What is this on a class A?

[OldFishStick]

Drove by a class A stream I fish quite often today,and decided to stop and check the water temp just for the fun of it,and after a few steps I ran right into this.

 

[Mike]

With your limited details, it’s hard to say. A stream name would greatly add clarity. At any rate, I’ll take a guess that that the entire stream isn’t Class A and that it also has a non-Class A, stocked section and that’s where you saw the sign.