The Vulnerability of Potable Water with Climate Change in Miami-Dade

by Pamela Cabrera (MDes '19)

The environmental exposure to Miami’s drinking water, once mitigated with wellfield protection areas, should be reassessed to be resilient to future climate scenarios. Climate change has increased the vulnerability of potable water by blurring the lines of the wellfields with the imminent risks of saltwater intrusion and surface runoff water pollution from flooding. The adaptation of Miami-Dade to climate change will depend on the resiliency of its drinking water, and therefore of its aquifer. Three recommendations are presented in this work to achieve a more resilient aquifer: the re-evaluation and strategic enforcement of wellfield protection areas, a comprehensive implementation of urban strategies for water retention and reuse, and finally, to prioritize potable water resilience over other adaptation measures that jeopardize the aquifer’s health.  

Miami’s potable water relies entirely on the Biscayne Aquifer, which is superficial, unconfined and has exceptionally high transmissivity. The aquifer is continuously recharged from rain and surface water through the ground but mainly through the hundreds of canals and pools that are used to drain the natural swamp of Miami. The county’s primary threat from climate change is the excess of water from sea level rise and increasing precipitation. Warmer temperatures are expanding the volume of the sea and causing sea level rise, which in turn reduces the groundwater storage capacity. There will be more water pouring from the sky and less ability to drain it to the sea or store it in the ground. Flooding will occur well before sea level rises above the land, and with flooding, and water pooling, surface contaminants will become a higher risk to the Biscayne Aquifer.  

Miami-Dade's potable water system is highly vulnerable to these events as it depends entirely on underground water that is currently at risk of pollution from surface contaminants and saltwater intrusion. Now, 97.5% of all drinking water distributed to Miami-Dade’s population above SW 8th St., including the city of Miami and Miami-Beach, is sourced from two wellfield sites: the Hialeah-Preston Miami Springs Wellfield and the Northwest Wellfield in the Lake Belt mining region of the county. Florida declared these sites wellfield in 1981 after the EPA revealed that approximately 90% of the wells had traces of industrial contaminants due to a lack of regulations. Today these wellfields have a fragile equilibrium with all the surrounding risks of contamination that have crept into their boundaries over the years. There are multiple risks of contamination within each of these wellfield zones including vicinity to the largest mining extraction region in South Florida and numerous Superfund and active National Priority List (NPL) sites. This work highlights the vulnerability of the shallow aquifer to surface and underground industrial contaminants due to climate change stresses. The resiliency of Miami-Dade county depends on access to drinking water, and therefore the county should re-evaluate and enforce new wellfield protection areas, incorporate new strategies for water retention and reuse, and prioritize potable water resilience over other adaptation measures that jeopardize the Biscayne Aquifer’s health. 

 

Read about this project in Bloomerg Businessweek.