Big Spring near Van Buren is the largest spring in Missouri and one of the largest single-outlet springs in the United States, with an average flow of 286 million gallons a day. The water boils up out of a rock face at the base of a dolomite bluff, fills a pool that is an unnatural opaque blue, and runs down a short channel into the Current River.
The flow varies but it is always huge. After heavy rain, the spring can push 800 million gallons in a single day, and the channel turns brown with sediment churned up from the cave system. In normal conditions the water is cold and almost cobalt — the colour comes from minerals in the bedrock the water passes through.
The 1930s CCC-built structures around the spring — the dining lodge, the cabins, the trails — are themselves worth a look. The short paved loop trail puts you on top of the bluff for a view down onto the spring.