Beavers Damming Flow into My Pond

I have a beaver problem.  

I have a property with beautiful pond (mane-made, not by the beavers).  It's about 9 feet deep and stocked with trout.  Inflow to the pond is a natural creek that runs through the pond and then out over a dam when the pond is full.  Along the creek there are extensive channels to beaver habitat with lodges and dams.  

Last year the beaver decided it was time to dam the inlet to my pond. It's now getting ridiculous, I have to pull out their new construction every 2 days. If I don't the pond will dry up as the exit dam has a few leaks at the base, plus evaporation takes its toll.  I can see the water level drop about a foot in a day when the beavers block the inlet.  So does anyone have a good method of keeping the inlet open? I feel I need to let the beavers "think" they've dammed it and keep the water flowing somehow. I tried french drain submerged in the creek and running to the pond but I think they've blocked that all up with silt.  I'm going to try to bang on it today to see if I can get some water flow through it.

Also how would one go about fixing a dam that's leaking at the base. It appears to be concrete that has cracked and shifted. I don't want to drain the pond but not sure how to stop the water leaks at the base temporarily so I can fix it?  No water is currently flowing over the dam, so to fix this I need to stop or slow the flow. I was wondering if I put pond membrane on the non-pond side of the dam if that would slow the leaks down enough to build a new dam?  Suggestions? I'm totally over my head with this!
!

In terms of sealing your pond, concrete is out of my experience.

I have clay loam and can improve seeps by casting forest duff (leaves) and clay (bentonite, kitty litter, etc)

The leak pulls the leaf litter and clay into the cracks over time.

I imagine big cracks in concrete might be tougher.

The key with beavers is as you stated, they need to believe they have stopped the flow of water. You need a "Beaver Baffle" (Google it).

Essentially, it is the installation of long pipe (say 10-20 feet) that extends 50% up the intake, 50% into pond, deep, preferably on the bed of both water courses.

Ideally the diameter would be 10-20 inches, but that is dictated by depth of water. Beavers will damn the junction, where pipe meets pond, but generally do not associate the ends of the pipe with water loss - which I believe they source by sound.

As to the leak, membrane outside pond is likely a waste of money, repair must be from the inside so the weight of water presses against the leak. Done from the outside the membrane has no supporting structure.  

I suspect you need a professional pool builder/repair person, at the very least for a consult, and quite possibly to do the work. This sort of is NOT the thing to mess with, a failure of the concrete dam wall could, theoretically be life threatening to you and/or your neighbors - and t the very least do significant property damage to buildings, land and crops.

Lorinne Anderson wrote:The key with beavers is as you stated, they need to believe they have stopped the flow of water. You need a "Beaver Baffle" (Google it).

Essentially, it is the installation of long pipe (say 10-20 feet) that extends 50% up the intake, 50% into pond, deep, preferably on the bed of both water courses.

Ideally the diameter would be 10-20 inches, but that is dictated by depth of water. Beavers will damn the junction, where pipe meets pond, but generally do not associate the ends of the pipe with water loss - which I believe they source by sound.

My second-hand understanding is that beavers generally *will* dam the pipe inlet, even though it should be fully underwater and those not making much noise. The supposed way around this is many small slits in the sides of the pipe upstream of the dam, and closing off the upstream end of the pipe..

Not sure how fish would handle this obstacle, if that is worth considering here...

The key is the very long length of the pipe, it must extend significantly into stream, and into pond - a road culvert, say, is different, as the road "reads" as a massive dam, and the pipe culvert as a "hole" in the dam.

As to fish, as this is an existing pond, they will not have had access previously, unless jumping the existing barricade to exit or following the existing entrance into pond - which they can still do through pipe.  

Carolyn Miller wrote:

It's now getting ridiculous, I have to pull out their new construction every 2 days. If I don't the pond will dry up as the exit dam has a few leaks at the base, plus evaporation takes its toll.  I can see the water level drop about a foot in a day when the beavers block the inlet.  So does anyone have a good method of keeping the inlet open?

Maybe this is a mixed blessing, and you can use Principle 12 to "creatively use and respond to change"?

More water stored uphill is generally a great thing from a permie perspective.  Especially if it is created with free labor!  I have beavers and I am hoping they'll work just a little higher each year in my own landscape in order to assist in future gravity irrigation possibilities, by building new ponds in the landscape for instance.

Other thoughts to help prevent worrying:
If the watershed's water source (input) is fairly constant, then all the water that the beavers are impounding upstream has to go somewhere, right?  I would think that it must eventually saturate into the landscape and then run down the watershed into your pretty pond, and/or evaporate or transpire off.  So I would think that, eventually, after the beavers have sufficiently started their new pond, your current pond will naturally rehydrate again.  They may also make natural fish passes if you are lucky.

But from a system perspective, focusing on fixing the outflow (the leak) and resiliency may be more beneficial in the long run than focusing on the inflow side.

Goals:
1) Keeping the fish alive.
2) Fixing the leak in the pretty pond.
3) Mitigating inlet flow to ensure 1 and 2, to get a pretty pond.


For Goal 1, perhaps now is a good time to assess whether there are sufficient (long term) deep water kettles and temperature havens in case of drought?  

The PaDM shows examples in Chapter 13, Figures 13.5&13.6

Perhaps a small backhoe could dig fish refuges and disturb and distribute the clay closer to where the leaks are?

An aeration plan could also mitigate and give you more time for a long term fix if the water level gets dangerously low.

For Goal 2, Geoff Lawton had a video or two on using ducks' manure to fix a leaky dam.  I think pigs and cows have been used in other videos to help with the gley.

https://youtu.be/NNv1bFEzIyQ

So perhaps if you have animals, you could let them manure the pond and increase compaction at the dam as the water level drops.  

Maybe now would be a good opportunity to focus on the downhill side of the dam to see if it needs some vegetation maintenance?

Perhaps there is a sector with evaporative warm winds and sun, which may be better blocked with trees to reduce evaporation?

For Goal 3, to buy you time, and depending on the height of the impounded uphill water, rather than destroying their work, consider jamming some long metal conduit or piping through the lower half of the beavers work to get a slow leak going.   As other permies have noted, extending piping (plus exclusion devices) further from the dam is best, and expect the beavers to put sticks and mud into and around any piping.  Make it hard for them to do so using wire netting or hardware cloth cage.  You could also consider getting a super long flexible pipe and go way further up the creek to help bypass their system.  When you are ready to get the water flowing after making fixes downstream, then just lower the uphill pipe.

I WISH I had Beavers.  But that's because I can't  (legally) make a pond without them...

Lorinne is right on the Beaver Baffle thing.  There are different designs, but the key is that it allows the beaver to fulfill their instinctual drive to dam flowing water yet subverts their goal by sneakily moving the water past their dam.  Beaver comes, builds dam ... and goes away to tackle some other beaver-perceived problem.

And yes, as George suggests the new beaver dam might achieve a new normal.  There is the possibility that the dam will help filter the water so your pond gets less debris etc.

For a large-picture understanding of Beavers and their role in ecology, I love Eager.  Here it is at Powell's

D Nikolls wrote:
My second-hand understanding is that beavers generally *will* dam the pipe inlet, even though it should be fully underwater and those not making much noise. The supposed way around this is many small slits in the sides of the pipe upstream of the dam, and closing off the upstream end of the pipe..

My second-hand understanding is that the pipe is protected by a large box (hence the "baffle" in the name).  Apparently the beaver is very specific about placing sticks where they can hear the water.  If the water noise is inside a 2'x2' box then its like it doesn't exist (adding doulbe-entendre to "baffle"). If a creek flows in a forest, but a beaver isn't there to hear it, does it make any noise?

The beavers know your dam is about to collapse and are trying to save you...

There are so many things going on here, it's nearly impossible to figure out from a designers point of view, exactly how to approach this.  First of all, 9 feet deep doesn't tell us anything about size and volume. How many fish are we talking about? what are the zoning/permit requirements?  How big is the dam? did you ever see the pond empty?  How much property downstream of the dam do you own? what is located downstream?

You say the dam "appears" to be concrete--if you are unable to say for sure whether it is concrete or not that may be an indicator that you need greater expertise on the scene to evaluate this dam as to whether it is safe enough to keep full.

As was already mentioned, the beavers may be able to save you by taking pressure off the dam. Depending on the situation, if the beaver dam ends up deep enough you may be able to let yours dry up and transfer the fish to the beaver pond as your water level goes down

I do understand not wanting to get into a big project (replacing the dam) while still wanting to maintain it with a quick fix, I have enough to do that is my first instinct as well, but don't let expediency end up costing you heartache, you may lose the fish and a great deal more.

If you still want to ask for diy help here, pictures would be good, overall dimensions, situational details as well. At 1 foot per day loss,that means a muddy hole in about a week  this sounds more serious than beavers blocking the flow of water.

I have used a couple of “beaver deceivers”  (probably similar to beaver baffles as I am not familiar with that term. The University of South Carolina originally designed and tested them.  What I have done is to add a pipe through the dam. I typically use pvc pipe. I perforate the first few feet of the pipe with multiple round holes. I then using T fenceposts and cover the space between them with fence fabric. The area fence in should have space between the pipe and the barrier. I understand that for water leaving an area, beavers will hear or sense a flow and use that as a starting point for plugging the leak. The multiple holes reduces any significant current to attract the beavers. The pipe outlet is more pvc or even flexible French drain perforated or both. All of the piping remains underwater. Works for me.

Hi Denis,

Welcome to Permies.