It's not only salt.
Let me give you an example for comparison reasons. Salt water from the sea contains in the order of 31 grams per litre. The salt water in the area of the Athabasca has ten times more, 350 grams per litre, of TDS, or total dissolved salts.
That is brine. It is extremely salty. It comes from the Devonian types of rocks, which are lower than the basal magma formation, which is the one they extract in the sands--the bitumen. If you fly over the area--I have done it--you will see spots of salt springs. There are salt springs naturally flowing out there, which means, for us, hydrogeologists, that there are hydrologic connections between the three types of aquifers. Really salty water can come up to the surface naturally.