Western Riverside National Wildlife Refuge Act This bill establishes the Western Riverside National Wildlife Refuge. On the first acquisition by, or transfer to, the U.S. Fish and Wildlife Service (FWS) of any land, water, or any interest in land or water within the acquisition boundary of the wildlife refuge, the FWS shall establish the wildlife refuge as a unit of the National Wildlife Refuge System. The uses of the wildlife refuge shall include providing (1) opportunities for scientific research, environmental education, and fish and wildlife-oriented recreation; and improved access to nature for communities; and (2) engaging communities in fish and wildlife conservation, restoration, education, recreation, and outreach activities through the pursuit of urban partnerships. The wildlife refuge shall be administered as an urban wildlife refuge. No acquisition or transfer of property under this bill shall modify or revoke existing access to or use by affected Indian tribes, except as specified.