Mark the correct statements.

There are thousands of artificial lakes in Finland.
Most Finnish lakes are shallow.

The water type of Finnish lakes is brackish water.
Many Finnish lakes have formed in depressions and pools created during the last Ice Age.
Some Finnish lakes have formed in meteorite craters.

Eutrophication causes a lake to lose water.
Eutrophication is caused by nutrient accumulation.

Sewage treatment facilities use mechanical, chemical and biological processes to clean waste water.
Groundwater is usually of a very high quality.