Floating Docks and Plastic Pollution by Peter Adams

Floating docks are very functional for our region of Georgian Bay. They are easily adjusted to fluctuating water levels, they can be moved to protected bays or pulled up on shore to avoid winter ice damage and they’re not as disruptive to shoreline ecology as crib docks. But did you know floating docks can be a significant source of plastic pollution? Walk your shoreline paying special attention to aquatic grasses and shrubs in bays and around rock outcroppings. You’ll be surprised to see how many fragments of dock foam there are, not to mention plastic bottles, old bags and polypropylene rope.

Most floating docks use billets of rigid polystyrene foam as floatation. The billets are popular because of their high buoyancy, light weight, compact size, ease of handling and cheap price. They’re also prone to break down from ice, gnawing/scratching animals (mink, muskrat, beaver and otter), wave action and contact with rocks.

Plastic is not biodegradable. It continually breaks down into smaller and smaller fragments until we can’t see it. When it comes to plastic, out of sight should not be out of mind. Those tiny pieces of plastic, know as micro plastics, are showing up in plankton, fish, birds and our drinking water. A recent study showed 100% of fish sampled in Lake Huron, inclusive of Georgian Bay, contained micro fibre plastics.

In the context of being a Guardian of the Bay, there are several things we can do to help mitigate this form of plastic pollution:

1. Take the time to pick up plastic on your shoreline. Recycle what you can. The polystyrene foam may not be accepted for recycling at the transfer station but at least it’s being removed the aquatic ecosystem.

2. When it comes time to replace an old dock, or purchase a new one, consider a steel pontoon dock or a plastic modular floating dock system. Steel pontoon docks don’t use plastic so they are probably the best option. Plastic modular systems utilize high density polyethylene for the exterior plastic. This type of plastic is more robust than polystyrene and less susceptible to break down from the factors mentioned earlier. Time will tell how it stands up to UV radiation and subzero temperatures. It’s still plastic.

3. If you’re going to purchase a traditional foam billet dock have the manufacturer or contractor incorporate heavy gage wire mesh to keep animals out. Consider a design that minimizes billet exposure to ice and rocks.

4. If you are rebuilding an old dock, take extra care to dispose of the old billets ensuring none of the foam ends up on the shoreline or in the bay. If you’re going to stick with the rigid foam billets for floatation, install wire mesh to keep animals out and install extra dimensional lumber to protect the billets from ice and rocks.