Algae are tiny aquatic organisms that, similar to plants on land, produce oxygen from photosynthesis. They're a common part of fresh and saltwater environments; most people have seen green "pond scum" at one point or another. Algae is not inherently bad, either. In fact, when in the proper balance with their environment, algae provide food and oxygen to marine life, such as fish.
However, when provided with an excess of nutrients, such as occurs when fertilizer runoff from farms contaminates waterways, algae can quickly grow out of control, causing environmental destruction along the way. As the U.S. National Oceanic and Atmospheric Administration's (NOAA) National Ocean Service explains, a small amount (less than 1 percent) of algae blooms can produce harmful toxins that sicken marine life, people and pets.
Beyond this, algae blooms that don't produce toxins can still pose a threat by depleting oxygen from the water, blocking light to organisms lower in the water column and clogging fish gills.1
Algae is growing out of control in so many areas of the U.S. that the U.S. Environmental Protection Agency (EPA) has called it a "major environmental problem in all 50 states" with "severe impacts on human health, aquatic ecosystems and the economy."2 An AP investigation also revealed that, despite government agencies spending billions of dollars to help farmers prevent fertilizer runoff and circumvent the problem, algae blooms are getting worse instead of better.3
Despite Billions Spent, Toxic Algae Is Getting Worse
The AP investigation revealed alarming trends, including that levels of nitrogen and phosphorus from fertilizer runoff are getting higher in lakes and streams. The problem is both runoff from synthetic chemical fertilizers as well as the excessive amounts of manure from concentrated animal feeding operations (CAFOs) that's often sprayed onto farm fields.
The U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS) has spent more than $29 billion on incentive-based programs, including the Environmental Quality Incentives Program, or EQIP, to encourage farmers to stop polluting waterways.
Reportedly, about 500,000 farms have become "more environmentally friendly" since the program began in 2009, but there are about 2 million farms in the U.S. and only about 6 percent take part in the programs at any given time.4 While the agency paid out or pledged billions from 2009 to 2016 to curb runoff and water pollution from farms and livestock operations, the Chicago Tribune noted that "some of the lake's biggest algae blooms showed up during those seven years," continuing:
"The largest on record appeared in 2015, blanketing 300 square miles — the size of New York City. The previous year, an algae toxin described in military texts as being as lethal as a biological weapon forced a two-day tap water shutdown for more than 400,000 customers in Toledo [Ohio]. This summer, another bloom oozed across part of the lake and up a primary tributary, the Maumee River, to the city's downtown for the first time in memory."5
Meanwhile, while most factories are prohibited from releasing waste directly into waterways, a loophole in the Clean Water Act of 1972 does not make the same distinction for farm fertilizers that run off fields into lakes and streams.
The Chicago Tribune added, "Without economic consequences for allowing runoff, farmers have an incentive to use all the fertilizer needed to produce the highest yield, said Mark Clark, a University of Florida wetland ecologist. 'There's nothing that says, 'For every excessive pound I put on, I'll have to pay a fee.' There's no stick.'"6
Algae Blooms Contaminating Drinking Water
In 2014, citizens in Toledo, Ohio, were warned not to drink their tap water as it was found to contain significantly elevated levels of microcystins, caused by algae blooms in Lake Erie.7 Microcystins are nerve toxins produced by freshwater cyanobacteria (blue-green algae) that can cause fever, headaches, vomiting and seizures.
The city and surrounding areas have become the first to report drinking water–associated outbreaks caused by harmful algal blooms, as highlighted in the U.S. Centers for Disease Control and Prevention's (CDC) surveillance for waterborne disease outbreaks report.8
"The cyanobacterial toxin microcystin caused the largest reported toxin contamination of community drinking water in August 2013 and September 2014 and was responsible for extensive community and water disruptions," the CDC noted.9 The agency is now tracking harmful algal blooms (HABs) via its One Health Harmful Algal Bloom System (OHHABS), calling them an "emerging public health issue" and stating:
"Exposure to HAB toxins through water, food or air may cause a range of mild to severe symptoms in both humans and animals. HAB-associated exposures can result in symptoms that affect the skin, stomach and intestines, lungs and nervous system.
Animals, such as dogs, cattle, birds and fish, are likely to be affected before people during HAB events as they are more likely to drink from or swim in waters that contain HABs. People can be affected by HAB events from exposure during work or recreational activities, or from ingestion of contaminated water or food."10
Even in areas where algae blooms aren't apparent, nitrates from fertilizer runoff may still contaminate drinking water. The U.S. Department of Agriculture (USDA) estimates that removing nitrate from U.S. drinking water costs nearly $5 billion a year,11 which the industrial agriculture industry has been largely shielded from. A report released by the Iowa Environmental Council (IEC) has attempted to summarize the related health risks of such nitrates in drinking water.12
Researchers reviewed over 100 studies on the health effects of nitrates in drinking water and found multiple studies linked them to birth defects, bladder cancer and thyroid cancer. While many of the health problems were found with nitrate levels higher than the drinking water standard of 10 mg/L, some studies suggested nitrate levels lower than the drinking water standard may still pose health risks.
About 15 percent of private wells in Iowa may have nitrate levels that exceed federal standards,13 and the EPA notes that reported drinking water violations for nitrates have nearly doubled in the last decade.14 Researchers are also looking into whether another toxin, BMAA (Beta-N-Methylamino-L-alanine), in blue-green algae may be linked to neurological diseases like Alzheimer's, Parkinson's and amyotrophic lateral sclerosis (ALS or Lou Gehrig's Disease).15