RIVER LIFE: Clean drinking water may be in short supply

“Water, water everywhere, nor any drop to drink” goes the line from “The Rime of the Ancient Mariner,” by Samuel Taylor Coleridge. The statement may soon be more true than many in our area would like to believe in the not-too-distant future.

Florida is surrounded by water, and the St. Johns River flows through Jacksonville, with billions of gallons a day heading to the Atlantic Ocean. So it might be hard for some to accept the idea that pure, clean drinking water could be in very limited supply in the future.

I’ve noted in this column before that the St. Johns is termed a “black water river” because of its dark tea color. The color comes from the same tannins that give tea its color. Various tree species such as oak, gum and cypress shed their leaves into the swamps, wetlands and marshes at the head waters of the St. Johns. Just like making iced tea, the water gradually absorbs the tannins and becomes a slightly acidic, dark liquid. The water tastes sweet, hence the name “Sweet Water” for such dark rivers and streams.

Early explorers would look for dark-colored water as a sign the water was safe to drink.  They would sail upstream, periodically tasting the water until it lost its saltiness and became “sweet” and drinkable.

Most of the water on earth is salty. Water has dissolved the salts and minerals from the earth to a point that about 97 percent of the earth’s water contains salt. And of the 3 percent of the earth’s water that is fresh, most of it is frozen, leaving less than 1 percent available to drink.

Some of the water that flows into the St. Johns River comes from underground springs that originate in the Floridan Aquifer. This extensive layer of porous limestone extends under most of Florida and the coastal regions of the Southeast, including Georgia and Alabama. It is one of the world’s most productive fresh water aquifers. There are more than 900 springs in Florida, with about 70 flowing into the St. Johns River.

But recent reports are that we have exceeded its sustainable limits to continue to supply the growing number of people in the region. And to make matters worse, about half of the drinking-quality water we withdraw is used outside the home, on yards and for agriculture. Even the nutrients we use for our lawns and crops are getting back into the aquifer and affecting the springs.

We must conserve this precious supply of water if we are to have water for future generations. As we withdraw water from the aquifer, we also slow the flow out of the springs that feed into the St. Johns River.

Ask River Life

Are there sharks in the St. Johns River, and do I have to be worried about shark bites if I swim in the river?

Yes, there are sharks in the St. Johns, especially toward the mouth in the saltier portion of the estuary. We get reports of sharks farther up the river during periods of drought, too. But these are generally small sharks, and you do not need to be overly afraid of being bitten by a shark in the river. Always be careful and swim with a friend.

River Life runs the last Friday of each month in The Florida Times-Union. E-mail A. Quinton White, executive director of Jacksonville University’s Marine Science Research Institute, with questions about our waterways at qwhite@ju.edu. For more on the MSRI, visit ju.edu/msri.