Lake Erie Pollution on the Decline Despite Algae Bloom

Lake Erie

The National Oceanic and Atmospheric Administration (NOAA) released its forecast on Lake Erie’s summer algae bloom for 2014 this week, and at first glance, the numbers are alarming. NOAA and the International Joint Commission say that even though pollutants causing the algae bloom in Lake Erie are high, they are still on the decline from 2011.

Lake Erie is the smallest and shallowest of all five Great Lakes and also has the most river tributaries. Ohio, New York and Ontario, Canada share its borders, and Lake Erie is seen as a vital economic waterway, a source for drinking water and a valuable sewer treatment. The lake has been plagued by many ecological problems since the late 60s, including the toxic algae blooms, a number of invasive species and high levels of Mercury in its edible fish supply. Unfortunately because of all these problems, Lake Erie has come to be known as an environmental sore spot for the Environmental Protection Agency (EPA) and the NOAA. Efforts to clean up the lake’s shores and protect species have thus seemed like an uphill battle at times.

Cyanobacteria is a form of blue-green algae which is toxic to plants and animals. Algal blooms have been a problem in Lake Erie since the 60s, with the Lake’s largest bloom numbers occurring between the late 60s and the 80s on the western shore. The Harmful Algal Blooms (HABs) are largely caused by pesticides and herbicides in agricultural runoff into Lake Erie’s many tributary rivers. Many of these chemicals, such as atrazine, acetochlor and cyanazine, contain a type of phosphorous which causes cyanobacteria to thrive when combined with warm summer temperatures. This is what makes the algae bloom each summer a pollution issue.

Lake Erie is especially vulnerable to algal blooms because of its size, location, topography and large number of tributary rivers. These rivers push phosphorous into Lake Erie’s western basin in a process called “loading” by scientists. NOAA and the Joint Commission have found that other Great Lakes have had higher concentrations of phosphorous and larger algae blooms than Lake Erie. However because of their larger volume, positions in relation to their tributaries and the direction of their tides, the blooms were more widely dispersed and thus less harmful. Lake Erie is the smallest of the great lakes, and is oddly shaped with three large basins at its bottom. That coupled with its industry-lined tributaries has caused HABs to concentrate in the western corner of the lake, and causes much more damage to plant and animal life than in other lakes. This also creates a higher safety concern for humans.

Many have thought that the “dead” status on the western shore of Lake Erie came from the industrial and agricultural pollutants themselves, but the Ohio Sea Grant says that is not quite accurate. The low concentration of oxygen in the water  is caused by the overgrown algae, which can kill plants and fish quickly as it envelops large areas. When the bloom finally ends, the decaying plant and animal matter chokes the water of nutrients, especially oxygen. A lack of oxygen, called hypoxia, can make the area hostile to habitat and plant growth for some time afterward. While the toxic material is still active, the lake is not able to be used for recreation.

In 1972, President Nixon signed the Great Lakes Water Quality Agreement along with Canadian Prime Minister Pierre Trudeau. The agreement was regulated by the International Joint Commission and set gradually decreasing limits on the amount of phosphorous-enhancing chemicals allowed to enter the lake. More stringent procedures for the treatment of raw sewage were adopted as well. Interestingly, all of the Great Lakes states except for Ohio and Pennsylvania have also passed legislation banning detergents containing phosphorous. Ohio has ownership of the largest area of Lake Erie, so this could be a factor in the larger bloom concentrations as well on the western shore, though this has not been conclusively proven.

Between 1972 and 1995, cleanup efforts for Lake Erie and all the Great Lakes saw excellent results. In 1969 the lake’s annual phosphorous load in metric tons was just under 30,000. By 1995, it was reduced by over three times. Additionally, the levels of mercury and other toxic chemicals that affect the edible fish in the lake reduced dramatically and have not increased since the 80s. 1997 saw a spike in phosphorous load, however, and between 2003 and 2011 there has been a growing concern over the rising levels once again. The higher levels have resulted in larger blooms each year.  The chemical compounds which are the catalysts for the oversaturation of phosphorous were reported to be 50-100 percent concentrated in the western basin of Lake Erie in 2003, and the levels of oxygen in this “dead” zone were four times less than what fish require to be able to live in a certain area of water.

In 2011, Lake Erie had the highest HAB severity on record. Researchers believe an increase in temperatures over the past 10 years may be an additional factor, because phosphorous loads were not as high in Lake Erie in 2011 as in 2007. Data are just beginning to be collected with relation to climate change, and the results once calculated could prove useful.

In 2012, the International Joint Commission put a new Great Lakes Water Quality Protocol together and established the Lake Erie Ecosystem Priority (LEED). LEED aims to set new phosphorous load targets. It also plans to study the changes in the lake’s ecosystem resulting from all external factors including phosphorous loading, climate change and invasive species. The Harmful Algal Bloom and Hypoxia Research and Control Act (HABHRCA) was amended and extended by Congress until 2018, allowing LEED to contract with different research teams to gather data which may help predict the algal blooms.

This year NOAA predicts that the bloom severity on the western shore of Lake Erie will be significantly less than in 2013, and about half the severity of the 2011 levels. NOAA and the Ohio EPA also showed that despite the prediction for a large HAB in Lake Erie, levels of pollutants across the board have either been on the decline or have seen no increase since 2000. Thus it is likely that much of LEED’s efforts and resources will go towards studying the influence of climate change on the summer algae blooms.

NOAA supplies residents and businesses in the area with a weekly HAB report in order to keep the public informed on the levels of chemicals in the water and the likelihood of a cyanobacterial bloom each week. With rising summer temperatures and phosphorous levels in Lake Erie controlled but not perfect, those living and working on the southern shore of Lake Erie will be paying close attention to these updates. Despite declining pollution, phosphorus levels and a smaller bloom over the last few years, cyanobacteria algae and its effect on Lake Erie’s ecosystem is still a major concern. While LEED and NOAA continue to work to improve the pollutants which contribute to the algae bloom, clearly not all the factors which cause cyanobacteria to bloom are known, so much more research and data will be required by these agencies to determine what else, if anything, can be done to control it.

By Layla Klamt

Ohio Environmental Protection Agency
The Ohio Sea Grant College Program
Joint International Commission
National Oceanic and Atmospheric Administration
Canadian Geographic
Ohio Sea Grant (Lake Erie)