Dillon Powers picked up a goal and an assist as the Galaxy's woeful form outside LA continued.
Colorado took the lead a few minutes before halftime. Hendry Thomas escaped his marker in the scrum to put his head into Dillon Powers' corner kick and send LA scrambling.
The Rapids picked up where they had left off after the interval, and in the 47th minute, Dillon turned from creator to finisher, running onto Edson Buddle's flick to catch LA on the transition.
The win means Colorado is now up to six games without a loss, and the Rapids now occupy second place in the West. The loss drops LA down to fourth. The Galaxy have lost their last seven games in all competitions not played at the StubHub Center.