Document, Document, Document!!!!
It sounds like you have a stong case against the develper and you need to file against him to be sure he does what's right. I don't know the exact law, nor where to find it, but it is illegal to divert the natural flow of water onto a neighbors land. He is liable for all damage he causes because of it, and then some. Making this happen might be as easy as talking to him and having him make it right, or it will take the legal system to force him to do so.
A few things to consider is the developer might not be as strong financially as most people think. Allot of them are operating on a shoe string and just a few mistakes away from bankrupcy. A good example is the development where the HGTV Dream Home was built here in Tyler. The develper is a fairly big name here in this area with quite a few developments successfully completed. This time they got in over there head and it didn't turn out as they had expected, which lead to bankrupcy. The development is pretty much at a standstill because of all the legal battles and lack of interest in anybody buying anything there.
If you file a lawsuit against the developer, you might cripple him and be worse off then you are now. Of course, you will be able to put a lien on the entire development and force him, or whoever owns the development to satisfy your lien before they can sell a single home. That's a good incentive for them to make things right.
I would consider having them pave your road, expanding your pond and replacing your fence.
My wifes uncle let the county use one of his roads to access a pipleline they were installing. They tore up the road and he told them to repave it before he'd sign off on it and relieve them of the bond they had to post before he allowed them access. So far, they have paved half of it.
Be sure your lawyer has actual experience in this. Most lawyers will take any job you give them, but not have a clue about what they are doing. The right lawyer will get you everything you want, and the wrong one will be a money pit and accomplish nothing.
Do not rely or expect any help from a government agency in this. You might get somebody out there to listen to your complaint, but at the very most, all they can do is stop the developer from proceeding until he improves or changes the runnoff issue. Fixing the damage to your land is not what they do, nor can they force the developer to do so.
Good luck,
Eddie
Naturally, a lot of people inquired about that and learned that what it really meant was that you needed the county's approval any time you altered the topography in a manner that would affect storm water flow.
