Can't speak for northern states, but echo Shan's thoughts. I manage about 40 subdivision, neighborhoods lakes around Atlanta. Grass carp are a life saver for me. I must maintain the asethetic appeal of the ponds and lakes. If I had to use herbicides to consistently rid of weeds, I would be losing money. Also most use the lake as a source of irrigation making herbicide use restrictive. So what if all weeds are gone? (yes you are right it is an all or nothing soultion with grass carp) We place other types of manageable cover if a lack of fish habitats are a concern.

Doc, as far as your comment about testing to determine upstream nutreint source. This is great in theory, but how many times have you tested to actually determine this and then how did you reduce the nutreint loads from what can be several sources? Very difficult and extremely costly to do and you still may have "weeds". I work in reality. Weeds grow in most of these ponds because they have been sedimented in due to urban development resulting in a shallow area. Mix this with clear water and weeds will grow no matter what holistic appraoch you take.

Greg Grimes
www.lakework.com