Some of greater Miami’s massive landfills, known by clever names like Mount Trashmore, will run out of space by 2026, according to a report from Cava’s office. More urgent are the septic systems that serve the city’s 2.7 million residents. Many of those front-yard sewage tanks overflow when it rains, releasing fecal bacteria and other contaminants that transform patches of tropical paradise into toxic swamps that kill fish and sicken people.

“It’s very critical,” said Cava, who was elected the first woman to lead Miami-Dade County in 2020. “We have to address all of that aggressively.”

It’s all bad news for Miami’s status as a magnet for people fleeing aging cities with failing infrastructure, rising crime, higher taxes and cold weather. No other major American city depends so heavily on septic tanks, a system of treating sewage normally reserved for rural areas. That’s the case for properties all over the county — from the wealthy enclaves of Coral Gables to Miami Beach, and 50 miles southwest, to Homestead, near the Everglades.

“It’s unbelievable, not just to me but to most of the planning and environmental community, that you can have a county as urban as Miami-Dade and not have everybody on water and sewer,” said Howard Nelson, who heads the environmental practice at Bilzin Sumberg.

Ditto for trash. Miami, like many US cities, buries much of its garbage in landfills in far corners of the city, away from the rich. They are smelly, man-made hills rising 130 feet or more, swarming with flies, birds, bulldozers and trucks. By law, the county can’t issue building permits unless it has at least five years of garbage disposal capacity. Cava’s solid waste director, Michael Fernandez, abruptly quit in July, warning that the county won’t have enough space for trash if Cava doesn’t act fast. “At this point, the County will have to issue a moratorium to stop all development,” Fernandez wrote in his resignation letter. (Cava disputes that assessment.) 

Cava, a Democrat elected on promises of hardening the city for climate change, says she will come up with a solution soon. She’s proposed piling trash higher atop the landfills and building a $1 billion incinerator and power plant, in part to replace an incinerator used to process 1 million tons of trash a year that burned down over four weeks in February and March.  

Keeping the toilets flushing is a more complex and expensive challenge. There are 108,000 homes and businesses with septic tanks in Miami-Dade County. Many bathe the ground with human waste within two feet above drinking water aquifers, falling short of minimum limits to avoid contamination. There are 50,000 more in neighboring Broward County, part of the city’s sprawl. Under Cava, the county has spent $1 billion on water and sewer lines, and has allocated another $160 million.

But ridding the county of septic tanks will cost at least $4 billion, according to government estimates. Residents will likely have to pay higher taxes and fees to fund those efforts, as well as the expansion of landfills and other trash collection costs. They already pay more than $500 a year for garbage collection, and could be charged another $36 in pickup fees per Cava’s $10 billion proposed 2023 budget. Homeowners must also cover the cost of connecting their properties to sewer lines — $20,000 on average. 

Other cities have their share of problems. In San Francisco and Los Angeles, heavy rains routinely overwhelm sewer systems. Houston’s aging water system is so fragile that on some days it springs more than 1,000 new leaks. And New York’s sewer system frequently overflows when it rains. 

Until Miami fixes its woes, infrastructure problems could stymie the development Cava needs to attract more wealthy residents like Griffin, who moved his financial empire, Citadel, to Miami in 2022. “We say, ‘Be like Ken Griffin,’” Cava said. 

There are already problems. On Belle Meade Island, a waterfront neighborhood on Biscayne Bay where homes cost $10 million or more, sewage pumps run 16 hours a day to keep up. That’s almost double the allowed maximum operating time, so there’s a county moratorium on new construction there. “Right now, if we do not have sewerage pumping capacity, it stops development,” said Cava.

These are crises decades in the making, exacerbated by the complexities of governing the mishmash of 34 municipalities that make up greater Miami and putting off expensive solutions.  As Miami-Dade County Mayor, Cava oversees an annual budget of about $10 billion and nearly 30,000 employees.

For years, Miami failed to address warnings of a sewage calamity, even since the federal government levied massive fines and ordered a fix. There’s a long history of leaky septic tanks sickening people by contaminating groundwater with deadly E. coli bacteria and killing fish when the muck reached the ocean. In 2020, 27,000 fish died in Biscayne Bay due to septic tank runoff, and there have been multiple massive kills since. 

In 2018, Miami-Dade County, in one of its many studies over the last decade, warned: “Improperly functioning septic systems can pose an immediate public health risk.” But Cava, a former sociologist, has struggled to find a way to fix it.  

“We are not in a crisis,” Cava said almost four years later, at a July 17 news conference. “Not on my watch.” 

–With assistance from Nadia Lopez, Laura Nahmias and Joe Carroll.