Don,
Pray for cold fronts from the North in January. You will usually get the cold front, but last Jan (05) it was too warm for a couple of weeks and they went out to feed/rest in deeper, darker water.
Ahem, Ahem, Ahem, do I hear an echo?? Who I wonder clued in Ryan? 
Regardless, well done Ryan, on a Sunday too, see I wouldn't even go on a Sunday and you made me wish I had!!!
As far as a canoe or kayak, yea right........ <_< Tomorrow AMs temp there will be a balmy 36 degrees, Thursday will be a balmier 32 degrees. Perfect, Perfect for manatee, they will be basking in the warm, shallow water near the clear springs. The wind will be north at 10 knots or so, wind chill, yes. There is a good slack tide for 3 sisters if we end up there. The 72 degree water and sun coming out (somewhat tomorrow, but not totally clear like it should be, we will see.......) anyway the water feels great for 3 hours or so!! In a kayak you will freeze your *&%$* off, even if you wear a drysuit, but go ahead, I'll go with Bird's who only have 9 people going out tomorrow and stay warm behind the plastic sheeting, drinking hot cocoa and being first out.
BTW, the manatee don't usually retreat into the sanctuaries, the sanctuaries are set up where most of the manatee traditionally like to sleep, especially when it is cold and where the new mothers feel most at home with calves, etc. So the manatee frequently retreat from (not to) the sanctuaries in the AM to go feed, etc., that is why you need to get there early, before the manatee exodus. Yes manatee retreat into the sanctuaries later on if very much harassed, but the great network of volunteers, education, rules, etc. really greatly curtails this, thank goodness. Still, yes go mid-week.
I'm going tomorrow AM, diving on Florida's East Coast was so horrible today that I just high-tailed it back home here, 1 hour south of manatee land. I've got extra accoutrements picked up from Ryan just day before yesterday, I'll certainly be able to use them more on our loveable manatee than in the current soup that is the East Coast when the current quits running north and the seas are confused!
And, Uh??? viz on the lower end, oh please, you obviously haven't been out at the proper times or at the outflows of the springs. I frequently go there and see manatee in 100 ft viz, only problem then is there can be so many manatee that they stir it up and mess up the viz from too many manatee!!
Yes, viz can be bad if you aren't clued in by the proper operators (like Birds) where the clear water is, there is always clear water, sometimes more than at other times due to tidal conditions (there is salt water intrusion from the Gulf of course, that is how the manatee get there), wind direction, etc.
It's good to be back home and visiting manatee again!!
PS-You are welcome Ryan 
PPS-Don, if you luck out and it is clear and cold you may get the gorgeous rainbow effect through the clear spring water on the manatee backs, faces, etc. It is magical and I have let someone else know that he hasn't even gotten a proper manatee shot until he has captured them in the changing light of the rising sun!! 