Have you heard of copper sulphate treatment which lake silver wood will be closed July 22 2020 to do and lake silver wood is ground water you drink

This appears to be true and will effect the day use. Copper sulfate treatment is an algaecide which helps to control algae and also the microscopic organisms which can cause swimmer's itch. Lake Silverwood is a man made lake that is part of the local water table.

I looked on Goggle, your statement appears to be accurate regarding the sulphate treatment, however it does not affect camping, just day use. Again, according to Google, Silverwood Lake is a man-made reservoir and is used for drinking water.