“...an old dictum..”
I didn’t catch the age of the guy...
I did some work near a reservoir. We had to make sure that no dirt from the forest got into the water. Dirt!
I should clarify - not talking bulldozers or rivers of mud flowing into the reservoir - it was hitting the ground with a sledge hammer - and we had to be far enough away so none of the splatter would get into the water. Although 15 feet away the water is lapping the shores of the same dirt!