I looked at your photo and I am assuming that the area of concern is behind the dry streambed, since I cannot see the trunk of the willow. There are a couple issues to consider. If you add soil, you run the risk of smothering the roots of the tree. Even a few inches of soil spread on top of the root system of a tree can smother them, preventing air exchange from taking place in the original root zone. The fibrous roots that are currently near, or just below, the surface would be buried and you risk a slow decline or death to the tree. The same concern would be with adding a retaining wall and building up the bed. The other concern with the retaining wall is that to build it properly requires digging a footer for a compacted stone base. Digging that trench, roughly 4-6" deep, will cut off another large part of the root system as it extends from the tree. Without the footer, the wall will most likely shift and settle unevenly in the years ahead. The other concern with raising the area is that there is a wooden fence. If you raise the dirt level along the fence, ,it will cause premature rotting of the fence pickets. If you have a better pic of the area, I might be able to give you some other ideas of what to do. Try taking a pic while standing in the yard, so I can see under the tree.

Any progress on this issue? Do not add any soil to you property until you have a full drainage plan! ÃÂ Getting an engineer involved is advisable, but expensive, I know, I am one. :-) ÃÂ Consider these issues: 1. Drainage should take water away from the house, as quickly as possible, w/o flooding or causing erosion to you or others. Water near the house can cause many problems: ÃÂ movement near the foundation can move soil, which could cause the house to move. More immediately is the dry rot the moisture will cause to the wood of the house. Mold can form ÃÂ Maintaining any vegetation is a problem. Mosquitos will love it.ÃÂ 2. Adding fill material improperly could make matters worse.ÃÂ 3. Water always flows downhill. So, where is the water going. Try to follow it. The best way is to get the elevations of your property surveyed. I love the ability of a contour map to communicate slope of the ground. And water will follow the slope.ÃÂ 4. Decide on the outlets for water from your property. ÃÂ Drain water to the street, if possible. ÃÂ If not, build dry wells, but check percolation rates carefully. ÃÂ Be very careful about draining water on to neighboring property.ÃÂ 5. Find the sources of the water.ÃÂ 6. ÃÂ Create drain paths from (or near) sources to the outlets: There are several options to do this: (a) ditch, which needs a slope of at least 1%, 3 % is recommended; (b) Underground drain, such as a French Drain, which needs no slope, or a mini-storm drain pipe, which only it needs at least 0.1% slope, or combine French Drain and pipe; (c) pressure pipe,collect the water at a central spot and then pump the water. There are a lot of pages about all of these issues on the Web. This can be a big job.ÃÂ Good luck!

I think your only choice is to bury them deeper. You could do this by digging them up, removing some soil from below them, and re-laying them, or start to gradually topdress the area with topsoil (not "enriched" topsoil, you don't want much organic matter in the stuff as it will just break down) or sand. I personally would try topdressing first, especially since you have apparently already lost a bunch of soil due to runoff (which has probably accumulated into high spots further down the slope), so I imagine this would also improve the grading there. Spread a quarter inch of soil or sand over the area by shoveling it on and sweeping it in with a broom, once every two weeks. Idea is to slowly encourage the existing grass to adapt to the new soil level each time. A quarter inch is conservative, so if it looks like your grass can take more than that without getting stressed I would try that too. And while you're at it, do the same over every low spot in your lawn, if you have any. You'll love the results! Good luck, Paul

Aargh! So here's the latest: The waterproofing/drainage guys visited today. They said it was possible that the pipe is perforated and is somehow channeling underground water to one spot at the lowest point in our yard. They said it's also possible that the water is actually coming from the property next door with the massive new build (which is on the opposite side of the property from where the water is collecting, at a much higher grade). Either way, all they can do is excavate the pipe and see what happens next. They suggested it would be wiser and cheaper to have a handyman or landscaping firm do that. I put in a call to our lawn guys in hopes that they can do that. But what worries me is that the waterproofing guys said that if eliminating the pipe doesn't resolve the water pooling, any other solution is going to massively complicated and expensive (like, tens of thousands of dollars.) Our house is bounded on either side by other homes and by other homes behind us on a cul-de-sac, and there is only about an 8 foot side yard to direct any water out to the front of the street - and that slopes in the wrong direction. I feel a little sick about the whole thing. Yaardvarck, you asked about the house directly behind our fence. Without specific measurements, my sense is that our muddy spot is in fact the lowest point between our yards. The previous owners installed a row of pine trees on their side of the fence to shield the views (which we appreciated since they had painted the house neon yellow.) Do you see any other options for dealing with this? Spending thousands to dig up a pipe we didn't even know existed and doesn't appear to have a purpose seems painful, especially if that is not even likely to solve the water problem.