Hydrotools: Blanking irrelevant data out

[PhilippKlippert]

Hello
I have a Question. Right now I am using DGM Data and the Hydro Tool is working fine.
The Situation is:
I used the flow-direction tool. The result is absolutely fine. But now i need to relate the results to (for example) a lake. Can i somehow filter out only the relevant flow-directions that go towards the lake? All the other directions are not relevant, so i want to blank them out.
Thanks in advance

[DuncanHornby]

Upload an image of what you are trying to achieve.

[MarkBoucher]

Can i somehow filter out only the relevant flow-directions that go towards the lake?

If you have the fdr grid, you should be able to deliniate all areas that flow to the lake by creating a watershed from the lake outlet. This would give you a polygon. Then you can use a polygon of the lake to mask out the lake and result in the areas that flow to it.