Meghan Hodges
Lake Superior, the largest freshwater lake in the world by surface area, is known for its pristine waters and diverse ecosystems. However, it is not immune to pollution and environmental challenges. The lake's vast expanse and surrounding landscapes play a crucial role in maintaining water quality and supporting a rich aquatic food web. While it has historically been less polluted than other Great Lakes, the cumulative impacts of human activities, invasive species, and pollution sources, particularly from historical mining activities, are posing significant threats to its delicate balance. With ongoing efforts for restoration and protection, the overall status of the Lake Superior basin ecosystem is currently rated as Good, but addressing pollution and preserving this precious resource remain crucial.
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What You'll Learn
- The lake's fish contain what are known as forever chemicals
- The Minnesota Pollution Control Agency is tackling restoration and protection
- Invasive species are causing harm to predatory fish
- Climate change is increasing lake water temperatures
- The lake's tributaries are degraded by agriculture, mining, and industrial effluents
The lake's fish contain what are known as forever chemicals
Lake Superior is the largest freshwater lake in the world by surface area, spanning approximately 31,820 square miles (82,410 square kilometers). The lake is home to over 80 species of fish, a rich aquatic food web, and diverse ecosystems.
However, the lake's fish contain what are known as "forever chemicals," or PFAS (per- and polyfluoroalkyl substances). PFAS are synthetic chemicals that have been used in a variety of industrial and consumer applications since the 1950s due to their unique ability to repel water, oil, and grease. These chemicals are incredibly persistent in the environment and can accumulate in the tissues of living organisms, earning them the nickname "forever chemicals." While PFAS contamination has been detected in all five Great Lakes, Lake Superior fish have the least amount of PFAS among those tested.
The sources of PFAS in Lake Superior are not yet fully understood, but contaminated sites may provide some clues. For example, PFAS have been found at the Duluth Air National Guard Base, adjacent to a PFAS-polluted creek that leads to Saint Louis Bay. Additionally, Michigan’s PFAS Action Response Team reported high levels of PFAS at Houghton County Memorial Airport, which is located next to a creek that flows to Keweenaw Bay. Firefighting foam used in training exercises at military bases is a common source of PFAS contamination.
The presence of PFAS in the lake's fish is a significant concern, particularly for indigenous tribes around Lake Superior who depend on fishing to survive. The EPA has monitored PFAS in Great Lakes fish since 2011 and has published a list of PFAS as guidance for fish advisories. In 2020, Michigan adopted a strict standard to limit two of the most toxic PFAS in drinking water. Other states, such as California, Maine, and New York, have also passed laws to curb PFAS in food and water. While efforts are being made to regulate and reduce PFAS, it remains to be seen if these steps will be enough to protect the health of both the lake's ecosystem and the people who depend on it.
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The Minnesota Pollution Control Agency is tackling restoration and protection
Lake Superior is the largest freshwater lake on Earth by surface area, spanning a vast 31,700 square miles. Surrounded by dense forests and relatively sparse populations, it is home to over 80 species of fish. Despite its immense size, Lake Superior is surprisingly vulnerable. The year-round cold temperatures and the small amount of nutrients entering the lake result in a simple and fragile food chain.
The Minnesota Pollution Control Agency (MPCA) is tackling the restoration and protection of Lake Superior through a variety of approaches. Their Lake Superior programs include the Great Lakes Water Quality Initiative, which involves passing water quality regulations that apply to toxic chemicals in the Lake Superior watershed. As part of this initiative, the MPCA is working with other Great Lakes states and the U.S. EPA to address the issue of toxic chemicals.
Another key program is the Lake Superior Binational Program, a collaborative effort focusing on the entire ecosystem of Lake Superior, including its air, land, water, and human and wildlife life. The MPCA, as one of the partners in this program, is committed to achieving zero discharge and zero emission of nine toxic chemicals from sources in the Lake Superior basin.
The MPCA is also actively involved in the St. Louis River Area of Concern, partnering with the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers to address water, sediment, and habitat quality issues in the lower St. Louis River. One of their cooperative efforts includes locating and recovering barrels dumped by Honeywell Corp. into Lake Superior in the 1960s.
Additionally, the MPCA is working on the Lake Superior South Watershed, which covers 402,371 acres. This watershed includes the city of Duluth and towns like Two Harbors and Beaver Bay. The MPCA is collaborating with various partners to monitor water quality in Duluth streams and develop effective restoration and protection strategies.
The MPCA recognizes the importance of long-term strategies and community engagement in effective lake management. They promote the use of guides and best practices to address issues such as nutrient enrichment, invasive species, and toxic contamination. The agency also requires permits for certain projects, such as the continuous treatment of inflow to a lake, to ensure proper monitoring and reporting of pollutants.
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Invasive species are causing harm to predatory fish
Lake Superior is the largest freshwater lake in the world by surface area, spanning approximately 31,820 square miles (82,410 square kilometers). The lake is home to over 80 species of fish, including trout, whitefish, and herring. While the lake has historically been less polluted than other Great Lakes, it still faces challenges from invasive species and pollution, particularly from historical mining activities.
The introduction of invasive species is often due to human activity. Lake Superior has a rich history of mining and fur trading, with iron, copper, silver, gold, nickel, and uranium all being mined in the area. The mining industry has introduced toxins such as mercury into the water, which has built up in the food chain and poses a health risk to humans who consume the fish. Additionally, barrels containing unknown substances were dumped into the lake by Honeywell Corp. in the 1960s, and more recently, PFAS contamination has been detected at military bases and airports near the lake.
Efforts to restore and protect Lake Superior are ongoing. The Minnesota Pollution Control Agency (MPCA) is working on the restoration and protection of the lake through initiatives such as the Great Lakes Water Quality Initiative and the Lake Superior Binational Program. The Clean Water Act and the creation of the U.S. Environmental Protection Agency (EPA) have also been established to help reduce pollution in the lake.
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Climate change is increasing lake water temperatures
Lake Superior is the largest freshwater lake globally by surface area, spanning 31,700 square miles. It is surrounded by dense forests and relatively sparse populations, with more than 80 species of fish living in its cold waters. The lake's overall ecosystem status is "Good," and the trend is "Unchanging." The lake's water quality is maintained by its forested watershed and coastal wetlands, and it serves as a source of high-quality drinking water.
However, climate change poses a significant threat to Lake Superior and other Great Lakes. Climate change is increasing lake water temperatures, with Lake Superior warming faster than many of the world's large lakes. The average wind speeds over Lake Superior have been increasing by 5% each decade since 1980, and the lake has experienced several extreme storms in recent years. The increasing water temperatures in Lake Superior have several impacts on the lake's ecosystem and the species that depend on it.
The lake's surface temperature has been rising, with wild fluctuations. Warmer surface water temperatures contribute to higher air temperatures, which can negatively affect certain species such as wolves, moose, loons, balsam fir, cisco, and disjunct plants. Additionally, warmer water provides a suitable habitat for invasive species like zebra mussels, which can cause harm to native fish populations. The changing water temperatures also affect the lake's stratification, influencing water nutrient levels and the availability of food sources at different depths, further impacting the ecosystem.
The health of Lake Superior is closely linked to the health of the watersheds and tributaries that connect to it. The lack of habitat connectivity has already impacted native fish species such as Lake Sturgeon. Climate change-induced alterations in water temperatures and nutrient levels can further exacerbate these issues, threatening the delicate balance of the lake's ecosystem.
While Lake Superior faces the challenges of climate change and pollution, efforts are being made to protect and restore its water quality. The Minnesota Pollution Control Agency (MPCA) is actively working towards the restoration and protection of Lake Superior through initiatives such as the Great Lakes Water Quality Initiative and the Lake Superior Binational Program. These programs aim to address toxic chemicals, emissions, and other environmental concerns affecting the lake and its surrounding ecosystem.
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The lake's tributaries are degraded by agriculture, mining, and industrial effluents
Lake Superior is the largest freshwater lake in the world by surface area, spanning approximately 31,820 square miles (82,410 square kilometers). It is home to over 80 species of fish, a rich aquatic food web, and diverse ecosystems. While the lake has historically been less polluted than other Great Lakes, it still faces environmental challenges, including pollution from historical mining activities and invasive species.
The health of Lake Superior is closely tied to the health of its watersheds and tributaries. Unfortunately, the tributaries of Lake Superior have been significantly degraded by various human activities and pollutants. Agriculture, for example, has led to increased surface runoff and erosion, introducing harmful chemicals and pesticides into the water. Mining activities, particularly iron and copper mining, have also contributed to the degradation of the tributaries by releasing toxic substances like mercury into the water, which has built up in the food chain over time.
Industrial effluents and waste are another major concern. For decades, mills and industrial sites have discharged polluting effluents containing dioxins, furans, and other toxic substances into the tributaries, contaminating the water and severely impacting the health and population sizes of aquatic life. Additionally, the development of the shoreline, including recreational home construction, has further degraded the tributaries and disrupted the natural habitat.
The degradation of Lake Superior's tributaries has had far-reaching consequences. It has led to habitat loss, endangering and disrupting the lives of numerous animal species, including mammals, birds, insects, reptiles, and amphibians. It has also contributed to the decline in fish populations and the contamination of fish with harmful substances, posing risks to humans who rely on fishing for sustenance and cultural practices.
Efforts are being made to address these issues and restore the health of Lake Superior's tributaries. The Minnesota Pollution Control Agency (MPCA), in collaboration with other organizations, is working on initiatives to tackle restoration and protection. This includes programs like the Great Lakes Water Quality Initiative and the Lake Superior Binational Program, which aim to reduce toxic chemicals and achieve zero discharge and emission goals.
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Frequently asked questions
Lake Superior is the largest freshwater lake in the world by surface area. It has historically been the least polluted of the Great Lakes due to its remote location, limited industrial activity, and low population density along its shore. However, it still faces environmental challenges, including pollution from mining activities and invasive species. Overall, the lake's ecosystem is considered to be in "Good" condition.
Lake Superior's water and fish contain toxic contaminants such as polychlorinated biphenyls (PCBs), mercury, dioxins, the pesticide toxaphene, and PFAS. These contaminants are linked to cancer and have been introduced through activities such as mining and industrial effluents. The lake has also experienced algal blooms and invasive species, such as zebra mussels and quagga mussels, which can disrupt the ecosystem.
Efforts to restore and protect Lake Superior are ongoing. The Minnesota Pollution Control Agency (MPCA) is implementing various programs, such as the Great Lakes Water Quality Initiative and the Lake Superior Binational Program, to tackle restoration and protect the lake. The Clean Water Act has been passed, and the U.S. Environmental Protection Agency (EPA) has been created to reduce pollution in the Great Lakes, including Lake Superior. Additionally, states like Michigan have adopted strict standards to limit toxic PFAS in drinking water.
