CHARLESTON, S.C. — A federal judge says that both the Georgia Ports Authority and a South Carolina agency overseeing activities in the Savannah River may take part in a $650 million lawsuit challenging the deepening of the river shipping channel.

But U.S. District Judge Richard Gergel also denied a motion Tuesday to expand the lawsuit to deal with what South Carolina environmental laws pertain to the project.

So the case will center on the original complaint that the work needs a South Carolina pollution permit.

Environmental groups in both South Carolina and Georgia say the project will dredge toxic cadmium from river silt and put it on the South Carolina side of the river.

In addition to the Ports Authority, the judge is allowing South Carolina’s Savannah River Maritime Commission to participate.

Environmental groups in both Georgia and South Carolina originally sued the U.S. Army Corps of Engineers, saying the deepening work needs a permit under South Carolina’s Pollution Control Act. The plaintiffs last week then asked the judge to consider the wider issue of whether all South Carolina environmental law applies.

The lawsuit was brought by the Southern Environmental Law Center on behalf of the Augusta-based Savannah Riverkeeper, as well as the South Carolina Coastal Conservation League and the South Carolina Wildlife Federation.

Maritime interests say the river deepening is needed so the Georgia ports can handle the larger container ships that will routinely be calling when the Panama Canal is expanded in 2014.