The control zone is very accurately described in the ODFW book. It uses a combination of buoys, jetty ends and latitude and longitude. It's cryptic, but here's a picture.
Not sure, but the CR buoy is called 'spark plug' because that's what it kinda looks like. It's labeled on the chart as:
RW 'CR' Fl 2.5s strobe Mo(A)
Red and White named CR with a strobe light flashing Morse Code "A" every 2.5 seconds. A slow spark plug, but I can see the connection.