Aquarobics in Modesto, CA????

I have been searching for a swimming class in my area with no luck. Does anyone have any info to pass along so I can get in the water and start losing more of my required 10%. I have been approved for the surgery, met the surgeons, nutritionist, and have my second appt. with the head doctor on the 17th. I am in the process of losing the weight Kaiser requires to prove to them I am willing to change my life style to utilize the surgery to its fullest. I have very bad knees and my weight of 342 (I have lost 4 lbs in two weeks so far - big thing for me!!) just kills them! Thanks for any help