Overview
Lake Superior is the largest of the five Great Lakes – and is also the largest freshwater lake in the world. The lake spans nearly 31,700 square miles and is shared by two countries – the United States and Canada. While the lake is unmistakably freshwater in character, many visitors and locals alike are often confused; is Lake Superior saltwater or freshwater?
Background
The desire to understand more about the lake’s makeup dates back to French explorer, Étienne Brûlé, who first crossed Lake Superior in 1622. Since that time, many have studied the lake, its water composition, and its contents. While the lake has a strong salt smell, there are some notable differences in its makeup that have been determined over the years.
What Type of Water is Lake Superior?
Lake Superior is freshwater. However, this does not mean that there is no salt in the water due to its size and the large number of tributaries that feed into it. The freshwater comes mainly from precipitation and runoff, which has very low levels of salt. The detection of salinity in Lake Superior is measured in parts per thousand (PPT). The salinity level is usually around 0.05 to 0.15 PPT. This is much lower than the surrounding ocean water, which usually range from 5 to 40 PPT.
Sources of Salt in Lake Superior
While it may be true that Lake Superior is classified as freshwater, there are numerous sources of salt within the lake that contribute to its composition. For example, much of the salt found in Lake Superior originates from the tributaries that feed it. These tributaries can bring in high levels of salt from lakes and rivers further inland. In addition, humans have continually been adding salt to the lake through road and industrial runoff, as well as snow and ice melt. Small amounts of salt also enter the lake via atmospheric inputs and the substances that it absorbs from the soil.
Effects of Salinity in Lake Superior
Unfortunately, the higher salinity levels in the lake have had a significant impact on its ecosystem. The increased salinity levels have killed off many species of freshwater fish, while promoting the growth of invasive species. In addition, the salinity levels have been found to reduce oxygen levels in the lake, leading to further drops in biodiversity.
The Role of Scientists
In order to prevent further destruction of Lake Superior’s ecosystem, scientists have developed programs to monitor the salinity levels of the lake. By studying various bodies of water upstream, scientists are able to determine whether the water is getting saltier or not, and what environmental factors could be causing it.
The Human Role
Humans also play a role in reducing the salinity in Lake Superior. Constant monitoring and awareness of runoff can help to reduce the amount of salt entering the lake. Additionally, measures such as the implementation of green infrastructure and the promotion of natural landscapes can help to protect the lake’s waters, mitigate flooding, and reduce pollution.
Monitoring of Water Quality
The quality of Lake Superior’s waters is constantly monitored by government agencies, researchers and citizen scientists. Additionally, there are organizations such as the Lake Superior National Estuarine Research Reserve and Great Lakes Commission, which are dedicated to monitoring and protecting the lake’s waters.
Role of Local Residents
The participation of local residents is vital for the preservation of Lake Superior. Residents can get involved by participating in surveys, joining monitoring initiatives, and promoting community efforts such as beach cleanups and responsible waste management habits.
Conservation Efforts
To ensure the longevity of Lake Superior, governments and organizations have implemented a variety of conservation efforts. These include the Great Lakes Water Quality Agreement, which was developed to restore, protect and maintain the chemical, physical and biological integrity of the lake.
Role of Academics
Academics have contributed vast amounts of research to the preservation of Lake Superior. They have studied the lake’s water composition and the effects of human activities on its ecosystem. Furthermore, they have outlined ways to reduce salinity and improve the overall quality of the lake’s waters.
Limitation of Studies
Unfortunately, there are still gaps in our understanding of the long-term effects of salinity on Lake Superior. To address this, studies should be conducted in the future to gain a better understanding of the lake’s overall health.
Initiatives for A Brighter Future
Citizen initiatives and government programs have proved beneficial for the preservation of Lake Superior. Organizations such as the Great Lakes Fisheries Commission have also played an important role in understanding the lake’s ecosystem and have outlined steps towards a better future for the lake’s inhabitants.
The Problem of Climate Change
Perhaps the most pressing concern for Lake Superior is the threat of climate change. The effects of climate change are already being felt within the lake and its waters, with higher temperatures and changes to the lake’s circulation patterns. To address this, initiatives should be taken to reduce our carbon footprint and preserve Lake Superior’s water cycle.
Questions to Consider
As we move forward, it is important to ask ourselves how we can ensure the safety of Lake Superior in the long-term. What steps can be taken to reduce salinity levels? How can we better understand the effects of climate change on the lake’s water? What role can we all play in preserving Lake Superior for future generations?
