HOWEVER, having said that, I believe that anything that makes your feet and legs stronger will help and you can do that on dry land. Get a book from the library and have a look at stretches that go to the foot -- hamstring stretches work. I saw someplace on this message board instructions for standing on a step with the front half of your foot on the step and the back half hanging off. (Of course hold on to the railing). Then just hold that for a while. Start off by counting to 10 and then keep working up. I don't know why but this helps and I hope the description makes sense.
My favorite is just to put my fingers on the edge of the pool and stand up on my toes and down and up and down, etc. I started out with six and now do 30 or 35. You can hold on to the back of a chair, but make sure to use the chair only to maintain balance -- you're working on your feet and legs, not on your arms.
This won't work on its own but might help in combination with everything else. (I even considered acupuncture, but was told it probably wouldn't help)
I was swimming 5 times a week at the time I started this. Now I swim 3 times a week and do the treadmill for 30 minutes 3 times a week. I also walk a lot just "around town."