Here:
http://www.cpakayaker.com/uploads/re...afety3fold.pdf
The actual wetsuit season in the DC area is very short. Most of the winter you will need a drysuit to safely paddle (various discussions over on cpakayaker.com in their forums). You need to dress for what the water temperature is and how long you will survive if you are immersed in it, not the air temperature. I don't paddle most of the winter around here because I don't have a drysuit - even though I know that I can roll my boat back up quickly if I flip without actually being fully submersed in the water and have drytops and drypants. And I very rarely flip - but the risk isn't worth it to me if the water temperatures are such that I can't swim 100 feet without dying...
So the amount of time you need or can use neoprene boots up to your knees is pretty limited around here. Go in water deeper than your knees and those boots will fill up with cold water. So fall out in cold water, and you're submersed - it's hard to have a wetsuit on with boots up to your knees. Same with having drypants or a drysuit on with knee high boots you gotta yank up. Not to mention, yanking up tight neoprene sucks - and if it's not tight on your calves it doesn't really work as an insulator. So in any situation that you're wearing knee high boots, you really should be in a wetsuit or a drysuit of some sort and if you are, putting on knee high boots is gonna be a major paint in the *** and ankle length boots will work. Of my ankle height neoprene booties, I use the pair with the zip up the side because the pull on pair is a pain in the neck.
You could also just put on knee high rubber galoshes for that matter. They're looser and they'll go on over wetsuit or drypants legs.
I use this:
http://www.palmequipmentusa.com/gear/bibs_pants.html
The palm sidewinder pants, although the bibs are also good - they've got built in waterproof booties, so I just put those into whatever shoes I want to wear.
And... you've got a plastic boat, no reason for you to get your feet wet at all. Just put your boat half on shore, get in, and slide the boat into the water. Paddle fast & ram the shore & you'll get far enough up you can climb out without getting your feet wet. Or if you paddle up parallel to shore or a floating dock, you can use your paddle to brace the boat and climb out.
Also various types of waterproof neoprene socks you can use instead of knee high boots.