Something shifted underground in our yard and we now flood after every good hard rain and every spring thaw (where we never had since 1962).
Long term, we added a lift pump station - 4" corregated pipe (wrapped so dirt won't fill it immediately) for 300' of our yards (neighbors too) up to and connected into the storm drainage system for our area. Cost - $25K for everything. Don't recommend this option unless you think this is a permanent situation - ours is.
Short term, we dug a 'dry well' pit (bought at Lowes? or Menards?) - it's like a black plastic garbage can with a fitted lid meant for long term installations. We dug out (in the muck, was a LOT of effort) 3' down and about 2' wide to fit this thing into the wettest, lowest part of the yard. Into the pit goes a Craftsman 1/2 hp submersible sump pump fitted out with 400' of corregated tubing - that's how far it is from the wettest part of our yard to the storm drain inlet near our street. Buy a Craftsman pump - keep the receipt - it's warrantied forever and when it goes out, you simply take it (the box and the receipt you taped to the box) to your Sears store and they hand you a new one, free.
Our pump is similar to this one:
http://www.sears.com/shc/s/p_10153_12605_08302655000P?prdNo=6&blockNo=6&blockType=G6
For our permanent installation, we dug 4" pipe to a couple different spots in the yard with a surface inlet, so any standing water is then sucked out by the Craftsman pump. Complete pain in the back. Call your chiropractor prior to starting this project! Don't have one? Get one before starting!
This is what keeps our yard dry enough to use year round, instead of being a cess-pool of mosquitos. Now, it's just a cess-pool for about 2weeks of the year. Ok. Maybe 4 weeks. But it's so much better, who's counting?!
