Yes, it's civil, not criminal.
And cops have discretion. He's neither a surveyor nor a judge. It's not up to him to decide your property dispute, it's up to him to keep the peace (which, at that point, you were breaking).
Don't blame the cop for not doing SOMEONE ELSE'S job. As noted above, you need to get the city involved, let them prosecute for any civil ordinances, then file your own civil suit.
