Great Lakes

Available for Public Review: Draft Binational Screening Criteria for Nominated Chemicals of Mutual Concern

Keeping the Great Lakes healthy requires binational efforts when it comes to Chemicals of Mutual Concern. Photo: Infosuperior.

Canada and the United States each have policies and mandates that deal with the management of toxic substances and chemicals and their release into the Great Lakes Basin. In Canada, this is covered by the Chemicals Management Plan under the Canadian Environmental Protection Act, 1999. In the United States, it is the Toxic Substances Control Act that deals with these matters. The two countries have previously identified 8 contaminants that require cooperative binational efforts to manage the severity and extent of their potential contamination. These are known as Chemicals of Mutual Concern (CMCs).

Defining Criteria With Public Input

How exactly do these chemicals become designated as CMCs? To make a consistent framework for this decision, under Annex 3 of the Great Lakes Water Quality Agreement, Environment and Climate Change Canada and the U.S. Environmental Protection Agency have drawn up a set of 6 criteria that are described in The Draft Binational Screening Criteria for Chemicals of Mutual Concern. This document is currently available for public review. Comments and questions will be accepted until Dec 16, 2019. Draft Binational Screening Criteria for Nominated Chemicals of Mutual Concern Available for Public Review

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[Research] Invasive Mussels Complicate Efforts to Reduce Mercury in Great Lakes Food Chain

Zebra Mussels are making it harder for native fish species to get nutrients and researchers at the University of Wisconsin-Madison are finding that this is leading to fish that are enriched in mercury despite efforts by Canada and the U.S. to reduce mercury loading in the Great Lakes. USFWS Photo.

Mercury is a naturally occurring element which poses several challenges when incorporated into fish as a contaminant, methylmercury. When released to the environment from the earth’s crust, either via natural degassing processes or due to anthropogenic activities like burning fossil fuels, mercury enters into a complex cycle, interacting with other elements and forming a variety of compounds. It can remain in the atmosphere for 6-12 months before being deposited in a water soluble form. Water soluble mercury can then be converted to the highly toxic and bioaccumulative methylmercury, which can cause both long-term and short-term damage to kidneys, the brain, and developing foetuses, when consumed in significant amounts by humans.

A new study published in the November 2019 issue of the “Proceedings of the National Academy of Science” shows that Canadian and U.S. reductions of mercury inputs to the Great Lakes (mercury emissions went down 60% between 1990 and 2005 in the U.S., and 85% between 1990 and 2010 in Canada) hasn’t been reflected in reduced mercury in fish to the extent that might have been expected. Through stable isotope ratio analysis in fish and sediment samples from 1978 to 2012, the researchers of Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan (Lepak et. al) discovered that an initial decline in mercury concentrations in fish immediately after efforts to reduce domestic mercury inputs did not continue at the expected rate into the 90s and 2000s. An explosive increase of invasive dreissenid mussel populations in the region, zebra mussels in the 90s and quagga mussels in the 2000s, coincided with this stunted rate of mercury reductions in fish. The researchers suggest that this may be due to the impact of invasive species on food web pathways.

Infosuperior spoke with lead author Ryan Lepak, postdoctoral researcher at the UW–Madison Aquatic Sciences Center (ASC), over email to get a better idea of what this research tells us about the Great Lakes ecosystem and shifting mercury sources.

Lead author Ryan Lepak at work, testing Lake Michigan sediment for mercury. Photo courtesy of Ryan Lepak.

Q:  Your research found that reducing the mercury load on the Great Lakes hasn’t been reflected in reduced mercury in fish because of the effect of invasive species on what foods are available to fish. Is it possible to estimate how long it will take for the reduced mercury emissions to be depicted in the food chain if we take these findings into consideration?

Ryan Lepak: As you might know from the many examples worldwide, we cannot begin to predict the interactions invasive species might have on the trophic structure of a lake and the energy pathways fish use to survive. Contaminants like mercury are closely linked to these pathways adding an increased level of complexity. That said, here’s what we’re sure of:

  1. Without reductions to mercury emissions in the past, [mercury levels in] fish today would be even higher (we know this because the air, water and sediment mercury are all lower now than they were 20 years ago.)
  2. Mercury is an element and unlike many contaminants (like organic chemicals) it cannot be destroyed. Human activities have increased the amount of mercury cycling in the world and we’re highly unlikely to ever achieve zero mercury fish.

That said, it is reassuring to find that our strategies to reduce mercury in the environment is actually resulting in quicker declines locally than we’d ever expect. (See: PNAS: Zheng et al., Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions)

Photo courtesy of Ryan Lepak

Q: In the news release from University of Wisconsin Sea Grant, it is explained that dreissenid mussel invasion of the Great Lakes has pushed fish to seek food sources that are more enriched in methylmercury from the lake bottom and nearshore environments. What makes these food sources more enriched in methylmercury?

Ryan Lepak: In many lakes, the bottom is enriched in methylmercury because the microbes that make methylmercury from mercury do their work in the absence of dissolved oxygen. Lake Michigan does not have an appreciable layer of water lacking oxygen. Instead, fish are now eating items from the bottom and nearshore that are nutritionally less valuable and they are working harder to find a meal thus becoming leaner, which in the fish world is bad. The rate of change to these nutritional/diet/energy pathways is changing faster than we are reducing mercury loading to the lake, leading to the false impression that fish [mercury levels] are increasing. In fact, to compare mercury concentrations between fish now and in the past you need to consider how lifestyle changes have impacted the overall well being of the fish. Presently, because of invasive species, lake trout are growing slower and therefore a fish at 400 mm I collect today might be 3-4 years older than a 400 mm fish from 1995. With increased age comes increased time to accumulate mercury.

Q: So fish are having to consume more food that is contaminated with mercury to meet their energy needs and they are becoming leaner because they have to work harder for that energy, which results in higher concentrations of mercury in the fish than would be present if they did not have to adjust their eating habits. Do we know what the concentrations of Mercury in the dreissenid mussels are, relative to what is found in the fish?

Ryan Lepak: They’re actually quite low, maybe 1/10th the amount. 

Q: What is the biggest take-away from your research?

Ryan Lepak: The important story here is that using carbon, nitrogen and mercury fingerprinting (isotopes) we are able to identify shifts in sources of mercury to lake trout following the removal of major mercury sources regionally. Without that aid, we would assume that mercury controls do not work if we solely looked at mercury concentrations in fish through time. In fact what we’ve learned is that the great lakes benefit greatly from local mercury reductions and that invasive species have altered contaminant cycling and bioaccumulation pathways in a considerable way. This highlights the tremendous value of programs focused on monitoring and archiving. Environment Canada and the Swedish hold the only such archives in the world. It’s ironic, collectively we’ve focused intensely on reducing chemicals in the Great Lakes (for good reason) to improve chemical burden on fish for human and wildlife safety while largely ignoring the biological “contaminants” (invasive species). Now we’re finding that due to invasive species, the chemical burden on a similar sized fish is greater, not because we’ve mismanaged chemical loading/inventories but because the biology of the system has changed. 

Ryan Lepak and his co-authors’ research allows us to better understand and monitor Mercury contamination in the Great Lakes food web. They show that we cannot solely focus on the total amount of mercury emissions, but must also look at how these emissions reach the fish we eat through a dynamic system where invasive species are having a major impact on food availability for native fish populations.


Lepak, Ryan F., et al., “Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan.” Proceedings of the National Academy of Sciences Nov 2019, 116 (47) 23600-23608; DOI: 10.1073/pnas.1907484116

Zhang, Yanxu, et al., “Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions.” Proceedings of the National Academy of Sciences Jan 2016, 113 (3) 526-531; DOI: 10.1073/pnas.1516312113


University of Wisconsin Sea Grant News Release – Aquatic invasive species are short-circuiting benefits from mercury reduction in the Great Lakes

2005 Water Quality Association Mercury Fact Sheet

EPA Mercury Emissions: The Global Context

IJC 2015 Article – Reducing Great Lakes Mercury Contamination: Regional Efforts May Not Be Enough

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Water Levels a Concern as Fall/Winter Storm Season Begins

Plaques and drift wood had been displaced up to the tree line at Neys Provincial Park this summer. High water levels in Lake Superior and throughout the Great Lakes have resulted in major impacts to lakeshores, which may be the new normal as climate change leads to increased precipitation in the region. Photo: Infosuperior

Great Lakes water levels have been making headlines all year, and October was no different. Wet conditions since September, 2018, have resulted in record high water levels in Lake Superior. Record levels were reached in almost all the Great Lakes this summer. Lake Ontario levels, in particular, led to deviations in the IJC Plan 2014 for the regulation of outflows by the International Lake Ontario-St. Lawrence River Board. These deviations have been maintained throughout the summer. Although Lake Ontario levels have been declining, Lakes Michigan, Huron and Superior are still experiencing very high levels and those water levels, combined with high winds, led to huge waves and further erosion in October.

The Headlines for October

Damage from Lake Superior was particularly bad in Duluth and Thunder Bay, catching the attention of various news outlets. MPRNews’s Paul Huttner reported that wind gusting up to 68 mph / 109 km/hr on Oct 21, 2019, lead to flooding and damage to parts of the Lakewalk in Duluth, MN; however, the newly constructed section of the Lakewalk held-up well according to Duluth News Tribune’s coverage by Andee Erickson. Despite the damages sustained, residents interviewed by Kare11 news appeared to be keeping their heads up and Star Tribune even posted images of surfers taking advantage of the waves. The same day, 45 mph / 74 km/hr winds and 35-40 mm / 1.4-1.6 in. of rain in Thunder Bay lead to flooding and erosion that resulted in the closure of a popular boardwalk and trail at Mission Marsh, as reported by the CBC.

In Chicago, damage from Lake Michigan is expected to require billions of dollars in prevention and repair efforts according to an article by Jay Koziarz of Vox Media Curbed: Chicago. Travelling towards Lake Huron through the Straits of Mackinac, further damages were apparent. MLive’s Emily Bingham reported on October 24, 2019 that a local tour guide had noticed that the foundation of the Waugoshance Lighthouse had begun to erode. The historic lighthouse’s foundation is in danger of complete collapse if mitigation isn’t attempted. Lake Huron also caused thousands of dollars in damages to sidewalks and other public spaces along Alpena’s lakefront with waves up to 7 feet tall according to Alpena News’s Steve Schulwitz.

Officials Responding to Impacts

In response to the extensive damage that has been observed across the Great Lakes this summer, the IJC’s Great Lakes-St. Lawrence River Adaptive Management (GLAM) Committee with the IJC’s  International Lake Ontario – St. Lawrence River Board (ILOSLRB) and the International Lake Superior Board of Control (ILSBC) are reaching out to landowners and businesses that have been directly impacted. They are asking those affected to fill out a survey and/or provide images documenting how high water levels have impacted them: Great Lakes-St. Lawrence River Shoreline Landowners and Businesses 2019 High Water Impacts Questionnaire.

In a news release on October 30, 2019, Governor Gretchen Whitmer and the Michigan Department of Environment, Great Lakes, and Energy announced that they would expedite the permit process required for any alterations on shoreline property. Officials hope to cut permitting times from several months down to days, where there is imminent danger to structures, Michael Kransz reports for MLive. A new webpage was also created to help property owners with the permitting process and provide a centralized area for high water level information:

Water Levels Resource Links:

Government of Canada – Great Lakes Water Levels and Related Data

Government of Ontario – Flood Forecasting and Warning Program

U.S. Army Corps of Engineers – Great Lakes Information

International Joint Commission Boards, Studies and Committee

International Lake Ontario-St. Lawrence River Board

International Lake Superior Board of Control

International Niagara Board of Control

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Decommissioning Nuclear Power in the Great Lakes

Perry Nuclear Power Plant in Lake County, Ohio next to Lake Erie. Photo: First Energy Corp. Flikr

In a two-year project titled Decommissioning Practices of Nuclear Power Facilities in the Great Lakes Basin, the Great Lakes Water Quality Board (GLWQB) will assess the potential environmental impacts associated with decommissioning all remaining nuclear plants in the Great Lakes basin. By 2020, the GLWQB aims to complete all three phases of this effort: an informational report, a consultant’s report and outcomes of an expert workshop. These three components will be used to develop actionable recommendations and advice for Canadian and U.S. governments that will reduce the risk of releasing radioactive material into the Great Lakes during decommissioning.

In a news release on October 16, 2019, the GLWQB announced that the International Joint Commission had approved the publication of the GLWQB’s informational background report, the first phase in their assessment of the potential environmental impacts of decommissioning nuclear power facilities in the Great Lakes basin. The background report describes the current status of nuclear plants in the basin, radioactive waste storage techniques and applicable regulatory regimes.

You can view the Water Quality Board’s informational report on nuclear power in the Great Lakes here: Nuclear Power Facilities in the Great Lakes Basin: Compendium of information related to the current status and decommissioning of Great Lakes nuclear power facilities to support the development of a Great Lakes Water Quality Board report

An accompanying GIS story Map is available here: Nuclear Power Facilities in the Great Lakes Basin

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IJC seeks comments after the Step In and Speak Out series

Great Lakes public meeting locations for Step In and Speak Out series that was run by the International Joint Commission. (Source: International Joint Commission website.

The International Joint Commission (IJC) held public meetings from June through September, 2019, in six communities within the Great Lakes watershed (see image above). These gatherings were intended to create dialogue between all people interested in and affected by the ecological status of the Great Lakes. The IJC also completed these meetings as public consultation in the assessment of the United States and Canada’s progress towards the 2012 Great Lakes Water Quality Agreement goals. 

Wether you attended one of these meetings or not, you can now provide input online. The IJC is accepting public comments until October 31, 2019.

To submit a comment, you will have to log-in to, or create, an account on the IJC website. Links to do this are at the bottom of the IJC Invitation to Step In and Speak Out webpage.

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Green Infrastructure and Living Shorelines

High water levels have prevailed across the Great Lakes watershed this season. While many are calling for higher outflow in order to lower lake levels, experts agree that the main issue is changing climate. (Photo: NOAA)

Flooding and Coastal Erosion in the Great Lakes

This spring, extremely high water levels and windy weather have lead to major flooding and extensive damage to coastal infrastructure in the Great Lakes. While the issue of how much we can mitigate these impacts by adjustments to the outflow of each of the Great Lakes is complicated; most experts agree that the main culprit is record level precipitation and more frequent and intense storms due to a rapidly changing global climate.

If these types of changes are expected to continue, then solving these issues will require adjustments to more than policy. One area that is receiving a great deal of attention amongst Great Lakes communities is green infrastructure.

GLC Green Infrastructure Champions Program

The Great Lakes Commission (GLC) is helping Great Lakes Communities to implement green infrastructure in their planning in order to repair the natural water cycle and therefore reduce flooding in cities. They have developed the Green Infrastructure Champions program, which coordinates a peer-to-peer mentorship program so that mid-size municipalities can work together. Mini-grants are available to those in the mentorship program. The Green Infrastructure Champions program also runs workshops to share successful green infrastructure projects and discuss green infrastructure tools. The program began as a pilot project from 2016-2018, but will continue through September 2020.

For more information visit

An example of a green roof in Halifax, Nova Scotia. The use of vegetation on the roof reduces runoff and results in more water retention in accordance with the natural water cycle. (Photo:

Living Shorelines

Shorelines are naturally dynamic environments. Sedimentary materials tend to erode slowly from upstream to downstream so that little change is observed over a human lifetime. Unfortunately, there are many types of human activity that increase the severity and speed of shoreline erosion. For example, motorized water vehicles can exponentially increase the eroding force on a shoreline by creating waves that are stronger than what would normally be produced there. Simply getting too close to fragile shorelines like bluffs will also accelerate erosion.

Shoreline erosion at Neys Provincial Park. Trees are toppled into the river and a fence deters human traffic from accelerating shoreline erosion where no trees exist and a bluff has formed. (Photo:

The main defense used against shoreline erosion has often been the construction of engineered hard barriers like seawalls and bulkheads. Efforts to stop shoreline erosion through the use of these structures can often become counterproductive, as they interfere with natural erosion processes. The issue here is that shorelines are meant to be dynamic, and what is eroded from one place is transported to another. Artificially limiting erosion in one location can then reduce deposits downstream, thereby accelerating erosion elsewhere.

The Lasalle Park seawall in Buffalo, New York, is an example of an engineered hard barrier. It protects the Colonel F.G. Ward Pumping Station, the main source of drinking water for the city of Buffalo. (Photo: Andi Kornaki/USACE)

In some cases an engineered hard barrier is necessary, but where there is an option, living shorelines are often your best bet. They are cheaper and result in a much more longterm solution that also benefits wildlife by maintaining natural shoreline habitats.

A living shoreline built at the Thunder Bay Marina uses native plantlife to bioengineer a marsh that mitigates erosion from wave action in a protected bay. (Photo:

These types of shorelines work with nature, rather than against it, to ensure steady but slow erosion rather than dangerous accelerated erosion. They involve the use of native vegetation to reinforce the soil and protect against wave action. Where wave action is stronger, a combination of hard structures and living shoreline can be used.

For more information on Living shorelines, visit these websites:

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Invasive Species – The Battle Against Asian Carp Continues

Aerial view of Brandon Road Lock and Dam, Joliet, Ill., April 22, 2014. This dam acts as a choke point between Asian carp and the Great Lakes where the implementation of Asian carp deterrents has been approved by the U.S. Army Corps of Engineers. (Photo: U.S. Army Photo by Dave Wethington/Released. CC BY 2.0)

The fight to prevent Asian carp from entering the Great Lakes is kicking into high gear. On April 29th, the Asian Carp Regional Coordinating Committee released the 2019 Asian Carp Action Plan, which involves efforts to find effective Asian carp deterrents. Plus this May, the U.S. Army Corps of Engineers approved plans to implement defensive structures in the the Brandon Road Lock and Dam, which acts as a choking point between the Illinois River and a variety of tributaries that lead into Lake Michigan.

Crews search for invasive Asian carp near Chicago , Aug. 2, 2011, following several recent discoveries of their genetic material in Lake Calumet. Teams swept the lake with half-mile-long nets. Six boats from government agencies and four commercial fishing vessels took part the search. No Asian carp were found. (Photo: U.S. Army Corps of Engineers photo by Jessica Vandrick)

The U.S. and Canada have been working together for years to avoid the damage that this invasive species would cause to native species in the Great Lakes. Both sides participate in frequent monitoring and prevention techniques like electrofishing and eDNA (environmental DNA) collection. Asian carp pose a serious threat to the health and ecology of native plant and fish species in the Great Lakes.

Electrofishing for the asian carp invasive species. (Photo: Public Domain by U.S. Fish and Wildlife Service)

Asian carp is actually a blanket term for several related species of fish. The Asian carp that have invaded North American tributaries include four specific species of the cyprinid family: Bighead carp, Black carp, Grass carp and Silver carp. Asian Carp were first introduced in North America in the 1970s to manage algae in aquaculture ponds and are believed to have escaped into natural waterways during flooding events shortly after. They traveled northward in the Mississippi River towards the Great Lakes and were found to have already outcompeted native fish in the Illinois River area at 9 to 1 by 1990.

Asian carp in the United States and Canada refers to four species of carp. [Top] Black carp and Grass carp are invasive and the new 2019 Asian Carp Action Plan will look at improving our knowledge about these less pervasive species. [Bottom] The Silver Carp above the Bighead Carp can be hard to distinguish. Both are referred to as bigheaded carp and have presented the greatest threat to the Great Lakes. (Photo: Retrieved from Asian Carp Regional Coordinating Committee’s photostream on Flikr. [Top] Photos by Ryan Hagerty/USFWS. CC BY 2.0)

These fish are bottom feeders who eat huge amounts of algae and reduce the availability of food to native species. Silver Carp and Bighead Carp are the most pervasive. Silver carp are also sensitive to the vibration of motors and will jump out of the water, causing damage and injury to boaters and those using waterways recreationally.

You can join the fight against asian carp by reporting their presence. Get to know the distinguishing features of each species and get in touch:

  • Call the Invading Species Hotline at 1-800-563-7711, or report it online at

To learn even more about Asian carp visit the following websites:

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Classifying Lakes: Eutrophication in the Boreal Forest Ecozone

Many policies and programs aimed at maintaining healthy lakes depend on measuring their level of eutrophication. Lake Superior is oligotrophic: relatively deep, clear and nutrient poor. – Image from

What is Eutrophication?

Lakes are classified based on trophic state, which is a measure of the nutrient level, clarity, and abundance of living organisms in a body of water. The trophic state for lakes ranges from oligotrophic lakes (deep, cold, clear water lakes with limited fish, plant and algal growth)  to eutrophic lakes (shallow, warm water lakes with an abundance of small fast growing fish, plants and algae). Mesotrophic is the middle state between these two. Eutrophication of a lake is the enrichment of nutrients (phosphorus, nitrogen, carbon and many others) that allows for increased growth of aquatic plant life (phytoplankton), which results in the depletion of the lake’s dissolved oxygen. Depleted oxygen or anoxia in lakes, can result in the lake becoming uninhabitable for fish. Anoxic conditions in lakes are also linked to internal loading (nutrients released from lake sediments) which further contributes to eutrophication and algal blooms.  

Eutrophication is a natural process. It normally takes centuries for lakes to transition from oligotrophic to eutrophic as precipitation (snow, and rain) erodes rocks and soil, picking up and transporting nutrients and particulates into lakes, which gradually become shallower and more nutrient-rich. Nutrients support primary production (plant and algal growth), which provides an abundant food source for zooplankton and small fish, which in turn support larger fish. As nutrient and sediment inputs continue over decades, the system will begin to have such an abundance of primary production that the oxygen within the system will not support fish and the lake becomes eutrophic.

The three trophic states of lakes from left to right, Oligotrophic, Mesotrophic, and Eutrophic. Note the increasing amount of sediment and vegetation in and around the lake as a result of increasing nutrients within the water. – Image credit to RMB Environmental Laboratories.

Eutrophic lakes are normally associated with warm geographic regions where lakes reach higher temperatures and where numerous sunny days provide the necessary light intensity to support large phytoplankton communities. The concept that natural climate conditions control a lake’s ability to produce large phytoplankton blooms has lead to the assumption that boreal shield lakes are generally oligotrophic.

Anthropogenic Eutrophication

Anthropogenic eutrophication is eutrophication expedited by human impacts, such as agriculture and urban development, which increase the nutrient load on nearby lakes. In the 1960s, research into anthropogenic eutrophication took off in response to the rapid eutrophication of Lake Erie. The scientific community was divided on the topic: large soap companies pushing carbon as the limiting nutrient responsible for Lake Erie’s issues, while others tried to argue that it was phosphorus.    

In 1969, David Schindler and colleagues established the Experimental Lakes Area in Northwestern Ontario where they could do whole ecosystem experiments on real lakes, in large part, to understand what causes anthropogenic eutrophication. Their eutrophication study divided Lake 226 with a plastic curtain into the North and South basin. The Northside had phosphorus, nitrogen, and carbon added, while in the Southside, only nitrogen and carbon were added. The North basin developed sickly pea green algal blooms while the south remained clear. This was a piece of crucial evidence that paved the way for worldwide policy changes.  

Aerial image of Experimental Lake Area (ELA) Lake 226 showing the curtain dividing the North and South basins and show the classic green algae bloom. – Image is taken from

Both nitrogen and phosphorus were added to a separate lake, Lake 227, until 1990. From 1990 to present only phosphorus has been added with continued algal blooms ( The now-famous eutrophication experiment proved that phosphorus, from anthropogenic sources, was the nutrient responsible for massive algal blooms in Lake Erie.  

Aerial image of Experimetnal Lake Area (ELA) Lake 227 showing lakewide algal bloom. – Image is taken from

How is Eutrophication Measured?

The level of Eutrophication in a lake can be approximated by measuring the clarity of its water, the concentration of chlorophyll in the lake, and the total phosphorus content of the lake. Clearer water means less ‘stuff’ floating around in the water and is associated with more oligotrophic lakes. Less light penetration usually means more ‘stuff’ (i.e. algae) in the water and is associated with more eutrophic lakes.

The clarity of water determines how far light can penetrate into the water and light is a driving factor for photosynthesis and chlorophyll concentration. Light penetration is measured using a secchi disc, a flat disc of about 4 inches in diameter that is checker pattern, black and white, in quarters.

A secchi disk is used to measure the clarity of a body of water. – Image form:

The disc is lowered into the water until you can no longer distinguish the pattern, then brought back up so you can just barely see it. This is the light penetration or secchi disc depth. Chlorophyll ‘a’ is the pigment associated with plants and a higher concentration of chlorophyll is associated with higher concentrations of algae in the water. Additionally, total phosphorus (TP) provides an indication of the available nutrients used by the algae in the water. Higher TP is again associated with higher algae, which will mean higher chlorophyll, which means limited light penetration.

Research by Vollenwieder (1969) and by Dillion and Rigler (1974) determined that collecting total phosphorus concentrations during the spring freshet, when ice and snow are melting and rushing into rivers and lakes, was ideal because the water within the lake is mixing. A sample of water at this time could provide a representative sample of the whole. Specifically, the TP at this time could be used to predict the concentration of phytoplankton seen on the lake later in the summer, removing the need for the additional sampling of lakes throughout the open water season.

Image depicting the phosphorus cycle for terrestrial and aquatic ecosystems. – Image is from

Currently, the Ontario Ministry Of Environment, Conservation, and Parks collects samples and monitors surface water conditions following this line of thought. Technicians go to lakes throughout Ontario during the spring (April and May) when lakes are mixed to collect water samples for analysis. This work provides data on the current abundance of TP in and entering lakes. The Ontario guideline stipulates that 20ug (micrograms) per litre of water is the assigned threshold in which a water sample is deemed micrograms too high and associated with a high probability of nuisance algal blooms.

Is Eutrophication a Problem in the Boreal Forest Ecozone?

Boreal Shield: “The Boreal Shield is the largest (about 20 percent of Canada, or over 1.9 million km2) of all the ecozone units. It is broadly U-shaped and extends from northern Saskatchewan east to Newfoundland. From northern Saskatchewan, it passes north of Lake Winnipeg, the Great Lakes and the St Lawrence River to Newfoundland. The rocky hills, coniferous forests and abundance of lakes are recurring parts of this well-known landscape”. (

Boreal Shield Lakes

The studies previously mentioned in this article, which advanced our understanding of phosphorus’s role in aquatic ecosystems,  were conducted at the Experimental Lakes Area (ELA), a large section of land with 58 lakes located just East of Kenora and within the Boreal Forest Ecozone. The lakes at the ELA are oligotrophic Canadian Shield lakes and are a small portion of the thousands of lakes in Northern Ontario that fall into the Boreal Forest Ecozone.

Lakes within the Boreal Forest Ecozone are generally assumed to be oligotrophic lakes: cold, clear, relatively deep, and generally pristine. Because of limited nutrients, lakes in this region are not associated with having algal problems. Although the ELA contains lakes that are representative of many oligotrophic lakes in the Boreal Forest Ecozone, there is a wide variety of lakes with varying trophic states throughout this region. This is clear to those who have had the opportunity to visit the lakes. Furthermore, oligotrophic lakes are not immune to eutrophication. Even the region’s deepest and most well-known oligotrophic lake, Lake Superior, experienced a cyanobacterial bloom last summer.

Sediment flowing into Lake Superior observed after major flooding in June, 2018. Flooding in Summer 2018, which brought nutrients and sediment into Lake Superior, was closely tied to algae blooms. – Image from NASA earth observatory

Anthropogenic Eutrophication of Boreal Shield Lakes

As previously stated, anthropogenic eutrophication is often caused by phosphorus loading associated with agriculture and urban development, but other anthropogenic nutrient sources exist. In Northern Ontario, there is very little agriculture, with forestry and mining being the major industries.

Although comparatively minimal nutrient contribution is associated with mining and forestry, there is still a possible increase of contaminants entering the aquatic systems. These contaminants are not exclusively nutrients but can also be harmful chemicals. When forested areas are cleared for logging or mining it can cause increases in surface-water runoff. Rainwater running over the ground, no longer absorbed by the vegetation, picks up nutrients and transports these nutrients into the watershed where they are available for use by phytoplankton.

Northern Ontario watersheds are also home to camps (lakeside cabins) that provide great fishing and leisure activities. The development of these properties can also contribute to nutrient enrichment of the lakes where they are built resulting in loss of the riparian buffer along the shore that would help keep surface runoff from entering directly into the lake. If you have the opportunity to walk the trails around Thunder Bay you will notice the many sections along McVicar or the MacIntyre where people’s lawns come right down to the river’s edge. Any grass or plant fertilizer that happens to be on the lawn during a rain event can easily end up in the river and ultimately Lake Superior.

Author: Nathan Wilson is a PhD candidate at Lakehead University. His focus is on examining lakes within Northwestern Ontario to better understand nutrients and cyanobacteria.

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Great Lakes Shipping Breaking Out of the Off-season

Ice cover just over 20% on the Great Lakes on March 25, 2019. Canadian and U.S. Coast Guard icebreaking vessels will be clearing things up as the Great Lakes shipping industry gears up for spring and summer. (Credit: NASA Earth Observatory image by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview)

The Off-season Ends When Locks Reopen

After a highly successful shipping season in 2018, ports are optimistic that 2019 will provide equally substantial traffic. Shipping within the great lakes continues throughout the winter, but to a much lesser degree because the Great Lakes’ Soo locks and the St. Lawrence Seaway’s Montreal – Lake Ontario locks are shut down for maintenance and repair.

Icebreaking ships, USCGC Mackinaw and USCGC Alder, transit through the Soo Locks. Photo from the USACE Detroit District Facebook Page (Credit: U.S. Army Corps of Engineers Detroit District)

The off-season ends when these locks are reopened and ice breakers head out to the northern ports to get things moving again; this year the CCGS Samuel Risley, USCGC Mackinaw and USCGC Alder headed north through the Soo Locks on March 20th. On March 25th, the Stewart J. Cort was the first of the shipping season’s big ships to pass through the Soo locks. The Montreal – Lake Ontario locks opened on Tuesday March 26th.

Ice Breakers

Ice cover on Lake Superior reached 90% in early March, but the ice quickly began to dissipate and is now down to about 25% according to NOAA data. But that is still more ice than the coast guard has seen in several years. Ice breakers from the Canadian and U.S. coast guards work together to create passable shipping lanes in the Great Lakes. If you are curious about where the icebreaking ships are currently located on the lake, you can look for them using the live map on (they fall under the “Tugs & Special Craft” category and are light blue).

Canadian icebreakers

The Canadian Coast Guard (CCG) has an ice fleet of 15 that is dedicated to ice breaking efforts along Canadian shores on the East and West coasts, in the Arctic and in the Great Lakes. The fleet boasts 2 heavy icebreakers, 4 medium icebreakers, 9 multipurpose vessels and 2 hovercrafts. Vessels are assigned to one of three regions: the Atlantic, the Central and Arctic, or the Western Region.

The CCGS Samuel Risley, one of the Canadian Coast Guard’s light icebreakers that operate in the Great Lakes, is named after Samuel Risley, a pioneer in shipping safety regulation in the late 1850s. (Credit: U.S. Army Corps of Engineers Detroit District – On her way, Public Domain)

According to the CCG website, two Central and Arctic region light icebreakers—the medium-endurance CCGS Samuel Risley and the high-endurance CCGS Griffon multi-tasked vessels—are assigned to the Great Lakes throughout the winter, but additional vessels are used at the beginning and end of the ice breaking season.

The CCGS Griffon is the Canadian Coast Guard’s high endurance multi-tasked vessel light icebreaker. It is named after Le Griffon, one of the first sailing ships constructed to travel across the Great Lakes. (Credit: simon*** from England – CCGS Griffon on the Welland Canal, Canada, CC BY 2.0)

Canadian icebreakers active in the Great Lakes and St. Lawrence Seaway on March 30, 2019 at 12:00pm EDT:

  • CCGS Samuel Risley – Port of Thunder Bay
  • CCGS Pierre Radisson – Lake Erie
  • CCGS Griffon – northeast Lake Ontario near the St. Lawrence River
  • CCGS Des Groseillers – St. Lawrence River
  • CCGS Captain Molly Kool – Gulf of St. Lawrence

U.S. icebreakers

The USCGC Alder, also known as the “King of the Waters,” operates throughout the Great Lakes but mainly works in Lake Superior and northern Lake Michigan. (Credit: Pete Markham. Some Rights Reserved, CC BY-SA 2.0)

The U.S. Coast Guard Atlantic Area’s Ninth District units are dedicated to all coast guard operations in the Great Lakes, Saint Lawrence Seaway and parts of the surrounding states. Vessels involved in icebreaking operations fall under the Cutters Unit, and include the USCGC Alder, Biscayne Bay, Bristol Bay, Hollyhock, Katmai Bay, Mackinaw, Mobile Bay, Morrow Bay, and Neah Bay. In Lake Superior you will mostly hear about the USCGC Alder and USCGC Mackinaw.

The USCGC Mackinaw is the U.S. Coast Guard’s only heavy icebreaker in the Great Lakes. (Credit: U.S. Coast Guard)

U.S. icebreakers active in the Great Lakes and St. Lawrence Seaway on March 30, 2019 at 12:00pm EDT:

  • USCGC Alder – Port of Thunder Bay
  • USCGC Mackinaw – Passing Whitefish Point destined for Whitefish Bay
  • USCGC Katmai Bay – Munuscong Lake
  • USCGC Bristol Bay and Neah Bay – Northern Lake Michigan


USACE Press Release: “The Soo Locks open as 2019 shipping season begins”

Great Lakes St. Lawrence Seaway System: Canadian and U.S. Press Releases

CBC: “Canadian Coast Guards ‘looking for new recruits’ in video showing ice breaking process in Thunder Bay, Ont”

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