Ryan - The lakes Brian is talking about are located in Mecca, about 30 miles south of I-10 on Hwy 111. They are pretty shallow.We've run wakeboard boats in there before, but you kick up a lot of mud. Water conditions are always great. Really almost no one ever there. On the flip side, the lakes are pretty primitative. If anyone is interested, the site is for sale. He's asking 1.5M for the entire lot which includes 2 lakes and 3 slalom courses.
Here's a picture if you're interested. http://www.terraserver.microsoft.com/image.aspx?t=1&s=11&x=1468&y=9277&z=11&w=1
Some other thoughts are:
Ironwood Lake in Arvin, CA - memberships available
Sunset Ranch in Mecca, CA - memberships available
Great Lakes in Newberry Springs, CA - lake rentals and memberships available
Note all of these lakes are tournament lakes where the average depth is in the range of 4-7 ft. They all probably have fairly differing policies regarding wakeboard boats and use of ballast. Except for the the West? Lake at Paradise (the one with the jump ramp), this will be true for nearly all private lakes you will find. Water is just too dang expensive to build a manmade 12' deep ski lake.
Good luck with your search.