David proudly proclaims that the Kentucky lake near which the couple wants to buy a home, Lake Cumberland, is the largest man-made lake in the U. S. Not even close. The nation's largest man-made lake is Lake Mead, Nevada, site of the historic Hoover Dam. Lake Cumberland ranks SEVENTH. I guess simple fact checking isn't part of the show's production process. David proudly proclaims that the Kentucky lake near which the couple wants to buy a home, Lake Cumberland, is the largest man-made lake in the U. S. Not even close. The nation's largest man-made lake is Lake Mead, Nevada, site of the historic Hoover Dam. Lake Cumberland ranks SEVENTH. I guess simple fact checking isn't part of the show's production process.