Blue Holes – a natural river phenomenon
Blue Holes are usually created in the hot summer months when water recedes and exposes sand bars at the edge of islands or in dried-out back chutes. Take a look at this amazing picture (courtesy Big Muddy Adventures). According to local river guide, Michael Clark, these depressions hold river water and in many cases the River continues to fill them by a spring-like connection. The water becomes sand-filtered, resulting in a sedimentation that changes the color and turbidity of the water in the hole.
On a hot summer day, Blue Holes make fantastic swimming holes and the perfect place to set up camp and enjoy the pleasures of an early swim or an evening of star gazing.
Mosenthein Island has a series of three blue holes which are revealed when the River recedes to a low water stage.
Swimming stop in Mosenthein Chute
It’s the ultimate Tom Sawyer experience! Sand bars and sand filtered water offer great opportunities, particularly off Mosenthein Island, about 6 miles north of downtown St. Louis. The sand bar here has a large eddy in front of it making swimming a much safer and enjoyable experience. The River current is slowly revolving in a pool like arrangement and the main current flowing downstream is 100 yards away.