[TowerTalk] ground and conductivity

[Bryan W5KFT]

The recent discussions on conductivity have talked about different soil types and saltwater.  Is there any information available about conductivity for antennas mounted above "fresh" water (ie lakes)

Is the additional conductivity worth the hassle for installation above a LARGE body of fresh water?
Trying to figure out if its worth it to use Lake Buchanan, Texas (8 miles wide, 35 miles long)

Bryan W5KFT