During her four year tenure as Neuse Riverkeeper, Katy Hunt gets asked one question more than any other: what is the greatest threat to the state’s rivers? “Nutrient pollution,” she answers without hesitation.
Her response takes a lot of people by surprise because most have no idea what that means. How is it possible to have too many nutrients? After all, nutrients are supposed to be a good thing. Hunt explains that, just like chocolate, which she also considers a very good thing, too much is a bad thing.”
Nutrient cycling, also known as ecological recycling, is a normal and vital part of a healthy ecosystem and the two most harmful nutrients – nitrogen and phosphorus – are essential for plant growth and a healthy food chain. But things like plant fertilizer, large scale agricultural operations, sewage and stormwater runoff add far more of these nutrients than our waters need or can handle. And that’s a bad thing.
Despite being one of the biggest environmental threats, nutrient pollution receives little attention because few understand its impact on the ecosystem. According to a 2019 study, it threatens air and water quality, marine life, biodiversity and human health.
Depending on who you ask, livestock and poultry CAFOS produce between 10 and 20 times more waste than the entire U.S. population. But unlike human waste, animal waste doesn’t go to a wastewater treatment plant. It remains untreated and used as crop fertilizer which is really industrial farming’s unofficial waste management plan.
Poultry litter makes up the largest and fastest-growing source of agricultural nutrient pollution in the state. Birds produce roughly five times more waste than hog farms and chicken poop has considerably more nitrogen and phosphorus than hog waste.
An analysis of global data by NC State researchers revealed that fertilizer pollution can cause harmful algal blooms, lead to fish kills and can have significant ripple effects in the food webs of streams and rivers. “Overall, we found that high levels of nutrients affect streams and rivers everywhere,” said the study’s lead author Marcelo Ardón, associate professor of forestry and environmental resources at North Carolina State University.
Algal blooms greatly reduce or eliminate oxygen in the water, leading to fish illness or death. These toxic blooms can also make us sick after swimming or if we eat tainted fish. They kill pets and livestock, and raise treatment costs for drinking water. Harmful blooms elevate toxins and bacterial levels that can leach into water and cause significant cognitive loss and nervous system impairment in humans.
Not all algal blooms are harmful but there’s no way to distinguish between the benign and toxic ones without inspection and testing.
Climate change is also a factor in nutrient pollution. The impact on rainfall patterns creates alternating periods of drought and intense storms which increase nutrient runoff and warmer water temperatures are more conducive to toxic blue green algae.
Notice a pattern? Human activity is the common denominator.
Hunt says fish kills happen with such frequency in the Neuse River Basin that they are almost passe. “In 2020, there was a month-long fish kill and more and more dead fish were washing up on the shores every day. Dead fish in the river should really set off those alarm bells but people were just like ‘I’m just gonna avoid the water over there.’”