36 CFR 3.13 - What conditions apply to the use of Marine Sanitation Devices (MSD)?
(a) Discharging sewage from any vessel, whether treated or not, in any body of fresh water is prohibited.
(b) The owner or operator of any vessel on park fresh water that is equipped with toilet facilities and/or a MSD that is capable of discharge, must lock or otherwise secure the valves or mechanism of the device. Acceptable methods of securing the device include:
(1) Closing the seacock and removing the handle;
(2) Padlocking the seacock in the closed position;
(3) Using a non-releasable wire-tie to hold the seacock in the closed position; or
(4) Locking the door to the space enclosing the toilets with a padlock or door handle key lock.
(c) The superintendent may modify the requirements of this section through a special regulation.