Harmful Algal Bloom in Ohio River Shows Effects of Nutrient Pollution

Map from http://www.orsanco.org/ showing extent of current Harmful Algae Bloom and Advisory Areas on Ohio River (updated 10/21/15)
Map from http://www.orsanco.org/ updated 10/21/15

A record algal bloom extending over 664 miles of the Ohio River has halted recreation, threatened public health and put a spotlight on nutrient pollution and its impacts. Ohio is all too familiar with these impacts after a toxic algal bloom in Lake Erie last summer prevented nearly 500,000 Toledo residents from drinking their water. This year’s bloom stretches from West Virginia to the Illinois/Indiana border. It far exceeds the previous most extensive bloom, which covered 30 miles of the Ohio River in 2008.

The rapid growth, or blooms, of algae can discolor the water or produce floating scum on the surface, especially along shorelines and in warm, shallow water that receives a lot of sunlight. Algal blooms are fed by excess nutrients, nitrogen and phosphorus, which are discharged into waterways from fertilizer runoff from agricultural land, urban stormwater and sewage treatment plant effluent. These blooms can devastate aquatic ecosystems and threaten the safety of drinking water sources. They can force utilities to spend more money to treat water in order to fight off the toxins that can cause rashes, diarrhea, vomiting and breathing difficulty. During much of last month, Cincinnati was forced to spend $7,700 more per day on added chemicals to make its tap water safe for drinking.

When a blue-green algal bloom is producing toxin(s), it is referred to as a Harmful Algal Bloom (HAB). The poisonous blue-green algae in the Ohio River give off a toxin called microcystin which can cause liver and nerve damage in humans and animals. The current bloom has forced the cancellation of the annual Great Ohio River Swim and triggered warnings to boaters to stay out of the water.

Blue Green Algae
Blue-green algal bloom (Image from Illinois EPA)

These problems are not unique to Ohio, but are real threats to all states with heavy agricultural use and urban areas including Illinois. In late summer 2012, highly elevated concentrations of microcystin were found in several northern Illinois lakes. One lake was reported to have a concentration of 31,500 µg/L, an astounding 1,575 times greater than the 20 µg/L World Health Organization (WHO) guidance value indicating a “high” probability of acute health effects due to recreational exposure. In response to these reports, the Illinois Environmental Protection Agency (IEPA) and the U.S. Geological Survey (USGS) sampled ten lakes and two rivers for several toxins over the period of August to October. Virtually all of the water bodies sampled had high or very high probabilities of associated health effects based on total cyanobacteria cell counts and four of the lakes had high probability for adverse health effects based on microcystin concentrations. The highest microcystin concentration detected was 240 times the WHO guidance value at 4,800 µg/L. Microcystins were found in five other lakes and one river, representing 85% of the water bodies sampled [1].

The Illinois Department of Public Health and the Illinois EPA have recently posted warnings urging residents to “use caution while in or on the Illinois portion of the Ohio River due to potential toxins from blue-green algae.” The Agency says that “while a harmful algal bloom has not yet been confirmed in the Illinois portion of the Ohio River, river and weather conditions are favorable for such a bloom, particularly along shorelines” [2]. These warnings and results from the 2012 monitoring clearly indicate that blue-green algal blooms and algal toxins can be cause for concern in Illinois surface waters.

Fortunately, the state is taking steps to address this concern. The Illinois Nutrient Loss Reduction Strategy released earlier this year represents a historic agreement among stakeholders and government agencies to address the problem of nutrient pollution to reduce algal blooms within Illinois and in the Gulf of Mexico. Nutrient pollution from states along the Mississippi River travels downstream and collects in the Gulf, causing a dead zone where aquatic life cannot survive and giving it the name “Gulf Hypoxia.” The Strategy aims to reduce the amount of nitrogen and phosphorus leaving Illinois by 45% in order to help improve conditions in the Gulf.

Implementation of the Strategy will also reduce the amount of nutrients in Illinois waterways, helping to prevent more algal blooms in Illinois and situations like those suffered by Ohio residents. The headlines from Ohio must be taken as a call to action in Illinois to take the steps necessary to reduce nutrient pollution. Our health and the health of our waterways depend on it.

[1] Illinois EPA. 2012 Drought and HAB Reconnaissance Monitoring Effort. http://www.epa.illinois.gov/topics/water-quality/surface-water/algal-bloom/2012-drought-and-monitoring/index.

[2] Illinois EPA. Blue-Green Algae May Cause Harmful Algal Bloom.  http://www.epa.illinois.gov/topics/water-quality/surface-water/algal-bloom/illinois-urges-precaution/index