Try a class and see if you enjoy it, including theory/solfege with "sight singing," if you want the challenge (you might like it), or a class on certain composers, or a music history class (American Music in Wartime is offered in our local university and covers Souza etc., or you could take classes on medieval/Renaissance, or classical composers, contemporary "new music," Balinese Gamelan, all kinds of possibilities).
My daughter is a music major but has discovered along the way that she loves art history. She takes a class in art history every chance she gets, but hasn't really worried about a minor. My son was a computer science major but took a lot of political science.
If your school has distribution requirements, and your environmental science major has a lot of requirements in sequence, it can be hard to find room, but whenever you have space for a class, you could take a music class.
Or, as others have said, you can continue to practice and take lessons and play regardless. But if you love music, you will probably enjoy some of the classes offered in the music department. So, maybe the best way to decide is to go ahead and take one!