Buck,
I'm afraid if it didn't cause the problems, it sure contributed to them.
Recommended maximum sulfate level is 2500 ppm (which is same as ml/l) so you've got almost 2 times that level.
Recommended maximum TDS is 7000, so you're getting close to that too.  The specific conductance is about the level of ions in solution in the water - it literally means your water conducts electricity a lot better than distilled water with zero solids, but for livestock it's basically a measure of how much salt is dissolved in the water.

High sulfur levels are often the cause of brainers.  If you have any high sulfur feeds (that is, any co-product) that would make the problem worse.

Beyond brainers, the sulfur level and the TDS level indicates a high risk that the water is tying up trace minerals (through chemical bonds) that the cattle need for health and metabolism.  The TDS can also result in lower water intake because of poor palatibility - low water intake leads directly to low feed intake and low feed intake leads to poor gain and can lead to poor health.

The mature cows are a lot more resistant to these problems than the calves, so it's no surprise that the cows look good but the calves look tough. Also remember that the calves are getting it when they drink water, and the calves are getting it again when they nurse the cow.  It is a little odd that you lost a cow, but if she was really thirsty and tanked up on a lot of water all at one time it's definitely possible it directly caused the brainer.  At the very least the water made it more likely she would  be a brainer.

This is a bad deal