Miami sewage leak didn’t stay at sea; it flowed toward wildlife preserve, ritzy residences

After 24 hours, drifters indicated the incoming tide flowed both into Biscayne Bay and out Government Cut.
After 24 hours, drifters indicated the incoming tide flowed both into Biscayne Bay and out Government Cut. University of Miami Rosenstiel School of Marine and Atmospheric Science

After news broke that a massive ocean sewer pipe had been leaking, possibly for more than a year and the fourth time since 2000, scientists at the University of Miami’s nearby Virginia Key campus wondered, where did all that stuff go?

This week they got a possible answer: around ritzy Fisher Island, into a wildlife preserve and up the coast of Miami-Dade County.

While it’s likely that much of the treated waste was diluted — tests this month showed no elevated levels of fecal matter or enterococci and campus operations staff found no impacts in seawater facilities — less is known about other chemicals in the leak, including phosphorus and nitrogen that can damage marine life. According to a county pollution report that covered just four days between July 31 and Aug. 4, about 92,000 gallons leaked, or more than 20,000 gallons a day.

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Miami Waterkeeper staff attorney and program director Kelly Cox tosses a drifter overboard off Key Biscayne on Wednesday. The drifters were used to track the path of micro currents near the site of a break in a sewer outfall pipe. Courtesy Miami Waterkeeper

The break is located within a mile of shore in 17 feet of water, where a smaller, older pipe connects with a larger new one that has broken at least four times since 2000, county officials revealed Friday. It came to light this month after a citizen complained to Miami Waterkeeper that the county had been ignoring the latest break for a year. Miami Waterkeeper threatened to sue to get the county to stop the leak and improve maintenance of the 60-year-old pipe.

County officials have said staff investigated the leak after the initial report, but found nothing. Last week, the county plugged the break and is in the process of figuring out a permanent fix.

The county’s Division of Environmental Resources Management is also investigating. While water tested at the surface had levels of waste well below acceptable limits, testing for phosphorus and solids from the treated waste could take another month, said DERM spokeswoman Tere Florin.

Because micro currents swirling offshore and around Biscayne Bay can carry pollution to unexpected places, DERM also contacted UM’s Rosenstiel School of Marine and Atmospheric Science to ask about tracking currents. The school’s marine science program pumps seawater from the nearby ocean into tanks for experiments so water quality there is critical.

Scientists from CARTHE, an oil-spill research program created after the BP spill and based at UM, have previously used devices called drifters to look at how water moves. The drifters were originally developed to track oil after the Deepwater Horizon exploded and dumped at least three million barrels of oil in the Gulf.

Last Friday, DERM released three drifters from the location of the leak during an outgoing tide. This week, a team from Waterkeepers, the International Seakeepers Society and Fleet Miami set out three more on an incoming tide.

Incoming tide drifters
Drifters equipped with GPS trackers plotted the path of micro currents from the point of the outfall pipe leak. University of Miami Rosenstiel School of Marine and Atmospheric Science

As the tide rolled in, the drifters headed west through Norris Cut, south of Fisher Island. One swung within about 300 feet of a restored turtle and crocodile nesting beach on Virginia Key while the current swept a second within about 600 feet of Fisher Island. Both then floated back toward the leak. A third floated around Fisher Island and into Government Cut.

After 24 hours, the Government Cut drifter headed offshore. A second followed the same path to Government Cut. But a third stopped in a critical wildlife area west of Virginia Key.

On the outgoing tide, the drifters washed up the coast, about a mile to two miles offshore.

Outgoing tide drifters zoom
Three drifters released near the site of the leak during an outgoing tide show micro currents travel up the coast, within a couple miles of shore. University of Miami Rosenstiel School of Marine and Atmospheric Science

The county’s two outfall pipes, constructed in the 1950s and 1970s to dump water more than 3.5 miles offshore in water 100 feet deep, have not been inspected in more than a decade, according to emails obtained by Miami Waterkeeper. The county now plans to have both pipes inspected within 60 days, said water and sewer department spokeswoman Jennifer Messemer-Skold. Depending on the results, they’ll determine what future inspections may be needed, she said.

The county is also in the process of examining repairs made over the years to determine what kind of permanent fix should be made, she said in an email.

“By having a more complete assessment prior to the contractor beginning work, it is believed that this second phase of the repair will increase the longevity of the outfall pipe,” she said in an email.

The pipes, along with four others in South Florida, are slated to be shut down by 2025 under a state law prompted by evidence that showed that dumping so much waste offshore damaged marine life and the state’s reefs, the only inshore reef tract in the continental U.S. Since 1995, the Keys tract alone has lost about 44 percent of its coral.

After 2025, the county must reuse at least 60 percent of the wastewater. The outfall pipe can only be used as a backup during the South Florida rainy season when the demand for reuse drops. Waste must also undergo more intense treatment to cut the amount of phosphorus and nitrogen it carries.

Follow Jenny Staletovich on Twitter @jenstaletovich