A quick Google search shows the definition of Green Space -

"an area of grass, trees, or other vegetation set apart for recreational or aesthetic purposes in an otherwise urban environment."

California is the "Golden State" because of the golden color of grasslands as the Spring-time green phase dries up. That should qualify as "other vegetation". I hope the software could be more inclusive.

This is quite nice. One suggestion I will offer is to have an option control color-based grading. This could for example allow for a grey scale. Could be useful for people with various forms of color-blindness.

Best of luck with the competition.