Details about lake Geneva can be found on www.cipel.org and, of course, https://en.wikipedia.org/wiki/Lake_Geneva.

The data are a subset of variables from three extensive sampling periods in 1978, 1983, and 1988. Units of metals are in ppm (mg/kg).

Regarding observations from 1978 and 1983:
  - There are duplicate observations (e.g., obs 69,208).
  - To align the data from 1978 and 1983, remove observation 118.

Regarding observations from 1988: there are some wrong location encodings:
  - Obs. 16 should probably read (505,127)
  - Obs. 74 should be close to (514,144)
  - It is unclear to me where to place 199.
  - The locations show a noticable difference between the published ones.