If a pool extends upstream into the structure, where do you take the pool entrance depth? Also, where should the "distance from hydraulic control" question be measured from? From the pool entrance (inside structure) or at the outlet?
Edit: Clarity
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The purpose of the parameter "Pool entrance depth" is to describe the distance a fish would need to leap in order to enter the culvert for the AOP score. I suggest measuring from directly below the outlet for simplicity sake and safety (you cannot enter the culvert). I would recommend doing the same for measuring hydraulic control distance- just use the outlet as you endpoint. Add in the comments that the pool actually extends into the culvert itself and use your range finder or a visual estimate to include that additional distance. Is the outlet backwatered then? Be sure to select that option for "outlet grade".