<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">One other thing to be aware of — does “boundary is the river” necessarily mean the centerline of the river? There are many cases where an island in a river belongs to one town or another (typically the closest), but the island extends across the centerline of the river. Or to take a more extreme example, in the 18th century New Hampshire argued with New York over control of Vermont, settled in 1764 when NY agreed to place the boundary at the west edge of the Connecticut River 😀. And then in 1933 it was made clear it’s at the low-water mark: <a href="https://supreme.justia.com/cases/federal/us/289/593/" class="">https://supreme.justia.com/cases/federal/us/289/593/</a>.<br class=""><div><br class=""></div><div>— Andy</div><div><br class=""><blockquote type="cite" class=""><div class="">On Jun 11, 2020, at 4:11 PM, Greg Troxel <<a href="mailto:gdt@lexort.com" class="">gdt@lexort.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Leaving aside the consensus process and alignment, I see two points as<br class="">both quite valid, although contradictory:<br class=""><br class=""> Wayne's point that the MassGIS dataset is the data of record for<br class=""> boundaries<br class=""><br class=""> Yury's point that for boundaries that are defined by rivers, when the<br class=""> actual river location is clearly different from the MassGIS data, OSM<br class=""> should have data that is more accurate<br class=""><br class=""><br class="">In thinking about this, I have a number of questions that I think need<br class="">answering:<br class=""><br class=""> (There is probably some datum fuzz going on, in terms of NAD83/WGS84<br class=""> confusion, and I'm trying to figure that out for other reasons. We<br class=""> should keep that in mind, but I don't think we are getting things<br class=""> right at the sub-meter level and I think that the mismatch from<br class=""> MassGIS data and imagery that Yury is pointing out is well more than a<br class=""> meter.)<br class=""><br class=""> In MA, only licensed surveyors can "authoritatively determine"<br class=""> municipal boundaries, says MassGIS. I suspect that this is in the<br class=""> same sense as determinging parcel boundaries, not drawing them on a<br class=""> map and am willing to go with that interpretation.<br class=""><br class=""> Town boundaries are set by state law. We're a bit out a limb here as<br class=""> far as really looking up the statutes and/or things in the Atlases.<br class=""> I'd like to pick a good example -- perhaps Yury can suggest one --<br class=""> where the river is quite different from the MassGIS data. But the<br class=""> MassGIS data is coded to say 'boundary is the river', and I don't see<br class=""> any reason not to take that at face value.<br class=""><br class=""> There is some notion of "center". Law is complicated about that and<br class=""> we should understand what it means. My fuzzy understanding (not to be<br class=""> used for reasoning) is that center in MA means the points equidistant<br class=""> from the shore/water line when the water is at "normal" height. If we<br class=""> use imagery, that leads to another meter or so of fuzz (unknonw<br class=""> height) on top of the imagery datum fuzz and the imagery alignment<br class=""> fuzz. I am ok with not worrying about this, because we are delusional<br class=""> about better than 3m absolute accuracy for tracing river centerlines<br class=""> anyway. I suspect we can achieve 5m.<br class=""><br class=""> Town boundaries are very much a thing dealt with by the selectmen of<br class=""> the two (or more) towns. While being defined in statute, each town<br class=""> has an obligation to visit the stones, and if any are missing, to<br class=""> jointly with the other town straighten it out. So I really wonder if<br class=""> there is some record of the water boundary that is agreed to by the<br class=""> two towns, or not. I am guessing not.<br class=""><br class=""> MassGIS seems to have just drawn lines from imagery. If so, then<br class=""> their drawing isn't necessarily any better than ours. But it is easy<br class=""> to ask if there is more to it. I will write to them, and report back.<br class=""><br class=""><br class=""><br class="">If anyone knows people in town governemment in a town with a river<br class="">boundary and is willing to call them and ask how this really works, that<br class="">would be really useful. My town doesn't have river boundaries (there is<br class="">a lake, but the boundary is set by coordinates in law). Besides, if<br class="">anyone called my town and asked a question like this, the town would<br class="">tell them to call me :-)<br class=""><br class="">Greg<br class=""><br class="">_______________________________________________<br class="">Talk-us-massachusetts mailing list<br class=""><a href="mailto:Talk-us-massachusetts@openstreetmap.org" class="">Talk-us-massachusetts@openstreetmap.org</a><br class="">https://lists.openstreetmap.org/listinfo/talk-us-massachusetts<br class=""></div></div></blockquote></div><br class=""></body></html>