According to the Pueblo Chieftain, U.S. District Judge John Kane on Wednesday granted a request by Christo's company to intervene in the lawsuit.
Intervening allows Christo to protect his interests by joining the U.S. Bureau of Land Management as a defendant.
Rags Over the Arkansas River Inc., a group opposed to the Over the River project, sued BLM in February to block it.
There was no comment from the opponents.
Christo wants to hang six miles of luminous fabric for two weeks in 2015 above the river in eight sections along 42 miles between Canon City and Salida.
(Copyright 2012 by The Associated Press. All Rights Reserved.)