When we (I didn’t really participate being a noob at the time) imported the municipality borders back in 2012 from 2011 data from swisstopo what we didn’t really know at the time that that data was still very very much a work in progress. As we typically did our following annual updates much much earlier than swisstopo we relied on information from the BfS which in general was and is OK but certain aspects were not covered, for example as I noted in the relevant threads we didn’t catch certain cantons changing the way they handled lakes and municipality borders.
Now this one is the opposite, the 2011 dataset from swisstopo (https://www.swisstopo.admin.ch/dam/de/sd-web/8JnajYNPw9B0/swissboundaries3d-release2011-DE.pdf) extends municipality borders in to lake Zürich (and likely for the Greifensee too, haven’t checked that yet), but it seems that was never actually legit and in 2014 swisstopo (https://www.swisstopo.admin.ch/dam/de/sd-web/nJR36HzMz5ao/swissboundaries3d-release2014-DE.pdf) changed it to the correct, lake doesn’t belong to the municipality borders (except Zürich itself it seems).
As @habi is running QA checks on the borders now it would be advantageous to adjust the borders to follow the lake line as the swisstopo data set does to avoid false positives, but it could just as well be argued that nobody noticed to now so who cares. Then there’s the separate question if we should then add the fake municipality in just as swisstopo has.
Anyway for once a poll:
- Shrink munipalities to the lake boundary
- Leave as is