Rising seas pose threat to South Florida freshwater resources

Drinking water appears plentiful around the University of Miami’s Coral Gables campus, so it’s hard for visitor Annabel McDermott, 16, to imagine that South Florida is facing a water crisis.

“My bottle is full,” McDermott said. “There is a water fountain on every floor.”

Like McDermott, an Australian track and field athlete, many people are unaware of the threat to South Florida’s water supply. As climate warms, sea levels rise and freshwater faces demise. Refilling water bottles may not be so easy in the future.

Randy Smith, spokesperson for the South Florida Water Management District, said saltwater intrusion is a direct effect of the rising sea level and it is becoming a major problem for Florida aquifers.

These aquifers are being encroached upon by saltwater because of the rising sea level. Since South Florida sits above a porous limestone plateau, it is especially easy for this saltwater to intrude into the aquifers because the rock acts as a sponge.

“We don’t want the saltwater coming in from the ocean,” said Smith. “We are still early in the process of accurately figuring out what the level of rise is and how fast is it rising.”

Samantafinal from Trevor Green on Vimeo.

Cities, towns and businesses get most of their freshwater from aquifers. According to the Florida Department of Environmental Protection, the aquifers contribute 90 percent of the state’s drinking water, supplying more than 8 billion gallons of water each day.

The South Florida Water Management District is working to protect regional water supplies and aquifers by building more coastal structures such as seawalls to prevent saltwater from coming into freshwater canals.

“When it comes to our drinking water, these coastal structures are very important because most of our water supply here comes from the Biscayne aquifer,” Smith said, noting that this aquifer is just below the surface of the land and is prone to contamination.

“So it’s of ultra importance to us to be able to maintain that wedge and keep the seawater out of our drinking water supply.”

Drinking saltwater dehydrates the body, which is why humans cannot use saltwater as a drinkable source. Desalination, a process that makes saltwater safe to drink, does exist, but most cities don’t have the resources to build plants.

“The technology is definitely there, but desalination plants can take up to 10 years to build and cost up to billions of dollars,” said Arjen Bootsma, former mechanical engineer at the Miami-Dade Water and Sewer Department. “They are only built when there is no other viable option.”

It is becoming challenging to meet the freshwater needs of Floridians. According to the 2014 Census report, Florida is the third largest state with 19,893,297 residents, after California and Texas with 38,802,500 and 26,956,958 respectively. As a result of the growing number of inhabitants, Florida’s water districts will have to find alternative ways to supply water.

“Because South Florida has grown tremendously, the Biscayne aquifer is sucked dry due to the high demands for water,” Bootsma said.

Every year, South Florida faces a shift in the boundaries between saltwater and freshwater. The Biscayne aquifer is in jeopardy because saltwater is seeping in and rainfall is decreasing.

“We’re going to the deep wells, going down to the Floridan aquifer rather than relying solely on the Biscayne aquifer, which is practically tapped out at this point,” Smith said. “It would be hard to get any substantial withdrawal from the Biscayne now.”

Smith added that a contributing factor to the seeping of saltwater into freshwater is the excessive pumping of wells. When water is pumped at a faster rate than the aquifer is replenished, the possibility of seawater leakage into the aquifer is more likely. These wells are also built too close to the shore and face a threat every year as sea level rises.

“The Miami-Dade Water Department has, in the last 15 years or so, built new well fields all the way out west in the Everglades to get as far away from the ocean,” said Bootsma. “By doing so they can utilize those wells as long as possible before saltwater encroaches on them, too.”

South Florida’s saltwater intrusion, population growth and related water demands mean that maintaining conservation efforts and finding alternative water sources will be inescapable.

“Conservation is critical for South Florida,” Smith said. “It is a tremendous way to save the finite supply of water that we have.”