A) Make sure you're taking necessary steps to prevent mosquito infestation
such as fish and even BT.

B) Tell your neighbors to pound salt.

There are thousands upon thousands upon thousands of ponds in residential
communities throughout the US. As long as you are caring for your pond
properly, there's no issue. They can complain all they want but it's no
different than complaining that you are responsible for the alien abductions
in the neighborhood. (It's not you, right?)