Sarasota County and SWFWMD groundwater study to fill gaps in water quality knowledge

By Darcy Young, Director, Sarasota Bay Estuary Program (SBEP) Planning and Communications

Most Floridians know that water surrounds us, from the Atlantic Ocean to the Gulf of Mexico to our smallest neighborhood retention ponds. Yet the feeling of solid ground beneath our feet often blinds us to the water lying underground. That groundwater may hold keys to better understanding important connections between land and sea. Sarasota County and the Southwest Florida Water Management District (SWFWMD) will embark on a project this year to study how groundwater travels through different landscapes in Sarasota County and what it may be bringing along with it as it flows toward Sarasota Bay.

Simply put, groundwater is water found underground in the spaces between sand, soil, and rock. Dig a hole in your southwest Florida backyard and before long, you’ll hit water. That’s the area scientists call the “water table.” It sits closer to the surface in some areas, like freshwater marshes, than in many dry areas of the western United States. The U.S. Geological Survey estimates that there is over a thousand times more water in the ground than there is in all the world’s rivers and lakes. About 51% of the U.S. population relies on groundwater for drinking water. The Floridan aquifer system alone supplies drinking water for nearly 10 million people in Florida and Georgia.

Like stormwater, groundwater recharge absorbs fertilizers, pesticides, pet waste, septic tank leachate, gasoline, and other pollutants from the land surface. To some extent, plants and soil filter out these contaminants. Groundwater flow is also very slow, which allows time for pollutants to slowly adsorb to soils and rocks underground. The direction and speed of groundwater flow depends on the characteristics of subsurface rocks. If subsurface rock is relatively permeable and porous, like Swiss cheese, then water may move through it more