While some aquatic plants are needed in a Lake or Pond for a healthy fishery, controlling them so they do not become lake or pond weeds can be a challenging task. Many times a lake or pond owner will start by using a chemical treatment. We are accustomed to running to the hardware store to get a herbicide to handle our dandelions in the yard, so this seems to be a logical place to start. 

Another problem with chemicals is that the plants that were killed with each application drop to the lake or pond bottom. While the initial decomposition pulls oxygen out of the water depriving the fish, the nutrients contained within the plant are released back into the local ecosystem. This in turn feeds the next generation of plants and possibly and algae bloom that takes advantage of the lack of competition. The next generation of plants is now a little resistant to that chemical as they were exposed but survived. The next time that chemical is used, more is going to have to be used to get the same effect. Much like a drug addict, your pond is now hooked and will need more over time and costs will go as product needed goes up.

Applications of herbicides, pesticides or other aquatic chemicals are a very useful tool for SHORT TERM CONTROL of aquatic plant growth. They do NOT, however, address the underlying problem that is causing the unwanted growth. They are best used to keep an ecosystem under control while targeting the root problem and improving the conditions that are causing the problem.

One very successful option is to harvest those lake and pond weeds mechanically. As the growing season begins the plant grows absorbing nutrients, producing oxygen and providing great habitat for the young fry just hatched. Once the growth level nears your desired level manual harvesting can begin. This can be done manually in small scale or with an aquatic plant harvester for large scale applications. Removing the nuisance and with it the absorbed nutrients from the bottom material without adding to the bottom muck. There isn't any oxygen deprivation as there is no material decomposing at the pond bottom. As with chemicals, this will have to be repeated throughout the growing season but usually not as often and it does not leave residues behind. Leaving some plant growth in areas keeps the fishery in good order and buffers the water column from wild swings and algae blooms.

There are many tools in the pond owners' bag to deal with lake and pond weeds. Consider your ultimate goals in determining which management technique you wish to use and remember that short term success does not always mean a long term triumph.