How to choose my major based on what I wanna be?

I am from Texas, and I am looking into a degree that will help me pursue a career in working with water. No, I am not talking about water that comes from your sink. I am talking about preserving the natural springs. All my life I have grown up around natural springs and rivers (for example: San Marcos River, Barton Springs, Etc.) and I have enjoyed all the experiences I have had with these waters. I am not sure on what kind of degree I should be going for though. For the job I am seeking, I am basically looking to take samples of the water, researching the water (for chemicals, pollution, etc.), preserving the natural wildlife and surroundings of these waters. If anyone could give me some advice or more info I would appreciate the favor. Thanks.