Legal challenges and months of political fighting have followed a South Carolina board's decision to permit the deepening of the Savannah River, and now environmental groups are calling on the state Supreme Court to step in and settle key questions.

Specifically, groups represented by the Southern Environmental Law Center are asking the state's highest court to take their case -- skipping the lower courts -- and declare as unlawful the S.C. Department of Health and Environmental Control board's actions regarding a clean-water certification, construction permit and coastal zone consistency for the Savannah River deepening project.

As in several cases pending at the Administrative Law Court level, the groups argue that the DHEC board usurped the authority of S.C. Savannah River Maritime Commission.

"DHEC had no authority to cut a backroom deal with Georgia and issue a permit for this destructive, wasteful project because the South Carolina legislature gave authority over this matter to the Savannah River Maritime Commission in 2007," said Frank Holleman, a senior attorney at the law center.

The commission's role relative to DHEC has been in dispute and subject to different interpretations by lawmakers, the governor's office and the current and former state attorneys general.

Most lawmakers and environmental groups argue that the commission has the say regarding dredging the Savannah River, and the legislature last week overrode the governor's veto of a joint resolution stating that position.

Georgia wants to deepen the Savannah River, which the two states share, to accommodate larger container ships bound for the Port of Savannah. South Carolina Gov. Nikki Haley's appointed DHEC board controversially approved needed permits for the work in November, reversing a decision by the DHEC staff after Haley asked the board to give Georgia's governor a hearing on the issue.

An outcry followed in the General Assembly and in Charleston, where supporters of the Port of Charleston, which is pursuing plans of its own for a deeper shipping channel, saw the DHEC permit approval as a betrayal of South Carolina's port interests.

Environmental groups say Georgia's plan would be devastating to the environment, and lawmakers have echoed those concerns.

A DHEC spokesman said the agency would not comment on the litigation or the legislature's resolution.