Addressing this to Travis particularly, but figured it was general interest
Dealing with wetlands (at the scale of an acre to several acres).
First I want to bypass questions about use - I do want to get agricultural benefit from my wetlands, and where I am in Michigan we have lots of precipitation, low evap and lots of wetlands.
Primary goal is probably grazing - I currently graze mixed herds including cattle, sheep and pigs (no purchased grain)
Are you describing a serpentine swale that basically leaves the entire marshland in ridges and swales, and maximizes surface area; with forage growing on the berms?
I also have an option to somewhat control a flood/drain cycle (at least to drain the rain buildup in the spring and let it grow)
Also open to other options.
Honestly mine does both; it drains a field on the uphill side that may be in corn, small grain or hay depending on crop rotation so it MUST be dry, then the water goes into a serpentine swale for grazing, picks up more water from another wetland area, then crosses a second field and drains into another wetland area that is a non-agricultural part of my land. In total it covers about 32 acres of ground.
I'll see if I can get you a map to show how my swales work, because they are part of a rather overall water control system. It is interesting in that you posted this today as I just completed my major earthworks project for the year which is an extension of these swales. The USDA-NRCS just inspected the project this afternoon and signed off on it. Its been a lot of work, but a lot was accomplished. Still I will admit there is more to go. I got two pretty big problems. The biggest is my rock dams are designed to stop sediment and not water which I would like to have control of, and the second is my upper, upper most field has a wet spot that should be swaled into this system. I was hesitant to do that before today because the soil engineer mentioned rip raping some 800 linear feet of ditching if that proved too much water for my swales to handle. I did not want to do that, but like my 10 acre field, that 15 acre on needs to be dry for corn, small grain and hay production.
Now unlike greening the desert, I should state that I live in Maine and climate change has actually INCREASED our annual rainfall and not reduced it; by 5 inches of rain more per year. So for me, its not a lack of water that is a challenge to farm in, but controlling too much of a good thing. Wetlands do that for me quite well. The other thing is, my farm is literally divided in half by two watersheds, so this hillside is where all the water starts, so directing it in the right paths can be crucial.
By the Way: Legally you can graze any wetland. This is how the USDA gets around the wetland exemption for agricultural use rules our ancestors put into place. It is when a farmer gets into row crops and hay ground that "limited agriculture use" comes into play for wet ground. Swales are a real gray area in grazing areas only because it is digging into wetland soil, but not for row crops or for making hay ground. I can legally get around quite a bit because I can ditch anything to aid in logging. I know it makes no sense, but that is how it works as crazy as it sounds.
On my slopes I use serpentine swale setup but at the turns I have shallow ponds these help with heavy downpours by giving a place to sheet down the slope.
I plant my pasture mix both in the swale and over the berms.
The hogs we grow tend to wear down the berms as they travel back and forth over them, when they are to low to work any longer I just rake the moved soil back into place and reseed.
This is one of the swales that terminates into forest land beyond. I call it my super swale because it is designed to catch any silt that somehow makes it past my other 5 rock check dams above it. Once, or if, it silts up, I can recapture it and redistrubute back into my fields, that is why it is shaped kind of like a pond with a porous dam (rock check dam) at the far end...which is the big rock check dam that you see.
The smaller check dam is designed to dissipate water flow from the rock ford used as access into this small field. The rock ford itself is designed of course to keep my tractor and other equipment from sinking into the mud. The ford also serves as a path across the swale for my sheep to cross. It is not a laneway, I do not believe in them, but just a point where the sheep can go from field to field for rotational grazing.
We are in a drought now so all this seems silly, but during spring run off when 32 acres of snow 5 feet deep melts over frozen ground and is not soaked in, flows are substantial.
posted 2 years ago
Thanks for the pics...Wish I could see a map of your water management features laid over topo.
I'm going to try draining the swamp with a monk controlled dam and a few drainage ditches (might have to do some hand digging) to bring water to the dam.
Then let it flood over the winters and drain it after spring rains.
Well I finally figured out how to capture Google Maps into a format I can overlay. Its not the one I like to use, but I got a crude depiction of my swales, and future swales laid out.
A couple of notes:
(1) First the bottom of the map is almost a perfect line representing the top of our watershed on this side of the farm. All water in this photo flows to the upper left part of the page.
(2) You will note the wet area is sadly adjacent to the sheep barns
(3) The middle field (at the time of the photo being a corn field, now crop rotated into an oat/clover/timothy field) lies directly south and up hill of a roadway, and the wetland. Sadly 25% of this field could not be fertilized if I had a farm pond located there.
A few other key points:
Dark blue lines represent existing swales
Black lines represent rock check dams
The orange circle is the area of my super swale and where the photo was taken...note the rock ford in it
The orange line represents a 4 season truck haul road
The light blue represents future swales I would like to build
The red squarish area is the wetland area in my pasture
It is not a perfect situation yet for sure. But slowly it is coming together and reducing erosion.
You can't have everything. Where would you put it?