I am looking to constrain my contour map attached within this discussion post to only the river system within the map for the parameter controlling color. I understand that adjusting the alpha may constrain the area, but it does not accurately reflect the river system. An example of what I want to accomplish is attached within this email.
The clip shape can be applied to any segment. Use right-click->Customize to figure out which segments you want. Above I made a triangle clip around three cities in NC. The path string is easier to read than the matrix.