New home grading in backyard soil stays muddy for days
First might I say..wow that's a big back yard. 

If it is a new home I'd get the builder to take a look. If it's heavy clay you, or they, may need to add a drainage trench, filled with rocks, out to the lowest point on the property line (Not the neighbors yard), then covered over with soil and turf.. 

I would not be too tempted to raise that area though. You want to keep the water AWAY from your house. The soil around the house will also settle with time so the higher it is there now, the better.