Drain laws vary, but you may be able to get the tile run around your pond so water will not end up in it at your neighbors expense. However, you will lose that watershed. If a sediment pond is more desirable for you, and cheaper than the drain extension, your neighbor may go for that. Yo should find out the drainage laws and then talk to your neighbor to see if you can both work things out before involving others. The NRCS may be able to help with the water drainage laws.
