If you stop in Concord at the DES office they will give you lots of advice and hopefully some mylar tape and scary eyeball balloons (beachballs with reflective tape) that may help. We have been battling the geese for years and have tried everything. The best defense is a low fence of fishing line. Hammer in a post every 10 feet and string heavy fishing line from post to post. The DES folks will explain why this works. I seem to remember that geese do not fly during summer months and can only walk on shore, so the fence really helps. If you can make your property undesirable enough they will not visit. Good Luck!
http://des.nh.gov/organization/commi...ents/bb-53.pdf