i'm considering creating a 4~6 acre seasonally flooded marsh in a flat portion of my pasture.

when constructing dikes for a shallow water impoundment (ie wetland), how deep should the core trench be? the marsh will average 12" of water w/ the deepest spot being around 3'.

strmchzr,
There are plenty of experts with practical experience that will chime in on this one, but since I have recently been exposed to another couple of facets of wetlands, allow me to share a couple of thoughts. The NRCS div of the USDA is VERY interested in anything related to promoting wetlands, whether it be creation, maintainance, or improvement. You may already be well aware of this, so you will also know that they will cost-share it's creation and offer engineering assistance. There may be a flip-side to this, though. Once a wetland is established. they are also very interested to make sure that it is not destroyed or compromised. At this point, I don't fully know the legalitites, but I do know that if there is ever any plans to make negative changes to this wetland that you are about to create, there may be mitigation later. At 4 - 6 acres, it will likely be picked up eventually whether you contact the NRCS or not, so make sure that you understand the potential ramifications down the road...and...please share your findings.

my nrcs guy has been very helpful w/ my various habitat projects. i'm hoping to have a seperate 8~10 acre shallow water impoundment built this summer as part of the CP 9 program of CRP.

the wetland i was referring to in my original post doesn't qualify for this program. the only gov. program available would allow the general public to have access to the marsh ~ which i don't want.

so.......... i'm considering building the marsh myself w/ the guidance of the nrcs folks. the marsh would be created out of pastureland and doesn't currently hold water. the soil in my area has a high clay content, so creating a watertight barrier shouldn't be too difficult.

my concern is primarily the cost of creating the dikes. to keep costs down, i was thinking of a modest dike w/ minimal dirt work necessary.

I kinda expected that you already had a handle on the NRCS thing....just covering the bases. I am curious, though, that the only program that they will cost share specifies public access...? Which program is that? (for my own education)

Strmchzr,
On the wetlands I've built for the NRCS all they requested for a core was stripping the vegetation off.

brettski, you really need to talk to your local nrcs guy for more details. my understanding is that CP9 is a cost sharing program, as is WRP (but WRP has 15 yr., 30 yr., or permanent easements on the land).

zhkent, very cool homepage!!!
once the vegetation has been stripped, is it still necessary to compact (every 6~12") the dike soil to create a watertight impoundment?
any other thoughts or comments would be greatly appreciated.

thanks

Strmchzr,
Glad you like the homepage. A personal web site comes with the dsl service. It's not supposed to be for business, but I did build all the ponds, lakes, and wetlands on there. Need to add more....
If you don't mind you might let me know where you are.
I'm at Burlington and would like to invite you and others to stop by if you get the chance.
I'd say you would want to compact the berms, but not get to worried about it. Get the layer of dirt you are putting on to bond to the one below it, compact some and that should get it.
There is one wetland I did that does leak very slowly. It is seeping through where a small stream channel was, below the dike, probably a seam of gravel. You might watch for that.

i sent you an email, kent.