This Artesian Spring was discovered by the Civilian Conservation Corps in 1938, when they "built Pokagon". They installed the piping to tap the well at that time, and to make it more useful. They also built a trailside shelter there, so people could rest and refresh themselves before moving on.
Artesian basins and wells themselves are actually very simple in "design". In areas where rainfall seeps underground between two layers of impermeable rock or clay, an aquifer is formed. An aquifer is a porous layer of rock filled with water up to the level of the water table (the highest level of water saturation in the ground).
Where an aquifer slopes, the force of gravity on upper levels of water presses on water lower down. Its impermeable "walls" maintain this pressure. An artesian well pierces the walls of the aquifer below the water table, and the pressure from the weight of the water above this level forces the water out of the well. The difference in elevation between the water table and the point the well enters the aquifer determines the pressure of the well. As water from this source flows indefinitely under its own hydrostatic pressure, it is also known as a "flowing well." Likewise, springs occur where the surface of the ground naturally taps into the aquifer below the water table.
In areas where a sloping aquifer occurs fairly close to the surface, artesian wells can be placed quickly and inexpensively, if the upper wall of the aquifer is soft material such as clay. Just two men with a small water pump and sections of pipe can tap such a well by hand in a single day. The water pump is used to force water down the pipe, washing away debris and soil as the pipe is worked into the ground. Once the aquifer is reached, water flows by the force of gravity as described above, and the end of the pipe is plugged with weighted material to keep large debris from entering. The lowest section of pipe has slit-like openings, or "windows", allowing water into the pipe but keeping gravel and rock out. A cool, pure drink now awaits the laborers, refreshing them after their day's work!
The Spring Shelter, near the Artesian Spring, is also a very beloved and historical structure. See the attached picture, labeled "Spring Shelter" for an article that Fred Wooley, the Pokagon Interpretive Naturalist, wrote about the shelter for a local newspaper.
One man who had helped to build the Spring shelter with the CCC, called it their "pride and joy". Once you've stopped and refreshed yourself at the shelter and the spring, it's easy to see why.
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Take a picture of you at the Artesian Spring, and log the picture, date you were there, and the number of people in your group.
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