That depends...........
How much do you like accessing your pond from the shore?
If you only think you want them in a certain area, fergettaboutit.
A fellow PB'er 2 years ago said "I want them to help control soil erosion. They can't be that bad, any that start growing out of place I'll just pull out."
This year he hit them all multiple times with a glyphosate product to eradicate all of them. He couldn't keep up with their spread, and they were hiding and attracting muskrats, which started to tunnel into his dam.
Right Mikey?