Is there a source that OSM was pulling from?
I’m curious why there is an obvious clip where Canada is missing water/swamp/green data? If you zoom in just slightly you will see the clip, and if you zoom in on the green edges you will see all the water is missing as well.
Was there an original source I can pull from? Is there a fix to come?
Not sure what you exactly mean. But the source is usally a guy who walks there with a GPS-Tracker and later puts in the data manually. If aerial images are available via JOSM or iD you would be able to implement the data as well. So, if you know the place, go there, walk around, take pictures, record GPS and put in data.
Otherwise https://forum.openstreetmap.org/viewforum.php?id=16 would be good choice or the mailing-list https://lists.openstreetmap.org/listinfo/talk-ca
As Negreheb said: OSM-Data is primary entered manually by volunteers. There are cases where data has been uploaded from other sources (like TIGER in the US). So if you can help to improve the map by adding features from aerial images or local knowledge feel free to improve OSM.
I think you are probably seeing the effect of CanVec imports. @Negreheb has given links to contact Canadian Mappers who can probably give you a lot more details.
Canada was never complete in the first place, so data isn’t really “missing”.
Some people with good intentions have partially imported CanVec data (free old data from the government), which I think is garbage. It’s full of “mock accuracy”; detail that looks believable when zoomed out, but poorly matches reality when you look closely. (Notice example in my avatar, on your left.)
CanVec imports were never finished (thank goodness), but some people keep working on them, mostly (I think) in areas like the far north where people might never look closely.
In the meantime, mappers like me are adding detail manually, working from clear satellite imagery among other quality sources. Patience please; we’re working on it…
If I misunderstood what you’re seeing, could you give a precise example, eg a link to a map showing the problem? Thanks.
Great feedback, thank you! Completely an issue with incomplete CanVec imports. Other mapping companies just did a full import, but I see it’s being put in manually for OSM.
I don’t mind the slightly lack of accuracy if it LOOKS complete, but I agree that for OSM it’s better to be accurate. If I want Canada to look finished I just need to add the CanVec data.
I apprecaite the feedback.
Just for future reference, here is the most obvious place that it just full stops:
https://imgur.com/gallery/IZy1Vuv
https://imgur.com/gallery/uHLntrH
https://imgur.com/gallery/d01PgNM
Ah yes, the patchy low-zoom view. Definitely a work in progress.
I’ll admit, it’ll be a while before Canada looks as green on the map as it truly is in person. (But hey, we’re ahead of the neighbours!) At least, in some areas of interest, say the Rockies, once you’ve zoomed in, things look pretty good. Priorities first. 
PS, you may have noticed, the cycle map and siblings (http://opencyclemap.org/, various layer options) switch to a different landcover source at lower zoom levels. Maybe a hybrid approach like this is suitable, depending on your application.
Isn’t that the definition of “missing data”? 
As Viajero pinted out at first, the CanVec data is not good and should not be imported, if i understood him correctly. Ask him how he does all the stuff, but my guess would be, get JOSM, get good aerial pictures and work from them. (As he pointed out as well )