If a neighbor re-graded the property that causes run-off to flow to your property, you may have a suit for nuisance and may seek injunctive relief.
If the shade violates a city building code, file a complaint with the local code enforcement officer.
I am not a CA attorney, laws vary from state to state, therefore you should always consult a local attorney.
If this answer was helpful, please mark it as helpful or as a best answer. This answer is for general education purposes only. It neither creates an attorney-client relationship nor provides legal guidance or advice. The answer is based on the limited information provided and the answer might be different had additional information been provided. You should consult an attorney.Ask a similar question
Mr. Millar gave you good advice. I would add that the letter you sent to the broker will have to be disclosed to the new buyer. Your best and cheapest bet is with the complaint to the City. As for the water issue, I would say that you sue both the new and old owner and let them hash it out. But I suspect that the issue will probably get resolved before having to do that, because the new buyer may force the seller to fix it.
I will caution you however, to make sure that your claims are well supported, since the seller could sue you for interfering with their sale.Ask a similar question