I've noticed that maybe two days after heavy rainfall that my small 500sqf back yard is still saturated with water to the point where I get mud on my shoes just walking back there. I have low cut grass and a bunch of weeds I'm trying to get rid of but I was wondering if this is normal or if there's anything I can do to fix it.
I've also noticed that water is pooling a few yards away behind my fence.
In general (until you provide some details/pictures, the best I can do) you can probably improve the situation with drainage tile (aka pipe) (perhaps aided by stone and filter fabric) from your yard area to the low spot behind the fence where water pools, if nothing else - presumably that is lower than your yard if that is where water pools. Slope the pipe at 1/8 to 1/10" inch per foot (1% slope, 1 cm per m) to drain water and carry any silt with it - excessively steep or too flat pipes plug with silt eventually.
My personal experience suggests using rigid pipe that's perforated with two lines of holes - the flexible/corrugated stuff with slits all over it seems more prone to problems over time. The holes go on the bottom (at roughly 5 and 7 o-clock, or perhaps 4 and 8 o-clock, if you imagine the end of the pipe as a clock face) - it prevents dirt from falling into the pipe and maintains a lower water level in the trench - yet there are still people who insist on putting the holes up, since they think it "helps water fall into the pipe" which couldn't be more wrong, or that putting the holes on the bottom will make the pipe "leak" - people just are not used to thinking of the role that perforated pipe in the ground plays, and it leads to some bizarre ideas as a result. I used to walk by a lovely display case in an agricultural engineering department where they tried the holes in the pipe several ways (and then carefully extracted that chunk of ground, pipes and all) to help cure these myths, but I have not found that on the web.
One icky question does come to mind (though it seems unlikely with only 500 sq ft) - you don't have a septic system, do you? (i.e. are you on a sewer system?) A failed septic system can start to show up this way, so let's eliminate that possibility if it can be eliminated - draining surface water won't help that one...
