I need some help with rebuilding a dam for a pond behind my house. We recently purchased the house and the previous owners pretty much gave up on it. Speaking with a neighbor, the pond used to be 3-4 feet higher. Here are some pics of how it sits now:


The first picture gives a pretty good view of the size of the pond, and you can see whats left of the dam in the lower left corner.


Here is the 'canyon' that is on the back side of the dam! I believe that bent pipe was once a spillway for the dam.


Here is a picture of where I'd like to try a construct a new dam.

I really have no clue what I'm doing, and was hoping some of the experienced users on here could provide some insight. My plan was to lay some cinder blocks with rebar and then lay some thick rubber (pond liner) or plastic sheeting between each row of cinder blocks and then add concrete into the cinder blocks to hold everything secure. Would this work at all??

Welcome to pond boss. Are you wanting to raise the level of the pond or keep it at about this level? I'm no expert, but I really don't think that is going to be that hard to fix. Do you have a good water source - creek, spring.
Hang on you'll get some good advise shortly.

I agree with rmedgar, this looks to be fairly easy fix. I don't think block, rebar and plastic is the answer. I think pure clay dumped in and packed is the answer. There are experts in soils on this site, lets see what they say.

Yeah, there is a small stream that runs in on the opposite side. I'd like to bring it back up to where it used to be, about 3 feet. Using clay definitely sounds easier than trying to engineer something out of concrete. Would I be fine with just clay, or would I need sometype of spillway as well to keep the water from flowing over top? Thanks

I am going to throw out the idea that once you try holding back 3' of water, thats a lot of weight pushing and its going to have to be pretty strong.

If you just fill this ditch that has the water flowing thru it, will that make it go 3' higher? Looks like you will have to add more height and width than you show in the pic to get the water higher?

To avoid erosion on top of the dam area, you would be better off to have a pipe go thru for the overflow. Be sure to put an antiseep collar on it. Also make sure the pipe is big enough to avoid water going over the top of you dam, or build an emergency spillway. Skim thru some old posts (in the pond construction areas) and you will find lots of posts talking about this stuff.

Here is a picture of where I'd like to try a construct a new dam.

Would the new dam be where the piece of wood is floating in the water? Would that bring it back up 3'? I still think it can be done w/o a whole lot of expense, but you MUST spend some time and thought on a very good & reliable emergency spillway. That will be the key to success IMHO...

Good point rmedgar, That area could be three feet down. Pictures are deceiving...

Yeah, it might be close to 3 feet higher if I just fill up the ditch, I'd be happy with that. Any recommendations on what type and size pipe to use? Wolud PVC be fine?

I'm not sure just plugging the hole will work. Dumping and packing dirt into the soil just might be a short term fix.

I see trees on the dam. At some point, the roots could cause more problems.

New soils for the dam should be mixed/knitted with the existing dam soils.

I think you need to either pump it dry and redo the whole works or at least lower the water level and do it right.

The pros will have to help you with the details about pipe size. They may know of a gov't service that could tell you how much watershed you have and size the pipe accordingly. How big is the pipe that was there? I would go at least that size and/or bigger. I wonder if the old one gave out because of age, or was water going over the top of the dam.

You haven't lived there for a long time, so I imagine it is hard for you to have any kind of track record to know the amount that can flow thru there in a bad storm. You want it big enough to handle everything except that "one in ten year storm". That's where the emergency spillway is used, and you don't want that on top of the newly packed dirt.

As DD1 eluded to, it looks like there might be a lot of other stuff to be addressed around the pond. One option is you can just fix this now, and learn a bunch of good stuff here by reading over the next few years and apply it to a major overhaul later. Another option is to tackle it all now. I think if you fix it, you'll want to tie it into the existing ground areas much like they do with new dam construction, just on a smaller scale.