Table-1 In which year lake-water spread area is more? Why? Why do you think weeds are more dense in the lake? What are the reasons for decrease in lake area? How do the above said reasons lead to pollution? What could be the reason for the migration of birds to this lake? How was the threat to the lake due to pollution discovered?
Being a profitable business, Aquaculture in Kolleru was started
extensively in the eighties which later spread to other areas in the Krishna
Godavari delta and attracted a large number of investors to the area. In
1996, almost entire lake was brought under cultivation and bunds were
constructed to keep water out to protect the crops. This diversion affected
the natural flow system of the lake. The water holding capacity of the lake
is also found significantly reduced.
n due course of time activities such as agriculture and industries came
along in ever growing intensity in the catchment area of the lake. Consequently,
the drains and rivulets carry substantial quantity of various types of pollutants
into the lake. The major sources of pollution are agricultural runoff
containing residues of several agrochemicals, fertilizers, fish tank discharges
industrial effluents containing chemical residues and different types of
organic substances, municipal and domestic sewage. Excessive nutrient
addition, especially from anthropogenic sources, led to explosive weed
growth. Ex: Eichhornia, Pistia (Eutrophication).
As a result, the water of the lake turned more alkaline in nature, turbid,
nutrient rich, low in Dissolved Oxygen (DO) and high in Biological Oxygen
Demand (BOD). Which had great effect on aquatic animals. Water borne
diseases like diarrhoea, typhoid, amoebiasis and others are said to be
