St Marks River Rise

Is it a spring or not?

Technically this is spring of the 1st magnitude. The average discharge of this giant spring is 12,800 l/s (average discharge in 1956-2017, 2.) and it starts as a 130 m wide river. Only four other springs in Florida have higher discharge – and Florida has some of the largest springs worldwide.

River rises though seem not to be true springs. The water of the river rises is not lucid and clean, as it is with true springs. After all, this is just a river, which has passed some distance underground.

What happens below the ground?

St Marks River submerges at Natural bridge – true natural bridge, the famous site of an important battle in American Civil War.

Afterwards the river flows underground for approximately 1.1 km until the Rise. In between the river reappears on the surface several more times.

Woodwille Karst Plain Project in 2006 spent some time researching this part of St. Marks River. It turns out that several underwater caves join the river, bringing in additional streams and thus increasing the power of the stream in the river. The joint length of these explored passages – St Marks Natural Bridge System – is 3,690 m long and up to 110 m deep.

Future protected area?

The area around Natural Bridge and St Marks Rise is not entirely wilderness – here and there are built houses and the forest is dissected with roads. Nevertheless, the hardwood hammock has been preserved here.

The land around the sink and rise belongs to several owners and sooner or later there will be a possibility, and, let’s hope, a wish to purchase it and to create a nature-protected area.

References

1. Chris Werner. Natural Bridge – St. Marks River Rise Exploration. Global Underwater Explorers.
2. Minimum Flows
   for the St. Marks River Rise, Northwest Florida Water Management District, 2019. Accessed on September 6, 2023.

St Marks River Rise is included in the following article: