Cape Coral Fishing

We are leaving our villa early when we go out there in July to spend a week in Cape Coral. I am of course renting a villa whilst over there (is there any other accommodation that comes close) which backs onto one of the canals.
Does anyone know where the salt water from the estuary finishes and the fresh water begins?
I asked the owner of the villa but she hasn't got a clue. Hoping to do some fishing from both the back of the villa and also on the boat that comes with the villa and need to know what I will be fishing for.

Sorry can't help with your question but maybe you could help me. Is the villa your using listed on these forums? I would love a villa with the use of a boat. Too late for this year but I'm already thinking about returning next year[laugh]

EDIT
I've just searched the cape coral area and looks like there are plenty properties with the possible use of boats[clap]