Is rel=canonical needed for URLs with Google Analytics query strings?

[WayneBlankenbeckler]

If a page URL has Google Analytics query strings, does the page need a canonical tag? e.g.,

something.com/?utm_source=newsletter&utm_campaign=mar-2013-nsl

I have rel=canonical on all our pages because some of them will be accessed via URLs that have non-Google strings. The strings are only for marketing purposes, not for identifying a specific page to display. e.g.,

something.com/?source=acme

Should I only implement the canonical tag on the pages that might have non-Google marketing strings in the URL?

[TakeshiYoung]

I would add them every page on your site, because pages with query parameters can get indexed by Google. Even if you don't use any parameters yourself, other sites can tack them onto your URL. Best to be safe and add them to all pages.

[JDatSB]

Agreed.  It can only help to set canonical.  Google is smart enough to figure out to discard those parameters, as they are their own parameters.  But you could also set those parameters to be ignored in GWT.

[ThompsonPaul]

Another vote for proactively adding canonical tags to all pages. They're a great preventive measure in case someone else links with unusual parameters.

Also, Google is "supposed" to understand the UTM tags and ignore them, but we've all seen cases where Google's actual processes don't work quite like they're supposed to. (I've seen plenty of utm-tagged URLs indexed in Google)

(Plus, there's even less guarantee that other search engines would discount them and avoid dupe content. Bing et al may not be a huge traffic source on your site, but no sense throwing it away unnecessarily.)

Paul