The Silvan Outflow Aqueduct ran through tunnels where major roads crossed: under Monbulk Road at Hazel Street, and under York Road just below Mount Evelyn township. The tunnel and channels were periodically emptied for cleaning and checking while the Aqueduct was in use.

A tunnel in the McKillop area was probably Aqueduct-related. Located close to the junction of the Silvan Outflow Aqueduct (built late 1920s-early 1930s) with the older O'Shannassy Aqueduct (built 1912-1913), the tunnel was most likely an outlet to allow for a section of the O'Shannassy to be drained for maintenance. This theory is supported by a cryptic comment among research notes for the Mount Evelyn Primary School history: 'bore – drainage spot – caves underneath 60' deep – tunnel comes out nr creek’. Part of the tunnel collapsed in 2009 and was fenced off for safety reasons.

The Aqueduct tunnel under Monbulk Road. These photos (and the top photo) were taken by Mount Evelyn Primary School former Principal Phil Comport on the Aqueduct land next to 2 Hazel Street about 2008.