you can be fined
if you do not tie it off somehow to prevent you from turning the y valve to the overboard position.(plastic wire ties work great). Taken from BoatUS.......Federal law says that untreated sewage (even if it's been dosed with a deodorant product) can NOT be discharged in inland or coastal waters. This means the sewage from a portable toilet or a Type III holding tank can not be discharged unless you are in the ocean more than 3 miles offshore.Federal law also states that if you have a holding tank with a "Y" valve allowing direct overboard discharge of untreated waste, it must be secured in the closed position while operating in all inland and coastal waters. Using a non-releasable wire tie, padlock, or removing the valve handle is considered adequate securing of the device.Operating in a federally designated “No Discharge Area” further restricts what sewage you can discharge overboard. In these areas, there is no treated sewage discharge allowed from boats. That means if you have a Type I or II MSD, you are not allowed to discharge it while in those waters. There is a trend towards more local waters being designated as No Discharge Areas, so if you rely on using your Type I or II MSD, check a cruising guide before venturing into new waters.