The Folsom Lake Area was also a significant mining site during the California Gold Rush of 1849. During recent drought years, water levels had been so low at Folsom Lake that the old mining town of Mormon Island was revealed. Mormon Island was a sandbar about 300 feet long where gold was found by members of the Mormon Battalion. When news of gold discovery spread, Mormon Island grew and gained a population of up to 2,500 people by 1853. However, By the 1940s, very few families were left in the area due to fire, diminished gold, and a new railroad.