Dorf-1 Vignette Question

[Archer40]

1st Try on Dorf-1 Vignette, any comments will be appreciated!

Question: when the section A-A line cut part of the lake within the property line, should we show the grade as FLAT for this portion? (because the water is flat). Or should we only show the grade on the ground (as shown on my solution attached)?

Thanks for any answer!