Guys I'm currently having sediment load issues stemming from a fairly large feeder creek which outflows into my pond. Over the past weekend we had 3" of rain in 90 minutes which flooded the creek, yet again, and deposited a ton of sediment in to my water. A buddy of mine happens to be a civil engineer specializing in drainage and green solutions to runoff issues - he suggested slowing the creek outflow by building a series of weirs along the creeks path. I'm going to start on this project this evening and thought I should share the progress.

The water had to have reached 3-4' in order to displace the grass this high on the creek bank


Here you can see the amount of clay sediments at the outlet of the creek and the leaves/grasses caught by the deadfall. The clay extends 4-5' into the water and quickly drops down to 8' of water within the next 5'

This entire peninsula didn't exist 20 years ago (the pond was built in the 60's) and has added 10' of length into the pond over the last 10 years.

This is the creek mouth before I dropped the pond water level 18" by clearing obstructions from the outlet pipe about 6 weeks ago


Here is a map of the roughly 12 acre watershed for the creek


My pan is to build the largest weir first, starting this week, just upstream from the mouth of the creek. I'll be building a wall of cinder blocks anchored by old steel fence posts reclaimed from my lot. I'll obtain some free bricks from recent area building demos to line the outfall from the weir and over fill with gravel washed down our seal coat subdivision roads.

The 2nd phase will include hauling straw bails further up stream to be placed in very low flow areas of the creek.

Sounds like an interesting project that should work well.

Althouh weirs would not specifically be a pond as such, I'm still going to add this thread to the list of sediment, forage and specialty ponds I keep.

Weir's, if tight enough to hold back water should help drop out sediment even if they are not tight enough to maintain even a wet spot after the rains subside. My take is that you want the weir to cause a backup situation that ultimately slows the linear velocity of the water stream down enough to allow debris, caught up in the current, to settle out in the temporary pool. If the weir works well, eventually it will fill up with dirt and such and the water stream will be able to maintain its velocity and carry the debris on down to the pond. Hence weir maintenance instead of pond maintenance. And, anytime you slow the water velocity down, it is not eroding the creek as fast. I would place the weirs were they can create the largest pools possible yet allow for future clean out access with a skid steer or the like.

I agree with snrub...cool project! I hope it does not involve a hand shovel too much.

I started early since there's some rain on the way. I laid two cinder blocks in the creek channel and placed another pair on top which are anchored into the banks with 4' sections of rebar. There's a pair of steel fence posts in the two center holes of all 4 blocks. I'll reinforce the upstream side with bricks and cover the downstream side with the bricks, gravel and rock I can get. As is it backed up amost 6" of water and allows a small trickle to pass through - it should be pretty decent at slowing the water down when all said and done.








Here is how you transport cinderblocks down a steep hill to the pond where motorized equipment cannot access

If you can throw some leaf rakings and shrub trimmings on the uphill side of your cinderblocks (not too much is the trick) you could slow it down some more and get a bit of a filtering effect along with some baking up of the water. Even some sticks and twigs alone would start to collect the leaves and such coming down the hill and naturally create filter.

Nice repurposing of the sled!

Great idea!!! I have some arborvitae trimmings that should do the trick

I lugged 4 buckets full of bricks down and placed them on the weir

upstream side


downstream side


tonight I will add some evergreen trimmings to the upstream side and maybe two more buckets of bricks

I took my sons to collect materials for the next large weir to be built on my pond inlet - there's another 1 acre pond 100 yards from this point, my inlet is direct runoff from the upper pond's 12" outlet. The water passes though a very shallow, boggy, threaded delta of a marsh which is extremely heavy with light clay sediments as it meets the pond. Max cfs is right around 10 where as max cfs on my feeder creek is around 50-100. max outflow of my pond's outlet is near 40-60



I have 10 cinder blocks, 4' sticks of 1/2" emt (for anchors), 2 large steel fence posts (primary anchors), 50 bricks, 100lbs of large river rock, and some filter aggregate. So far the filter aggregate is a pair of 5 gallon buckets of 1" to 3" sized river rock and 3 gallons of mixed sands. We will need to gather 3x this much aggregate to finish off the project. I've enlisted my 10 and 12 year old sons to help with this one haha

This weir will be vshaped with cinder blocks focusing the flow to a central outlet where it will flow over a field of bricks. The open end of the v will be layered with the large river rock, bricks, mixed aggregate and sand. Ahead of the aggregate will be a series of rock/brick/aggregate riffles to slow high flows.

Looks good but you may have a problem of washing dirt out aroung the edge starting a new wash to the side.

Trick is to keep the water flowing against something that will not erode.

Try what you have and add as needed.

I've been keeping an eye on the small weir and so far so good. It has backed up quite a bit of clay and sand since being installed and the sides are holding up fine. During big rains the water tops that weir and flows over instead of pounding the steep bank. The v-notch allows quite a bit of flow during moderate rain events.

Here is the 2nd weir so far


I still need to add 5 more cinder blocks, 25 bricks, and ~300lbs of rock just to the front side. The backside of the weir will need around 500lbs of rock total. We have managed to filter about 60% of the incoming flow at current state.

The ultimate test took place last week - over 6" of rain in a 4 day period, all of which were short heavy rain fall events which swelled the creeks to max capacity. The pond peaked at 26" above normal level, and as of Saturday it was still 18" over.

The small weir did its job this time around




This is the view looking downstream toward the weir


The creek absorbed quite a bit of the upstream sediment but another 3' was added to the delta/peninsula in the pond.

The large weir at work

You can tell the water flowing through on the right is still pretty muddy but the sediment trap to the left is working wonderfully.



Overall water clarity is garbage but it is better than what it would have been without these two weirs. I have much, much more work to do.

Matzilla well done, I can definitely see a difference between the upstream and downstream turbidity. Some hay bales might be helpful down the road too...I've used those and just driven a couple stakes through them to keep them in place, but certainly not as permanent as your weir system! Good work and thanks for sharing with us!

Some wire cages to contain small rocks might work better as a coarse sediment filter, and they could be two feet high or so.

Thanks guys! I definitely want to improve on what we've done so far and add more weirs upstream (hay bales, log jams+rock) on the creek. Due to all of the overgrowth this will likely wait til fall/winter.

We're going to add some more rock, bricks and block to the large weir when the weather allows - the trail is a bit muddy to be dragging a lot of material down at this time.

The weir on the small creek blew out after some big rain events a month ago

My sons and I rebuilt it a little further up stream


We're going to do some more watershed improvements in the up coming months. Things have just been too darn busy lately.

I checked out this weir on Sunday - it has been working like a champ!

We still need to build some small version up stream of this one but it is apparent the existing weir is reducing the sediment load to the pond tremendously

I'm wondering if sequential rip rap piles would be another way of doing this... it seems like it is readily available in most parts of the country. It seems like you could start large and go smaller in increments... dunno, just a thought...

I like that idea John. A cattle or hog panel, cut in multiple pieces to height and size needed with bolt cutters, would make a durable fence to retain rocks/debris also. Stake it in with T posts and pile rocks up against it.

I think that would work great! Rip rap was my first choice but its just too darn hard to get a lot of material down to our pond. I'm going to try some anchored logs next spring to see how they hold up.

I did some more work on this issue lately...I added some more rock to the low head weir between my pond and the upper pond - this thing works like a champ in low flow and my shallow water areas are much clearer due to the sediment filtering/trapping going on in this location. I still need to widen the weir a bit more to capture even more sediment.

The creek weir is a constant pain. The creek eroded the bank adjacent to the weir a bit so I've reinforced with some sapling poles hammered into the creek bed along the bank. I added a small weir of poles supporting a stack of 6" and smaller logs in a narrow creek run about 20 yard upstream of the cinder block weir.

I decided to gauge the potential for flow and source of all the sedimentation over the last decade. Several HUGE trees have fallen upstream in the 4 branches of the feeder creek, the trees rerouted the creek bed and its carving a new path through the ravines. One branch has a very large natural rock weir/water fall but the other 3 are extremely deep ravines with nothing to stop or slowdown the inflow of runoff.

I have come to the conclusion that a few small but well built weirs will still help contain sediment (I shoved quite a bit already this spring) before it enters the pond. It also cuts down on bank erosion and further sediment load. I addition, the sediment build up at the mouth of the creek has started to seed and grow a very nice stand of mixed grasses!

All in all this project seems to be improving water quality in my pond and plant diversity. I'll update with more pictures and results when available. I have gotten permission to use an old access road to load material down the pond and will be able to add more rock, bricks, blocks and aggregate as needed.

After years of maintaining rock lined low water crossings we use to get tractors and equipment across small seasonal creeks, one thing I have learned is the need to run the rock up each side of the bank far enough to force the water to stay within the rock lining. If you just fill up a ravine with rock, it works for the time being. But as soon as there is significant rain the water will wash out around the edge of the rocks and make the ravine wider.

So if you can with your weirs, extend the rock in a U shape up the bank so that as the water flows over it it can not get to the banks edge to wash out around the rocks.

Although your weirs are not technically a pond, I have included this thread in my unofficial list of Specialty ponds.