Last season's Supporters' Shield winners will miss out on the postseason, while the two-time defending champions are in.
The Galaxy had goalkeeper Jaime Penedo to thank for keeping the match scoreless in the first half, as the Panamanian made a string of impressive saves to ensure the match entered the break at 0-0.
The game opened up in the second half, as San Jose pushed for the goal which it needed to keep its postseason hopes alive. Quakes goalkeeper Jon Busch made a stellar diving save on a Marcelo Sarvas volley to keep his team in the game late on.
Despite pushing frantically for the last 10 minutes, the goal never came for San Jose, and last season's Supporters' Shield winners will miss the playoffs without a double-digit goal total in next week's finale against FC Dallas.
With the result, Seattle clinched a playoff berth, despite losing four straight matches, and Colorado is also now all-but-qualified.