DULUTH, Minn. (AP) -

Minnesota is giving Great Lakes freshwater freighters known as "lakers" that enter the Minnesota waters of Lake Superior an extra two years to install ballast water treatment technology.

The Minnesota Pollution Control issued draft regulations Monday, giving supporters and opponents until Sept. 11 to comment.

"It's acknowledging that we don't think the technology yet exists for (lakers) to meet the ballast treatment guidelines, but that we think it will" by 2018, Jeff Udd, the MPCA's director of industrial water quality permits, told the Duluth News Tribune.

The new rules also essentially allow the federal government to regulate oceangoing ships that enter Minnesota waters, deferring to new Environmental Protection Agency guidelines, Udd said.

"We didn't want to duplicate what the EPA is doing on saltwater ships," he said. "We wanted to focus our attention on what we think are gaps in the federal rules."

The ballast rules are part of a broader effort to reduce invasive species that hitchhike in ballast water — such as zebra mussels, ruffe and goby — both from foreign ports to U.S. ports and also those that spread between Great Lakes ports.

Minnesota is the only Great Lakes state with ballast rules that target boats that stick to fresh water.

The Great Lakes shipping industry opposes Minnesota's regulations, saying freshwater freighters are not responsible for bringing new species into U.S. waters. It also contends no technology may be possible that would kill nearly all the aquatic organisms in their tanks. The industry is expected to contest the new rules at a PCA hearing this autumn.

Environmental groups, however, have called for even stricter guidelines and quicker deadlines, saying invasive species are wreaking havoc with native ecosystems.