Newsletter and Technical Publications
Lakes and Reservoirs vol. 3
Water Quality: The Impact of Eutrophication
We are pleased to introduce Volume 3 of the Short Series on the “Planning and
Management of Lakes and Reservoirs”. The present Volume entitled “Water Quality:
The Impact of Eutrophication” provides an overview of the problem of the
enrichment of surface freshwater bodies due to organic compounds originating
from urban and agricultural activities as well as from industrial effluents.
Eutrophication is a process that once started is difficult to control unless
immediate action is taken. Eutrophication ultimately leads to the reduction of
oxygen in water, the release and accumulation of toxic substances in the water
and sediments-polluting the aquatic environment, which can lead to the death of
aquatic organisms, ecosystems and humans that may inadvertently drink or be
exposed to the polluted water. If eutrophication has already started it is very
difficult and costly to control or revert. Around the world there are some
eutrophied lakes, but the majority of the world’s lakes are not. This situation
is changing rapidly.
Waters in eutrophic lakes and reservoirs bring enormous losses of
biodiversity, reduced water quality and availability. Furthermore, such lakes
and reservoirs represent a significant health hazard for humans and animals
alike. This is primarily due to the explosive growth of microscopic algae which
once dead and in the process of decay release one of the most powerful classes
of toxins known to man: Cyanotoxins. Damage to electric power plants and
recreational activities are also well recorded as negative impacts originated
from these process cause large economic losses.
To control the process of eutrophication there is a need to understand the
causes and the stages of development. Similarly, it is necessary to carefully
assess and evaluate the technological solutions to be applied in the mitigation
and remediation of the eutrophication process. In general conventional
wastewater treatment systems are sufficient for the purpose although they tend
to be very expensive to maintain. Alternative methods of eutrophication control
and mitigation include the use of natural wetlands as well as constructed ones
since they are based on the capacity of self purification of nature and are
usually much cheaper to maintain and operate.
Eutrophication in many ways can be considered as a reflection in our lakes,
reservoirs and rivers of the careless way in which society is dealing with its
liquid wastes as well as the application of unsound land use practices.
Therefore, the society as a whole needs to be aware of the problem in terms of
health, finance, environment and recreation as well as the costs related to its
solution. It is expected that through this publication citizens together with
the authorities, industries, farmers and other members of the society can grasp
the principles of this process, the effects and remediation so that proactive,
co-operative action can be taken to prevent or significantly reduce the risk of
surface water bodies becoming polluted through the process of eutrophication.
We hope you enjoy it.
International Environmental Technology Centre
International Lake Environment Committee Foundation