Normally it would be worth five points on a mellow day with some fish present. Another thing to look for is shade. Shade kind of ties in with season and temperature. Midsummer, high temperature days, it is something to look hard for. Shade can be worth from zero to ten points.
Flow is the volume of water that is moving past a given point in the river.
It is measured in cubic feet per second or per minute. Both the width and the depth of the river influence the speed at any given location while in a situation such as mine, where there are dams both above and below where we fish, the dams control the flow. The flow is always downstream. There is a value there, I just am not smart enough to be able to quantify it. Islands are another factor.