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New wetlands project north of Lake O hopes to consume phosphorus from polluted runoff

Max Chesnes
Treasure Coast Newspapers

A newly approved wetlands project aims to suck nutrients from an area plagued by polluted water flowing into Lake Okeechobee, all in the hopes of reducing the fuel that ignites harmful algal blooms. 

The Lower Kissimmee Basin Stormwater Treatment Project, located just northwest of the 730-square mile lake, was unanimously approved by state water managers in May. 

The 3,350-acre swath of constructed wetlands could remove up to 26 metric tons of phosphorus from the water column per year once operating, said Kyle Graham, Senior Program Manager at Ecosystem Investment Partners, the company overseeing the project. 

A newly approved wetlands project could clean out 26 metric tons of phosphorus per year, according to Kyle Graham, Senior Program Manager at Ecosystem Investment Partners.

What's wrong with the P?

There's no shortage of phosphorus at the site's location: The S-154 Basin in the Taylor Creek/Nubbin Slough has one of the highest phosphorus loads of any watershed flowing into Lake Okeechobee, according to the South Florida Water Management District.

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"When we first started looking for a project, we wanted to be in the 'hottest' spot possible," Graham said, referring to nutrient pollution levels in the water. And the subwatershed is "the hottest of the hot" for polluted water heading into Lake O. 

"It's the place that needs the most work," Graham said. 

It will take between 18 and 24 months for the estimated $280 million project to work through the engineering, design and permitting process before construction begins, Graham said. The project is slated to have a 50-year lifespan. 

How will the project be monitored?

Once completed, the group must achieve five successful years of measurable nutrient reduction in the water during a seven-year window, and will maintain upkeep on the marsh's vegetation, Graham said. Then, the wetlands will be turned over to the District. 

Water samplers have a clear-cut technique for measuring how much pollution is siphoned out of the water as it passes through aquatic plants, Graham said. 

Nitrogen and phosphorus levels are measured before water enters into the wetlands. Then, after working its way across the fields, and phosphorus and nutrients attach to plants or deposit into the soil, another sample is taken on the opposite end. 

That difference is the total amount of pollution being cleaned from the water, Graham said. 

How will it help prevent algal blooms?

Water laden with nitrogen and phosphorus from farm and urban stormwater runoff promotes algae growth. An estimated 150-square mile blue-green algae bloom on Lake O — larger than the city of Detroit, Michigan — was documented by the National Oceanic and Atmospheric Administration May 25.

Preventing harmful algal blooms begins with lowering the amount of nutrient-load in the "upset" watershed system, which is the purpose behind the new wetlands project, Graham said. 

"You need to take the nutrients out so that you reduce the blue-green algae that is present in the lake," he said. 

A new wetlands projected as unanimously approved by the South Florida Water Management District in May. Here's what the plan looks like.

Algae blooms can be red tide, brown tide or blue-green. The latter, formally called cyanobacteria, can contain the toxin microcystin. Exposure can cause rash or hay fever symptoms if touched or inhaled and nausea, vomiting and fatal liver disease if ingested.

The Environmental Protection Agency deems water unsafe if it contains 8 parts per billion (ppb) of microcystin or more. A bloom at the Pahokee Marina in April measured at a staggering 860 ppb, and was recently recorded at 22 ppb at the Port Mayaca Lock & Dam.

Water carrying these toxins can enter waterways attached to Lake O. The latest was an algae bloom documented Tuesday in the C-44 Canal, which flows into the St. Lucie River when the floogates at the St. Lucie Lock & Dam are opened.

State water samples are pending for this current bloom, according to Alexandra Kuchta, a spokesperson for Florida's Department of Environmental Protection. 

For more news, follow Max Chesnes on Twitter.

Max Chesnes is a TCPalm environment reporter covering issues facing the Indian River Lagoon, St. Lucie River and Lake Okeechobee. You can keep up with Max on Twitter @MaxChesnes, email him at max.chesnes@tcpalm.com and give him a call at 772-978-2224.

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