Twenty years after the pervasive zebra mussel was first detected in the Great Lakes, the U.S. Coast Guard is preparing rules to prevent new invasive species from infiltrating the nation’s freshwater systems.

Ecologists, environmentalists and public officials have mixed feelings about the rules. Some expressed their sentiments during a public comment period that ended earlier last month.

While they are delighted over the prospect of the first national standard for treating ship ballast water — the main conveyor of invasive species — they’re disappointed by the timetable.

“We’ve been dealing with this issue literally for decades,” said Matt Frank, secretary of the Wisconsin Department of Natural Resources. “We know what the costs of invasives are. And we don’t believe the Coast Guard rules are aggressive enough.”

Emphasizing a sense of urgency, the department issued its own standards on Nov. 18. Beginning Feb. 1, all large commercial ships traveling the Great Lakes will have to adhere to best management practices for cleaning ballast water tanks. On Jan. 1, 2012, ships will be required to treat ballast water to meet a numeric standard for the amount of live plants, animals and organisms.

Wisconsin joined Minnesota and New York among Great Lakes states with their own ballast water standards. Wisconsin’s and New York’s standards are 100 times more stringent than the regulations set by the International Marine Organization. In all, 11 states have such standards.

On Aug. 28, the Coast Guard proposed standards to be implemented in two phases to be completed by the end of 2016. Ultimately, the standards will be 1,000 times more restrictive than what’s in place now.

Critics complain that the proposal includes feasibility studies and the possibility of revising the standards, which they say could be a loophole. They also say the timetable is too long and note that some ships might not have to comply with the stricter standards until 2021.

“With new invasive species entering the Great Lakes every year, and the annual costs associated with invasive species measured in the hundreds of millions of dollars, we cannot afford unnecessarily long implementation timelines, or timelines with escape clauses that render the timelines meaningless,” six Minnesota organizations wrote in a Nov. 30 letter to the Coast Guard urging stronger action.

Henry VanOffelen, a natural-resources scientist with the Minnesota Center for Environmental Advocacy, said the groups want to see the stricter standard take effect by 2016. He said a national standard would accelerate development of technologies to treat ballast water.

The history

Invasive, non-native aquatic species have been entering the Great Lakes since the early 1800s, but it was the opening of the St. Lawrence Seaway 50 years ago that led to the ecological and economic threats posed today.

The seaway opened the Great Lakes to the rest of the world — and to a variety of aquatic nuisances that hitch rides in the ballast water that ships take in to maintain equilibrium. There are 185 invasive species in the Great Lakes, 60 of which have taken up residence since the St. Lawrence opened.

The intruders disrupt the food chain, spoil beaches and clog water intake pipes, creating a nuisance for people and businesses. Cornell University professor David Pimentel estimates that invasive species cost the U.S. $9 billion a year.

No species is a better example of the threat than the zebra mussel, detected in Lake St. Clair in 1989. The zebra mussel has cost the Great Lakes region more than $3 billion over the past 10 years, Wisconsin DNR Secretary Frank said. The damage caused by the zebra has spawned the growth of cladophora, a foul-smelling algae that spoils beaches. Frank said the state spends $200 million a year cleaning beaches.

A cousin to the zebra, the quagga mussel, has begun to shove the zebra aside as the Great Lakes’ biggest nemesis. Some have called it a “zebra on steroids.”

Gary Fahnenstiel, a senior ecologist with the Great Lakes Environmental Research Laboratory in Michigan, said the quaggas have formed a carpet at the bottom of Lake Michigan.

“It’s displacing the zebra mussel,” Fahnenstiel said. “If you go out to Lake Michigan and pick up shells, 99 percent of them are from the quaggas.”

Ecologists are wary of a new threat — the Asian carp — that has sparked congressional activity.

Sen. Kirsten Gillibrand, D-N.Y., urged the U.S. Army Corps of Engineers to close shipping locks south of Chicago to block a possible route for the voracious carp to enter Lake Michigan. And Sens. Carl Levin, D-Mich., George Voinovich, R-Ohio, and Amy Klobuchar, D-Minn., just introduced legislation aimed at preventing its spread to the Great Lakes.

Once an invasive species takes root, getting rid of it is a tough task.

“It’s almost impossible,” said Jake Vander Zanden, a biologist at the University of Wisconsin. “That’s why I’m a firm advocate for preventing them from getting here in the first place.”

Scientists and shipping industry officials for years have called for a national standard on invasive species. The closest they came, before the Coast Guard proposal, was legislation that the House of Representatives passed last year. The measure died in the Senate.

The Coast Guard’s proposal is a welcome development that just needs to be strengthened, said Jennifer Nalbone, campaign director for navigation and invasive species at Great Lakes United, a citizens group in Buffalo.

“If the rules are implemented, they’re going to have a significant impact,” Nalbone said. “Our concern is the rules aren’t going to be implemented in a timely fashion.”

For some, the wait already has been painful.

“It’s been excruciating,” said Allegra Cangelosi, who oversees the Great Ships Initiative, a ballast treatment research program at the Lake Superior Research Institute in Superior, Wis.

Without a national standard, the research has been moving slowly, Cangelosi said.

“It’s been holding everything up, as potential investors have been waiting to see ultimately what they have to do,” she said. “Granted, this is a difficult thing to regulate, and it’s new ground, but we should have been out there making mistakes instead of waiting and trying to do it perfectly.”