Manual/Mechanical Control Options
This may be as simple as cutting a tallow tree or removing a few objectionable plants that have just gotten started along the water margin. While cutting and removing a few plants by hand can be effective in small and limited areas, mechanical aquatic weed control on a large scale is generally difficult and expensive.
One mechanical technique, called a drawdown (removal of part of the water), can be effective and economical in controlling many kinds of aquatic weeds. But there are many cases, such as in a natural system, where a drawdown is not feasible.
(Source: Mississippi State University Extension Service http://msucares.com/wildfish/fisheries/farmpond/mechcontrol.html)