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Best Way to Bridge a Beaver Pond?

 
Posts: 47
Location: Halifax, Nova Scotia
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I need to access the other side of the pond and would like some feedback on how I Intend to bridge it.

In the satellite shot I've attached the dam is in brown, approximate extent of the pond in blue, existing/submerged roadbed in red, property boundary in black and the proposed path of the bridge is in orange (ignore the bit of orange in the bottom right-hand corner near the road). I've also attached a picture of a bridge that I'm going to imitate. Mine will be black spruce posts pounded into the mud with a roughsawn 2x4 on top and a handline strung between the posts so I have something to help me stay balanced.

My question is, how high off the ground should my walkway be and how far back from the leeside of the dam should it be to hopefully prevent the beavers from creating a new dam along the walkway? I'm assuming that if I keep the elevation of the walkway lower than the dam and keep it setback 10'-15' from the dam then I should be safe but I'd like to hear everyone's opinions/experiences. I'd prefer to simply bridge the river that feeds the beaver pond but I don't own the property that the river runs through.
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Posts: 92
Location: Vancouver Island, BC, Canada
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Why not just use the dam itself as your bridge?
 
gardener
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Lorinne Anderson wrote:Why not just use the dam itself as your bridge?



I was thinking the same thing.

Would the beavers be annoyed if you added a bit more material to their structure and created a walkway over it?  I'd drive posts down into the dam until you hit something so hard that the posts don't move anymore and nail the planking to them.  Bada bing, bada boom, you've got yourself a bridge.
 
Lorinne Anderson
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Assuming it is not something you need to cross with groceries and infants ten times a day I have regularly walked atop beaver dams. They are master engineers, quickly repair (literally overnight) any low spots or breaches, and short of a taut line strung as a handrail should more than work as it's own "bridge" with out the addition of upright supports or boards.
 
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Lorinne Anderson wrote:Assuming it is not something you need to cross with groceries and infants ten times a day I have regularly walked atop beaver dams. They are master engineers, quickly repair (literally overnight) any low spots or breaches, and short of a taut line strung as a handrail should more than work as it's own "bridge" with out the addition of upright supports or boards.




Me too! Really the biggest issue I found is the "approaches" to the beaver dam being wet and hard to walk through. I would put my efforts into improving that. All beaver dams are different though, so it is hard to tell.

Honestly, I need more information to give you a better answer like what are you trying to access that part of the land for? How often is access needed, etc? I make the assumption that since there was a road there at one time, beavers built a dam and it flooded across the roadway.

That really seems like a cool project though.
 
pollinator
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Interesting idea and beautiful execution with that log bridge over the water. From the looks of your situation in the screenshot it doesn't appear from the quantity of trees still around the site that your beaver's have been terribly busy. Currently at what stage is their project? Is this a new pond and dam project?  I tread lightly over the beaver dam across our little creek to get to the other side. Beavers are good, well really good at blocking water by sound, but they aren't making a bridge so as Travis says the areas by the banks  are a little sketchy.
Brian
 
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I wonder if you might be able to lower the water level in the pond to make the roadway passable? Or at least to make it easier to install steps or a path? If you partially dismantle the dam you can lay thick drainage pipes through the dam wall and use them to control the pond level.  Look at the "Monk" designs for adjusting pond water level. It is about the only way that works reliably with beavers as they cannot work out how to block them up, which they could do if you used culvert or similar.

https://permies.com/t/1360/Sepp-Holzer-ponds-monk
 
Jay Colli
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Thanks for the responses everyone!

I wish I had of taken a picture of the dam last week when I was down to the property as it would show why I'm hesitant to use the dam itself as a bridge. The dam is at least a year old as a family friend was on the property last fall trying to trap them out and it appears that they are still actively working on the dam as new material appears most weekends that I've been on the property over the last 3 months. In late October through November this means there is a narrow, jagged, icy ridge to the dam that doesn't lend itself well to walking along, which is when I'm trying to access the property on a regular basis for hunting. Water on the pond get deep quickly; I measured 4' at arm's length at the deepest point and there is a 5'+ drop on the lee side down into a mess of dislodged dam material and pointy alder stumps that are continually multiplying as the alders regrow from the bases and the beavers chew them off. Needless to say, a fall in either direction would ruin my day!

Adding material to the dam itself to make a walkway sounds like a good idea but I'm hesitant to add any more material as it could encourage them to fill in the gaps and increase the height of the dam. Then I'd have an icy mess come November with a forest of punji sticks on one side and an ice bath on the other lol. I could be wrong about them building their dam up to the same level as the walkway but for the same amount of effort I could build the walkway in the same manner on the lee side, which would also be a safer working environment as I wouldn't have to be on the dam itself.

I'm trying to access the other side of the pond so I can reach the trailer that shows up as a white square-ish object on the sat photo. That trailer doubles as my hunting blind so from Sept-Nov I only need to access it one day a week. The rest of the year I don't spend much time on the property. It's maybe 8'-10' higher in elevation than the top of the dam.

I'd like to avoid draining the pond at all to encourage the beavers to stay. The main reason I chose to use the trailer as my hunting blind is because the pond and beaver activity along the pond edges gives me a good view across a large area that is continually being thinned and renewed with deer forage. Most of the good foraging area isn't part of the property but they regularly use the lee side of the dam to cross and its nice to be able to see them out there, even if they aren't in my crosshairs.
 
Lorinne Anderson
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I suspect a bridge built downstream would simply become the frame work for their next dam...

Once the current pond reaches sufficient depth (5-10 feet; depends on what will keep flowing in winter where you are) they, or their offspring will then continue to dam downstream to create additional beaver friendly habitat. As you have noticed, this also creates habitat for a multitude of other animals.

I might be more concerned about the longterm situation with the trailer/hunting blind and be looking at ways to get it to higher ground or elevated in some way to ensure you don't arrive one day at a flooded out building. You may want to put your efforts towards creating a floatable deck beneath the structure, especially if you are not there regularily.
 
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how high off the surface isn't as important as how much noise the water makes. Beavers build damns in response to the sounds rushing water makes. In the post BEAVERS - our bridges are gone! we discuss a bit about beaver interactions with bridges. in your case, if you are bridging over the still water of the beaver pond, there should be no issue. It's only when your bridge posts interact with the flowing water of the river/creek that beavers go wild as building.
 
Jay Colli
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Lorinne, point taken. After putting the time, effort and money into building the bridge I'd rather not see it become part of their next dam. I wasn't aware they (or their young) would move on once their pond had reached a certain depth - thanks for that tidbit of knowledge. Unfortunately, the trailer is in such bad shape that even if I was able to get to it with a tractor or a truck, I don't think I could move it without ripping it apart. If beavers generally work towards achieving a 10' deep pond then I think it should be ok where its at.

Bill, good point! Adding softwood posts to the pond would be similar to what's already there in the form of standing dead softwoods so hopefully the beavers wouldn't pay any attention to a few more. I'll need significantly longer posts but winter might be an ideal time to build the walkway as I'll be able to auger holes in the ice and simply drive the posts down into the mucky bottom - a two-person job for obvious safety reasons. It's also a lot safer than building a walkway through the mess of sharp stick they've created on the lee side of the dam. I'd get soaked if I fell off but at least I wouldn't get impaled! I'll check out the thread you linked to.
 
Jay Colli
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Here's the revised plan.

It might be hard to get good site pictures this Saturday as there's a significant amount of snow coming Friday but I'll try to post some.
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I purchased a book recently which talks about reintroducing beavers to areas save the area.
I have not read it yet. BUT, It may have information about working with them.
I think lowering the water level is something the beaver may not cooperate with.
So perhaps get the book

I did research ' loving with Beavers' and it is very interesting
Here is one
living with Beavers

Walking over the dam seems impossible looking at the images, but I guess if you have, that great. I guess you could add planks etc??
 
Jay Colli
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Location: Halifax, Nova Scotia
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John C Daley wrote:I purchased a book recently which talks about reintroducing beavers to areas save the area.
I have not read it yet. BUT, It may have information about working with them.
I think lowering the water level is something the beaver may not cooperate with.
So perhaps get the book

I did research ' loving with Beavers' and it is very interesting
Here is one
living with Beavers

Walking over the dam seems impossible looking at the images, but I guess if you have, that great. I guess you could add planks etc??



Hi John, thanks for the response.

Adding planks to the dam might work but they'd have to be placed high enough on posts so that water wouldn't flow over them in the winter and I think adding posts every 8' along the length of the dam would encourage the beavers to increase the height of the dam.

My current plan is to wait until January/February and simply walk out on the frozen pond to install posts through the ice. The rationale behind this is that the beavers will hopefully ignore these posts the same as they do the dead trees already standing out in the pond since there won't be any water rushing past them creating noise.

For anyone interested, I've attached picture of the dam from the north side of the pond standing on the road. It may look like an easy walk along the lee side of the dam but it is a mess of deep boot-sucking mud, tall grass and small sharp stumps.
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Travis Johnson
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After hearing a bit more what you are going to do on the other side of the pond, and seeing the photo (it looks just like a beaver dam I have actually), I think you have a sound plan.

When we were kids we were playing soldiers and my foster brother suggested we slither through the mud like my father did in Vietnam. We got into the mud and found it was only a few feet deep. It just looked 20 feet deep and miserable.

I think building the bridge you showed, the way you described on the ice, would work. IF you were going to be gardening on the other side or something, we would be having a different conversation, but a crossing to hunt...I think you got a solid plan. I would help you build it if I lived closer. Sounds like a fun project.
 
Jay Colli
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Travis Johnson wrote:After hearing a bit more what you are going to do on the other side of the pond, and seeing the photo (it looks just like a beaver dam I have actually), I think you have a sound plan.

When we were kids we were playing soldiers and my foster brother suggested we slither through the mud like my father did in Vietnam. We got into the mud and found it was only a few feet deep. It just looked 20 feet deep and miserable.

I think building the bridge you showed, the way you described on the ice, would work. IF you were going to be gardening on the other side or something, we would be having a different conversation, but a crossing to hunt...I think you got a solid plan. I would help you build it if I lived closer. Sounds like a fun project.



Thanks for the response Travis, should be a pretty straight forward project! Cutting down all the dead trees to give me a clear line of sight across the pond will be a bit more of a bother...
 
Lorinne Anderson
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Trimming up lower branches of dead trees may be simpler, safer and better encourage wildlife diversity.

If the standing trees in the pond are removed, the remaining stumps could be a serious hazard, down the road, for boating/snowmobiling, not to mention the danger of removing them (chainsaw+boat???). Further, the dead trees provide "cover" and nesting sites for a multitude of wildlife both flora and fauna.

I suggest the safer alternative would be a pole trimmer to strategically remove lower branches that are in danger of obstructing your view. The pond itself would be healthier and the wider amount of wildlife attracted the better the hunting should be.
 
Jay Colli
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Lorinne Anderson wrote:Trimming up lower branches of dead trees may be simpler, safer and better encourage wildlife diversity.

If the standing trees in the pond are removed, the remaining stumps could be a serious hazard, down the road, for boating/snowmobiling, not to mention the danger of removing them (chainsaw+boat???). Further, the dead trees provide "cover" and nesting sites for a multitude of wildlife both flora and fauna.

I suggest the safer alternative would be a pole trimmer to strategically remove lower branches that are in danger of obstructing your view. The pond itself would be healthier and the wider amount of wildlife attracted the better the hunting should be.



Good point Lorinne. I haven't spent much time considering how much work will need to be done to clear my field of view but I suspect you're right in saying that taking out the lower branches will be easier, safer and ultimately more beneficial.
 
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dry stack retaining wall
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