[Talk-us] Creating a multipolygon of a body of water across state boundaries

[Will Skora]

I noticed that some islands within Pymatuning Reservoir
ttps://www.openstreetmap.org/#map=12/41.6074/-80.5203 , a large reservoir that
cuts across the Ohio and Pennsylvania borders for 8 miles, weren't
visible on the main map layer and was going to trace them.

The islands were tagged natural=land, what I recall was an outdated
tagging scheme. The water is consists of multiple adjacent closed ways
tagged 'natural=water'

I wasn't sure whether natural=coastline was the correct current
tagging for them, so I checked the wiki page and noticed that for
waterways and bodies of water (that aren't the ocean), to use a
multipolygon relation with tagging the islands as 'inner'

My hunch is that if I create the multipolygon relation across multiple
states, some state extracts [OHIO, PA] may not contain any of the
reservoir if I were to create one multipolygon relation for all of the
Reservoir. Is this correct?

What's the recommended course of action to satisfy consumers of OSM
data and mappers?

Regards,
Will