Don't drink the sea water. It's already a bad idea.
There is an expression in research "dilution is the solution to pollution". The parts per billion exposure (but probably even lower) contamination that you might experience is not a public health crisis. You have drinking water in states contaminated with carcinogens. Ain't nobody got time to worry about seawater interfacing with a dead body.
You’re not wrong. But there are still tools available at the federal level. States also have control over their legal drinking age, but if they want federal assistance for maintaining their roads it has to be 21.
You could set a functional tuition cap by saying Federal Student Aid is only available if tuition is <$15k/year