Michigan waters of Lakes Michigan, Huron, Superior, Erie 
and St. Clair, all waterways connected thereto, and all 
inland lakes are designated as a No-Discharge Zone 
(NDZ). Under the Clean Water Act, Section 312, all vessels 
operating within a No-Discharge Zone (NDZ) are completely 
prohibited from discharging any sewage, treated or 
untreated, into the waters. Commercial vessel sewage shall 
include graywater. All vessels with an installed marine 
sanitation device (MSD) that are navigating, moored, 
anchored, or docked within a NDZ must have the MSD 
disabled to prevent the overboard discharge of sewage 
(treated or untreated) or install a holding tank. Regulations 
for the NDZ are contained in the U.S. Coast Pilot. 
Additional information concerning the regulations and 
requirements may be obtained from the Environmental 
Protection Agency (EPA) web site: http://www.epa.gov/
owow/oceans/regulatory/vessel_sewage/