Miami's skyscrapers overlook Biscayne Bay.

(NOAA)

At a Glance

A grand jury says Biscayne Bay's declining water quality may become irreversible. A NOAA study says the estuary could become a murky system dominated by phytoplankton.A task force is seeking ways to save the bay. It's recommendations are due in January.

Biscayne Bay, the "crown jewel" of Miami's environment, is clinging to life.

The in the Intracoastal Waterway on Florida's southeast coast was once home to expansive seagrass beds, thick stands of mangroves and abundant sea life. Now it is being killed by sewage spills and failing septic tanks, nutrient-rich runoff that causes toxic algae blooms and plastic pollution.

" Without corrective action, the declining quality of this body of water may become irreversible," warned a grand jury report in August. Saying the bay "sits as the crown jewel of our environment," the grand jury said, "Clearly, the health and cleanliness of Biscayne Bay is vital to our community and our economy."

That same month, a study by NOAA’s Atlantic Oceanographic and Meteorological Laboratory said .

“If current management practices continue, it could lead to a regime shift in Biscayne Bay from one with clear water and lush seagrass meadows to ” Chris Kelble, a coastal oceanographer at the lab and co-author of the study, said in a statement. “This would alter the ecosystem and the species that live in the bay.”

(MORE: Drought Reveals 'Spanish Stonehenge' That Has Been Submerged Since the 1960s)

In hopes of avoiding this bleak future, Miami-Dade County created the . It is supposed to give the County Commission recommendations by January.

Some of the task force's ideas will come from this past Friday's Biscayne Bay Marine Health Summit. The gathering at Florida International University’s Biscayne Bay campus was the second meeting of scientists, activists and policy makers to seek ways to restore the bay.

The group agreed, according to the Miami Herald, that it's time to .

Caesar Creek provides an opening from Biscayne Bay to the Atlantic Ocean.

(National Park Service)

Other proposals from the summit included creating a Biscayne Bay authority to focus on restoration efforts, setting regional water quality goals and pollution reduction targets and raising sewer fees to help upgrade Miami-Dade County’s failing infrastructure, the Herald reported.

The sense of urgency to do something to protect the bay has grown in the past year.

A report in January by Miami-Dade County environmental officials said nearly off since 1998, and much of it was killed by poor water quality.

The grand jury, which was convened to explore the issue of the bay's health, noted several ways pollution is entering the water, including the county's sewer system and private septic tanks.

The grand jury's report listed several instances of untreated sewage being spilled into the bay. In February, for example, clogged pumps led to 750,000 gallons of untreated wastewater being spilled into the storm drain system that ultimately flows into Biscayne Bay.

Septic tanks are also contributing to the pollution. More than 100,000 properties in Miami-Dade County still rely on septic tanks for waste disposal, according to the grand jury report. Old, leaky septic systems are an obvious problem. But even when they work correctly, septic tanks aren't a great idea on the coast because there's not enough soil to filter waste out of the water coming out of the tanks before it flows into the bay or into the groundwater supply.

Rising sea levels will make this problem even worse, the grand jury said.

A Miami-Dade County grand jury said, “Biscayne Bay is at a tipping point. Without corrective action, the declining quality of this body of water may become irreversible.”

(National Park Service)

In addition, the grand jury report described how excessive nutrients, particularly nitrogen and phosphorous, are leading to harmful algae blooms in the bay. These nutrients come from the sewer system and septic tanks as well as stormwater runoff and agricultural activities.

The study by NOAA’s Atlantic Oceanographic and Meteorological Laboratory found an increasing trend in chlorophyll a and nutrient levels at 48 monitoring stations throughout Biscayne Bay. The bay is slowly eutrophying, or becoming more nutrient rich.

"Excessive nutrients in an aquatic environment – from sources like fertilizer runoff and septic system discharge – can lead to algal blooms and low-oxygen levels that can kill fish and vegetation and impact essential fish habitats," a news release about the study said. "Increased levels of nutrients ultimately reduces water quality and can degrade the health of coastal ecosystems."

The study is one more source of ideas as officials seek ways to improve the bay's water quality.