Throughout most of the year, outflow from Garibaldi Lake occurs only via seepage through cracks in the lava dam, with Rubble Creek appearing from springs at the base of The Barrier.

The unstable lava formation of The Barrier has in the past unleashed several debris flows in the area below the lake, most recently in 1855-56 forming a large boulder field which gives Rubble Creek its name.

Concerns about the Barrier's instability due to volcanic, tectonic, or heavy rainfall activity prompted the provincial government to declare the area immediately below it unsafe for human habitation in 1981.

Collapse of the barrier has been speculated upon, and there have been suggestions of potential catastrophic downstream consequences, however, the "District of Squamish, Integrated Flood Hazard Management Plan Background Report" (PDF).

concludes that there has never been any suggestion in any scientific evidence that the Barrier will eventually collapse to the point of creating an uncontrolled release of Garibaldi Lake or cause extreme flooding in downstream neighbourhoods along the Squamish River.