I'm going to have to check on the pond during the storm since this is going to be this first real test of durability for the dam and the overflow pipe
I went out to our property with a bunch of the little survey flags that last time we had major flooding. (The creek went at least 6' over the bridge on the county road.) They are like $9 for a 100 at Menards, and I always keep a few in the truck to mark herbicide test sprays, etc.
It was very handy to mark some edges to the creek floodplain so I wouldn't build anything there. Also nice to see the exact locations where my waterways run in the fields if I ever need to catch (or divert) that water in the future.
It might be worth if for you to do some marking on your property, where the water will show some exact survey "levels".