Wivell...
Water can't flow up-hill unless there is a pump pushing it. As long as the source of the seepage is above the waterline of your pond, it won't flow backwards. If it was me, I would leave the spring be for now and see where your pond tops out at. It could be a good way to ensure that you keep a full pool. If it becomes and issue, drain off 5-8 feet of water and try to fix it.
