Sour Lake is a city in Hardin County, Texas, United States. The population was 1,813 at the 2010 census. It was originally named Sour Lake Springs, after the sulphurous spring water that flowed into the nearby lake; the sulphur was a sign of the crude oil that lay in proximity to local groundwater. The city is part of the Beaumont–Port Arthur Metropolitan Statistical Area. Sam Houston visited Sour Lake in his later years.