Property values and ad valorem taxes may change for lakefront property owners after a long-term study of those properties by Hall County. As county staff and consultants gear up to do a complete re-evaluation of lakefront property, real estate agents said the market is active, especially for luxury houses on Lake Lanier. The Hall County Board of Commissioners awarded $327,500 to GMASS Inc., based in Dawsonville, in late July to reappraise between 6,500 and 6,800 properties on the lake, said Chief Appraiser Steve Watson.