Pond Boss Forums INTRO Questions & Observations Rimming the bank

I have questions about the practice of rimming ponds.

One thing I would like to determine is roughly how much difference rimming makes in controlling aquatic weeds. Can you expect to get only 10% of the weeds you would have in an unrimmed pond, or 50%? I know it all depends, but I'm looking for a generalization here.

If a rimmed pond does succeed in being low maintenance with regard to aquatic weeds, what is the maintenance like for land weeds around the shoreline? Would it be as easy maintaining the dry portion of a gradual embankment or is it easier?

If you have a perfectly functioning rimmed bank, what happens if your water level drops 2 or 3 feet and stays in that range for many months, or even a few years? What happens on the exposed rim and how do you maintain it? How does it look? Does it have an effect on fishing from the shoreline?

Then there's the question of diversity. How does a pond that goes from 3 to 12 feet deep compare to one that goes from 0 to 12 feet? I would think that the additional habitat in the 0 to 3 foot range would add a very large degree of diversity. Obviously it adds diversity concerning aquatic plants, but how does that compare to the diversity it adds to animal life? What cost is there to the pond in giving up that habitat for the goal of reducing maintenance?

I would like to hear from people who own or manage ponds where the bank is rimmed and this has created a low maintenance situation with respect to both land and aquatic weeds. These same ponds should also look good because I think aesthetics matter to everyone to some degree. In other words, I'd like to hear some success stories about rimmed ponds.

I'm also curious if some people have gradual embankments and feel that they don't have excessive maintenance issues.

I can't offer any experience with rimmed ponds nor have I ever seen one but a I do have 1 bank that is 3:1 above water and it can be a little unnerving mowing it. I am personally much more comfortable with the 5:1 or more gradual slopes.

What exactly is a rimmed pond? Is some sort of soil retaining structure placed forming a straight down drop off like a swimming pool?

I have a very gradually sloped bank on about half of the pond, and the alligator weed is very difficult to keep under control. I use a pitchfork to rip it up by the roots, but it grows back fully within a month. It can't tolerate deeper water, more than about 1.5 feet, so I can see an advantage of having steeply sloping banks. The weed does make great habitat for minnows, fry, and frogs, with less shoreline vegetation you would see a decrease in these population.

In our area people call a bank rimmed when it has an immediate steep drop to several feet deep. I think it can be a 3:1 ratio and usually it's even steeper.

Mr. H's big pond had examples of both steep and gradual. It's also a pond which has had very little management other than regular mowing and occasional herbicides applied to the steeper banks where the mower can't safely reach.

This is how the "rimmed" bank looked last February, but the weeds are thicker now:



This side of the pond was left with the existing gradual slope. In this area Mr. H can run his Bushhog right up to the shoreline. I've never seen anything growing there other than the Bahia (?) that is the dominant grass. There are also not many more aquatic weeds in the shallow water in his pond, but I understand it will vary in each pond. (That is my faithful companion Flop Ear Dog)


I'm not trying to prove that steep banks aren't the best approach. A big factor influencing me now is the large number of ponds around here that are 5 feet below full pool. Most of them are steeply rimmed and in most cases it looks pretty ugly.

robo2011, your example interests me for a few reasons. If do this design and I'm holding the pond at the lower level I might end up with a similar Alligator weed problem. The difference would be that I could close the lower siphon and during the wet season the weeds would be covered with 2 or 3 feet of additional water, killing them.

Then after holding the water at the high drain level for several months I might get the weed growing again. This time I could open the lower drain and leave the weeds high and dry.

I'm sure there would still be problems controlling aquatic weeds with this design, but I'm trying to get to a point where I can intelligently weigh the variables. One thing I'm fairly confident of at this time is that a gradual bank will be noticeably easier to maintain.

I appreciate all of your personal experiences very much.

GW contemplate this pic wrt you question. Pic by Bill Cody.

Well, I don't see any weeds....



edit: Wait! There's a Thermos jug.

edit 2: Concrete is the only way to eliminate weeds?

This pond/lake was drained/lowered for a purpose related to some of mine?

Is that a pond dock or a loading dock?

Hmmmm... 1" thick concrete multiplied by 64000 sq feet, multiplied by cost per yard, plus cost of 100 concrete finishers...

Uh, never mind. Weeds aren't so bad.

It is just what it says a "concrete beach". It is used to have an easy to get in and out method (and swim etc) for ponds with steep sides. With it plus steep sides you have few weeds. With this you have easy entry/exit and a clean hard place to wade , float etc.

concrete beach.....i really like that.

BTW GW, i went with really steep sides all the way around, my water level uncontrollably drops 6 feet every summer, it is impossible to mow anywhere near the pond, the strip of open space caused by the dropping water (between water's edge and former high water mark) is the only open access to walk around the pond when not full (well you actually stumble and tread lightly on steep slopes around the pond). it is a wild, woolly, ugly, but beautiful mess....its my pond and i love it for all its faults. i dont spend a second worrying about weeds. i really like looking at pics of you guys back east with your manicured lawns all the way to pond, neat as a pin......just not gonna happen that way in el dorado.

good luck, you have a cool design.

GW:

Alligator weed will die in deep water, but it can survive, even thrive out of the water, mine has actually spread out of the water and climbed up the bank about 5 to 10 feet. If you stay on top of the weed problems from the beginning, it won't get to bad.
Alligator weed does die quickly when in deep water, when we got about 3 or 4 inches of rain in a two week period the water level rose about 6 inches, and all the deepest weed turned brown and began to die off.
Good luck.

My pond has a steep bank all the way around it. 3:1 and in some places 2:1 make it very interesting to mow. On the inside of the pond we used rip rap to control erosion. It also controls weeds.

D.I.E.D, we're building a swamp here man!

I would like to be able to mow the banks so that I can manage for native grasses if possible. I'm only concerned about any weeds, land or water, when they get to a point were they adversely effect other important systems. I did mention aesthetics as a consideration, but in our case that doesn't refer to manicuring anything like a lawn (not that anything wrong with that). We're trying to create a habitat that looks as "natural" as possible, maybe like beavers made it.

That's it really, I would be happy if this pond looked like it was formed by beavers. If there were significant and clear advantages to rimming the pond I would do it, but I still have doubts that it really helps very much.

Just to clarify, I don't find ponds with weedy and/or steep banks unappealing. As you can see (in my dual level pond thread), my design has both gradual and steep grades depending on the water level. Mostly I'm trying to understand any advantages before I commit to the dozers.

Above the water line the banks can be fairly flat for easy mowing. Below the water line most recommend 3:1 to discourage weed growth. I have two sides where the slope is 3:1 and two at 5:1 below the water line and have found no significant difference where submerged and emergent plants grow but this is only year 5 for me and I do manage for a weedless pond. Above the water level the banks vary from nearly flat with very moderat swales for surface drainage to 3:1. If I had it to do over I would have built the 3:1 bank at a more gradual slope for safer mowing. One nice thing about steeper banks is less mud is exposed as the water level drops in dry weather. I think any steeper than 3:1 would be a hazard if someone were to fall in because 3:1 is about as steep as I can climb out of when swimming.

GW, a lot of folks like cattails - I don't.

It's been mentioned on this forum before, and I find it to be the case in our ponds, cattails don't grow well on solid clay as they do on sandy soil.

When we had invasive cattails, they were growing on sandy soils.
When we deepened this area, the pond bottom is hard clay, and the cattail problem is solved.
By deeper water?
By clay soil?
Both?

Your desired aquatic vegetation may be as dependent upon soil type as engineering.

"It all depends"...

Clay vs. sand - good question, george.

My bottom and edges are all clay and cattails have never taken hold. I pull 3 or 4 small plants a year, and that's all the control that has been needed.

Thanks George, I hadn't read about the soils influence. Maybe I can get the contractor to add some extra clay around the perimeter and possibly compact it more.

Ryan, do you use herbicides for controlling aquatics?

Robo, do you find that the Alligator weed is accceptable on the dry banks? I guess it would be easy enough to kill on the dry areas if you wanted to.

Cheyenne, thanks for the rip rap idea. I wonder if smaller rock would be effective. I want to be prepared for this pond to be 5 feet low at times and smaller rock seems like it would be better material for a bank to fish from. Rock also seems like it would enhance the habitat for some animals.

Tightly packed rock would work very well. It would depend some on the size, but it should work well.

Maybe we've come up with a new strategy for limiting aquatic weeds - form a gradual slope into the water and line it with compacted rock and clay.

It might cost more than rimming, but I think it would give an easier shoreline to maintain and it would likely adjust to lower water levels more efficiently.

I might run this by our contractor.

I use Cutrine plus to control filamentous algae as needed when conditions are not suitable for tilapia, or if tilapia are unavailable. It appears that if tilapia are readily available I could limit algae treatments to a single application in the spring and fall and be algae free. I have a very small 2'x5'patch of cattails growing out of a moist bare area between the limestone border and lawn. I don't mind a few and allow them to grow. I do cut off the flower spikes before the go to seed. They don't grow throught the geotextile fabric and limestone and can't compete in the lawn. This year, with excessively low water levels, some grasses have started to grow between the rocks that were below water level and have some silt between them. They are easily pulled or spot treated with a herbicide.

If you look past the dock you can see the easily maintained edge between the lawn and the stone border. The stone is lower than the mower deck height allowing me to mow over the line. A couple of spot treatments of herbicide are visible at stone/lawn trasition, spot treatments are done twice per year. The greenery at the water's edge is water hyacinth that was planted as an annual in an attempt to take up excess nutrients and form some shade. The hyacinth hasn't been noticably effective. It is a very invasive plant in warmer climates but hasn't performed well in Ohio and it is unlikely I will plant it again.

GW:

Yeah, the alligator weed can just be mowed when it is up exposed on the dry bank, but if the water level rises, it already has a head start on other plants.

I imagine that if the water level was held at a lower level it would be good to kill the Alligator weed and replant something desirable.

robo, I'm curious whether you would redo your gradual banks at this point if there was no cost or inconvenience involved.

The upper picture illustrates what I consider a difficult to maintain bank. The steep grade makes it more difficult to establish desireable grasses, promoting erosion and weeds. It is also more dangerous to operate machinery on and not as comfortable to walk around. The lower illustration still has the advantage of being steep below water level to discourage aquatic weed growth but is much easier to establish grass, mow and walk around. At very wet times, the ground above water level in the lower picture may get wet and mushy making it a little more difficult to mow but a wet steep bank is slippery both by foot and dangerous for operating equipment on.