Birdlady, if the pond is drained, you will likely need to remove some bottom sediments to get the desired results. Plus, the source of the pollution must be stopped. Speaking as a pro, I think you need some hands-on advice from your home base. ewest, on this forum, might be able to offer some thoughts how to handle this.
My gut reaction is for you to build the swimming pool, if you can afford it. It can be designed and built for the specific reason. The pond will always be a pond.
