Minnesota regulators have allowed a sewage treatment plant in Alexandria, Minn., to emit pollution into a chain of popular nearby lakes for nearly a decade -- a clear violation of the environmental laws they are charged with enforcing, according to a lawsuit filed Tuesday in Ramsey County District Court.

The suit, filed by a nonprofit environmental law firm, is the latest in a steady drumbeat of complaints by advocacy groups who say the Minnesota Pollution Control Agency is not doing enough to protect Minnesota's lakes and rivers.

Lake Winona has been a case in point for some time. Using the west-central Minnesota lake as an example, the nonprofit law firm petitioned the U.S. Environmental Protection Agency (EPA) in 2009 to either force the state to toughen its standards or strip it of authority to enforce the federal Clean Water Act in Minnesota.

"Federal law requires the PCA to calculate limits that comply with water quality standards, and they fail to do that routinely," said Kevin Reuther, an attorney with the Minnesota Center for Environmental Advocacy, which filed the complaint Tuesday.

Officials at the PCA said they have responded to the EPA's requests for information in connection with the petition, which is still pending.

They also said they have made significant progress in figuring out limits for the treatment plant that would improve the quality of Lake Winona and other downstream lakes. But the shallow lake, with a sewage plant on its southern shore that serves 23,000 people, presents unique and potentially intractable problems, officials said.

"There is a lot of science, and it takes time," said Shannon Lotthammer, manager of water assessment for the PCA.

Concern spreads downstream

Advocates say the state has already had time -- in fact, it won an earlier legal fight before the Minnesota Supreme Court by promising to have a cleanup plan in place by 2009, Reuther said. Instead, the lake is still polluted with chloride and phosphorus, which clouds the lake, kills the fish, causes blue-green algae blooms, and is now raising concerns among some property owners in recreational lakes downstream from Lake Winona.

"It's very troubling for us that a state agency told the Supreme Court it was going to do something and it didn't follow through," Reuther said.

The legal wrangling over Lake Winona illustrates how difficult and expensive it can be to clean up a lake even when the source of the problem has been known for years.

"This is a problem all over the country," said Alexandra Klass, an environmental law professor at the University of Minnesota, who also is a member of the advocacy group's board. "The whole system breaks down if the states are not capable of setting those [pollution] limits."

Bruce Nelson, executive director of the Alexandria Lake Area Sanitation District, which operates the treatment plant, said it already removes as much phosphorus as possible.

Moreover, he said, in the decades since the plant and regional sewer system were built, water quality has improved substantially in nearby lakes that are more heavily used for recreation than Lake Winona.

Pollution not new

Now, it could cost $20 million to $30 million in public funds to install the kind of technology that would bring phosphorus down to the level the PCA says is necessary to fix Lake Winona. It was polluted long before the sanitation plant was built, Nelson said, and it's also full of bottom-feeding carp that stir up years' worth of pollution deposits that float up from sediment on the bottom.

"We've done the science," he said. "Even if we spend that money to treat to a higher level, there is substantial doubt on our part that the water quality standard will be attained. I am very frustrated."

That's why the sanitation district last year asked the PCA to present the case to an administrative law judge for review, he said, even though it slows the process even further.

"It's a difficult situation, and the [PCA] is trying to figure their way through it," he said.

But some local property owners said they believe a lawsuit is the only way to make progress.

"It gets attention," said Arland Hirman, who lives on Lake Winona and is head of the lake association. "If it doesn't get attention, then nothing will happen."

Josephine Marcotty • 612-673-7394