-off systems and directly enters waterways.
Once in fresh water, nitrogen breaks down to form ammonia, a process which removes the available oxygen from the water. If too much oxygen is removed in the breakdown process, there may not be enough left for fish to survive, resulting in fish die-offs. Pathogens, two of which are Giardia and E. coli, remain viable and may infect pets or humans who consume the fresh water.
Once nutrients and pathogens reach the lake, excess nitrogen and phosphorus feed algae (that are always present at some level) and can cause algae blooms. When bacteria decompose an algae bloom, it removes oxygen from the water, which then kills fish and marine life. Some types of algae blooms, such as cyanobacteria (also known as blue-green algae), can produce toxins that are harmful to people and can be fatal to dogs.
Water recreation areas are frequently tested to see if harmful levels of E. coli are present, and visually monitored for blue-green algae blooms. If unsafe levels or conditions are found to exist, areas are closed to all recreation, which results in loss of tourism and outdoor recreation opportunities.
Nature can easily handle the feces breakdown of wildlife and maintain a balance. Our environment cannot handle and effectively process high concentrations of pet waste, which creates an unnatural balance. Simply stated, there is too much pet waste left behind which cannot be processed naturally, and the results are toxic.
So, what is the best way to dispose of pet feces? It does not just break down or go away. If it is buried, it still leaves pathogens on site below the surface, and nutrients and pathogens can still enter the groundwater. Composting is only effective if temperatures can be maintained at or over 140 degrees for extended periods in order to kill pathogens such as E coli and salmonella. Flushing it down the toilet works well (feces only, not a plastic pick-up bag) if you’re on a city sewer system where it can be treated, but septic systems can’t handle the load. Scooping, bagging and disposing of feces in the garbage is the most ecological and responsible way to clean up after your pet. Landfills are specifically designed so that wastes are contained and do not leach into groundwater.
We can do something about many of the non-point source pollutants, and ALL pet owners can do something about their pets’ waste. Pick it up and dispose of it properly, don’t pollute the soil, and keep it out of our waters.
Lisa Liotta is a park ranger at Niquette Bay State Park.