Oyster modules could be key to cleaning urban waterways

“Anywhere you go, the lagoon is connected to all of us. It doesn’t matter where we are, it’s one big part of us,” said Janel Altman, an Indian River State College biology student.

It’s why she’s one of many volunteers who often help St. Lucie County Coastal Resources Coordinator Jim Oppenborn with various water quality projects.

His latest endeavor involves Moore’s Creek, an urban waterway running through Fort Pierce out to the Indian River Lagoon. The creek collects stormwater runoff starting out west past 33rd Street and winds east. Seventh Street between Avenues C and D has a picturesque red footbridge crossing it, allowing visitors to take in a bit of green in an otherwise developed area.

The challenge with urban waterways such as Moore’s Creek, according to Oppenborn, is that the water is heavily polluted with roadway runoff, pesticides, herbicides and trash. All of which, unless filtered out, ends up in the lagoon.

To that end, there are quarterly cleanups of the creek hosted by volunteers, and Oppenborn is working on establishing tapegrass (freshwater seagrass) and developing a plan for implementing oyster modules as sediment traps.

The creek is in desperate need of cleanup, Altman said. “There’s a lot of trash.”

She noted that beaches are notorious for trash; urban waterways are even worse. “We just need more hands” to help out, Altman said.

Last week, the Fort Pierce Road and Drainage crew was clearing out water lettuce – the common name for pistia, an invasive floating plant. Each bunch dredged from the creek netted at least one piece of visible trash, be it a discarded gas station beverage cup or candy wrapper.

The quarterly cleanups will help with that issue, Altman noted. But to clean the water and improve its quality before hitting the lagoon, more needs to be done.

That’s where the tapegrass and oyster modules come in. Fort Pierce, St. Lucie County and the Florida Fish and Wildlife Conservation Commission are working with Carter Henne, of Sea & Shoreline, to plant tapegrass along the edges of the creek.

It’s currently in the pilot stage and they’re learning what works and what doesn’t. Oppenborn pointed to the cages that line the creek near 7th Street. The cages are meant to protect the tapegrass from hungry herbivores.

“The turtles and ducks just devour it,” Oppenborn said. The first planting was demolished by the animals. Cages had to be installed to protect them.

Now, several cages are filled with tapegrass and soon the cages will be removed.

Oppenborn said the hope is that there will be more vegetation than hungry critters can chew and the stock won’t be decimated.

Tapegrass will help filter pollutants from the water, leaving the water cleaner. It also serves as fish habitat.

To tackle the third challenge – sediment – Oppenborn envisions modules crafted from oyster shells sunk below the surface near each bridge along the creek. The modules would work like baffleboxes – slowing down the water in areas to allow the sediment to sink to the bottom.

A vacuum truck would then be able to run a hose down to the module and suck out the sediment, again leaving the creek cleaner before getting to the lagoon. Oppenborn is waiting on permits to deploy the modules and agreements from the city to pump out the sediment on a regular basis. Once he has the green light, he’ll need volunteers to help install the modules.

In a perfect world, Oppenborn said he’d like a module at every bridge over the creek. But, “realistically, we’ll take one.”

The hope for now is to put the first module at either 10th or 12th streets and see how well it traps sediments and how often it would need to be pumped.

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