RICHMOND, JAN. 29 -- A consortium of environmental groups filed suit today in U.S. District Court here challenging the federal Environmental Protection Agency's acceptance of Maryland's water quality standards.

The suit, filed by the Natural Resources Defense Council, the Environmental Defense Fund, the Audubon Naturalist Society, the Maryland Conservation Council and the National Wildlife Federation, alleges the Maryland water standards are 100 times weaker than those recommended by the EPA.

The groups are concerned about the permissible levels of dioxin discharged into Maryland waters. The environmental groups that claim dioxin, a byproduct of paper manufacturing, has contaminated the Potomac River.

The groups contend that if the less rigid Maryland standards are allowed to stand, other states may move to enact similar lax standards.

"By approving the Maryland standards, EPA indicates that it is acceptable for citizens in Maryland, Virginia, West Virginia and the District of Columbia who eat fish from the Potomac River to be exposed to almost 100 times more highly toxin dioxin than people in other states that properly adopted the EPA's recommended standard," said Robert W. Alder, a senior attorney for the Natural Resources Defense Council.

David Bailey, an attorney and scientist with the Environmental Defense Fund, said many other states, including Virginia, are waiting to see if the Maryland standards withstand the challenge.

"EPA's approval of the Maryland standard may be the first domino that will topple public health and environmental protection throughout the region," he said.

The suit also challenges the EPA for not having revised its criteria for dioxin discharge in light of new scientific findings. The EPA last issued its recommendations in 1984.

The EPA has 60 days in which to respond to the suit.