35th Anniversary logo for Friends of Casco Bay

Casco Bay is a No Discharge Area (NDA)

Casco Bay is a federally-designated No Discharge Area, which means it is illegal to release blackwater (raw or treated sewage) from any vessel into the Bay. All boats in Casco Bay must hold their blackwater until it can be removed at a pumpout facility. It is also illegal for any vessel to discharge graywater (shower, sink, or onboard laundry water) that is mixed with blackwater. 

Smaller boats without an onboard toilet are not exempt from the No Discharge Area rules, and must collect blackwater and human waste to be disposed of at facilities on land. Some boaters keep an emergency bucket onboard for such situations.

A Note on Graywater

Graywater is wastewater from a boat’s showers, sinks, or onboard laundry. While recreational vessels (specifically, vessels that carry fewer than 250 passengers) are legally permitted to discharge graywater (when not combined with blackwater) into Casco Bay, Friends of Casco Bay does not recommend this practice. Graywater still contains elements that can harm the health of the Bay. We recommend the following practices to reduce the negative impacts of graywater and help keep the Bay clean:

  • If your vessel is large enough, hold your graywater to be pumped-out with your blackwater at a pumpout facility. 
  • When cleaning or doing dishes, use nontoxic and biodegradable cleaners with no phosphorus or nitrogen compounds. Always dilute cleaners to the maximum extent possible.