Question

A lake with an inflow of domestic sewage, rich in organic waste results in

• A. drying of the lake soon due to algal bloom
• B. an increased growth of fishes due to lot of nutrients
• C. death of fishes due to lack of oxygen
• D. increased population of organisms of aquatic food web

Answer 1

The correct option is C

death of fishes due to lack of oxygen

An inflow of sewage rich in organic nutrients, into a lake results in eutrophication. The nutrients present in domestic sewage leads to biological enrichment of the lake and a dense growth of algae. The algae utilises the dissolved oxygen and deoxygenate the water which will lead to death of other aquatic life forms. Lake dies eventually over a span of several years.