The path to professional licensure normally begins with students graduating from an engineering degree program accredited by the Engineering Accreditation Commission of ABET. Typically in the final semester of their undergraduate education, students take the 5.5-hour Fundamentals of Engineering (FE) exam. All engineering students take a "General" exam covering fundamental topics such as chemistry, calculus, and thermodynamics during the morning. In the afternoon, there is a subject-specific portion for Environmental Engineering. 
After 4 years of practice under a licensed Professional Engineer (PE) and often further coursework and a Master's degree, engineers take the PE exam. Environmental Engineering is a recognized specialty on professional engineering licensing exams.