Springs… Not the season, but those bright blue bodies of water we all flock to on a hot summer day. Crystal River is famous for this natural phenomenon that attracts thousands of tourists to Crystal River each year. Remember that age-old question? “Why is the sky blue?” Well, what about springs? Why is Three Sisters Springs blue? To answer this question, we must dive into some geology. 

To start, a spring is a point in the ground where water flows from the underground aquifer to the surface. When it rains, water naturally seeps into the ground. In order to reach the aquifer, the water passes through pores in rock and sediment. Different layers of sediment have different sized pores which means different solutes, or components dissolved in the water, filter out in different sediment layers. Each layer acts as a filter, so when the water finally reaches the aquifer, it is filtered and fresh. While the water is underground, it cools and remains insulated. This is why Three Sisters stays much cooler than the rest of Crystal River during the summer. 

In some parts of the world, the aquifer is naturally closer to the Earth’s surface. When groundwater from the aquifer breaks through the surface, a spring forms. Florida naturally has a low elevation and the aquifers are closer to the surface. This makes Florida the perfect location for springs to appear. For more information about the aquifer and groundwater, click here.  

This image shows one of the springs at Three Sisters Springs underwater.

Recently, Save Crystal River has been working in the area around Three Sisters. Not only are they cleaning the riverbed and planting eelgrass, but they also search for clogged springs to clear and reopen. Clearing more spring vents means more freshwater flows into the River, therefore, lowering the salinity of the river. On July 1st, 2020, Save Crystal River’s contractor, Sea and Shoreline, opened three large spring vents just west of the water entrance to Three Sisters. 

So where does the blue come from?

When I paddled out to see how the work was coming along, I couldn’t help but stop at the springs and hop into the refreshing water. While I was drifting through the springs, it brought me to the question at hand. Why are springs blue? 

Well, the process of water seeping up from the aquifer causes dolomite, a mineral rock, to dissolve. Dolomite naturally has a blue-gray color and when combined with the depth of the spring, it gives the water a blue color. There is also one more aspect that makes a spring blue – the sky. The water is reflected in the spring and gives the illusion that the water is bright blue. I guess it really does come back to the age old question of why is the sky blue, but that’s a question for another day.

Next time you’re out at Three Sisters or any other spring, think about how the water you’re swimming through, or paddling on, is rainwater, filtered and cooled through rock, colored by minerals, and reflecting dissolved earth crystals and the blue sky. You’re not only swimming through the water we drink and wash our hands with, but also one of nature’s miracles. No wonder the manatees love it!

I’ll see you on the water,

Walker A. Willis 

Photo Credit:

Three Sisters Springs Above Water: Judy Wanamaker

Three Sisters Springs Below Water: Explorida