Is this based on local knowledge, or otherwise how do you know this?

At the Newell Hwy intersection here, I couldn't see any street signs on the street level imagery, and further south we don't have any street level imagery, so it's unclear.
It was originally named based on DCS data, which still records it as Sherriff. I have no local knowledge here but it appears this follows the original Sherriff street before the new bridge was built.

Based on the DCS roads data and DCS address data, Wambat Street only starts south of the lake.