Elevation is indicated on topographic maps by contour lines (Figure 1). Elevation can be measured by 10 ft, 20 ft, or even 100 ft intervals. The closer the lines are, the steeper the slope (Figure 2). When marking the high points of your watershed, the hills are the easiest features to locate (Figure 3). When connecting the high points of your watershed, be sure to draw your lines crossing the contour lines at right angles, even when the contours are rough (Figure 4).

V-shaped contour lines indicate a valley. The sharper the V shape, the more pronounced the valley. The point of the V lines point toward higher elevation or upstream (Figure 6). If you follow the V shaped contour lines uphill until they stop, you can assume this is the high point of your watershed. U-shaped contour lines indicate a ridge and point downstream toward lower elevation.