Both Canadian and American wastewater treatment centers do not have any provisions for the monitoring or removal of microplastics and also lack the filtration capabilities to remove the microplastics as well. As a result of this most of the wastewater treatment centers are reported to be leaking microplastics directly into the lakes. There are no cost estimates as to how much it would be in order to retrofit these treatment centers to have the filtration capabilities in order to prevent the microplastics from getting through. A somewhat recent report suggested that as much as 81% of the plastic debris found in the Great Lakes are classified as microplastic <1mm.
The other major source of smaller plastics in the lake come from plastic manufacturers that may sometimes have spills during transport and end up releasing many small plastic pellets which are then washed into the lakes via rain or other weather events. These small pellets are used as a raw material for the manufacture of plastic products.