First of two parts

DETROIT — Though still focused on the farm-enriched Maumee River watershed, Great Lakes scientists are increasingly curious how much phosphorus generated north of Toledo flows down the Detroit River and contributes to western Lake Erie’s algal growth.

Is it a major or minor source?

While scientists have no reason to upend the longstanding belief that most algae is formed by local phosphorus, the Detroit River is hard to dismiss as a contributor for the simple reason that it supplies 80 to 90 percent of western Lake Erie’s water and is home to the world’s third-largest sewage plant, the Detroit Wastewater Treatment Plant.

That sewage plant has a long history of violations.

Unlike the Maumee River, which begins in Fort Wayne at the confluence of the St. Joseph and St. Marys rivers, the Detroit River is only a river by name.

It is a 24-mile connecting channel between Lake St. Clair and western Lake Erie.

The Maumee River meanders gingerly through 137 miles of mostly agricultural land. The water is calm enough for canoeing in many areas, especially those designated for special protection because of their scenic beauty.

The Detroit River, on the other hand, has a current so powerful that large freighters need to adjust to it. It is a passageway for billions of gallons of Upper Great Lakes water to be pushed through in as few as 19 hours. The Detroit River shoreline is dominated by Motor City skyscrapers and the city’s huge sewage plant, steel mills, the Marathon oil refinery, and other heavy industry.

But go just a few miles north of the hustle and bustle of Detroit, and there’s a quiet, farm-enriched stream in southwestern Ontario that is unfamiliar to most Toledoans — the Thames River. It has a lot in common with the Maumee River; in fact, some people think of it as Ontario’s Maumee.

Farm runoff up north

It’s 170 miles long, covering more geography than the Maumee. It also shares the problem of excessive farm nutrients flowing off the land, especially where it empties into Lake St. Clair. The massive input of Thames River nutrients is a major source of microcystis algal blooms in Lake St. Clair.

So what are the odds of farm runoff from the Thames River having an impact not only on Lake St. Clair, but also the Detroit River and western Lake Erie?

Surprisingly good, according to Tim Davis, a National Oceanic and Atmospheric Administration research scientist who specializes in harmful algal blooms.

In a former job with Environment Canada, the Canadian equivalent of the U.S. Environmental Protection Agency, Mr. Davis was part of an ongoing research project doing a DNA-like investigation into strains of microcystis algae in Lake St. Clair and western Lake Erie.

One of the key findings: There’s a connection.

It’s unclear if that means farm runoff from the Thames River is creating some of the algae that flows down to western Lake Erie, or if it’s just a coincidence that algae with the same genetic material is being produced in two nearby locations.

“We know it’s not the source of the [western Lake Erie] bloom,” Mr. Davis said. “But could [the algal blooms] be traveling down? It’s highly likely. They could influence the toxicity of the blooms by adding to what is there. ... It’s very possible [the algal blooms] are traveling down the Detroit River and adding to western Lake Erie’s algae.”

Algae research

This information may sound anecdotal, but Great Lakes scientists are looking for more clues about how algae behaves.

They know that once blooms dissipate in the fall, that doesn’t mean the stuff is gone.

Microcystis is one of the oldest-living things on Earth, more than 3 billion years old and many times older than the Great Lakes themselves. Its seeds are resilient, even in harsh winters. As Mr. Davis explained, thick ice does less to kill off algae, contrary to what many people believe. Seeds go to the lake bottom, which is so deep that conditions don’t vary much each winter. Ice penetrates only a few feet.

U.S. and Canadian scientists see the Detroit River corridor as a challenging area for algae research.

It’s difficult — and dangerous — to get regular water samples out of such a powerful current.

At least one research effort appears to be successful in anchoring monitors that collect data round the clock now.

It is headed by Debbie Burniston, an Environment Canada scientist working in collaboration with Jan Ciborowski, a University of Windsor scientist.

Environment Canada would not allow Ms. Burniston to be interviewed. Mr. Ciborowski said much of the field work is being done by his research assistant, Jesse Gardner Costa, who said the monitors — while still in the early stages of collecting data — show promise of supporting the theory of a Thames River-to-Lake Erie algae connection.

Don Pearson, Lower Thames Conservation Authority general manager, said he doesn’t doubt farm runoff from the Thames creates algae that eventually finds its way down and into western Lake Erie.

“We know we’re part of the problem on the Canadian side and intend to be part of the solution,” Mr. Pearson said.

Although there’s a lower concentration of phosphorus in the Detroit River, there’s a much higher volume of water than what comes from the Maumee River.

Laura Johnson, a Heidelberg University research scientist, said it’s kind of like iced tea: Whether you put 2 tablespoons of sugar in a small glass or big glass, there’s still 2 tablespoons of sugar in there.

That is what scientists are trying to sort out when they compare higher concentrations of phosphorus in the Maumee River watershed to the Detroit River’s lower concentrations but higher volumes of water.

Phosphorus issue

There’s also the issue of how much “dissolved reactive phosphorus” exists in each body of water. That type of phosphorus incorporates more readily into the water column than phosphorus particles. It has become one of the hottest issues among scientists studying algae blooms.

According to a U.S. EPA fact sheet, even a modest increase in phosphorus “can, under the right conditions, set off a whole chain of undesirable events in a stream, including accelerated plant growth, algae blooms, low dissolved oxygen, and the death of certain fish, invertebrates, and other aquatic animals.”

“The emerging issue is the dissolved reactive phosphorus,” Mr. Pearson said. “Some of the pathways are not as easily understood.”

For all of the criticism the Detroit Wastewater Treatment Plant has received over the years, a Michigan Department of Environmental Quality official said it has largely gotten phosphorus problems under control.

Jodi Peace, Department of Environmental Quality senior environmental quality analyst, said the state of Michigan has gone “way beyond what’s required” to curb phosphorus discharges from the plant, as well as sewage overflows.

“We’ve been good stewards of the environment,” she said.

About four years ago, Ms. Peace said, Detroit started adding more ferric chloride to the front end of its treatment process at the plant.

Ferric chloride is a chemical that reacts with phosphorus and causes it to bind into larger particles that settle out.

That cut the phosphorus discharge in half. Plant operators are reluctant to remove all of the phosphorus, because some is needed to help healthy micro-organisms do their job during the secondary phase of sewage treatment, Ms. Peace said.

Ms. Johnson told reporters this summer that about 5 percent of western Lake Erie’s total phosphorus appears to be coming from that plant — a figure environmentalists such as Sandy Bihn of Lake Erie Waterkeeper question for accuracy and perspective.

Ms. Bihn, who began tracking Detroit’s wastewater discharges years ago, believes even a low concentration of phosphorus could be significant because of the enormous volume of water that comes down the Detroit River. She is skeptical about the history of Detroit’s sewage releases and spills, the impact of polluted sediment recirculating in the water column, and if Ohio researchers put an overemphasis on Ohio waterways because of how their grant money is allocated. She is calling for more research, citing documents as far back as the 1960s which she said raised the possibility of greater impact from the dissolved reactive form of phosphorus decades ago.

Members of Ohio Gov. John Kasich’s administration have called for more studies into the Detroit River’s potential impact too.

Contact Tom Henry at: thenry@theblade.com, 419-724-6079, or via Twitter @ecowriterohio.

First Published November 16, 2014, 5:00 a.m.