PortMiami dredge damages more coral than feds expected

A Miami Waterkeeper diver photographed buried and dead coral near the Port Miami dredge in June.
A Miami Waterkeeper diver photographed buried and dead coral near the Port Miami dredge in June. Courtesy of Miami Waterkeeper

Deepening Port Miami to make way for bigger ships has caused far more damage to rare coral at the bottom of Biscayne Bay than federal wildlife managers originally calculated.

In a series of letters and emails with the U.S. Army Corps of Engineers, which is overseeing dredge work, the National Marine Fisheries Service warned between February and June that damage “greatly exceeds” what was anticipated, risking harm to a stretch of reef on the south and north sides of Government Cut up to four times the size originally projected. Yet efforts to get an accurate take on damage have been rebuffed by Corps officials. And Fisheries Service divers hoping to survey the area have repeatedly encountered obstacles, they complained.

The correspondence reveals deep differences between the two federal agencies over impacts of a controversial Deep Dredge project long sought by PortMiami and South Florida political leaders but fought for years by environmentalists. In one count, a Corps contractor concluded that only a handful of coral showed stress — just 2 to 6 percent of the coral checked. But a Fisheries Service count of the same reef four years later showed damage to 67 percent.

On Monday, five months after the agency asked the Corps to provide a complete survey, a Fisheries Service spokeswoman said the agency was still waiting. The Corps did not respond to repeated requests emailed Monday to several people.

Even as work winds down — the underwater excavation is expected to end this summer — tensions continue between agencies and groups monitoring the $205 million expansion, which will deepen the port to 52 feet by scooping up 6 million cubic yards of bay bottom.

In 2011, when wildlife managers signed off on the project, they anticipated some marine life would be damaged. But as work proceeded, the project has drawn both warnings from state and federal officials and repeated trips to court by environmentalists and anglers angry as plumes of sediment smothered marine life.

“The Corps has been dragging their feet and not providing the information,” said Rachel Silverstein, a marine biologist and executive director of Miami Waterkeeper.

The more time that passes without an accurate survey, she said, the harder it will be to save struggling coral or determine just how much damage has been done. In June, Silverstein surveyed the area and found surrounding reefs dusted with silt. Fisheries Service divers found a similar moonscape, with sediment about a half inch to four inches deep.

“Everything is being eroded out there and it’s hard to tell what has died,” she said. “That information is critical to holding the Corps accountable.”

Moving the sediment to a dump site five miles offshore also continues to encounter problems. Six months ago, the Environmental Protection Agency, which oversees dumping, warned that the flat-bottomed barges that move sand, called scows, were leaking. The leaks can create large plumes of sand that block sunlight and smother marine life. Eight leaks were reported in March and five more in April. While he praised the Corps for improving its record, Water Management Division director James Giattina said in June the agency was considering assessing civil fines.

Environmentalists have long complained that surveys intended to count coral were incomplete.

The dredge work was expected to consume about seven acres of reef, including five undisturbed acres at the mouth of the channel, and eight acres of seagrass meadows. Reefs and seagrass are both critical to coastlines — coral provides a barrier against hurricane storm surge and rising seas, while seagrass can absorb carbon projected to rise in the next century. Meadows also provide nurseries and places for marine life to graze.

The Corps had originally planned on transplanting only threatened species, including 38 staghorn corals. But after environmental groups sued in 2011, Miami-Dade County and the Corps agreed to transplant coral from about 16.6 acres and eventually moved about 1,000.

But no complete surveys of the reefs on either side of the channel were ever completed. Divers for the Corps surveyed the south side of the channel. But only a small section on the north side of the channel — just four spots — were mapped. The Corps gave biologists a chance to rescue some coral before dredging began in June 2014, but rescuers complained the 12 days they were given were far too short for the hundreds of coral they could have saved. University of Miami biologist Andrew Baker has said the urban coral could be particularly useful for learning more about hardy coral that might do better in harsher conditions projected in climate change scenarios.

Less than a year ago, when Fisheries Service divers tried to survey the site, they not allowed to dive the entire channel because of the dredge work. In May, they made another attempt to survey sediment damage but were told they would instead be checking coral within a150 meters of the channel. Still, based on earlier dives, officials said they calculated sediment had settled over 161 acres on both sides of the channel, a larger area than anticipated. They also looked at other surveys done by state and Corps divers and estimate the total could rise to 262 acres.

Wildlife managers say the length of time sediment stays on the coral has also taken a toll and in May warned there “is no indication … effects will be temporary.”