Our city #lnk is over 3ppb. https://lincoln.ne.gov/city/ltu/water/pdf/water-quality-report.pdf?2018
the #EPA responded to rising concerns about the heavy metal’s health risks by lowering that level, initially suggesting 3 ppb as a “feasible” cutoff. The agency eventually settled on 10 ppb because it “maximizes health risk reduction benefits at a cost that is justified by the benefits.”
So the Government knows what is feasible, but won’t recommend it.