Let’s face it: The Indian River Lagoon and its tributaries are mucked up.

That is, they’re full of muck, a gooey mix of eroded soil, animal waste and both organic and inorganic matter that covers about 6,000 acres of the lagoon’s bottom and is up to 15 feet deep in some areas, especially where the water is wide, deep and slow-moving, so the suspended sediment can settle on the lagoon floor.

Besides being just nasty looking – it’s often called “black mayonnaise” because of its color and consistency — as muck decomposes or gets stirred up by wind and boat propellers, it releases nitrogen and phosphorus, nutrients that feed algae blooms. The Save Our Indian River Lagoon group in Brevard County estimates that muck adds 1.2 million pounds of nitrogen into lagoon waters every year, 35% of the total amount of nitrogen entering the lagoon. Septic systems, leaking sewers and reclaimed water add another at 878,000 pounds per year (or 26%). 

Although it usually settles into the deeper parts of the lagoon – including the Intracoastal Waterway — muck particles can be carried with currents into shallower areas such as tidal flats, salt marshes and mangrove forests, where it smothers young vegetation, kills oysters by clogging the filters they use to feed, and kills seagrass by depleting oxygen and shading the plants so they can’t photosynthesize food.

More muck, more problems

A small amount of muck is a natural result of water flowing into the estuaries. But the flows of many of the lagoon’s tributaries have been unnaturally increased by development.

Flows into the St. Lucie River estuary, for example, are now anything but natural.

First, the natural watershed of the north and south forks of the river has quadrupled in area by the construction of canals.

The C-23 and C-24 canals stretch westward across northern Martin County and southern St. Lucie County and drain thousands of acres of land (most of it agricultural); the runoff from all those farm fields and suburban lawns isn’t supposed to (naturally) be in the estuary.

But much worse is the C-44 Canal, which drains farmland and suburbs in west-central Martin County and connects the St. Lucie River to Lake Okeechobee – the source of environmentally disastrous discharges of nutrient- and sediment-rich water.

Historically, muck that flowed into Lake Okeechobee from the north would flow south out of the lake and spread over 400,000 to 500,000 acres in what is now the Everglades Agricultural Area. There, the muck has proven to be perfect for growing a variety of crops, particularly sugarcane.

The Herbert Hoover Dike was built around the lake to save farmland and farmers from devastating and deadly floods, but it also effectively ended the flow of muck south. 

Instead, water (and the nutrients and sediment it carries) has been sent east to the St. Lucie River and west to the Caloosahatchee River.

Between 2009 and 2020, about 150,000 tons of sediment flowed from Lake Okeechobee into the St. Lucie, nearly twice the weight of the Washington Monument; and another 68,000 tons of sediment from the lake went into the Caloosahatchee, not quite twice the weight of the Lincoln Memorial.

During the Lake O discharges in 2016, about 796,000 pounds of silt and sediment flowed into the St. Lucie River water each day. Of course, not all the sediment stayed in the estuary, as evidenced by the massive plumes of black water that stretched out the St. Lucie Inlet and into the Atlantic Ocean, covering near-shore coral reefs with sediment.

Lake O discharges in 2017 totaled about 192 billion gallons of water and dumped an estimated 155.7 million pounds of sediment into the St. Lucie River, while other canals and creeks added nearly another 14.4 million pounds.

Since then, the C-44 Reservoir and Stormwater Treatment Area was completed. The 12,000-acre project in western Martin County designed to store and remove algae-feeding nutrients and sediment from C-44 Canal water, mostly from western Martin County farms but also some Lake Okeechobee water.

The project’s benefits are yet to be fully realized because, well, it leaks (or in the preferred terminology of the U.S. Army Corps of Engineers, it is experiencing “seepage”). Bottom line, it can’t hold and clean as much water as it’s supposed to.

No one knows how much muck is in the St. Lucie River estuary. Estimates run from around 15 million cubic yards to around 50 million cubic yards. That’s enough muck to fill 3.6 million large dump trucks.

In 2022, The Ocean Research and Conservation Association reported that muck in the South Fork of the St. Lucie River — the stretch that connects tie C-44 Canal to the river’s estuary – contains muck that’s nearly 11 feet deep in the worst spots.

Get the muck outta here

To answer the problem of muck-clogged waterways, numerous dredging projects have been undertaken, and more are in the works. In Brevard County alone, remediation projects aim to remove roughly 6 million cubic yards of sediments that have accumulated over decades.

The first-ever muck removal project in the Eau Gallie River, a tributary of the Indian River Lagoon in Melbourne:

• Ran from Jan. 25, 2017, to March 31, 2019
• Removed more than 600,000 cubic yards of muck from the main branch of the 3.9-mile-long Eau Gallie and the southern branch of the river known as Elbow Creek.
• Eliminated 1,200 tons of nitrogen and 260 tons of phosphorus.
• Cost $23,950,000, with $20 million from the Florida Department of Environmental Protection; $3.9 million from the Florida Inland Navigation District; and $50,000 from the city of Melbourne. (Brevard County provided land to place the dredged material.)

That calculates to just shy of $40 per cubic yard, and the lagoon has an estimated 5 million to 7 million cubic yards of muck in the Brevard and Indian River County portion alone. Based on the timing and cost of the Eau Gallie River project, removing all that muck would cost up to $280 million and take about 25 years.

Then there’s the problem of what to do with all that dredged-up muck. Some of it can be used as fertilizer (Remember it contains a lot of nitrogen and phosphorus, key components of fertilizer). But a lot of it ends up in landfills.

(Another idea: A young Brevard County resident, Sophia Weiner, also came up with “muck-rete” by mixing muck with gravel, cement and sand. Does it work? Check out the path made with “muck-rete” pavers in the mangrove nursery at Marine Resources Council headquarters in Palm Bay.)

Although necessary, removing muck is an example of treating a symptom instead of curing a disease. The real answer isn’t muck removal but muck prevention — eliminating, or at least seriously reducing, the amount of soil, organic material and nutrients entering the estuaries.

To that end, the Save Our Indian River Lagoon Plan also calls for other projects such as building retention ponds and installing baffle boxes to slow the formation of muck.

But to really keep muck out of the lagoon will require curbing excess fertilizer use, curtailing stormwater runoff, fixing failing septic systems (or switching them to sewer systems) and eliminating wastewater treatment facility discharges.

Until then, we’ll have a continuing cycle of muck deposits and muck removal. And that’s pretty mucked up.