PENZZZ, clarity and flow are not always directly related. Oftentimes they are, but not always. The advice you were given suggests that the river will be fishable. However, if low water clarity bothers you, it sounds like you may waste a trip. A murky river is not anything to fear. High and fast water is to be feared, at least to me, no matter how clear, just because of the added risk of taking a dunk or getting a reasonable drift.
In other words, an angler looking at guage reactions over a short period following rain might be able to guess at the clarity, but this is dependent upon their familiarity with the stream. Guage height or cfs alone will not predict conditions of water clarity.