The report published Monday by the Environmental Integrity Project and Earthjustice highlights more than a dozen cases in which these substances have reached the drinking water supply. The full extent of the impact on drinking water supplies is not known, as private sources of drinking water are not tested, the report says.
"Virtually all coal-fired power plants poison our water," said author Abel Russ, a lawyer for the Environmental Integrity Project.
The ponds and landfills in which the coal ash is stored are often unlined, so that toxins reach the groundwater.
The report is based on groundwater monitoring data from more than 4,600 wells. The measured values were compared with drinking water or other standards. In the groundwater, contamination was found near 242 of the 265 installations that have recently reported the data required by the 201
5 Rule. Fifty-two percent of these sites are contaminated with carcinogenic arsenic and 60 percent are contaminated with lithium, which is reported to be associated with neurological damage.
Last year, a federal appeals court ordered the EPA to reassess the rule of the Obama era, saying it had not gone far enough. For example, it was suggested that the EPA should request the installation of coal beds, as government data showed that "a significant proportion" of the more than 500 ponds covered by the Rule "are likely to contaminate groundwater".
The Trump government passed the new regulations in July, but weakened them rather than tightening their ordinances, said Lisa Evans a lawyer at Earthjustice. The new rules allowed states or the EPO to waive monitoring requirements in some situations.
EPA spokesman John Konkus said Monday that the agency is reviewing the report "and can not comment on its content yet." He said the monitoring requirement "helps to create transparency and monitor a mechanism to monitor compliance by a body."
The authors of the report said they "underestimate" the contamination as only data on actively used coal ash sites are available. Ponds and landfills receiving coal ash but not receiving new supplies are not included.
"They are not regulated, they are not monitored, and we do not know much about them," Russ said about the unregulated pits.
CNN's Nadia Kounang contributed to this report.