Springs are great for swimming, and have such a high traffic rate, that you should be fine swimming as long as you stay in the areas that are roped off.
Florida fresh water (aside from those roped off areas in the springs) are not meant to be swam in. It’s not healthy, nor is it safe. After our Florida rains, alot of the water can have a high bacteria content, as well as…well, alligators. They live there.
Alligators, in most cases, won’t mess with you if you don’t mess with them. The PROBLEM is - alot of people feed them when they are babies, and so when they are older, they aren’t scared of humans - they see a human, and have been conditioned to think “food”…
My mom managed a golf course for YEARS, and there was gators in the some of the ponds on the course…well, those little old ladies fed those gators EVERY day…but, those gators grew up, and my mom had to have them removed, because they had no fear! THey were huge!