Episode 16: Floating Wetlands and Other Stormwater Treatments to Reduce Pollution to the IRL

Have you ever wondered why we treat stormwater? Well, I did. 

And I went straight to one of our partners who’s been tracking pollution reduction using floating wetlands and other techniques for over a decade now. And we’re liking the numbers.

We’re talking all things stormwater treatment today on One Lagoon – One Voice. 

Hi, I am Duane De Freese, executive director of the IRL Council and the Indian River Lagoon National Estuary Program. Welcome to our One Lagoon, One Voice Podcast.

Each week, myself or one of my staff members will host leaders in the community, scientists along the lagoon, people who know a lot about the system to talk about some of the problems.

And most importantly, some of the solutions to solve the Indian River Lagoon’s health and make sure it’s great for future generations. So let’s get the show started and let’s talk a little lagoon.

Greetings. Peace. Welcome to One Lagoon – One Voice. I’m Caleta Scott and I’ll be hosting today’s podcast. We’re going to be chatting about water quality, the benefits of floating wetlands and Martin County’s successful projects designed to clean up stormwater pollution before it gets into the lagoon.

I want to welcome my new friend, Scott Tedford, who’s the Environmental Project Manager of the Environmental Resources Division at Martin County Public Works. Welcome, Scott. Tell us a little bit about yourself.

Hey, good morning, Caleta. I’m originally from Connecticut and I’ve got a degree in ecology and evolutionary biology from the University of Connecticut. I came down to Florida in 2007 with an interest in working in the environmental field down here, and [I] started working for Florida State Parks. I was with the state parks for about 15 years, and was a regional biologist there, mostly working with wildlife issues.

I came over to Martin County two years ago, and once at the county, I’ve sort of expanded my horizons to doing land management and some water quality duties as well. I really appreciate you having me on your podcast this morning.

I’m so glad to meet you and add you to my bucket of new friends in Martin County. I love your background in biology and I want to thank you for your service. So the Indian River Lagoon National Estuary Program’s promise is clean water for people and nature.

Tell us why we need to learn more about water quality and how it flows into everything impacting the lagoon — and what role Martin County plays in that.

Well Caleta, the Indian River Lagoon and St. Lucie Estuary is obviously an extremely important precious resource within Martin County and South Florida in general. It covers… I want to say five counties. The St. Lucie River, the Loxahatchee River, the main flow ways into the Indian River Lagoon have been impaired for a number of reasons. So it’s really important for us to realize that things we do on land intimately affect the water in the Indian River Lagoon.

So Martin County is really committed to [doing] our best to decrease nutrients going into the Indian River Lagoon, to benefit the health of the ecosystem in the lagoon, not only for our recreation, but also obviously [to have] a huge impact on our economy.

So over the last 20 years, Martin County has put a significant amount of resources into projects in the lagoon — over 40 water quality projects have been done in the county. We’ve put in over 40… let’s see, I’ve got some numbers here… Basically, what we want to do is decrease the two major pollutants, which would be total nitrogen and total phosphorus.

Yes.

And those two nutrients are basically the culprits in causing harmful alga blooms within the lagoon. The harmful algae blooms decrease and have had a huge impact on our sea grasses. They decrease dissolved oxygen.

So if we can get those two nutrients under control, I think that’ll go a long way in helping out the health of the lagoon. So Martin County has done over 40 projects over the last 20 years, which have estimated to decrease the amount of total nitrogen by 70,000 pounds.

Oh, wow.

[Those projects] decreased the amount of total phosphorus in the lagoon by 15,000 pounds — and that’s a per year number. So that’s really huge. Part of the way we’ve done that is by creating new stormwater treatment areas or STAs, as we call them.

We’ve put up eight new stormwater treatment areas over the last few years, and we have more on the horizon. We’ve completed 3500 septic to sewer conversions with another 4,000 conversions under way.

All of these projects work in combination to try to get these nutrients under control, to increase our sea grasses, and to benefit the threatened and endangered species that are so important within the lagoon.

That’s a lot of work that’s taken place in 20 years. That must cost quite a bit.

It’s a huge undertaking, it’s a huge cost, and Martin County has leveraged about 50% of the cost. There’s been about 150 million dollars in total project costs to meet state mandated water quality targets, and 50% of those funds were from state and federal grant sources, and of course we thank the IRLNEP for your help in funding these projects.

It’s really important to have partnerships within our endeavors to try to help save the lagoon. A it really takes a village, it takes everybody — all hands on deck. All of us stakeholders and partnerships are extremely important.

That’s what it’s about, partnership, definitely. So based on everything you’ve said, it seems like there [are] many pollutants and they come from many sources. It looks like Martin County has looked at many ways to reduce the nutrients in the water.

So getting down to it, what we’re talking about today, what is a floating wetland?

A floating wetland is basically a floating mat. In this case it’s made out of a high density polyethylene material with what’s called aerator cups — or if you could picture a small planter with holes in it. Within these cups are planted vegetation.

These mats basically float in the water, and the roots, if you picture, are almost like a hydroponics set. The roots get their nutrients from the water and the plants grow up on these floating mats.

So basically the roots will soak up the nutrients from the water, and what we’ll do is we’ll harvest these plants three times a year. That [process] will effectively remove the nutrients from the water that’s soaked up by the plants.

Nice.

These wetlands are just one tool, Caleta, in many tools in combination with stormwater treatment areas. With some, [we use] baffle boxes and some upflow filtration systems.

[We also use] other nature based solutions, like swales, rain gardens and wet detention ponds. Any one of those tools does its small part.

But in combination, it’s what we call a treatment train, and the water basically goes from one tool to the other and each tool takes away a little bit of nutrients. All combined, it has a larger effect and benefit for the nutrients entering the Indian River Lagoon.

Nice. Nice. So [with] all of those different methods, we believe that every project equals progress. Tell us a little bit about some of the most recent projects that were funded by the NEP. I think it’s Old Palm City and the Golden Gate projects?

Yeah, actually [those are] really exciting, great projects. Again, thank you so much for the Indian River Lagoon National Estuary Program. Did I get that right? Did I get the letters right on that?

You did.

The IRLNEP.

That’s it.

You guys were so great in helping us fund these two awesome projects. The first one is the Golden Gate Floating Wetland Treatment Project. Golden Gate is an urban and built up community within Stuart. It’s just to the west of the Indian River Lagoon.

These areas were constructed prior to 1982 when stormwater treatment was not required as part of statewide stormwater regulations.

So we’ve got a stormwater treatment area there that effectively [carries out water run off] then goes into these wet detention ponds. The sediments will settle out, and then the water will slowly leave these areas and flow further along the treatment train. We’ve added floating treatment wetlands to this stormwater treatment area.

So tell me about how this impacted the residents. These types of projects, how do they impact residents?

So generally, they impact residents — I think — by providing the community with [almost like] a wildlife sanctuary.

Some of these stormwater treatment areas are really great and helpful for wildlife — wading birds, all sorts of reptiles and amphibians, fish. You know, a lot of these stormwater treatment areas have become great fishing ponds for the local community.

We do our best to kind of beautify the surrounding area, so it’s almost like a park where the community can go and walk their dogs, and really just enjoy nature.

Nice.

These areas serve multiple purposes — not only reducing nutrients going into the lagoon, but just beautifying the neighborhoods and making these communities better places.

I think it’s important that these old neighborhoods get some love, so that’s great.

Absolutely. So the Golden Gate STA, or stormwater treatment area, [its] pond size is 1.2 acres. And the floating treatment wetland area is 2,614 square feet. So, [I’m] excited to say [that] through the funding secured through the IRLNEP, we were able to replace [the] floating treatment wetlands that were added to the Golden Gate area in 2019.

The older floating treatment wetlands were sort of dilapidated — they were made out of an older material. So we’ve been able to upgrade the material to a longer lasting floating treatment wetland.

And so the huge thing about the replacement is [that] with the new design, we can now — instead of totally removing the plants when we harvest — greatly decrease the maintenance costs by simply cutting the roots, trimming the top vegetation and leaving the apical meristem within the mats.

Hm.

So when you do that, the plants just regrow from the apical meristem as opposed to totally removing the plants. That has decreased the cost by over 50%. And it also [produces] an additional harvest each year. It used to be that we would harvest these floating treatment wetlands twice a year.

Now we’re able to get a third harvest and at a fraction of the cost. So that’s decreasing a third more nutrients that were flowing into Indian River Lagoon. So we’re excited to say that over the past four years, these floating treatment wetlands have removed 530 pounds of nitrogen from the Golden Gate STA.

Whoa.

[The floating treatment wetlands also have removed] 67 pounds of phosphorus. So, you know, these floating treatment wetlands have really been a great addition to the nutrient benefits that we were already seeing from the stormwater treatment area itself.

Nice. Nice. It’s nice to hear that the cost decreased as well as the vulnerability for the residents and nature.

So, Scott, tell me about what’s next. Tell me about the older neighborhood in Old Palm City, you guys did a project there.

Yep, that’s right, Caleta. So [Old Palm City] is a similar neighborhood, a very high density urban neighborhood, also built before the existing stormwater regulations.

So at the Old Palm City stormwater treatment area site — which [has a pond that’s] 1.68 acres — the floating wetland area is just over 3500 square feet. And that STA was actually installed back in 2013. And so over the past 10 years, I’m excited to say that the floating treatment wetlands at that site have removed almost 1900 pounds of nitrogen and 366 pounds of total phosphorus that would’ve entered the Indian River Lagoon.

So [that project is] another, I think, huge success. Again, we thank the IRLNEP for helping us to move forward with this project and fund it.

Wonderful. So can you tell us a little bit about what’s next for Martin County? I know you have a lot invested in water quality. What kind of projects are you taking on next?

We’ve got an existing water quality monitoring program where we’re trying to identify where our hotspots are for nutrients — you know, what can we do about them?

We’ve also received a large amount of grant funding to increase our water quality monitoring, so that’s really exciting. Our staff has been moving forward to basically better identify all the drainage basins, outflows, so on and so forth within the county. We’re mapping them, we’re monitoring [them]. So we’ve got some really exciting projects on the horizon.

One of them is going to be an additional tool to be used at the Golden Gate STA, and that’s at the Golden Gate North — what we call the North Outflow. We’ll be adding a weir and we’ll be adding some nature based plantings to further soak up nutrients. The weir at that place will basically increase the amount of water that can be stored at that stormwater treatment area, and it’ll give it a high residence time, which basically means it’ll give the water more time for the sediments to sort of settle to the bottom.

The sediments are one thing that carry a lot of nutrients. So when those sediments flow into the Indian River Lagoon, that will increase the nutrient load. We’re going to try to do this project to counteract that. And we’ll also be adding what’s called an upflow filtration system, which is basically a box with material in there that further removes nutrients from the water. So again, it’s a combination of things that we’re looking for. Each little piece of the combination is going to contribute to nutrient removals.

Another project we have in the Old Palm City neighborhood would be the addition of backflow preventers to some of the stormwater conveyances that run from our stormwater treatment areas to the Indian River Lagoon. These backflow preventers basically allow water to flow out into the lagoon — but it does not allow saltwater to flow back into our stormwater treatment areas.

Nice.

And so what this does — sometimes when the saltwater flows back into the stormwater treatment areas — [is] it will kill some of the freshwater plants that are soaking up nutrients in those areas. And when the saltwater flows back there during king tides and what not, it’ll [also] actually decrease the amount of freshwater runoff that the stormwater treatment area can store.

So that’s another exciting project going on. Again, both [of] those projects are within the same communities [where] we’ve got the floating treatment wetlands. And then we’ve got a handful of stormwater treatment areas coming up soon, and we’re always looking for new and innovative ways to decrease nutrients and to help out the lagoon.

So glad to hear that these residential neighborhoods are going to have some reduced vulnerability, and that the cost was reduced for the county. Tell me about what’s coming up next for Martin County, some special projects you have.

Sure. So within the county, we’ve got a water quality monitoring program in-house that I think is really important to utilize in order to find out where we need to target these water quality projects. So [we have] two projects coming up, specifically within the same communities as we have the floating treatment wetlands.

The first would be what we call the Golden Gate North Outflow Project, where we’ll be adding a weir, nature based plantings and also an upflow filtration box to the existing stormwater treatment area. This project is going to increase water storage [and] increase residence time, which will decrease sediments floating into the Indian River Lagoon. It will add plantings, which will help further reduce nutrients. So that’s going to be a great project in combination with the existing floating treatment wetlands at Golden Gate.

A second project is the addition of backflow preventer valves within the Old Palm City neighborhood.

What’s a backflow preventer?

That’s a great question, Caleta. Basically these backflow preventers are going to allow water flow out of the stormwater treatment area into the Indian River Lagoon. But it will stop saltwater from flowing backwards into the stormwater treatment area.

So what’s important about that is, when there’s a king tide, when saltwater’s floating back into the stormwater treatment area, it can kill the freshwater plants that we’ve got there that are soaking up nutrients. It also decreases storage during rain events.

So if there’s a big rain event and saltwater [flows] back into the stormwater treatment area, basically, we’ve got less storage. These backflow preventers are going to counteract that and they’re going to help a lot with neighborhood flooding in that area. We’re really excited about those upcoming projects.

You were telling me about some sea grass plantings when we were talking before. What kind of work are you guys getting into with sea grass planting?

Yeah, so we’ve got over a million dollars in grants to go ahead and plant sea grasses in the Indian River Lagoon. As you know, the sea grasses have crashed over the last few years. Part of the reason for that crash would be nutrients entering the Indian River Lagoon causing harmful alga blooms.

What we’re doing is we’ve permitted, I want to say 18 acres, that we can go ahead and plant sea grasses. And we’ve got a lot of great partnerships — Florida Oceanographic Society, Ecosphere, and we’re going to be going ahead and doing some sea grass plantings. In addition to the plantings, we think it’s really important to figure out how we could be more successful with these plantings and [learn] some of the other reasons why— that we’re not aware of — these grasses have decreased.

So we’re working with our partners to do studies about things like how the Lyngbya — which is an algae — is affecting sea grasses. Can we remove this Lyngbya and be more successful with sea grass plantings? And can we add clams to these sea grass plantings and will they help the success? So there’s really a lot going on — not only with plantings, but doing research to try to figure out how to be more successful with our plantings.

Please invite me so I can plant some sea grass. I’m a successful monitor so far, but I want to get in there and do some planting. So don’t forget about me, okay?

All right.

Okay.

Well, it sounds great. We’re starting this week.

Oh, well let me look at my calendar. So we’ve got a lot of development, a lot of new projects coming. What else can you share with our listeners, like how they can maybe live lagoon friendly, or maybe even get involved with Keep Martin Beautiful?

Yeah, absolutely. So it’s important, I think, for everybody to know that what they’re doing in their yard, in their small space, has an effect on the lagoon. Every little bit counts, and so [it’s about] just doing little things.

One thing you can do is make sure that if you’ve got a storm drain or a swale next to your house, make sure it’s clear. If you see a storm coming and you look and there’s a lotta branches in there, go ahead and clean that out so the water can flow through there properly. A huge thing is discharging into storm drains — a lot of us have a storm drain in front of our home.

I realized coming down here how much nutrients something as simple as grass clippings contain. So if you’re mowing your yard and your grass clippings are in your driveway and you take your blower, you’re just blowing them out of your driveway. Make sure those clippings aren’t going into your stormwater drain. Everything that goes into that stormwater drain on your street is going into the Indian River Lagoon. Again, every little bit counts.

You may think that, “Hey, you know, I’m just one person, and it’s not going to matter if I put a couple grass clippings in there.” But you multiply yourself by the population that’s surrounding the Indian River Lagoon in this area, and it can make a huge difference. Also, pool water, fuel, or [if] you’re washing your car — think about these things. Another thing you can [consider] is fertilizers, which are obviously nitrogen [and they] can be phosphorous.

Think about planting native Florida plants. I’ve recently just changed the grass in my backyard to native frog fruit and sunshine mimosa. These plants don’t need fertilizers — they’re adapted to Florida’s climate. They really don’t need any additional water. So doing something as simple as changing to Florida-friendly plants [and] getting rid of fertilizers is another huge thing because these fertilizers during storms are running into the stormwater system and into the lagoon.

Martin County does have a fertilizer ordinance, and basically the ordinance says don’t fertilize between June and September — during the rainy season. It asks that you don’t use phosphorus at all, and then report illicit discharges. If you see one of your neighbors, say, pouring paint into the storm drain outside, report it. They may just not realize where that paint’s going, and it’s important to say something if you see something.

Scott, sounds like your tips are the same tips that we have for living lagoon friendly. And I just want to thank you for making the time to share your expertise, and also to share the good work being done by Martin County, our partners.

This podcast is a great way to achieve heightened public awareness and highlight the coordinated interagency management of the Indian River Lagoon ecosystem. Before we go, if you could make one wish for the Indian River Lagoon, what would it be?

Well, Caleta, outside of the simple wish of having the lagoon just be perfect immediately, I think my wish would be for everyone to realize that they can all play an important part in improving the health of the lagoon. Again, every little thing matters, every small action matters.

So I would just wish that our education efforts continue and that people really get bought in on the fact that even though the lagoon is impaired, it’s still a vital and important part of our community. And I think there’s a lot of hope on the horizon and a lot of good things to come. I really believe that we can help [and] that our ecosystem can be improved, and [that] our seagrass can rebound here in the near future.

I want to thank you again, Scott, for joining me today. And I look forward to getting out there and planting some seagrass with you soon.

Thanks so much, Caleta. I look forward to putting you to work out there putting seagrass in. I think we’re going to have a blast and I really appreciate you having me on your podcast. Thank you.