As part of a cost-savings initiative, an existing course of 'introduction to environmental engineering' offered using a 'traditional' format of didactic class meetings supplemented with hands-on laboratory sessions, was changed significantly. The 'modified' format uses 'blended', 'flipped', and 'mastery' approaches to teach "2601: Fundamentals of Environmental Engineering" to approximately 60 sophomores pursuing baccalaureate degrees in environmental, civil, or architectural engineering, each semester. This paper presents a summary of the results from eight course offerings over a period of four years to more than 450 total students. Assessments included student grades; open-ended invitations for anonymous feedback at the end of each semester; anonymous, online surveys at a mid-point and at the end of each semester; the results of a common quiz administered in the first week of a follow-up course on water and wastewater treatment; and in-depth, qualitative feedback from a selection of high-performing students collected during face-to-face interviews during a follow-up course of independent, undergraduate research. In brief, a portion of didactic class meetings was replaced with prerecorded, online digital lectures providing students with an opportunity for asynchronous, self-paced learning. The remaining twelve, 'required' face-to-face, inductive learning sessions promoted improved learning in the cognitive domain and introduced learning in the affective domain. A flipped-classroom coupled with a modified approach to mastery-learning 'required' students to review instructional content before meeting face-to-face including: a) reading the textbook; b) watching pre-recorded, online digital lectures; c) mastering online quizzes; and d) submitting written homework. All students who completed all 'required' assignments before the published deadline were assigned a grade of 'C', for the course. Students who completed additional 'optional' assignments had the potential to earn a grade of 'B' or 'A', for the course. The take home messages for this paper include: (1) a substantial initial investment of time may be needed to create course content using blended, flipped, and mastery pedagogy; (2) group and individual written work, oral presentations, and essays can be used side-by-side with quizzes, a midterm exam, and a final exam to create an 'all-you-care-to-eat buffet approach' to earn grades; (3) implementing a 'one miss' policy for 'required' assignments helps to lower student anxiety over grades; (4) costs were reduced and student learning was maintained through blended, flipped, and mastery pedagogy; (5) many students enjoy the new approach because they appreciate clear expectations and a flexible course format; (6) some students strongly resist the modified format; and (7) a willingness to persevere despite trial-and-error is necessary as students adapt to the new approach.