About 4” of rain annually so it means we are 99% reliant on the snow pack. I understand what you mean about floodwaters with a dam in their path. It’s a concern potentially. This could explain the placement of the first pond requiring a diversion but which failed. A new construction, even in a more suitable place though would be difficult so I stick with what’s established relying on the precedent.
4" of rain is tough to work with, but I did demonstrate my regional bias. I should have asked about total precipitation instead of rain!
I do like the idea of a diversion of the stream to create your pond. If that was not well constructed or well engineered the first time, then you might be able to get a decent pond this time by doing it right.
The good news about only 4" of rain, is that a big flood in your creek is not very likely. You just need to design for the maximum flow rate you experience at the peak of the spring melt.
How long have you lived on the property? Just asking, to see if you have a good gauge on how "sporty" your creek is likely to get.