“I bought a an acre and a half with a 30 foot easement with a ditch on my side of the property line that goes from the road to a canal. The parish of Iberia were I live was going to build a road that would have gone between our lots and the easement was 60 foot but they decide to do away with that easement and went with the 30 foot drainage easement on my side of the boundry line. I want my nieghbor to remove a septic drain line that runs onto my side into the ditch. Do I have the right to make her remove it. She has no easements on her side.”
There are at least a couple of reasons why your neighbor might have the right to maintain her septic line.
First, if she has some sort of documented right (an easement or otherwise) allowing her to do so, then of course she would be allowed. But also, the fact that a government agency has an easement may (depending on the nature of the easement) allow members of the public (including your neighbor) to make use of the easement to some degree. You would need to refer to the easement grant to the parish to determine this.
Second, even if your neighbor has no explicit right to this use, the fact that she has been using it may eventually mature into a legally-protectable right. This is known as a prescriptive easement. In order to get a prescriptive easement, someone needs to make use of property not their own, openly and notoriously and without permission, for a specified period of time (the period varies widely from state to state). Barring either of those, your neighbor is unlikely to have any right to continue this use.