Climate Change Could Increase 'Saltwater Intrusion'

Guest Blog By Andy Reid, Sun Sentinel, September 12, 2011 Summer rains can't wash away a growing underground threat to South Florida's water supply. Saltwater seeping in from the ocean keeps spreading farther west, threatening to foul underground freshwater supplies that provide most of South Florida's drinking water. "Saltwater intrusion" in South Florida has worsened through the decades as providing water and flood control for a growing population siphons away freshwater and allows more saltwater to seep into aquifers and well fields. Ninety percent of South Florida gets its drinking water from underground supplies, most from the Biscayne aquifer. Pumping too much water from underground supplies can allow saltwater to push in from the coast. Droughts can make saltwater intrusion worse as pumping to provide drinking water continues while rains don't come to replenish underground freshwater supplies. Now South Florida officials are projecting that sea-level rise due to climate change could increase the reach of saltwater that can make water from community wells undrinkable. That has city and county utilities along the southeast Florida coast exploring expensive alternatives, with costs passed along to ratepayers, to avoid getting cut off from freshwater. "It is still progressing westward," Hector Castro, Hallandale Beach public works and utilities director, said. "Eventually all coastal communities will deal with this in some way, shape or form." Hallandale Beach, Pompano Beach, Dania Beach, Lantana and Lake Worth are among local cities that in recent years have been most at risk from saltwater intrusion. But the line of saltwater spreading inland comes close to or reaches cities from Jupiter to Florida City, including West Palm Beach, Delray Beach, Boca Raton, Fort Lauderdale, Hollywood and Miami, according to theU.S. Geological Survey. Reducing well-field pumping, moving well fields farther inland and requiring utilities to pursue alternative water supplies have helped hold the line of saltwater intrusion in some areas and even push it back east. "It's a serious threat," said Pete Kwiatkowski, South Florida Water Management District water-shortage incident commander. "That saltwater front is very dynamic (and) it does shift." Six of the eight wells that Hallandale Beach relies on have been closed through the years due to saltwater intrusion. That's because 85 percent of the city is within the area where saltwater has seeped in, Castro said. As a result, the city pays to get half of its water from Broward County's western well fields and is working on a deal for new western wells of its own. Hallandale Beach proposes building six new wells and new water lines in West Park for about $10 million. Operating them over 40 years would cost about $36 million, Castro said. "Any given day, if we were to pull too much water … we could lose another well," Castro said. Instead of building well fields farther inland, some utilities build new water plants capable of tapping into and treating deeper, saltier underground water supplies. Lake Worth recently completed a $24 million reverse osmosis water plant to keep 5 million to 7 million gallons of water a day flowing, without threats from saltwater. Lake Worth also has stricter once-a-week landscape-watering limits intended to cut water use and help avoid saltwater intrusion. Rising sea levels are expected to add to the spread of saltwater intrusion, said Jennifer Jurado, Broward County director of natural resources planning and management. Man-made pollution produces more carbon dioxide and other heat-trapping greenhouse gases that capture the sun's heat, leading to climate change. Increased temperatures mean melting ice sheets and swelling oceans, projected to bring rising sea levels. South Florida sea levels rose about 8 inches during the past 100, but are projected to increase between 9 and 27 inches over the next 60 years, according to Jurado. That would lead to more saltwater forcing its way into freshwater supplies, she said. "Potable water supply is obviously a major concern long-term," said Jurado. Building water plants capable of converting ocean water into drinking water is one alternative that so far South Florida utilities have deemed too expensive. Making better use of regional water supplies could help beat back saltwater intrusion, said Ron Nunes, chairman of the Southeast Florida Utility Council, which represents water providers serving nearly 5 million residents. Flood control for cities and farms built on what used to be the Everglades leads to draining nearly two billions of gallons of storm water out to sea each day after a typical South Florida summer rainstorm. More of that storm water should be redirected to beef up groundwater levels depleted by decades of draining and paving land that once held water and naturally replenished the aquifer, Nunes said. "The biggest issue is the water is there and it is all going out to sea," Nunes said. "Why can't it be re-engineered to help keep the saltwater back?"