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Green Without Envy: Great Lakes Drown in Excessive Nutrient Pollution

Michael Mezzacapo


pointe pelee ontario lake erie algal bloom 2011
A photo taken off of Point Peele, Ontario, during 2011’s severe Lake Erie algal bloom. Credit: IJC

2017 was another significant year for algal blooms on Lake Erie, claiming the spot for the third largest algal bloom on record. Scientists believe the major factor of the massive bloom was due to excess runoff from agricultural areas due to high concentrations of phosphorus in the Maumee River watershed after heavy precipitation events in May and June. Excessive nutrient runoff from nonpoint sources is significantly degrading water quality in all the Great Lakes, with the exception of Lake Superior. Solutions to solving the excessive nutrient problem are complex and will involve widespread government, stakeholder and community participation. The US National Oceanic and Atmospheric Administration (NOAA) recently highlighted an alarming figure: in eight of the last 10 years, Lake Erie has had algal blooms that were classified as significant. NOAA classifies severity based on a bloom’s biomass over a sustained period. But nutrients aren’t the only cause of the excessive algal blooms; other factors contributing to the increases include intensive land use practices and changing climate patterns.

chart western lake erie blooms
Chart showing the severity of western Lake Erie blooms. Credit: NOAA

Runoff from agricultural areas into western Lake Erie is the major source of nutrient loadings. Of the agricultural sources, about 70 percent of the nutrients are from commercial fertilizer application and 30 percent from animal manure. Combine excessive runoff of phosphorus from commercial fertilizer and animal manure with changing climatic conditions in the Great Lakes and you may have a recipe for excessive algal blooms and potentially harmful algal blooms (which emit toxins harmful to humans and wildlife).

loading to st clair western lake erie
Figure showing a comparison of total phosphorus (TP) tributary loading to Lake St. Clair and the western Lake Erie. Sources: Michigan Sea Grant, M. Maccoux, Contractor ECCC, S. Wortman, USEPA, D. Obenour, NCSU, M. Evans, USGS. Credit: IJC

Analysis from a recently released IJC Science Advisory Board Report showed that excess phosphorus from fertilizer application is often stored in agricultural soils, nearby ditches, buffer zones and wetlands with the potential to leach nutrients for years or even decades. “Even a small ‘leakage’ of excess phosphorus may be sufficient to contribute to algal blooms,” the report says. (See also: “Less Fertilizer, More Transparency Needed in Western Lake Erie Basin”)

Want to Know More?

In addition to the IJC’s recent recommendations on nutrients in its TAP report, The IJC’s Water Quality Board and Science Advisory boards have released reports relating to the issue of nutrient pollution by highlighting watershed management tactics and investigating fertilizer loading issues. Click the reports below to learn more.

1. Fertilizer Application Patterns and Trends and Their Implications for Water Quality in the Western Lake Erie Basin. This report assesses fertilizer (primarily commercial fertilizer and manure) application and impacts in the western Lake Erie basin.

2. Watershed Management of Nutrients in Lake Erie. This report provides recommendations on how watershed management plans should be used to curb nutrient pollution in Lake Erie.

3. Evaluating Watershed Management Plans, Nutrient Management Approaches in the Lake Erie Basin and Key Locations Outside of the Lake Erie Basin. This report discusses watershed management plans to manage nutrient pollution in Lake Erie and identifies several key factors necessary for watershed management plans to achieve meaningful nutrient load reductions. ...

Eliminating all nutrient runoff isn’t the answer to solving this crisis. Just like the human body, lakes need nutrients to sustain life. Nutrients are chemical elements that support all animal and plant life. Nutrients support algae (technically known as phytoplankton), the primary producers which are the foundation of a lake’s food web. Eutrophication is the process a waterbody undergoes when subjected to an excessive load of nutrients. Eutrophication can set the stage for algae and aquatic plants to grow out of control. When the excess algae growth eventually dies, bacteria and microorganisms feed on the dead material and consume available oxygen in the water. If oxygen levels dip too low, massive fish die-offs can occur, which can severely impact ecosystems.

phosphorus cycle graphic ecosystem
A graphic illustrating the nutrient cycling of phosphorus in an ecosystem. Credit: Michael Mezzacapo

Excessive nutrient runoff also has the potential to impact conditions in and around the lakes and may affect human health. Research has shown that pathogens from bacteria in the algal blooms can cause avian (bird) botulism, which thrives in nutrient-rich, low-oxygen conditions. As environmental conditions become more favorable for algae and bacteria, humans may be at risk from the prevalence of diseases by consuming affected animals and fish, or coming into contact with contaminated water or objects.  Additionally, if municipal drinking water systems aren’t prepared to handle many of the toxins produced by harmful algal blooms, access to clean water may be impaired, as happened in the 2014 Toledo, Ohio, water crisis. (See also: “Beach Read: Cyanotoxins in the Great Lakes”)

The impacts of excessive nutrients and algal blooms are being felt across the Great Lakes basin as well as other waters in Canada and the United States. Governments are taking notice. Through the Great Lakes Water Quality Agreement, the United States and Canada have established updated targets for reducing phosphorus loading to the western and central basins of Lake Erie. Strategies, known as Domestic Action Plans, outline programs and policies considered necessary to meet reductions in nutrient loading. Updated targets include a 40 percent reduction in nutrient offloading between the US and Canada, especially in particularly sensitive tributary regions of Lake Erie, like Thames River in Ontario and the Maumee in Ohio. The 40 percent reduction target commits Canada to offloading no more than 212 metric tons annually, largely from the Thames River and Leamington area. American emissions, centered on the Maumee and Sandusky watersheds, cannot total more than 3,316 metric tons to hit a 6,000-metric-ton target. In its First Triannual Assessment of Progress (TAP), the IJC forwarded several recommendations to reduce nutrient pollution and improve water quality, urging the governments to provide more details on timelines, responsible parties and measurable outcomes.

nutrient pollution recommendations triennial assessment progress
A graphic outlining the IJC’s TAP recommendations to reduce excessive nutrient pollution in the Great Lakes. Credit: IJC

Although there are many non-regulatory or voluntary actions in place to reduce excessive nutrient runoff, such as agricultural best management practices (BMPs), the IJC has called for stricter standards and enforcement on nutrient runoff. Improving compliance on BMPs and using regulatory enforcement will assist the governments to meet set targets for nutrient reduction in Lake Erie. Western Lake Erie water quality has been greatly impacted by nuisance and harmful algal blooms, but there is hope. In the 1960s and 1970s, phosphorus pollution from municipal wastewater systems and detergents was causing excessive algal blooms. Governments at federal, state and provincial, and local levels as well as citizens worked together to install pollution controls and substantially reduce the algal blooms, voluntary bans on phosphorus detergent began in the 1990s. Bold action solved the problem in the past and bold action is needed now. Many new research studies and reports address the issue of nutrient pollution, but this should not delay stakeholders from performing early measures to reduce their share of nutrient runoff.


Michael Mezzacapo

Michael Mezzacapo is the 2017-2018 Michigan Sea Grant Fellow at the IJC’s Great Lakes Regional Office in Windsor, Ontario.

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