What has reduced since the massive pollution control program for the Great Lakes was instituted in 1972? 

A)  algal blooms 
B)  the amount of fishing (sport and commercial)  
C)  swimming 
D)  the dissolved oxygen level

Cultural Eutrophication

The process by which lakes, rivers, or coastal waters become over-enriched with nutrients from human activities, leading to excessive growth of algae and environmental degradation.

Pollution Control

Measures and strategies implemented to reduce or eliminate the release of pollutants into the environment, aiming to protect human health and ecosystems.

Algal Blooms

Rapid increase in the population of algae in aquatic systems, often causing environmental problems.