Welcome to the forum!

While this isn't for bridges, this might give you a starting point.

https://www.awc.org/codes-standards/spantables/tutorial

What will you be using for columns and how will you be installing them in the pond?


www.hoosierpondpros.com


http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).