Test wells for the region in question have had arsenic levels several times that being discussed here for years. In fact, the water district started failing Federal arsenic standards last summer[0] and has received three formal violation notices.

They were nearly in violation a year before the lithium plant even opened. At least in terms of arsenic, the levels coming out of the plant are significantly lower than background.

[0] https://www.kristv.com/running-dry/ncwcid-3-gets-third-arsen...