Under the belief that water could dilute any substance, industries and individuals during the 18th and 19th centuries often used rivers and lakes as garbage cans. People dumped industrial wastes, raw sewage, and animal carcasses into waterways, without much thought of contamination OR downstream neighbors.
This practice started changing in the 20th century as people became aware of the importance of clean water to health. However, more industries and more people moved into the Great Lakes region. And the the rivers and lakes continued to be polluted. Today, pollutants enter the Great Lakes in many different ways, but the main three entryways of pollutants are point source, nonpoint source, and atmospheric pollution.
When pollutants enter the waterway through a specific entry point, such as a drainpipe draining directly into a river, it's called point source pollution. Industrial water discharges and sewage treatment plants are the main culprits of this type of pollution. Point source pollutants can include many different organic and inorganic substances, including human waste and toxic metals.
Point source pollution can be traced to a specific discharge point and owner; therefore, it has been the easiest source of pollution to control and regulate. Since the Clean Water Act of 1972, nearly 100 percent of all industrial plants use control measures to reduce their toxic discharge, and the number of sewage treatment facilities has doubled.
In contrast to point source pollution, nonpoint source (or NPS) pollution comes from many different diffuse sources and is extremely difficult to regulate and control; therefore, many experts believe that NPS pollution is the top hazard facing the Great Lakes today.
NPS pollution is mainly caused by runoff, when rain and snowmelt move over the land, picking up pollutants along the way and eventually dumping the pollutants into rivers and lakes. Some common NPS pollutants include fertilizers and pesticides from agricultural lands and homeowners; oil, grease and salt from highways; sediment from construction sites and eroding shorelines; and animal and human waste.
Atmospheric pollution (or air deposition) is another form of nonpoint source pollution, though instead of polluting via runoff, the pollution falls from the sky. As water moves through the hydrologic cycle, it falls as rain or snow and then evaporates into the air from land and surface water. Pollutants emitted into the air, such as through smoke stacks, follow this same path, and can be carried through the atmosphere and deposited into waterways hundreds of miles away from its source. Acid rain is the most well-known form of atmospheric pollution.
The major sources of atmospheric pollution include coal-burning energy plants and waste incinerators. The combustion of fossil fuels and waste (such as from hospitals) produces large amounts of mercury in the air, a toxic chemical that is fatal to humans and animals in large quantities. Phosphorus and polychlorinated biphenyls (PCBs) are also transported to waterways via air deposition.
What can you do to help?
You can make some simple choices that help keep pollutants out of the water. You can also talk with your grownups about what your whole family can do together. But if you want to make a big difference, you will need to work with leaders in your community to make big changes!
Here are some simple things you can do:
- Wash the family car on grass instead of asphalt or concrete to avoid runoff of soap into the street.
- Compost waste material from your garden, kitchen, and lawn. Then you can use the compost to replace chemical fertilizers AND keep these resources out of landfills. so you can use it!
- Use a reusable water bottle instead of buying individual bottles of water in plastic bottles.
- Look twice at something before you buy it. Do you need it? Could you use something you already own? Could you borrow or make something instead of buying new?
- Find out more about pollution in the Great Lakes.
