SVG file won't fill, only outline

I’m trying to get an SVG file (the outline of a lake) to Fill (carve out the lake) and it won’t show up on the preview, so I’m not sure it will cut…I can outline, but can’t fill. Any suggestions?

Could you share the file?
What did you create the file in? Could you fill it in that program?

The lake shape is probably not closed, check your object nodes.

That seemed to be the problem. Thank you!