Is it crucial in college admissions to take 4 years of language? I’m currently taking AP Spanish language this year anyways and would want to replace my language class with AP Environmental.
If you are taking AP language you’ve reached level 5 so you’re good and can take whatever you want next year. 
I concur…it is more about getting to the 4th level of a language.
Make sure you have taken Bio, Chem and Physics
Yep, AP Spanish is considered Level 5, no matter how many years it took you to get there.
For anyone else listening, the number of years of foreign language you need depends on the recommendations of your targeted schools. This usually entails taking three or four years of foreign language, although it is possible to apply only to schools that only recommend two years (but let’s face it, it’s not like the a bunch of the other applicants haven’t taken four years anyway, which would still make them arguably more attractive).