In the 6 years that I've had this place I never had any submerged weeds growing in the pond. We renovated the pond last year, and this year Sago and American Pondweed reared their heads in late Spring, and I have no idea where they came from.

FWIW, it looks like Sago to me. I've never seen FA branch out.

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[Linked Image from lh6.ggpht.com]
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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).