"I don't have an answer for you today but I want to you know that's very much on my radar screen," she said during a meeting of the Great Lakes Commission in Washington, D.C.

Ballast water, which keeps vessels stable in rough seas, is a leading pathway for zebra mussels and other aquatic invaders, which have overwhelmed native species and cost billions in economic damage.

The EPA permit requires vessels heading for U.S. ports with full ballast tanks to exchange the water at least 200 miles from shore. Ships with empty tanks must rinse them with salt water to kill freshwater organisms lurking in residual puddles or sediment.

But those measures already had been required by Canada and the U.S.Coast Guard, and critics say they still could let some invasives get through.

Several environmental groups sued EPA last month, saying the permit did not meet requirements of the Clean Water Act. They want shippers to install systems for sterilizing tanks, which the maritime industry says are being developed but remain unavailable.

Activists praised Jackson's promise to revisit the issue.

"She recognizes what everyone in the Great Lakes knows: the permit was nowhere close to good enough," said Jennifer Nalbone of Great Lakes United, a U.S.-Canadian group.

As a candidate, Obama proposed a $5 billion "down payment" toward implementation of a $20 billion restoration plan released by the Great Lakes Regional Collaboration in 2005.

It includes drinking water and sewage system upgrades, toxic site cleanups, improvements to wetlands and wildlife habitat and continued efforts to keep foreign species out of the lakes.

Jackson said she was optimistic about prospects for progress toward those goals.

"I don't think there's any reason to question the president's continued commitment to the Great Lakes," she said.

Officials expect the region to get nearly $2 billion for wastewater and drinking water system upgrades under the recently enacted stimulus package. Jackson acknowledged more was needed.

"Investment in water infrastructure has tremendous payoffs" in improved water quality and job creation, she said.

Jackson also promised to seek more money for removing toxic sediments from highly polluted harbors and rivers across the region.

The House authorized boosting the program's budget from $54 million to $150 million last fall. But the bill died in the Senate after EPA turned against it.

"The EPA under the previous administration took the position that current funding was sufficient and they were content to move cautiously," MichiganLt. Gov. John Cherry said. "It sounds like Administrator Jackson is going to be more aggressive."

State officials and activists in Washington to lobby Congress on Great Lakes issues said administration support should help the region hold its own amid fierce competition for federal dollars.

"It's our sense the Great Lakes are a priority for them," said Jeff Skelding, director of the Healing Our Waters-Great Lakes Coalition.