Pollutants feeding the toxic algae blooms that have been turning parts of western Lake Erie green and contaminating drinking water in recent summers aren't just coming from Ohio.

They're flowing into the lake from farm fields in Michigan and Indiana, leaky septic tanks in southern Canada, and Detroit's wastewater plant.

That's why Ohio's governor and environmental chief are starting to ask some of their neighbours to look into what else they can do to cut down on the pollutants -- primarily phosphorus -- that end up in the lake's tributaries.

"We can't do it alone, and they can't do it alone," said Craig Butler, director of the Ohio Environmental Protection Agency. "I think everybody really understands that we need collaboration."

Discussions with officials from Indiana, Michigan and southern Ontario have centred on the overall goal of reducing phosphorus in waterways and not on specifics about what needs to be done, Butler said.

"We want everybody to come up with their own prescription based on whatever symptom they have," he said.

Ohio within the last year adopted regulations on livestock manure and commercial farm fertilizers. Researchers have found as much as two-thirds of the phosphorus in the lake comes from agriculture. The new rules include banning farmers in northwestern Ohio from spreading manure on frozen and rain-soaked fields and requiring training before farmers can use commercial fertilizers.

Whether anything like that will come in Michigan or Indiana remains to be seen.

Officials from both states say that they support efforts to improve water quality and that they already have policies that help reduce phosphorus from getting into rivers and streams.

Michigan has a voluntary program to help farmers reduce pollution that goes into waterways and is in the process of closing a loophole in how farm manure is handled, said Dan Wyant, the state's environmental quality director.

"There's not a silver bullet to solve this problem," he said. "More has to be done."

That includes improving wastewater treatment plants that send raw sewage into rivers during heaving rains and controlling invasive mussels that are thought to help algae thrive, he said.

Indiana's Department of Environmental Management wants to make sure the efforts are efficient and has asked Ohio officials for more information about how they see the states working together, said spokesman Barry Sneed.

Some work to fight the algae already is underway in Ohio, Michigan and Indiana.

The states will begin sharing $17.5 million to reduce farm field runoff by planting strips of grass or cover crops that help soil absorb and filter phosphorus. The federal money came about last fall after toxins from algae contaminated the drinking water for 400,000 people in Toledo and southeastern Michigan.

The algae blooms also have been linked to oxygen-depleted dead zones where fish can't survive.

The Nature Conservancy also is working with farmers in the three states, focusing on educating them about methods to reduce phosphorus. "What happened in Toledo was sort of like the shock heard around the world," said Carrie Vollmer-Sanders, who is leading the group's work.

Greg Lake, a farmer near Fort Wayne, Indiana, who also heads up the Allen County Soil and Water conservation District, thinks stricter regulations could be coming if the algae continue to thrive.

He has taken busloads of farmers and agribusiness retailers to Lake Erie to show them firsthand how the algae affect the water and those who depend on it. "It helps solidify why this is a fairly significant issue that shouldn't be ignored by other states," he said.

Blaine Baker, who operates a large dairy in Clayton, Michigan, went on a similar outing with farmers from Michigan the past two summers.

"Until you really see how green the water is, it's really hard to believe," he said. "That was the big eye-opener to me."