We ran into a situation where we could not measure the total height of an embedded concrete culvert pipe due to the presence of large cobbles/gravel in the pipe and the depth of the stream at the culvert inlet. We attempted to use the depth rod like a rock bar and move some of the cobbles out of the way but it was a futile effort. What do you guys recommend doing in these types of situations? Estimate height? Leave blank? We will make sure to leave detailed comments in any scenario.