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The Great Lakes threatened

Invasive species have been degrading the quality of the water and the biodiversity of the Great Lakes for several years and threaten the drinking water of certain North American cities. The authorities and communities are taking action, the former by using financial levers while the second make use of judicial procedures.

The Asian carp, a threat for the Great Lakes and the Saint Lawrence River

The fish farmers of Arkansas introduced the Asian Carp in the United States in the 1960s and 70s to combat the proliferation of algae and parasites in the breeding ponds. However, following floods, this species gradually colonised the River Mississippi and then numerous other rivers along a length of more than 1,500 kilometres. In certain locations of the River Illinois, only a few dozen kilometres from the Great Lakes, these carp now make up more than 90% of the animal biomass present. They have also reached the Canadian side of the Great Lakes and the Saint Lawrence River: in June 2016, the first Asian Carp was fished in the river and identified at sixteen places along it.

This species, which reproduces and grows rapidly, without any real predator to limit its proliferation, is particularly harmful for the indigenous aquatic fauna. It harms the habitats of other species by feeding on the plankton and aquatic plants. At home in temperate river habitats, it also threatens fishing activities in the Saint Lawrence.


In January 2018, the Canadian federal government launched a new plan with a budget of $20 million to control its propagation. The United States Army Corps of Engineers (USACE) has also taken measures. To what extent can they be implemented? The Alliance of the cities of the Great Lakes and the Saint Lawrence want the filtration actions at the dam and lock of Bradon Roads (southwest of Chicago, 460 kilometres upstream of the confluence of the rivers Illinois and Mississippi) to continue with the installation of a physical barrier between the Mississippi and the Great Lakes.


Pollution by algae in Lake Erie

The water of Lake Erie, the 11th largest lake in the world, has been subject to constant degradation since the 2000s. The reason is the proliferation of algae caused by the phosphorous flowing into the lake, mainly due to the intensive use of fertilisers for agriculture.


The blue-green algae, sometimes called “cyanobacteria”, reproduce rapidly and form blooms. Their toxins contaminate bodies of water and are a major health risk: the lake provides 3 million people with drinking water. In August 2014, 500,000 inhabitants were deprived of tap water for three days.

To protect the lake, the inhabitants of Toledo, in Ohio, held a local referendum at the end of February and voted in favour of a declaration bestowing rights on Lake Erie. This declaration stipulates that “the lake and its watershed are entitled to exist, prosper and develop naturally”. This vote was a victory for the environmental organisation Toledeans for Safe Water. Although farmers and industrial companies quickly riposted and took out a lawsuit against the Charter of Rights of Lake Erie for reasons of “non-constitutionality and illegality”, this was nonetheless the first step in acknowledging rights for nature, confronted by the degradations affecting it. Similar decisions have already been taken in New Zealand, India and Colombia to acknowledge bodies of water as legal entities.

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