We can see here that The purpose of the first paragraph in this case study is: E. to describe the reason for and approach to water quality improvement at Johnson Creek.
The first paragraph introduces the topic of water quality improvement at Johnson Creek and provides an overview of the reason for undertaking this project. In this case, it aims to provide an overview of the reason why there is a need for water quality improvement at Johnson Creek and outlines the approach or methods used to achieve this goal.
Additionally, it may outline the approach or strategies that will be used to achieve the desired improvements, which could include the construction of structures or implementation of specific techniques.