As an aside to this, for us Luddites that still use paper charts, it is worth looking to see when the area was surveyed. There is normally a little map with survey dates on the chart somewhere.
If the area of interest was surveyed in 2016 for example, it is probably going to be more accurate than an 1876 lead line survey.
Firms like Garmin use the same data but augmented by their own surveys plus user data - crowd sourcing I suppose.
Apologies for the thread creep.