In exchange, the Rapids sent one of their two third round picks in Thursday's MLS SuperDraft.
Harden, the Galaxy's 2007 Defender of the Year, did not play in 2008 after electing to step away from the game to pursue philanthropic endeavors last February.
A second round pick in the 2007 MLS SuperDraft out of the University of Washington, Harden appeared in and started a then-rookie record 24 games for the Galaxy in 2007, playing 2,086 minutes for the Galaxy, which were the second most on the club that season.
Colorado now hold six picks in the 2009 MLS SuperDraft.
The first is in the second round, the 20th overall selection, with another in the third round and four in the fourth and final round.
(Copyright 2009 KUSA*TV. All Rights Reserved. The Colorado Rapids contributed to this report.)