Mean error (ME) of the simulation of summer and winter epilimnion temperatures with the Ottosson modified model for different water body types (Q: quarry lake; P: pond; G: gravel pit lake; L: natural lake; R: reservoir) and LOWESS smoothing line over all data points (discontinuous line). In the summer data was available for 6 quarry lakes, 26 ponds, 27 gravel pit lakes, 63 natural lakes and 282 reservoirs; in the winter data was available for 4 quarry lakes, 4 ponds, 5 gravel pit lakes, 17 natural lakes and 89 reservoirs.