................ er ............. always loathe to butt in when DrainBabe is on the case, but there is one circumstance when they may not be your responsibility........... if they are a main sewer and/or storm drain, in which case they'll belong to your local Water Authority.
You can ring them and ask for someone to dig out their drain map of the area. They'll tell you right away if they have adopted them.
Excuse me going off topic Lanky, but DrainGurl, what happened to your new job?