wetlands effects on health

[Alex Kelley]

As a student, wetlands are always seen as a good thing to add to any almost any design. I understand and completely agree that wetlands have a positive affect on our water resources. However, historically wetlands have been removed because of negative affects on the health of human populations, specifically Malaria. I was curious whether this concern has been researched and if there is a certain way to construct a wetland to mitigate this concern. I would appreciate information on this and more importantly I would appreciate some sort of material I could use to further look into this.

[Phil Moorehead]

If I’m correct in assuming that you’re a student at The Ohio State University, you should contact Dr. Mitsch and/or visit the Olentangy River Wetland Research Park (of which Dr. Mitsch is the Director). Jacob Boswell is fairly knowledgeable on the topic of wetlands, as well (I’m assuming you know who he is because I’m also assuming you’re in Knowlton).

I wouldn’t call myself an expert, but it’s my understanding that the reputation wetlands have as being malarial swamps is a red herring (Developers: “Paving over wetlands is a good thing!”). If the wetland is healthy; invertebrates, minnows, frogs, bats, and bacteria should keep mosquito populations in check. We should probably be more concerned with poorly maintained rain barrels, birdbaths, and gutters. 

On the other hand, we’ve got West Nile virus to deal with now, too…

[Jordan Lockman]

Locally we have experienced deaths from an amoeba that comes from swimming in contaminated wetlands. Swimmers itch is another one that comes from swimming is wetlands. Depending on where you are at a wetland is habitat for animals that you may not want in your development. I heard a story about how a snake crawled out of a swamp and into someones car in Florida at a gas station. That is not a problem that is likely to happen up north.

Another negative of standing water is drowning. If the pond is not designed right it could be easy to get caught in the wetland.

[Rob Halpern]

While the notion that

wetlands are always seen as a good thing to add to any almost any design

strikes me as extreme and that such absolutes go against the very soul of the design process, I question the conclusions stated so far that wetlands are problematic because humans can’t safely splash around in them!

The planet is not 100% our playground, folks!

[Rob Halpern]

I doubt that malaria is an aberration due to wetlands out of balance. Malaria has been with us for a long time. Humans used to stay away from such places. Now we won’t. If that is the imbalance that makes malaria a problem (that is, we insist on living where our parasites flourish) then I suppose wetlands with malaria mosquitoes and humans are by definition unhealthy

[Andrew Garulay, RLA]

This is a good topic to discuss right now due to the huge increase in West Nile Virus and Eastern Equine Enciphilites (sp?). We just had a death reported this morning here in Massachusetts from EEE. These are diseases contracted through mosquito bites for those unfamiliar. Aerial spraying over entire communities is now being done for the first time in decades in Texas because of West Nile while EEE does bring on spraying in highly effected communities in Massachusetts almost every year, although it is much more widespread this year.

 

I know there are other created wetlands besides bioswales, but these are being produced at a higher rate in developed areas than other wetlands. It seems odd to have a health official telling us to patrol our yards to remove anything that can hold water for a few days while being required to create retention ponds (rain gardens, bioswales, bio-retention ponds, …) in even the smallest commercial site in the smallest parking islands.

 

At least the bioswales can absorb some of the pesticides that are now starting to be sprayed by air while the old catch basin to leach pit would have only a layer of soil to remove them. One big question is whether these are incubators for greater amounts of mosquitos and if they contribute to a bigger health threat.

 

Perhaps good solid studies have been done, but certainly a subject that we don’t hear much about that should be discussed.

[Jason T. Radice]

If you are creating retention basins that have standing water for more than a few hours, you are doing it wrong. 

 

[Phil Moorehead]

I don’t mean to imply that imbalanced wetlands spontaneously generate malaria, if that’s what I did. My point is that a functional wetland is probably no more likely to be a mosquito breeding ground than a poorly designed/maintained human-made structure that has the potential to hold standing water (roofs, playground equipment, storm sewers, swimming pools, parking lots, junk yards, etc…) If anything, the fact that a proper wetland also provides habitat for mosquito predators probably makes it less likely to allow a bloom in mosquito population than your average Walmart plot or suburban backyard.

What I mean to say is: Wetlands aren’t the only source of mosquitoes, and it’s possible they’re not even the primary one in your average square mile of developed land (that also includes wetlands).

The point that you and others have made that wetlands aren’t necessarily the ideal spot for human recreation is well taken. People shouldn’t be wading around in wetlands any more than they should be running full-tilt through a meadow in shorts and a tank-top. Nature is rarely cute and cuddly. It’s full of thorns, nettles, poison ivy, chiggers, ticks, scorpions, bees, wasps, fire ants, mosquitoes, leeches, and if you’re really unlucky… lions and tigers and bears.

Sometimes it’s better if we don’t get too close to nature all the time, but we should keep the option of visiting it open. Which more and more often means recreating it, however piteously. Which brings us back to the question of how accurately we as professionals (or a species) can design a complex ecosystem such as a wetland. The closest thing to a designed “true” wetland that I’ve ever witnessed is the Olentangy River Wetland Research Park that I referred to earlier, and it requires intensive intervention on a regular basis. It may function, but it’s on life-support. Perhaps that’s the best we can do.

I personally don’t know if anybody can design a self-sustaining wetland where one doesn’t (or didn’t) already exist (if then), let alone one that doesn’t host mosquitoes. I assume that the best we can do is something more like the “natural” pools that are growing in popularity. An analog of a wetland that requires human guidance.

[Frank Varro]

To over generalize, as long as it drains, within around 12 hours, or has enough flow to the water, mosquitos cannot breed, and malaria etc is uneffected.  Essentially, created wetlands need to have some flow pattern, and detention basins need to drain.

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