First a little background. There are two audio types provided to the stations airing the series: Dolby-E, with DD5.1 and MPEG-1 layer 2, with Dolby Surround.
You'll notice that AC3-DD5.1 is missing (the format that ABC uses and one of the formats The CW uses).
So what does this mean to you the viewer, who is is equipped to handle OTA DD5.1 audio? It means that your local station's 5.1 may not really be 5.1 when it comes to this series.
If your station is doing DD5.1, but doesn't have the necessary Dolby-E piece of expensive gear, it has to use the MP2 audio stream and bump it up to DD5.1. You therefore are not getting true DD5.1, but what electronic stereo was to analog TV when stereo TV first came along in the 80s. Unless your station is a CBS affiliate and they can use the Dolby-E gear with syndicated programs, the odds are that your station doesn't have the Dolby gear. Even The CW affiliates do not need Dolby-E, as the network also provides AC3-DD2.0 and AC3-DD5.1 audio streams.
How do you know if your station can handle Dolby-E? If the DolbySurround upconverter is set up correctly, you'll have a hard time telling. If you only get mono sound out of the rear channels, then your station probably can't. I have no idea how well they take advantage of the stereo rear channels. If your station does DD5.1 during non-network primetime, call the chief engineer and ask.
Videojanitor fully understands the situation.
So, not only do stations need to be listed in this thread as doing HD, it also need to indiate if they are doing true DD5.1 with this series.