3. To select watershed outlets, position the cursor close to the point(s)
chosen to be the watershed outlet. Hold down the left mouse button and
move the mouse to form a box on the screen around the selected outlet.
Release the left mouse button.
4. If a Point Source or Inlet of Draining Watershed was among the selected
points, a dialog box will report an error and the points will be unselected
(Figure 5.43).