So it seems like the OP here is a High School student looking for a good long term project.
First, a few things.
- Awesome that you are interested in this! You are showing a level of curiosity and dedication to research/ecology that will take you far in life.
- I hope other posters here recognize this, and are as supportive as you have seen them to be so far.
- Not sure if your school conducts a Trout in The Classroom project, but you might want to look into it or even encourage your school to do that. You might even be able to reach out to a different school close to you who has one, and nag them to join it.
- Record things. Temperature, PH, and other cheap to measure variables. Keeping good records will help you, and not just with fly fishing.
- Keep at it, and do not give up.
- Seek a good mentor if you do not already have one.
When I was in high school I worked on a program that monitored and stocked Native Brook Trout in NE Ohio. It was a genetic strain that was very pure, and I managed a small hatchery for a summer and did GIS mapping of habitat for the naturally reproducing populations. This was about 20 years ago, and the program is not around any longer - but it had a dramatic impact on my life. It was run by a private school that I did not attend. I bugged the crap out of them, and had my school administrator call them. They eventually invited me to join the program for the summer, and even opened it up to other students from other districts. Being persistent, showing up, and having a positive attitude will make an impact for you.