The challenges facing Miami water contamination have been escalating to new heights. Flooding, discharge of fats, oil and greases, buildings discharge, overloaded treatment plants, mined limestone quarries, saltwater intrusion, leaking septic tanks and cracked superfund sites, are all contamination problems on their own. When all of them are considered together, we can easily reach a crisis point, where short term solutions will have a very slim impact.
In addition to property damage, safety, and nuisance of flooding, dirty, contaminated water is washed into waterways. In the case of Miami and the other southeastern cities, this is more immediate than in other areas. Southeastern Florida has an added runoff caused by urban and local natural factors. As many other cities, Miami is built with impermeable surfaces. Paved areas and rooftops are perfect conduits for storm water runoff. This dirty water reaches our canals and Biscayne Bay almost immediately affecting the water quality and creating flooding.
Flooding is also more prevalent due to a stronger rainfall intensity. Miami’s rainfall during heavy rains has increased over 7% over the last 50 years. While this may not sound high, it can represent the difference between flooding and not flooding. The frequency of fair-weather flooding, where unusually high tides bring ocean water into streets and neighborhoods, is also increasing.
Miami is under an Environmental Protection Agency (EPA) consent decree to reduce the wastewater discharge that is contaminating Biscayne Bay. Fats, oils, and greases (FOG) are significant water contaminants and are a problem in Miami area, where the food service industry is a key component of the local economy and adds FOGs to the residential wastewater. These FOGs directly affect local waterways and can have adverse effects on wildlife and the quality of potable water. FOGs can clog pipes and cause raw wastewater discharge into major waterways such as Biscayne Bay which in turn reaches the Biscayne aquifer, Southeastern Florida’s main water supply.
Building discharge is created by water coming from toilet flushing, showers, washing machines, kitchen sink, dishwasher, bathroom sinks. This water goes to the sanitary sewer. A single family of four tends to generate about six thousand gallons of wastewater per month, that goes into the sanitary sewer. Additionally, garden irrigation and storm water discharge can add about three thousand gallons per family per month, going to the storm water sewage. Building discharge is a big issue in Southeastern Florida and many building permit requests are being denied in certain areas of Miami-Dade County because the sewage system simply cannot handle any more wastewater.
Overloaded Treatment Plants
Treatment plants can physically only handle a certain amount of water each day. When a major rainstorm occurs, the systems physically cannot handle the amount of water flowing through them, so raw wastewater is discharged into local waterways. This contaminated water eventually makes its way into the Biscayne aquifer.
Mined Limestone Quarries
About 20 years ago, limestone quarries were mined in close proximity to the Biscayne aquifer. Now, contaminated water, including mining chemicals, has less distance to get to the aquifer and is reaching our potable water source.
In the Miami area, the aquifer is quite close to the seafloor and saltwater can seep into its base. This occurs when sea levels rise and added pressure is put on the walls of the aquifer. This saltwater intrusion is contaminating the Biscayne aquifer.
Septic tanks are used throughout Miami-Dade County and there are over ninety thousand in use. These tanks are known to leak, and waste can easily get into the groundwater. Since Biscayne aquifer is so shallow, this contamination is a major driver of septic tanks water leakage with acetaminophen (Tylenol) being detected in many areas.
Leaking Superfund Sites
According to the EPA, South Florida has 11 superfund sites. The Superfund sites are underground storage tanks created to store hazardous waste and keep them safe from adverse weather or tampering. However, it is very common for them to leak. These tanks can sometimes be mere feet away from where groundwater runs. Many Miami-Dade area sites have been designated as EPA superfund sites and have been proven to be contaminating the aquifer.
Miami economic and urban growth coupled with the increase in rainfall in the last few years creates a perfect storm for water contamination. Building and food services discharge, overloaded treatment plants, mining chemicals, saltwater intrusion, leaking septic tanks and dripping superfund sites, are directly impacting the quality of the water we drink.
The Union of Concerned Scientists (UCS) estimates that by 2045, as much as 29 percent of Miami Beach and 26 percent of Key Biscayne could be “chronically inundated,” which UCS defines as flooding twice a month. This will be due to the combination of heavier rainfall, higher tides, and more impervious surfaces.
Miami area is facing water disruption and scarcity of potable water risks and more urgency is needed to build a water resilient habitat for all of us.
The solutions typically offered tend to be large scale in nature. Steps like increased release from the Everglades, large city sewer expansion, and piping and pumping infrastructure replacement-in-kind are under work. However, there are resilient complementary on-site solutions that are faster, easier and cheaper to execute.