Steam power plant wastewater discharges include arsenic, lead, mercury, selenium, chromium, and cadmium. Regulations for power plant discharges to surface waters were last updated in 1982 and did not focus on these toxic metals. Over the past 30 years, steam power plants – particularly coal-fired power plants – have begun generating new wastewater streams containing these pollutants, from installation and operation of air pollution control equipment and from gasification of coal.