Dam - What plants to filter silt?

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Dam - What plants to filter silt?

Postby Pam » Sun Jan 28, 2007 5:51 am

....or other suitable plants!

Mr Google and I just aren't on the same page this morning, so I hope some of you wonderful people might be a bit more helpful than he was.

We're looking for info on what plants would be suitable for filtering the silt from water as it flows into a dam.

Also, the small amount of water that our dam does hold, my hubby is talking about adding alum to make it clear. Can I have some thoughts on this please, and would it harm tadpoles or the ecosystem of the dam in general?
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Postby gardenlen » Sun Jan 28, 2007 6:18 am

g'day pam,

all we did with our dam was to encourage a good barrier of grass growth around the dam, the theory being that in the future if we introduced stock we would fence them away from that dam region.

we also encouraged the growth of water plants ie.,. reeds, rushes, frogmouths, lillies all sorts of stuff that grows around the edges.

the dam wasn't (not like lots of others) badly coloured with sedimentry flotsum but once the cattle were removed and all the above happens the water cleared rather rapidly.

also you may need to look at managing run off water, we did this with rip swales this puts some of that water into the sub-soil where it is as good as storage water, and managing run off slows the flow to the dam so there is less chance for errosion type activity to occur.

len
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Postby Longy » Sun Jan 28, 2007 6:46 am

Yeah i'd look into some rushes and reeds etc as Len suggests. I actually went to a native nursery yesterday and bought some tubes of carex, club rushes and others to help use up the nutrient in my small dam. It was hard to find a nursery that catered for water plants. Found it word of mouth but the way to go is to talk to any native nursery people in your area re finding the grasses and stuff. If they can't help you they may know someone who can. Wetland regeneration people are the ones who have the knowledge of what's best for your situation. Maybe try landcare. You don't want to be planting weeds. The one i went to was in Mullumbimby Nth NSW.
I intend to create a second, shallow pond (1metre deep)and fill it with these plants, pump the water up through it with a windmill and allow it to come back into the dam via the reed bed filter. One day...
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Postby Quenda » Mon Feb 12, 2007 6:32 pm

I have noticed that new dams here have a small catchment sort of area just before the water runs into the dam itself. I am thinking this may be used to catch the water before it hits the dam, the silt falls to the bottom and then this small area can be cleaned out before the following winter. It would be a good idea to plant sedges and rushes around the edge of this one as well, though I haven't seen it done.
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Postby Pam » Mon Feb 12, 2007 6:45 pm

Quenda, I think we're probably looking at having to build a few silt traps around here too
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Postby bubba louie » Mon Feb 12, 2007 10:49 pm

Fairhill Native Plant Nursery at Yandina has water plants.
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Postby gardenlen » Tue Feb 13, 2007 3:49 am

g'day pam,

i didn't notice earlier about hubby wanting to add alum sulphate to clear the dam, my advice would be not to do that, once you get habitat happening with grasses and water plants the water will clear.

not sure if it has been mentioned but fence the dam off from cattle and horses etc.,.

len
With peace and brightest of blessings,

len

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May You Find Serenity and Tranquillity In
A World That You May Not Understand."

http://www.lensgarden.com.au
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Postby enrico » Tue Feb 13, 2007 5:36 am

i think all the advice re the reeds and rushes is excellent :!: :!: :!: and :roll: :roll: i believe barley straw :roll: cleans the water.............but :roll: don`t quote me on that .................... :wink:
tha abc has had a couple of excellent shows ' australian' story recently......... :roll: maybe september 06 or so.....and this guy did all the reeds ,grasses and rushes, maybe google ???????????? aus/story
sorry not more help.....but it was excellent :D :D
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Postby Pam » Tue Feb 13, 2007 6:47 am

Fairhill Native Plant Nursery at Yandina has water plants.


Any excuse to visit Fairhill is a good one! :D

No horses or cattle here Len, they wouldn't fit.

Enrico, thanks for the tip on the Aust Story article, will have a look for it.

To give an idea of the area in question, I will post a pic of 'Enrico's hill' again here. It is basically the top wall of the dam, which has been badly eroded. As the eroded tunnels are dug out and the area refilled and compacted the plan is to recontour it to direct the water to a spillway which we will create there. Those contoured slopes is what we are researching suitable plants for, so that any water that does flow over them doesn't carry into the dam any silt that it has picked up along the way.

Image
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Postby midgin » Tue Feb 13, 2007 7:01 am

I don't know if Enrico is speaking of the same fellow but there was a two part Australian Story based on the ideas of Peter Andrews.. here is a link to the transcript of part one. I believe a DVD has been released on this topic and it's available at ABC shops.

http://www.abc.net.au/austory/content/2005/s1386591.htm
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Postby Pam » Tue Feb 13, 2007 7:12 am

Thanks Midgin! :D
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Postby Pam » Tue Feb 13, 2007 8:10 am

Very interesting Midgin! Thanks
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Postby gardenlen » Tue Feb 13, 2007 10:19 am

just looking at your pic' pam,

mmm big job there that is some sort of errosion.

to slow water travel over that area down maybe even to stop it to some degree, you will still need water there to get habitat growing.

would suggest not to plant trees in this area, instead go for the grasses with good root systems the kangaroo and needle grasse will do that for natives that is or you could go for the hybrid seteria nandi or the exotic hammil grasses especially the cane type ones that grow to 3 meters high.

i would be looking at ripping contour swales in through that tree line to slow the water running out of the area and even direct some of it away, this needs to be temporary obstruction so later once grass etc.,. is growing on that errosion area you can let the water come back.

maybe place some logs tree rubble end to end and make a rubble dam??

even consider som rubble/debris traps using old branches fence posts logs long the contour of that erroded area, don't do a continual block say stagger them and make them app' 3 meters long, you could use bales of hay whatever and mayb need some star pickets to anchor it all down?

here are the names of some of the stuff we had growing:

'Cyperus lucidus' - sedge
'Cyperus rutilans' - sedge
'Cyperus sanguinolentus' - sedge
can be a bit weedy but they get going and open the ground up[ and they can be smothered out later as the other grasses become dominant.

water plants:
Frogsmouth - 'Phylidrum lanuginosum'
'Myriophyllum verrucosum' - water plant
'Nymphoides indica' - Water Lilly
Rushes - 'Eleocharis nuda
Sword Rush - 'Lepidosperma gladiatum'
Tufted water herb - 'Schoenoplectus mucronatus'
Water lily - 'Nymphaea gigantea'

grasses:
Hamil grass - Guinea grass - 'Panicum maximum'
Kangaroo grass - 'Themeda triandra'
Mitchell grass - Curly - 'Astrebla lappacea'
'Setaria sphacelata sp. Nandi' - pasture grass
Spear grass - 'Austrostipa densiflora' or 'Austrostipa mollis'
Wallaby grass - 'Austrodanthonia spp'


other:
'Lomandra confertifolia'
'Lomandra longifolia'

soil improvers:
Lotononis - 'Lotononis bainesii'
Wynn cassia, Round-leaf - 'Chamaecrista rotundifolia' - nee 'Cassia rotundifolia'

other hardy woody square stemmed plants are those native dried looking blue flower things they grow to about 2 meters high never found out their names?

keep us updated and more pics as well?

len
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len

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