Pond Boss Forums INTRO Questions & Observations What Made These Nests............???

I walked down to the pond today and observed these nests. They appear pretty large. See the 6" ball point pen for reference.

What made them??? I have CNBG, BCP, LMB.

FWIW, the pond is 15"- 20" low





I found some smaller ones on the opposite side of the pond but didn't get pictures of them.