The U.S. Environmental Protection Agency(EPA) offers a free online Water Quality course.   

The following modules are included:

Introduction to EPA and the Clean Water Act,
• Waterbody Uses,
• Water Quality Criteria,
• Antidegradation,
• Standards Submittal and Approval, and
• Variances, Using Attainability Analyses, Mixing Zones and Other Flexibility Options

The course is interactive and includes links, video clips and quizzes.  It’s designed for people who are NOT water quality experts, though people in the field may find them a good refresher.

To sign up for the course click on EPA Water Science Academy