One of the true natural wonders of Missouri, the spring is the source of the Roaring River. It is basically a water-filled underground cave at the base of a dolomite bluff.
Refreshed by rainwater seep, the spring has been explored to a depth of 224 feet (more than 20 stories). It's average daily flow is a phenomenal 20.4 million gallons.

The pigeon flying into the cave had sticks for nest building in its beak. Numerous swallows were also flying into the cave, but I couldn't say whether it was for nesting, feeding or both.

In California, where I live, the spring would have been preserved in pristine condition as a nature preserve. In Missouri, it has been transformed into a state fish hatchery.
Immediately behind this view are a series of very large concrete pools filled with huge trout. The river adjacent to the hatchery is crowded with fishermen/women. I felt some
deep sadness being there, but I haven't lived in Missouri since 1959 and I don't fish. I fully understand that I'm not entitled to impose my retired-Park-Ranger values on others.