"bio, chem, and physics" - YES, all three, and MATH. The more of those types of courses you can take now will prepare you for university level courses that lead to a degree in environmental engineering.
Environmental engineering will require you to effectively integrate principles from bio, chem and physics, with math skills as the language to help put them together. I've heard folks give another name to environmental engineering - poo poo engineering - your will primarily deal with wastewater management. Bio is important to know what microbes will help digest the sludges from wastewater treatment, and what environmental conditions must be maintained to keep your microbe populations where they need to be.
Chemistry is important as chemical treatment is often important to wastewater treatment. Physics helps you with understanding energy transfers that occur, the thermodynamics involved with the varying masses/quantities of materials that you'll be treating. (e.g., chemists deal with molar quantities, chemical and environmental engineers deal with what has sometimes been described as mole-tons, many orders of magnitude more.)
Those are just some of my thoughts.