Thirty-nine environmental groups are urging president-elect Barack Obama to reject a pending federal rule that will make it easier to dispose of coal combustion waste from power plants in abandoned mines despite risks of water contamination.

The groups, including eight from Pennsylvania, say coal ash has already polluted water in 23 states and the new rule would open the way for more pollution by failing to require consideration of risks to human health and the environment before new disposal sites are approved.

"Disposal of coal ash in mines is a growing practice that threatens the health and environment of coalfield communities," said Lisa Graves Marcucci, president of Jefferson Action Group, in Jefferson Hills, who noted that 120 abandoned mines are used for ash disposal in Pennsylvania.

She said pollution of ground water and surface water has occurred in Pennsylvania, West virginia, Indiana, North Dakota and New Mexico.

Coal-fired power plants produce approximately 129 million tons of waste ash a year, the second largest industrial waste stream in the nation. About 25 million tons are already dumped in coal mines, including 6 million tons annually in Pennsylvania.

The waste contains numerous hazardous materials including arsenic, selenium, lead, mercury, cadmium, chromium, boron, thallium and molybdenum.

The pending rule by the U.S. Office of Surface Mining and the U.S. Environmental Protection Agency is the latest in a series of end-of-term rule making by the Bush administration aimed at easing environmental regulations to benefit various industries.

In a letter to Mr. Obama released by the groups from 10 states today, he is asked to send the rule back to OSM and the EPA and to restart the rule making process to allow for comment by environmental groups as well as industry.