There bound to be more than 130,000 registered voters in the district. Maybe that is the turnout expected. Most districts have some 600,000 residents; how many voters would that be, 350,000 or so?
Carity Elections has the number of registered voters in the district as 445,095. I think that number is from the GA SOS office.
The Election Night Reporting Site says there are 459,000 registere voters — and i assume that is for entire district.
My number is not exact but close.