If you follow environmental or climate news, then you have probably noticed the rise in reporting about harmful algal blooms (aka toxic algae). Over the past few decades, scientists have not only observed an upsurge in the frequency of these blooms around the planet but also an increase in their severity and geographic distribution. According to the US Environmental Protection Agency (EPA), these blooms – known as everything from red tides to blue-green algae or cyanobacteria – have been cropping up across the country; in fact, in all 50 states. Some areas like upstate New York are expected to have a “big bloom year” and a rough summer. And federal scientists are forecasting that this summer’s dead zone in the Gulf of Mexico is expected to be the third largest since monitoring began a little over 30 years ago.

Most news stories understandably focus on the negative impact (and sometimes lethal effects) these blooms can have on humans and animals, but give short shrift to what is causing the blooms. While this is a scientifically complex issue and there are a number of factors that have been linked to the blooms and their toxin production, there is a strong linkage between industrial agriculture and toxic algae outbreaks that we must not overlook. So with the 2017 toxic algae season well underway, here are 5 things to know about the link between agriculture and algal blooms:

1. The Link Between Toxic Algae and Our Broken Food System

First and foremost, these blooms are yet another reminder that we need to make significant and lasting changes to the way we farm and produce our food, especially in reducing nutrient pollution. According to the EPA, “animal manure, excess fertilizer applied to crops and fields and soil erosion make agriculture one of the largest sources of nitrogen and phosphorus pollution in the country.” It is this nutrient pollution and over-enrichment that is primarily fueling the harmful algal blooms. And thanks to the important work of NOAA and other federal and state agencies, we know a lot more today about the growing threat that these blooms pose to the nation’s aquatic ecosystems, public health and local and regional economies.

Pollution associated with industrial animal production or concentrated animal feeding operations (CAFOs) without a doubt contributes to nutrient over-enrichment which can be a factor in harmful algal bloom outbreak frequency and toxin production. North Carolina – home to a large number of industrial poultry and hog farms (third largest producer of poultry products and second largest pork producer in the US) – provides a unique window into this environmental problem. In June of last year, Waterkeeper Alliance, North Carolina Riverkeeper organizations and Environmental Working Group released a first-of-its-kind interactive map that documents the approximate locations of more than 6,500 CAFOs – large swine, poultry and cattle operations – across the state of North Carolina. If you’re thinking, “all those CAFOs must generate a lot of poop,” you’d be correct. Research associated with this project estimates that these CAFOs annually produce more than 10 billion pounds of wet animal waste and 2 million tons of dry animal waste in North Carolina.