Nick Rimando earned his 76th shutout, tying Zach Thornton for second on the MLS list.
Real Salt Lake (4-0) has won 18 consecutive regular-season games, moving within one of matching the MLS record. It faces Portland on April 30 and hosts Chivas USA on May 7.
RSL extended its home unbeaten streak against MLS opponents to 27 games, winning another close match against the defending MLS champion Rapids. Four of the previous six games between the two rivals had been decided by a goal scored after the 88th minute.
Javier Morales set up Espindola when he fired a shot that bounced off the right post. Espindola emerged with the ball after a scramble and sent the winner inside the post.