Cleaning with HCl on a lagoon

A. I live on a lagoon as well, and can identify. If done on a small scale and with care, muriatic acid is probably not dangerous to humans. Small amounts of muriatic acid is even used in swimming pools to keep the water good.

Anything to do with boats is dangerous to fish and marine life--it's a matter of degree. Cleaning the jet ski with detergent is probably worse for the environment than using muriatic acid. And washing your car on any street in a lagoon area is probably horrible for it. "Bottom paint" is designed to kill marine life and does a great job of it while still on the boat, but also after it has sloughed off and become part of the sediment. Bulkheaded lagoons are themselves extremely unnatural, and distort nature's balance. Pressure treated wood bulkheads have been found to be very bad for marine life, while plastic bulkheading has proven to be the ideal environment for jellyfish and sea nettles to breed at unnatural rates, run rampant, and ruin things for everyone.

I think the best way to look at it is simply that the lagoon is not a toilet! If he/she is trying to be neat, careful, non-wasteful, and considerate, that's one thing. If he/she's slopping it around and flicking his/her cigarette butt into the lagoon to boot, that's another.

As for 'legal', be careful with that! It is actually the law that you must report a fuel or oil spill "no matter how small", but I've rarely seen a refueling not involving a few drops of gasoline, so if we actually enforced that law there wouldn't be a single boat on the water nor a car on the road :-)