Eutrophication can be accelerated when human activity occurs in the watershed. If proper controls are not in place, pollutants from agricultural, urban, and residential developments can easily be carried into lakes and their tributaries.

Symptoms of human-induced (or cultural) eutrophication are:

• increased algal growth (stimulated by increased supply of nutrients);
• increased rooted aquatic plant growth (stimulated by the increased supply of nutrients as well as the creation of additional shallow growing areas via the accumulation of sediments, silt and organic matter); and
• lower dissolved oxygen concentrations in all or parts of the lake (as a result of increased plant respiration and the decomposition of organic matter by bacteria and other microorganisms. This lack of oxygen can kill fish and other aquatic life).

Although related, each condition nevertheless has a unique set of parameters that characterize its attributes. It is important to remember that sampling for one condition will not necessarily yield information about another. If, for example, a lake has an aquatic plant problem, a monitoring program that focuses on algae will not provide the necessary answers to solve that problem.

The reader should be aware that there are several other lake conditions that could be a potential focus for a management, monotoring and restoration program. Four notable candidates are:

• sedimentation on the lake bottom (reduction of water depth);
• sediment turbidity (reduction of water clarity as a result of suspended sediment);
• lake acidification; and
• bacterial pollution of bathing beaches.