My experience is that using NaCl softend water will eventually kill practically all vegetation, at least here in Minnesota.
We moved into our home in the winter of 2001. The previous owner came by in the spring to pick up a few things and I asked him about an area in the front yard adjacent to the tree line. It was an area that just looked dead. Black dirt, nothing at all growing, no weeds, no grass, nothing. He said he thought it was related to the trees. He said he had planted and fertilized and watered, grass would start and after a couple of months die.
That summer I tried the same. planted, fertilized, watered..and the spot grew! By the end of the summer the spot had grown to over half the front yard, about 3,000 sq. ft.
That fall, my water softner failed and after much research on softners, replaced it. The installer asked if I know of any problems with the split outside water. Huh??? The outside faucet in the front of the house is softened water, the outside faucet in the back is hard water. A whole Christmas tree of lightbulbs when off. Apparently in the neighborhood I am in it is common to have a softend water outstide faucet for cleaning windows and the car.
The following spring I reseeded, mixed in poatassium into the soil, and watered (from the back this time). Almost the same results, except the spot began to shrink. It has taken three years to mostly get the lawn back to normal.
By the way, I now have a brass tag on the front faucet that says "Softened water, not for use on plants."
I am not saying other things can't harm your plants and lawn, I just say that consistently using NaCl softened water on plants is harmful.