There is a method for glycol in oil using derivatization and headspace analysis, but I haven't had a chance to try it on water:
http://www.perkinelmer.com/Content/ApplicationNotes/FAR_GCEthyleneGlycolInEngineOil.pdf
Their 'derviatazation agent' is phenylboronic acid. EPA's answer for this analysis is an LC/MS/MS, but I don't know who would pay for that test! Otherwise, direct it is.

I use Absolute Standards, they have a good selection of glycol standards on their website.