Take me to the River
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Take me to the River
How mangroves are saving Queensland's Caboolture River, with Margie Dickson
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In today's episode, Margie Dickson, Environmental Project Manager at Healthy Land and Water, takes us on a journey through her experience leading an innovative project on the Caboolture River which re-establishes mangroves for long-term bank stabilisation and ecosystem resilience. This effort combines her engineering expertise with nature-based solutions, including the use of hardwood logs, strategic earthworks and mangrove revegetation to combat erosion. The project is not only addressing critical environmental risks like acid sulphate soils but also exploring how nature-based solutions can serve as alternatives to traditional 'hard' engineering approaches, increasing climate resilience and creating fish habitats.
Our favourite thing about this project, and Margie's approach, is the way she combines immediate engineering solutions with long-term ecological thinking — rather than building the concrete barriers of the past, the goal is to reinforce banks by creating stable angles, placing strategic barriers, and establishing mangrove communities that will eventually take over the protective role naturally. As Margie explains, "Vegetation is always the long-term strategy for keeping our rivers stable and keeping them healthy."
We also explore the fascinating world of mangroves - from their unusual root systems to their vital role as nurseries for fish and habitat for endangered species like the elusive water mouse. Margie shares how these remarkable plants propagate, sending floating "propagules" (not seeds!) up and down waterways, ready to take root and transform mudflats into thriving forests.
Margie is a civil and environmental engineer with a passion for protecting and regenerating Southeast Queensland’s waterways. She works on delivering on-ground projects that stabilise riverbanks, reduce sediment and nutrient runoff, and support healthier ecosystems and communities. Today, Margie shares the story of this fascinating project, the challenges of balancing engineering precision with ecological needs, and the importance of working with nature to protect our waterways.
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I'm always looking at the area and thinking, okay, where does the energy go, where's the energy coming from and where's the energy going? Because that's what erosion is essentially it's when you've got a certain amount of energy coming down the river, in the water and it's got to go somewhere. And erosion happens when that balance is off and there's more energy than the bed and the banks of the river can handle, and so then the river just shoots into them.
Dr. Siwan Lovett:Hello and welcome to Take Me to the River, sharing stories and inspiring hope with extraordinary people who care for our rivers. I'm your host, Dr Siwan Lovett. Today I'm joined by Margie Dickson , Environmental Project Manager at Healthy Land and Water. Margie is a civil and environmental engineer with a passion for protecting and regenerating southeast Queensland's waterways. She works on delivering on-ground projects that stabilise riverbanks, reduce sediment and nutrient runoff and support healthier ecosystems and communities.
Dr. Siwan Lovett:Margie is currently leading an innovative project on the Caboolture River which re-establishes mangroves for long-term bank stabilisation and ecosystem resilience. This effort combines her engineering expertise with nature-based solutions, including the use of hardwood logs and strategic earthworks to combat erosion. The project is not only addressing critical environmental risks like acid sulphate soils, but also exploring how nature-based solutions can serve as alternatives to traditional hard engineering approaches, increasing climate resilience and creating fish habitat. Hi, Margie, it's wonderful to be talking to you today and I know we're going to be covering a lot of topics, but what I first wanted to start with was I understand you have a civil engineering degree. How have you ended up in riparian restoration and conservation? What's that journey been?
Margie Dickson:A little bit of luck and a lot about sort of community and connections and the networks you didn't know were professional, I think. So I spent my first four years out of uni with a civil engineering consulting firm, which is where a lot of engineering graduates go, and I was in a team that was actually all about trying to get recycling infrastructure built, which is super important, and it was a really good team. But, oh my God, big infrastructure is slow and I don't think any of the big projects I worked on in my first four years out of uni have actually broken ground yet. So yeah, I was just starting to get a little bit impatient and I kind of thought maybe I'd like to work on something a bit smaller and kick some dirt and look some people in the eyes and see some things finished. And I don't think if I'd just been looking around on the internet I necessarily would have picked this job or thought I could do this job. But it was actually my old scout leader who reached out to me and said hey, you know, the company I work for has a team looking for good people. I think you're good people. You should give this a crack, and it was so important, I think, to have that little nudge of someone who knows you just enough to give you a bit of encouragement, a bit of a push. And I, you know, because he personally asked me I read the advert twice and I thought long enough to go okay, I don't do that, I don't know some of those things yet, but wow, I would really like to. That sounds awesome.
Margie Dickson:Yeah, so I started this job very much on the basis that, well, I started this job saying not, you know, I can do everything in this list, hire me and I'll be up and running from day one. It was a I learn fast. If that's what you're looking for right now, maybe I'm the person for your team. And it's been so much learning in the last sort of two and a half years at Healthy Land and Water. So Healthy Land and Water is the natural resource management group for southeast Queensland, so we're involved in all sorts of things in waterways, in grazing, best practice, in helping people in the horticulture sector, wildlife, coastal areas, but my team mainly works on restoring waterways and so that's a mix of, you know, bank stabilisation, things with earth movers and you know a bit of an engineering component. But also vegetation is always really important and the biodiversity side of things, and that's really been something that I've learned on the job, which has been excellent. I've really enjoyed that journey so far.
Dr. Siwan Lovett:That's just a great story. It's interesting. You know, I always say to people that your networks are gold, and there's so many people that I've talked to who have ended up in river management or working with communities. That was as a result of someone recommending them, and I just think we need to invest in what I call social capital. So that's the networks and relationships, and actually last week I was at a conference where I gave a talk talking about how powerful they are, so Healthy Land and Water. Then you're now working in and you're out on rivers. How are you applying your civil engineering training to working on rivers?
Margie Dickson:Can I just have a comment before I answer that? Yeah, I think I'd really agree about the networks, and something that I tell people often is it's not just the networks that are kind of in the room with the glass of bubbles, wearing the nice networking clothes and I think that was what you saw and heard about and got pushed towards a lot at university but the networks that are actually just in the rest of your life and you know, bringing your whole self to you know, whatever it is that you're interested in, it's still worth putting time into those and surprisingly often there are intersections with you. You know that journey through your professional life. At least that's definitely been my experience over the years.
Dr. Siwan Lovett:I love that reflection because I think you're right. Often at uni it's presented as you need to network, you know when you're in a meeting or you need to go to this or that, but in actual fact it's the day-to-day investment that you make in relationships and taking up opportunities that really, in your case, has come through in terms of you know, a scout leader, I mean, who knew that's fantastic. So over the last couple of years you've been having a really intensive course on how rivers work and they move and you know they cut new paths through areas that sometimes people don't want them to, or we take away the vegetation, which is sort of our natural engineering. What have you been really noticing about the rivers of your region and what are some of the biggest issues that you're facing in southeast Queensland?
Margie Dickson:Well, I think, as you said, vegetation is always the long term strategy for keeping our rivers stable and keeping them healthy. But where that vegetation has been lost or removed over the years, it can be quite a challenge to get it back. And that's kind of where the engineering component of river restoration comes in. It's never your long-term solution. You know, we're not trying to turn our rivers into a fixed concrete structure, but sometimes you need some level of engineering and design to create stability for long enough for the vegetation to get established well enough that it's then doing that job. And yeah, learning to look at rivers, understand how they work, to kind of think like a river a little bit, has been a really interesting journey. And I mean the people who specialize in that, they're the geomorphologists. But I get to spend a fair bit of time either walking the river with those guys or looking at the designs they've suggested and talking that back and forth. You know, does that make sense? Can we build it?
Margie Dickson:And I guess the way something that probably has come from my civil engineering training and way of thinking is I very often look at, you know, erosion issues that we're trying to decide if we should do anything, if we can do anything, how to fix them. And I'm always looking at the area and thinking, okay, where does the energy go? Where's the energy coming from? Go where's the energy coming from and where's the energy going? Because that's what erosion is essentially it's when you've got, you know, a certain amount of energy coming down the river, in the water, and it's got to go somewhere. And there are lots of places it can go. It can pick up the rocks and the gravel in the bottom of the river and move them along for a bit until it, you know, slows down and drops them out, or it can go into the bed and into the banks. And if the bed and the banks of river can handle that flow because it's a rocky gorge or it's a really dense forest, then that's fine, that's, that's a good way of taking energy out of the water.
Margie Dickson:And erosion happens when, when that that balance is off and there's more energy than the bed and the banks of the river can handle, and so then the river just chews into them, and that's essentially what erosion is. And so then, when we're talking about solving it, we're going okay, how can we get that back in balance? And there's a few different. You know parts of the equation, I guess, and you're looking at what can I influence here, which one can I change to get that balance back?
Dr. Siwan Lovett:That's a really great description and I think for people that don't understand rivers, you know it can be really frightening when they're flooding and it can be really frightening when they see erosion, but often our reaction in terms of fixing it is to move that water even faster away from our area, whereas a lot of the sort of nature-based solutions that we're looking at slow the water down. Is that the sort of work that you've been doing? And I understand you've got a project on the Caboolture River at the moment. Can you tell us a bit more about that?
Margie Dickson:Yeah, absolutely so. Our project on the Caboolture River is nine sites that we've been working through over about two years. They're all bank stabilisation of sections of the banks that were kind of vertical eroding cliffs, and it's come about. It's funded by the local water utility because when that dirt falls out of the side of the river and into the water it's got nutrients in it. It's got nitrogen and phosphorus and the water utility has regulations around those nutrients in the river. And fixing the bank erosion is one of the things that they can do to help meet the obligations that they've got around keeping the river healthy, to help meet, you know, the obligations that they've got around keeping the river healthy.
Margie Dickson:Most of our sites are down in the lower part of the river. So the estuary yeah, that landscape is a big flat floodplain and you can see the river meandering out through it. You've got Melaleuca forests or paddocks or housing developments in some spots on the flood plain and then the river itself is fringed with mangroves and as you get closer and closer to the bay, those mangroves and salt marsh take up more of the the land on either side of the river and even while we're working there is this beautiful dense mangrove fringe along the lot of the river, but then in some spots that's been lost and it just hasn't been able to restore itself Every year. The other parts of the river that have lots of mangroves they fruit and there's heaps of propagules floating around. You'll see them sprout up their first two little leaves as well.
Dr. Siwan Lovett:But you know, it's an urban area.
Margie Dickson:We've got recreational fishing, we've got boats going through and even that boat wash from fairly small powered boats kind of is enough to be a problem for the little baby mangroves and it's enough to nibble away at the.
Margie Dickson:The base of the vertical cliff is, which is what the banks have now become in the spots that we're fixing, and so the so the bottom of the bank gets nibbled away and the top of the bank falls in and then those little baby mangroves have gone and they just don't have the time to get up and sort of be holding the bank together and be protecting the bank from that wave energy. If they got big they'd be doing a great job, like sections of the river 100 metres further up. But it's really hard for nature to re-establish on its own and I guess that's where this project comes in. So it has a first stage that is some pretty serious looking construction. We're reshaping the banks and that is all about creating a stable area for then the riparian vegetation to be able to re-establish, and there's sort of a flat protected section at a good elevation for mangroves and then a gentle slope coming back up.
Margie Dickson:That's got different species transitioning from sort of more salt-loving ones down at the bottom to your kind of overbank, your eucalypts and other coastal vegetation up above the tide level.
Dr. Siwan Lovett:It sounds amazing. It must be a little hazardous at times, because Caboolture is quite a big river, especially out, you know, when you're getting down toward the estuarine areas. What sort of people have you got working with you? Are you getting, you know, barges with machine on them, or are you able to do most of it from the bank itself?
Margie Dickson:Yeah, no. So are you able to do most of it from the bank itself? Yeah, no. So we're able to work from the top of the bank and we're working with an earth mover that we've been working with for a long time. They've been doing this restoration work with Healthy Land and Water for much longer than I have and, yeah, this is their bread and butter. It can be tricky, but it's something that they've learned and they know how to do.
Dr. Siwan Lovett:So it's a fairly major intervention. You know, I know for a lot of our restoration projects you try and minimise that level of intervention, but it sounds like with a cliff that that's vertical and I'm sure people can think of cliffs that they've seen you actually need to do this reforming in a way. What's the reaction been with local community? Because I'm assuming that this work's being done on private property.
Margie Dickson:Most of this work is being done on private property. I think there's one site that's owned by the council. I'm actually not aware of any particular reaction or even strong opinions from the local community at this stage, other than sort of one day when someone fishing in their tinny stopped by to say, hey, what are you doing here? This looks a bit serious. But when you're able to explain that what you're doing is joining up the gap in the mangroves and the whole purpose of it is to make the river a little bit cleaner and make a little bit more fish habitat in among those mangroves when they get up, I think people are generally pretty comfortable with that.
Dr. Siwan Lovett:Great and, from the perspective of the private landowner, some landowners are more difficult to work with than others. Is your sense that for these landowners, they're seeing these cliffs as problematic I mean, it is their land disappearing and that they're comfortable with the ongoing management of those areas? I'm assuming that they will need to fence out their stock from the area that you're revegetating. Is that the case?
Margie Dickson:Yeah, so it's true that when you're trying to fix, you know, an issue of the river taking land in a kind of uncontrolled way, you do need to deliberately take some land out of production for grazing, and so in this case, it's about three times the height of the bank, plus a bit more for trees on top of the bank. And, yes, we're putting in permanent fencing around that and there's some ongoing maintenance as part of the bank, and, yes, we're putting in permanent fencing around that and there's some ongoing maintenance as part of the project as well.
Dr. Siwan Lovett:So what would have caused those cliffs originally? Like you're putting vegetation back, is the assumption right that it's been taking the vegetation away that's actually caused the problem?
Margie Dickson:So I think definitely sort of historically taking away the vegetation is absolutely part of what's caused the issue in these spots. They're also mostly on the outside bend in rivers, so that's a spot where the energy of the river moving past is highest, and so perhaps that's either why the issue started or part of the reason why it hasn't been able to heal itself over time and again. That's, I guess, why there is a bit of a heavier engineering component in these spots.
Dr. Siwan Lovett:And so, in addition to the sort of grading the bank, are you putting any structures in? I know that wood or groins are sometimes used. Is that happening here as well?
Margie Dickson:Yeah, so down on that flat area in the tidal zone where we're trying to recreate the mangrove forest. We definitely needed a little bit more protection for those baby mangroves as they're getting up, so that they're able to be sort of sheltered from the boat wash that's coming past for three or five or six years until they're big enough to then be really protecting themselves. And so we've got an arrangement of hardwood logs pinned into that flat section and those are breaking up any boat wash. That's sort of hitting the bank and it's creating, yeah, stiller zones, sheltered zones.
Dr. Siwan Lovett:And so that's really to protect them so that they can re-establish. I'm assuming that are you picking up fruit from the mangroves on either side of these areas, or are you actually propagating mangroves that get by a supplier to pop them in?
Margie Dickson:Yeah, so that's an interesting one. On the first the sites that we've been through so far, we have been deliberately placing mangrove propagules on the bench. We couldn't actually collect them from the Caboolture River because the Caboolture River, where we're working, is classified as fish habitat A and all mangroves are protected marine plants. So it's actually quite heavily regulated. What you own aren't allowed to do, so we had to go and get them from the next river south. And then there's regulations on. The regulations for collecting mangroves are different to the ones for propagating them, so we weren't allowed to propagate the seeds. It meant it had to be a sort of one day at a time strike mission where you head down to the pine river and you collect your buckets full of propagules and then you trundle back up to the kubilcha river and you pop them in the ground on the same day. Um, which has been a it worked. It's been a little bit of an interesting logistical exercise, but natural recruitment of mangroves is far and away bringing in more new little baby seedlings to these sites than anything that we've planted. And so for next year's sites, or perhaps the next round of a similar project, we would probably strongly suggest that collecting and planting mangrove seeds isn't really necessary if you've got established bits of mangrove forest fairly nearby.
Margie Dickson:We sometimes talk about mangrove seeds.
Margie Dickson:If you talk to a botanist they won't say that they actually call them propagules, because what mangroves make are, I guess, a little bit more developed than seeds.
Margie Dickson:They tend to be quite large, there's a lot of stored energy in there, they float and they're really almost ready to grow.
Margie Dickson:So we have two main types of mangroves on the river where we're working, and one of them makes propagules that are kind of roundish, a bit like a really big thick 50-cent piece, and then some of them make propagules that are more like a skinny version of your pinky finger perhaps, and they all float. And so the mangroves, yeah, come into a fruiting season all together and you'll have this big mass fruiting event and lots of these mangrove propagules sort of bobbing on the tide up and down the river. And if they happen to settle in a little spot that's, you know, at the top of the tide and it's sheltered enough that the water's slowed down and the mangrove propagules got stuck perhaps it got stuck behind a log that we pinned on the bench to help it out then it'll lie there for a bit and it'll pop down roots into the mud and that propagule will crack open and reveal those first two leaves, and so it turns from this little floating life raft into a tree.
Dr. Siwan Lovett:Amazing. So have you studied the structure of mangroves? I was just wondering about this, because when I see them, it's like they don't have one stem. You can see their roots, really can't you? And then they grow up and it's they're like I liken them to making little chambers, or like little chapels, almost where, um, you know, little fish live and a whole range of other things can can use them as a support. Um, what have you learned about mangroves that you didn't know before? Obviously, you're now an expert on propagules and I'll never use the word seed again.
Margie Dickson:Oh, I certainly wouldn't say I'm an expert. I haven't studied mangroves, but I guess, as part of learning on the job, suddenly I'm paying attention to them in a way that I wasn't before. Yeah, when I'm looking at the landscape that I might be trying to repair or I'm monitoring, you know our sites after completion and the different species of mangroves grow really differently. You know, one of the species in this area does have those unusual roots that you were describing, where, yeah, the one single stem of the tree seems to start a little bit in the air and then we've got all these kind of roots like some kind of strange tripod reaching down into the mud. Others are much more like trees with one stem coming out of the ground, but then they'll be surrounded by this bed of little hard pointy roots poking up out of the mud, and those are called pneumatophores and they help the mangrove to breathe.
Dr. Siwan Lovett:Wow, that's great. Thank you for explaining that because, as you were saying, I was thinking about those sticking up. They don't look like fun places to walk through. Have you been having a bit of experience in and amongst the mangroves?
Margie Dickson:Well, yeah, I also try not to walk on those because they crunch under your feet and you feel a bit guilty about, you know, repairing mangroves over here and stomping on their, their roots over somewhere else. So, um, there's some spots on the river where we can do the monitoring by kayak, and if you've got a mature mangrove forest that's already got a big pneumatophore bed, you know the best thing to do is not disturb it. We're not generally needing to get in there, and so I'm mainly walking on the the muddy bits of back that don't have mangroves and trying to figure out why, or trying to figure out if our site is helping to bring those back. And then by the time it is a nice, established, dense, difficult to walk through forest. We're pretty happy to leave it alone to do its thing.
Dr. Siwan Lovett:You've done your job, then. What are some of the creatures that you've noticed in amongst the mangroves, that you might not have been expecting to see?
Margie Dickson:Ooh, we've seen a stingray in the Caboolture River, which was a little bit unexpected, and a shark. We have bull sharks in sort of the Brisbane River, the Caboolture River.
Dr. Siwan Lovett:We know they're there.
Margie Dickson:But it did swim past just on the day that we were about to kick off the site, you know, walking over, scoping everything out, writing up the safety induction, and went we better put no swimming. Hey, we'll just add that as a site rule.
Dr. Siwan Lovett:And then the sharks went past. Oh my goodness, that sounds a bit scary. What about in amongst the canopy? Are they really important places for birds?
Margie Dickson:Yes, mangrove forests are definitely really important ecosystems on our coast. It's often, you know, quite hard to observe the wildlife that lives there because it's really hard to move through that ecosystem. It's not human friendly but it's excellent as a nursery for the little fish. It's a protected spot for them to to breed and to grow up. It's really good for birds. They're able to move through that landscape and then they're looking for those little fish. It's absolutely full of little crabs.
Margie Dickson:Um, and I learned recently this is not on the Caboolture River, but I learned recently that we've also got an endangered water mouse that lives exclusively in mangrove forests and builds little nests made out of sticks in among the mangroves. That's not one of my projects, but I work on another wetland up the top of the Sunshine Coast and I was arriving there one day to do my water quality monitoring and ran into someone from the University of the Sunshine Coast, all dressed up, looking very practical. I was like, oh, what are you off to do? I'm off to check my trap lines and my cameras to see if we can find endangered water mice in the conservation park next door. And he thought he had found them, which was really exciting because that's an area that is very low-lying um parts.
Margie Dickson:Large parts of it have historically been cleared for cane, but the sugar cane mill in that area closed over a decade ago and some of those cane areas you know will be underwater with sea level rise in my lifetime and so there kind of is planning and work and the beginnings of a transition, I guess, for that area underway. My work's part of that. The Sunshine Coast Council's also doing a lot of work in that space. For them they're looking at mangrove forests as carbon offsets and that's why they're looking for the endangered water mice in the bits of forest that are already there, because if they're there it means that as the new areas that are being managed to transition to a new mangrove forest, that'll actually be expanding the habitat for these sort of secretive little critters.
Dr. Siwan Lovett:That's a wonderful story. I didn't know that there was a water mouse, so we have our rakali, which we really love, which you know we're often called the water rat.
Margie Dickson:but rakali seems to be. I've just been to.
Dr. Siwan Lovett:Rakali as well. Yeah, yeah, oh, that's good. Yeah, rakali does seem to be catching on. I think it's really fantastic that we're talking more about the benefits of these areas, particularly. You know you were mentioning about sea level rise. You know climate change is real and the thermal refugia that areas like thick mangroves provide is going to be essential, not just for critters but also for humans too, because it actually creates a microclimate.
Dr. Siwan Lovett:Have you done any work on that? Has the Healthy Land and Water looked at that at all? In terms of the climate variability benefits of mangroves? I don't think we have. Yeah, I was wondering with the offsets, because we're looking at trying to develop a tool for being able to assess sort of the carbon sequestration benefits of riparian areas. We know that they're better than most areas because they've also got the blue carbon and the green carbon. Yeah, so we're also looking at that. Tell me a bit more about the other sort of work that you're doing. I know that you've got an interest in acid sulphate soils. How do they come about and what sort of work are you doing in that area?
Margie Dickson:Well, the acid sulphate soil management was a learning curve on the Caboolture job, simply because it was there and we had to make sure that we were managing them sort of safely. So what acid sulphate soils are is they're a legacy from the distant past when the sea levels were different and large parts of our coast actually were underwater, and so they formed in these hot, shallow seas. And it's chemistry I am not a chemist, but there's chemistry locked up in those soils that if they're just buried, you know, in layers under the ground, it's fine, that's all good, everything's stable, the environment on top's happily ticking along. But if you expose these soils to air, they start reacting and they generate really strong acid and that can then leak out into groundwater or adjacent waterways and quite dramatically change the pH and make it quite hostile for all sorts of life. So if there are acid sulphate soils in the landscape where you're working and they're most common, yeah, along the coast, sort of less than five metres below sea level you've got to be really careful. You've got to definitely check beforehand and if you think you'll be disturbing acid sulfate soils, you definitely need to have a plan so they are regulated um and some of the sites on the Caboolture River, part of what we were excavating had an acid sulfate soil risk.
Margie Dickson:Um, I think, to be honest, one of the best outcomes that we've had in terms of small design changes during the project is we were able to make some little adjustments to where that flat section for the mangroves was sitting, in terms of elevation, to make sure we didn't disturb the really nasty acid sulphate soil, disturb the really nasty acid sulfate soil. So on, you know, our first big site, the, the bank was about three meters high, so you've got a little bit of top soil at the top, and then you've got, you know, ordinary, non-acidic, you know paddock, and then below that there was some soil that you know showed up as, yeah, this triggers the thresholds for being acid sulfate, so you're going to need to manage it. But in terms of treating treating acid sulfate, so you're mixing it with something that's going to neutralize that acidity.
Margie Dickson:So in this case it was agricultural lime, and so we had our soil tests and they said, yeah, this stuff on top, like it's a little bit, you'll need to mix it with six kilos of agricultural lime per cubic metre of dirt. And then the soil tests go down a bit further and they go ooh. And then there's this estuarine mud layer and in that layer if you want to treat it, you're going to have to mix it with 100 kilos of agricultural lime per cubic metre of dirt. And that's a lot. You know it's a lot of stuff to cut in. It's a lot of stuff to cut in. It's a lot of stuff to mix through it's. You're just playing with much nastier material and the option should always be, you know, whether you're doing restoration work, whether you're doing a housing development, whether you're doing infrastructure, if you've got acid sulfate soils, you should be looking at them and going?
Margie Dickson:can I work around this? Can I actually not expose this to the air? And so we looked at the mangrove forests that we had upstream and downstream of our site and we went. Well, you know our design is one line on the plan. You know our flat bit for the mangroves will be at 0.7 metres above sea level. That's where we'll put it. But when we sort of looked in the environment where we were working, we went.
Margie Dickson:Well, the main species here it's actually able to grow and thrive across a wider tidal range than that, so it can handle being wetter and it can handle being less wet. So for the one sort of, it was just the top end of our site that was showing up the acesulfate risk. We went I think we can raise the bench so we just don't dig as deep. We don't dig up that really nasty 100 kilos of lime per cubic meter reactive acidic soil and we can be confident that ecologically and functionally the project's still going to work. And so we were able to make that adjustment. I think that was a much better outcome for the project and for the environment than you know me learning to treat and manage and test acid sulfate soils, which I've done for the lower risk stuff.
Dr. Siwan Lovett:I think so, definitely it, you know. As you're talking about it, though, I'm thinking about the enormity of this for a landholder who might not be anticipating that they've got acid sulphate soils. I think our knowledge has increased so much more now You'd kind of hope that landholders would get soil samples done so that they understand. You know, what the implications are of liberating that material. Does it tend to be in sort of a clump, or is it sort of a quite distinct line in terms of the layers of soil as you go down?
Margie Dickson:It's more like a layer because, like I say, it's formed at the bottom of these ancient warm oceans. So it's kind of like everywhere that was the bottom of the seafloor will have this chemistry going on and sometimes it can be quite visible in the soil profile. But you can't rely on visual identification.
Margie Dickson:You should definitely get a test. But the important thing is, if you're not digging them up, it's actually not a problem. So you can have these landscapes and you can grow crops on the top or you can graze or you can, you know, have a non-acidic ecosystem there and that will tick along quite happily and that's absolutely fine. You only run into issues if you're you know digging drainage, ditches and changing the groundwater level, or you know doing big excavation work. That's when you know this risk that's been dormant actually becomes a problem.
Dr. Siwan Lovett:So these designs have gone in and you've done this work. You've had some big floods. How are they holding up with?
Margie Dickson:uh, with floods, oh, yeah, there was a a couple of weeks in, uh, january 2024 when I think everything I'd worked on in my time at healthy land and water was underwater, and that was. I was sitting there a little bit nervous. They're going. Oh my goodness, if it's all in morton bay, I might need to have a little cry and get another job. But no, it was okay. It was okay.
Margie Dickson:Um we were really happy with how our first sites held up during those january 2024 floods. It was a it's an important test, um, I would definitely say. At that point they'd been planted and some of the little mangroves were up, but the vegetation wasn't doing the heavy lifting. It was still quite young and it was the engineering component of the project that did the heavy lifting in terms of how those sites fared. So reprofiling the bank and then placing those big logs as well was really important in, I guess, helping to protect the plants that were there.
Margie Dickson:It was also a flood that spilled out onto the floodplain, so it was. You know, our site was fully underwater and it was flowing over the paddock on top and that's actually a good thing in terms of the amount of energy that the trees on the banks are experiencing. Again, coming back to this idea of where does the energy go when a flood does break out, into the floodplain, that lets the energy spread out a lot and it does potentially less damage, unless we've put important infrastructure like people's homes, on that floodplain, and then the damage is really devastating for people.
Dr. Siwan Lovett:Yeah, definitely. And it never ceases to amaze me, actually, when people say I can live on this floodplain because the last big flood was 100 years ago and it's a 100-year flood risk and you're sort of going, yeah, but the hundred-year flood could happen tomorrow, like just because you've started here, it's not a hundred years from now. How do you go about explaining your sorts of work and the sort of you know? From what I'm hearing, it's a combination of engineering solutions that we can do and then nature-based solutions, really, in that we're trying to set nature up to succeed. How do you go about explaining your work and why it's important?
Margie Dickson:That's a big question, isn't it? I think it's a continuous conversation because these are big ideas and they're tricky ideas and there's always going to be conflict between room for the river and then room for people. So then, that understanding of this is where it floods. This paddock goes underwater, that's okay, is generally a little bit easier.
Dr. Siwan Lovett:So, having done all this work on the Caboolture, is it sort of a wait and see game now and you're going back and monitoring, monitoring, what are the sites looking like? Are you taking photos and all those sorts of things?
Margie Dickson:yeah, absolutely, and that's one of the really nice things, I guess, about having done a project that, like I said at the beginning, it's under a regulated framework, it's paid for by the local water utility.
Margie Dickson:It's part of kind of the whole suite of things that they do to meet their responsibilities around the quality of the water in the river, and so because of that, there's actually quite long-term monitoring on these sites. Um, we'll be doing it sort of for five years and then probably another five after that, and I think this whole job, one of the things that's been excellent about this whole job is the ability to learn small things as you go and then apply those. So I sort of mentioned that there's nine sites that we've been working on over two years. So even in the construction phase you go from site to site to site and you can, you can bring learnings and sort of improve things as you go, and it'll be the same in you know that longer term understanding how the sites develop and that same water utility is at different stages of developing up similar projects on other rivers up the coast, and so, yeah, the observations of these sites on the Caboolture River having been built and maturing are then able to inform kind of the design for the next rivers?
Dr. Siwan Lovett:You know you were saying that example of, initially you were, you know, going and almost foraging for proper gills, but this time around you're sort of saying actually, no, just just let nature get on with it. So it sounds like it's a it's continuing to go back. For people living on the Caboolture River or people who are interested, is there sort of a site that they can go and have a look at, either in reality as well as virtually online, that they can keep up to date with what's happening?
Margie Dickson:Yeah, absolutely so. The first site that we did is at the end of a public park called Heritage Park. It's part of the North Harbour development in Burkengarry East, but yeah, it is right on the edge of that public area. I think a park run goes past it on Saturday mornings and it's one that we did the earthworks on in the middle of last year, and then the plants have been growing up and we've had two, two really warm, wet summers, so all those trees on the top of the bank are looking pretty lush yeah, fantastic, that's great.
Dr. Siwan Lovett:I was always envious of the growth rates um, in queensland because I had a. At one stage I was managing demonstration sites across the country and the tasmanian ones were very, very slow. The veg was tiny and then I'd go up to Innisfail and the trees would just be, like you know, over my head and I'm just going. Oh, this seems so unfair.
Margie Dickson:Yeah, but then you have to do weed control forever, because it's not just the trees that grow, well, it's everything. That is a very good point. Yeah, yes everything.
Dr. Siwan Lovett:That is a very good point, yeah, yes, okay, do you have um any advice for someone who's looking at going into this area of work? If it's an early career person like yourself, what would, what recommendations would you be making to them?
Margie Dickson:I'd definitely be saying go for it. I do love my job. I really love the mix of getting out in the field and then sort of being in the office and planning the next projects. There is so much that you can know about rivers and the ecosystems that go with them. You need to be always learning and it's also okay not to know everything. There is so much there that it really does take a lot of different people bringing their input to be constantly improving, kind of what we're doing at our sites, and I think that's something to embrace rather than be intimidated by. It's definitely something that I love about my team.
Margie Dickson:You know we've, and my team and the people we work with.
Margie Dickson:So we've got people who worked, you know, on the tools with revegetation contractors, killing the weeds and planting the plants, and then have come across to be planning those projects.
Margie Dickson:We've got, you know, me and a couple of other people who had an engineering background and then have come into this space. We've got people who studied science and ecology and then have come into this space. We've got people who studied science and ecology and then have come to sort of put it on the ground as part of the team. And so, yeah, I think you hear a lot in the corporate world about diversity driving innovation and that being really important, and sometimes it sounds a little bit buzzwordy, but I look at my team and I look at my projects and I look at the other teams in other parts of the country also doing this kind of work and I think you know, in our river restoration space it's so true and it's it's really genuinely happening at that project and team level, because you can come into this space from so many different angles and have something to contribute, so long as you're also willing to learn.
Dr. Siwan Lovett:I think that's a really great summation because, I agree, I think it's got to be collaborative and the strongest projects are often interdisciplinary. And I remember someone telling me you know, oftentimes we have this view that experts are sort of my way or the highway, whereas I think it's more about saying, well, I know something, you might know something, so it's better together. So it's just a. It's a much more collaborative way of going about doing this work and I can see how you've brought in a whole range of different elements there and it's really nice, because often we think, oh, an engineer does this and a scientist does this, but in actual fact we're all people and we just talk about what we're doing.
Dr. Siwan Lovett:So you know, that, that seems to be the success here.
Margie Dickson:That was something that I was surprised to learn about. You know my job as I started doing it in the construction management space, like what we're doing on the kibbutz river. I am essentially in a construction management role and I've come to see my job as I am the person who understands and listens and knows enough about all the different specific things that other people care about. So we, you know, we have a specific person whose job is to come in and care about erosion and sediment control, and someone else you know, or a department or a regulator, who cares about fish habitat, and then we've got the revich guys telling me what they can do and they can't do and what's easy and what's hard and same for the construction guys, and you've got the project manager with their budgets and time frames. All of these different angles of you know very specific perspectives that have specific requirements and things they care about, and inevitably those are not going to all line up and it's my job to notice when they're not lining up and then kind of broker the compromise.
Dr. Siwan Lovett:That's lovely hearing you describe it and your eyes light up as you're doing it. So, yes, project management can be very exciting folks. So as we come to the end of our talk today, I want to ask you whether you have a favourite river or body of water. These are questions that we ask everybody on our show.
Margie Dickson:Oh, can I give you two?
Dr. Siwan Lovett:Okay.
Margie Dickson:In South East Queensland. I think a really special river for me is the Cullula River. So it's right up the top of South East Queensland and most of it flows through this tea tree country and then it winds its way out through a series of lakes to the sea at Noosa. But because it flows through that tea tree country it's red, it's stained with the tannins and when you kayak up it and you look through the edge of the river it's sort of yellowy where it's shallow and then changes to this almost wine dark reddish colour. That's just bizarre and incredible. And it's also drinkable. You know it feels really strange. You go on a kayak expedition and you're drinking this river but it doesn't look like what you would expect a river to be. And if you're up really early paddling up that river it almost looks black when it's really deep, like a black mirror, and then your kayak is kind of putting the first ripples on it in the morning.
Dr. Siwan Lovett:Well, that sounds amazing. You need to send us a photo. Okay, so that's that one. Which is the other one?
Margie Dickson:And another place that's really special to me is Mount Barney Creek. So it's down at the other end of southeast Queensland and you know, here winter is our dry season and then the rain comes in summer, and so there'll be this time often where it's heated up, it's getting, you know, almost too hot to be bushwalking and to go out into the playground. That is sort of the natural areas of southeast Queensland For me. You're looking for the water and sometimes you're waiting for the water to come because the little creeks are sort of dry or a bit stagnant and not that inviting.
Margie Dickson:And Mount Barney Creek is one that sort of flows strong and clear and cold through the whole year, and so it's one of the first places that you can go to as kind of the season's transitioning from the dry winter, warming up and still waiting for the summer rain to arrive. And it again flows through a big section of National Park that we have. So it's a place that you can walk off track and you can, you know, be part of this wild, rough country. The creek itself is full of big granite boulders that you kind of rock hop along, and it sits under not quite the highest but certainly the most imposing mountain in southeast Queensland, so it makes you feel, I guess, small and a little bit awe-inspired. We're all about the awe.
Dr. Siwan Lovett:Margie Awe is very important. But, I think you should get a job with Queensland Tourism, because I now want to go to both those places. Don't come in summer.
Margie Dickson:No, I'm not in summer, don't you worry it won't be in summer.
Dr. Siwan Lovett:It's the reason I live in Canberra. Where do you feel most connected to country and to nature? It sounds like these places are pretty important, but they may be somewhere else. Where's that connection come through for you?
Margie Dickson:For me it is about the off-track adventures, so it's not so much one place, it's about having built a picture in my head, I guess, of the wider landscape that is sort of my playground and my place. I was a scout for 20 years so we went on a lot of sort of local expeditions in that time and, yeah, being able to move through off-track country and sort of know where the water is and have an expectation of when it'll be there and looking at the landscape changing as I walk through it is definitely something that makes me feel, yeah, connected to this place that I'm in and competent, I guess, to to be there yeah, that confidence to walk through those environments is actually really important, because many people don't have that confidence um, so I think it's actually a really fantastic attribute to have and it's something that I feel strongly.
Margie Dickson:If I'm traveling like, I'm quite aware that I, you know, I don't know how an alpine environment works, I wouldn't know what to expect the weather to do uh, I really enjoyed, uh, a long hike up in the northern territory.
Margie Dickson:It's one of those kind of famous bookable ones called the jack bulla, but we did it right at the end of the season, when you're allowed to go before they say okay, that's it, you're going to be fried to a little crisp chip, go away till next year. So it's about 40 degrees during the day, but you, just you have to adapt yourself to the landscape and so that walk each day is pretty short. So you get up really early, you do your 7 or 8 or 10 Ks, you get to your next camp by 10 am and all of the camps are by this beautiful, amazing water and I was just amazed by how much water was there even right at the end of the dry season and then you spend your whole day literally in the creek like a little crocodile and it's excellent. But it is such a different pattern of the landscape and you have to adapt yourself to that, and I think that's something that I kind of look for and appreciate.
Dr. Siwan Lovett:That's wonderful. So what drives you to do what you do and what I hope you're going to continue to do, because you're obviously a? I hope you're going to continue to do because you're obviously a major asset for Healthy Land and Water. I would suggest.
Margie Dickson:I never really knew what I wanted to do as a career. I hated that question. You know people ask you all the time when you're at school, at uni, and every time I thought I'd made a decision it turned out there were still options. But I kind of thought to myself well, if I don't know what I want to do, I like at the very least I'd better make sure it's something useful. And this definitely feels useful. You know I picked engineering because it is a fundamentally useful profession in that it exists to make decisions and solve problems and answer questions that you know someone has brought to the table. Um, and so I'm getting to do that.
Margie Dickson:You know, for our rivers and for our landscape and for, you know, some of our agricultural landholders out there who don't have a heck of a lot of other support. You know they're a long way from the urban areas and so it. You know I am small, we are all small compared to the. You know the forces of nature and the, the scale of what's going on in our landscapes, but I guess, at the scale that I can work, I think it's worth doing.
Dr. Siwan Lovett:Fantastic. Thank you. I think that sentiment is shared by many of us. I often think to myself you know, a 100 year plan for a river is a much more realistic time frame, so I can do my bit and then pass it on to the next person, hopefully a little better than it was before. It's been such a pleasure talking to you today, Margie. Thank you so much for coming on the show. Thank you, it's been lovely to have a chat with you. Great. Until next time, listeners. Bye. For now you can subscribe to Take Me to the River wherever you get your podcasts. Visit arrc. au forward slash podcast to learn more. That's arrc. au forward slash podcast. We acknowledge and respect Aboriginal and Torres Strait Islander peoples as the traditional and continuing custodians of the country and the rivers on which we live, learn, love and play. We respect and learn from Elders, past, present and emerging, valuing their knowledge, insights, cultures and connections to the waterways we all love and care for.