Green Lake County, WI is located in east-central Wisconsin and has an area of 578 square miles with a population estimated at 19,803 according to the 2020 Census estimates. The county seat is Green Lake and its largest city is Berlin with a population of 3,505 people living within its boundaries. Green Lake County’s economy relies heavily on agriculture producing much needed crops while timber harvesting provides lumber necessary resources used by industry throughout this rural area as well as service industries like finance or healthcare playing small but important roles in employment opportunities available through out Green Lake County .