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Drainage with high water table

January 31, 2010

Our yard is a little bit of a challenge. At one point a few hundred years ago, my little piece of property was in the Arkansas River. The river has since moved almost a mile to the east, but it's left some great things and some not so great things behind for us. The soil is fantastically rich--you have to have a black thumb to NOT get something to grow in it. Unfortunately, though, it also brings with it an incredibly high water table, as we discovered when digging post holes for a privacy fence. The water table is only about a foot down, so when it rains for more than a day or two in a row, standing water and flooding is a major issue for about half of our backyard. We had 20 inches of rain above our average last year (for a grand total of 80+)--you can imagine I'm more than sick of water and mud.

I guess I'm looking for tips on ways to rectify this. A standard french drain won't work, I don't believe, since the high water table keeps the soil very saturated, even during the dry summer months. There's a section at the back of the property that I'd like to turn into a pond. It's already a low-lying spot that collects a lot of the standing water and rain runoff (but by no means all), so it shouldn't be much of a stretch to convert it to a pond. How could I divert some of the other problems areas to this one site? Also, what kind of plants and trees should I use to help drainage around the property and around the pond specifically? I've considered purchasing a weeping willow, a bald cypress or a river birch, but I know there are other possibilities out there. Cost is a factor. I've got a giant dead mimosa that will be coming down soon (yet another reason for standing water--the 40 foot beast no longer sucks up the excess), and I do intend to replace it with a variety of water-loving trees, shrubs and plants.

If anyone has any ideas or tips, I'd love to hear them!

Comments (14)

  • Toronado3800 Zone 6 St Louis

    For native trees the common bald cypress, black gum (nyssa sylvatica), red maple trees do well with a good amount of water. Bald cypress and nyssa sylvatica's cousin the water tupelo (nyssa aquatica) even thrive with standing water or frequent flooding.

    I find weeping willows to be great for large enough properties but a tad aggressive ANYWHERE near water lines or basements. If your pond is 75 to 100 feet from your house though, go for it.

    Dawn Redwood is a cousin of bald cypress. When left to grow naturally they typically have a more buttressed look to their trunks which I love and they share a like for damp areas.
    Changing drainage patterns will be easy enough with lots of dirt to raise some areas. I really question if you can change the water table though.

    The best image I'm getting is a dozen weeping willows sucking up water for themselves and a few sump pumps shooting water from near your house into your pond.

    Here is a link that might be useful: a gardenweb tree forum conversation about standing water trees

  • rhodium

    Have you researched a french drain system for those parts of the yard you want to keep drier? These will work but your network would have to daylight to a lower point.

  • Embothrium

    So maybe the river hasn't moved completely away, it's just no longer covering the surface of the ground.

  • gillie_girl

    I love the idea of weeping willows. I think if we planted out on the property line it would be far enough away from any water pipes so as to pose very little threat in that department. I'd put the distance between 65 and 75 feet from existing lines. Plus there's an empty lot behind us that floods with heavy rain, too, so the willow's roots would have more than enough water to sustain it by pulling from multiple yards and extremely saturated soil. I'm considering planting a bald cypress on the other side of the property line. The property is abandoned--no house, just swampy lot. Even if I don't get to see the beauty of the cypress all the time, just knowing it's there doing its job would be a perk. I hadn't thought of the water tupelo--I'll put that on my list of trees to ask about from a few of our local nurseries.

    Like I said, there are perks to living on former river soil. You can't stick your finger in the ground without hitting an earthworm. I've never seen so many earthworms in my life as I have at this place! I've just decided that there's no sense in beating my head against the wall with this flooding problem. Why not turn it into a plus rather than a con?

    So far the plan is to just exaggerate the natural contour of the property. The spot in the back that seems to collect most of the standing water will be dug out to create a wider, deeper collecting pond. I suppose we'll line it--I've got no experience in creating ponds, so I'm kind of groping in the dark here. Water-loving plants, trees and shrubs will be planted in and around that portion of the yard to help cope with the excess water and to make the pond more natural. Will have to figure out something to prevent mosquitos, though--they're a huge problem around here. For me, the challenge will come when I try to force the other low-lying, easily flooded areas to divert their runoff to the pond site. I've considered french drains and adding soil (although sadly it won't be the same high quality that I've already got) to help with this, but I'm just fuzzy on logistics. I've never tried to undertake something quite so massive before.

  • duluthinbloomz4

    There are physical limits as to how much water any tree can absorb. Your willows, eastern red cedars, bald cypress and river birches planted in wet spots are some of the trees that wonÂt die when their roots stay wet for extended periods of time. But don't look to them to suck up and solve excess water problems.

  • isabella__MA

    Would these tree roots really want to go after your water lines, if they are already in a saturated zone?

  • laag

    Good call, Isabella.

  • gillie_girl

    Yeah, I wouldn't think they'd be apt to seek out water lines given the high water table and the frequent flooding. It's not really high on my worry list. I'm much more concerned with figuring out the logistics of the french drain and the creation of the pond. The planting of the willow or the bald cypress or other trees and shrubs will come after that and serve really as extra insurance against erosion since not much else would survive in that part of the yard!

  • pls8xx

    Last year Arkansas got a record 80+ inches of rain, normal average is around 45.

    Arkansas is a national leader in rice production. Land along the Arkansas River and other areas in the eastern delta region often have slopes of less than 1%. Rich silt typically overlies a more sandy layer at some depth. There will be both surface flows and lateral subsurface flows. The elevation of the water table can be influenced by the geology, which is different for the western and eastern areas, the transition occurring at Little Rock. Along the Arkansas River, it also matters if the land is near one of the navigation pools.

    West of Little Rock, the deep underling rock is Ouchita shale which is non- permeable with no aquifer to absorb water. The lateral movement of water can result in a water table along rivers that has little seasonable change in elevation.

    East of Little Rock, lies the Sparta Sand aquifer which has seen reduced water elevations due to crop irrigation. Here ground water is influenced by rainfall and seasonable agricultural use in the vicinity. The water table may tend to vary through the season. An exception to this variation might occur in areas near the navigational pools above the locks on the river on low lying land.

    Because of the lateral subsurface movement of water in these soils, the water table exists at a uniform level across wide areas and changing it is not economically possible. For small areas, it is probably best to raise the soil level above the water table with fill and give close attention to discharging as much water as possible though surface flows. With flat ground of less than 1% slope and no lower area to accept a discharge, precise grading is indicated. Subsurface drainage systems are almost sure to be a waste of money in this situation.

    Begin with a base map of the property with good elevation data and notes on any change in the soil profile to a depth of three feet. The elevation of the water table should be determined in several locations by the same method used to determine ground elevation.

    I would think long and hard before installing a pond. Not only is there the problem with mosquitoes, but this type habitat near the river is almost sure have snakes, one of which will be the venomous cottonmouth.

  • gillie_girl

    I'm just northwest of Little Rock, sandwiched between the Arkansas River and the man-made Lake Maumelle, very close to the infamous Ouachita Trail. I haven't done a proper elevation survey of the property (it's 1/3 acre), but it'd be extremely shocking to find if it varied more than 8" from highest to lowest point. It's unremarkably flat.

    The mosquitos are a concern. We have a resident bat colony that helps with that, but there are more mosquitos in this humid, swampy area than they can handle. If we do go through with this small collecting pond idea, I would certainly need to implement something else to keep the mosquitos in check. I'm well versed in the local critter population--I spent some time as a Park Naturalist with our state park system. The cottonmouths here stick very close to the river on one side or the lake on the other and haven't been seen in our immediate area. Rat snakes are more common, but I don't have any problem with them. There are alligator snapping turtles, owls, and just a few miles south of us they've even seen an alligator. We don't have a shortage of animals that prey on snakes. Not that I expect alligators in my yard, either. :)

  • pls8xx

    I'm about 30 miles south of you down I30. It's been 30 years since I was out near Roland. I seem to remember doing an assessment of a large farm tract just north of you off Snipes Rd. Lots of very flat ground. Probably not much more than 0.4% downslope to normal river elevation. Are you east or west of the RR tracks?

  • gillie_girl

    Well hey there neighbor. :) I'm west of the RR tracks, but just barely. The train rattles the house a little when it passes, but I don't mind that a bit. The .4% downslope sounds about right for the area. Just a little further west, only a mile or two, and you'll find more variation (and poorer quality soil--where we have earthworms every inch they have rocks), but here where we sit it's flat and rich. Blessing and a curse.

  • pls8xx

    That high ground with underlying rock may contribute to the the subsurface flows through your area. But a water table that doesn't get too high can work to your advantage. You only need about 8 inch depth of unsaturated soil for a great lawn. Gardens and shrubs will do better with a 16" depth. Maybe you should consider raised beds or low berms.

    Determine the lowest spot along your property boundary. Grade the land for a uniform slope to this spot to discharge an excess of rainfall.

    If you would like to demonstrate to the forum how to do a base map and design for this type situation I could maybe come up and help with collection the elevation data.

  • gillie_girl

    The only good thing about the heavy rains we've been getting this week is that it makes the low points in the yard extremely obvious. I can watch from my kitchen window and see which parts pool water first. The first is the spot I would have pegged for the future pond, anyway. Of course at this point about 3/4 of backyard is pretty well covered. The ground is beyond saturated and simply can't absorb any more water. I find myself praying for a mini-drought this year just so my yard can dry out and so that I can have time to address the problem! Anyway, I appreciate the offer, though! :)

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