. "No person shall throw or deposit or cause, suffer or permit to be thrown or deposited any stone, gravel, earth, cinders, ashes or other material or rubbish that is liable to sink to the bottom in any water, any part of which is navigable or flows into any navigable water, where there is not a minimum depth of 36 metres of water at all times, but nothing in this section shall be construed so as to" . . . . .