Goat Walker,
I'm sorry you are having this problem. I dislike irresponsible pet owners, as well.
First, I would caution against responding in a way that might get you in trouble. Wronged people sometimes do the wrong thing in anger and that can get you in trouble and take the focus off of her poor behavior, which she may feel vindicates her, compounding your problem. I have confidence that you are mature enough to determine which advice on here may be a joke or may not be the best course of action. Also, please don't fib or exaggerate to law enforcement as it will diminish your credibility and get you nowhere. You are within your legal rights and your best bet is to keep it honest and maintain your credibility. You may know all that already, but I'm saying it just in case. Sometimes even the things we know well will slip our minds.
That said, regardless of leash laws in your area, a dog owner is legally responsible for any harm that comes to livestock because of their animal and, in many areas, even chasing livestock without direct contact is still illegal. I would recommend checking not only leash laws and dog handler laws, but local livestock and property laws, as well. Others mentioned taking videos and pictures and that is definitely the best idea. Document every incident. The lady and her dog may have the right to be on the public right of way, but it sounds to me like she is trespassing.
Definitely document any harm that comes to your ducks, such as bloody feathers, and if you have to get veterinary care, keep the receipts and ask the vet for a copy of any notes regarding injury. If the issue does not resolve itself, you may have to call the police and that could escalate to court, particularly if harm comes to your ducks. Your best weapon is knowledge of the laws involved and solid documentation.
I don't know if you are a member of 4H, but if there is one in your area, they are likely to have some knowledge about the local laws pertaining to livestock.
On a similar topic, we get a lot of hunting dogs out where we are. You can tell the responsible hunters from the responsible ones. In my state, a hunter does not have to ask permission to come on your land if their dog is on your land, and hunting dogs are exempt from most other dog laws including those pertaining to trespassing. Hunters are, however, responsible for getting their dog off of your land. We are one of only a few states so liberal when it comes to hunting dogs. Despite the lax laws, responsible hunters let us know their dog has gotten away from them and ask us permission before coming on our property for their dog. The irresponsible ones simply leave the area without their dog and when we call them to fetch their dog they don't come. One likes to tell me to catch and hold his dog for him, which would be illegal and I could be charged with a crime for it. Fortunately, even though we live out in the country where leash laws are not strict, we do have responsible neighbors who take care of their dogs and we never have problems with pets roaming loose.
I hope this lady ends up seeing the error of her ways before the issue escalates. I wish you the best.
