Can you help me formulate a hypothesis for a healthy stream analysis?

As a class we collecta data with macroinvertabrates that was in stream. We tested the air temp 70*F, water temp was 11*C =52*F, measured the dissolved oxygen between 5-10ppm it was 11, we also seen color of water, measured the nitrate and phosphrous which was <1. We used the record data sheet to find our Groups 1,2,3 as Group 1 is listed as Organisms are Pollution- Intolerant which were gill snail, stonefly, mayfly, rifflebeetle, caddisfly, dobsenfly Group 2 is listed organismsm that are moderately pollution-Intolerant was crayfish alderfly, dragonfly, cranefly and Group 3 is listed as organisms are generally moderately tolerant of pollution which were midge and watermites. Including the physical and bilogical parameters. Please help me. I tend to over analysis too much!