Iowa officials investigate fish kill following manure spill in Wolf Creek


Tyler Chalfant | November 5th, 2019

A fish kill was found in Wolf Creek in Tama County last week, after a manure applicator for Mayo Farm Inc. reported that about 2,600 gallons of manure leaked had from a drag hose. The applicator attempted to stop the flow, but estimates that up to 500 gallons reached the creek. Environmental officials from the Iowa Department of Natural Resources are investigating the spill.

Fresh manure contains ammonia, which kills fish at high quantities. Manure is used as a fertilizer because of the high levels of nutrients ‒ notably nitrogen and phosphorus ‒ that it contains. However, when too much of these nutrients enter an ecosystem, it can throw the system out of balance. Algae tends to bloom in nitrogen-rich environments, and certain types known as cyanobacteria can be toxic for aquatic life. 

Even when it isn’t toxic, overgrowth of algae can also kill fish through oxygen depletion, known as hypoxia. Nitrogen runoff from Iowa agriculture contributes not only to local hypoxia, but also to the largest ever “dead zone,” at the basin of the Mississippi River in the Gulf of Mexico. The voluntary practices recommended in the state’s 2014 Nutrient Reduction Strategy include reducing the use of fertilizers in order to reduce hypoxia. 

Blue-green algae toxins harm children and pets


Lakeside Park Boat Launch
Photo from Winnebago Waterways, flickr

Tyler Chalfant | August 28, 2019

A child was poisoned earlier this summer in southern Iowa by a blue-green algae toxin that has been blamed for the deaths of six dogs across the country this summer. The algae, also called cyanobacteria, can cause rashes, nausea, vomiting, diarrhea, and in severe cases liver failure. It is especially dangerous for children and pets.

Overgrowth of this algae occurs in waters that are rich in nutrients. In Iowa, nitrogen and phosphorus pollution in water primarily comes from fertilizer runoff. Besides the harmful effects of their toxins, overgrowth of these algae can also impact other forms of life beneath the water’s surface by blocking sunlight and stealing oxygen and nutrients from other organisms. 

The Iowa Department of Natural Resources tests state park beaches for microcystins, the toxic byproduct of blue-green algae, and issues swimming advisories if the water contains more than 20 micrograms per liter. However, this is less restrictive than the Environmental Protection Agency’s recommended standards of 8 micrograms per liter. 

Cyanobacteria blooms often look like foam or floating paint near the water’s surface, though they can also hide beneath the water’s surface and may not be visible. When cyanobacteria die, they produce a bad smell, similar to rotting plants. The Center for Disease Control recommends that people avoid swimming and boating in water where algae appears or where water is discolored, and to rinse off as soon as possible if you are exposed to water that may contain cyanobacteria.

On the Radio: Algae Blooms in Iowa


Photo by JoyBot; Flickr

This week’s radio segment discusses cyanobacteria and the potential harm to humans.  Read the transcript below or listen to the audio here. Continue reading