Saw a duck with fishing line wrapped around his leg and he was limping from it being swollen. Does anyone know who or where to call so duck can be rescued and treated?

ACS doesn't deal with wild animals. You'll want to call Parks and Rec or San Antonio Humane Society (https://sahumane.org/wild-life)

Or try and catch it

LOL... thanks Viper... I did try to catch him because I desperately wanted to cut the line off of him but he wouldn't let me... limp and all he got away. Going today with my nail clippers and tiny nail scissors see if I find him today. And Mr. Oisten thanks for the advice. I've already sent email to the humane society & left message (thanks for the link)

I think animal care services.