The ornamental design for a free-standing, multi-unit waterfall support structure with shelves, comprised from material of bamboo appearance, as shown.
FIG. 1 is a perspective view of a waterfall support structure showing my new design
FIG. 2 is a front elevational view thereof
FIG. 3 is a rear elevational view thereof
FIG. 4 is a right side elevational view thereof
FIG. 5 is a left side elevational view thereof
FIG. 6 is a top plan view thereof
FIG. 7 is a rear perspective view thereof; and,
FIG. 8 is an in-line perspective view thereof.
The broken line showing is included for the purpose of illustrating and forms no part of the claimed design.