The best APPs is the Internet and word of mouth and some research. Don't go snowflake on is and expect the googler to spit out the info with one, one word search.
Look at fly fishing outfitters and see what creeks or rivers they are on and then look for campgrounds nearby.
Trust me, you can "steal" some great fishing for free where outfitters charge big bucks. Waters of a state are public property!
I'm sure there's a million unheard of fishing holes that you'll never find on the googler, only experience or word of mouth will get you there, but there are MANY places that are published.
Depends where you're looking but I can tell you a few in CO and MT if you PM me!
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