Another Lake Hefner question: the "inverted siphon" in the Bluff Creek canal?

[Joe Kimball]

When reading in the Oklahoman archives about the history of the then-Bluff Creek Reservoir, construction of the canal was almost equally mentioned, along with the addition of an "inverted siphon [syphon]" under the NW Expressway.

I can barely understand what exactly an inverted siphon is from searching online, much less figure how this would be relevant to the canal. Why not bridge the canal like it is elsewhere? How exactly does this work? Any idea who these days would know?

[Patrick]

Cheaper to just siphon the water down under ground in pipes than to build a large bridge for NW Expressway at that location.