Urban sewage and runoff from farm fields are driving down the quality of water in lakes and rivers across southern Canada, according to a report to be published this week by Environment Canada.

And while federal Environment Minister John Baird is promising tough new rules and an $8-billion plan to build sewage treatment facilities, the draft regulations won't solve the biggest problem identified in the report: an excess of phosphates that has led to blooms of toxic blue-green algae in lakes from Quebec to Alberta.

"The standard they're setting will not have a big impact in central Canada," said Elaine MacDonald, senior scientist with the environmental organization Ecojustice Canada.

The growth of blue-green algae is driven by an overdose of phosphates that wash into rivers and lakes from animal manure, fertilizers on lawns and farm fields and inadequately treated human sewage, said Jean-François Bibeault, manager for water quality indicators development and integration at Environment Canada.

He said phosphates are the most common reason why water quality was rated as "marginal" or "poor" in nearly one-quarter of monitoring stations in southern Canadian lakes and rivers, based on data collected between 2003 and 2005. The data, which was released by Environment Canada to the Citizen, will be published on Thursday in the Canadian Environmental Sustainability Indicators 2007 report.

"The intent of the index is to highlight some critical problems that the country may have, that may require action at the political level," Mr. Bibeault said.

Blue-green algae, also known as cyano-bacteria, can release toxins that attack the liver, nervous system, or skin of humans and animals. Water contaminated with cyanobacteria is unsafe for swimming, and especially dangerous for drinking.

"We've seen huge blooms that are covering the whole north basin of Lake Winnipeg in the summer," said Al Kristofferson, managing director of the Lake Winnipeg Research Consortium. "Farmers know if they get a bloom on their dugout, it can kill animals within minutes."

But phosphates also stimulate other plant growth, said Brian Meagher, a biologist with Trout Unlimited, an organization dedicated to protecting cold-water fish and their habitats. Too many plants can deplete the oxygen supply of a lake, both as they grow and as they die and decay. This chokes off the oxygen supply for other aquatic life.

"You're going to lose some of the species of fish that cannot tolerate the low dissolved oxygen," said Mr. Meagher. "You're also going to have a blanket of vegetation across the bottom, which is going to impact species that are spawning in the river, because you're going to reduce the area where they can spawn."

Besides Lake Winnipeg, phosphates also plagued Quebec this summer, where 156 lakes were temporarily closed to swimming due to cyanobacteria. Not confined to cottage country, phosphates are a significant problem in the agricultural area of the Yamaska River on the south shore of the St. Lawrence River between Montreal and Trois-Rivières, Environment Canada's Mr. Bibeault said.

According to data released by Quebec's environment department, the Yamaska River ranks as one of the most polluted in the province, with scores at different monitoring stations ranging from a high of 80/100, or "good," to a low of 27/100, or "poor." Most of the stations show the river in mediocre to poor condition.

And the excess of phosphates has become an "epidemic" in Alberta's parkland belt between Lac La Biche and Red Deer, said University of Alberta water ecologist David Schindler.

The draft regulations proposed by Mr. Baird, obtained by the Citizen, show they will not set a standard for phosphate levels in municipal effluent.

In an interview with the Citizen this week, Mr. Baird said he's focused on cleaning up raw sewage.

"The big thing is we're going to ban the dumping of raw sewage into our lakes, rivers, streams and oceans," Mr. Baird said. "The regulations will kick in, in 20 years' time."

The draft regulations -- which are expected to be formally tabled in December, 2008 -- will make sewage treatment mandatory and set standards for the amount of chlorine, suspended solids (like fecal matter) and oxygen-consuming organic material that can be left in sewage water before it is discharged.

Mr. Baird said that over the coming seven years up to $8 billion in federal money out of a $33-billion infrastructure fund will be available to municipalities to improve their water and sewer facilities. At the top of his list are new facilities for Victoria, B.C., and Saint John, N.B..

But the dumping of purely raw sewage is mainly an issue in ocean-side cities, like those identified by the minister, said Ms. MacDonald.

The vast majority of municipalities whose effluent goes into lakes and rivers already clean their sewage to the standard set out in the new regulations, she said. Even after that treatment, high levels of phosphates often remain.

As well, even when sewage treatment plants that meet the regulations are in place, rainstorms can overwhelm the older sewer systems in some cities like Toronto and Montreal, sending untreated sewage directly into waterways instead of treatment plants.

The draft regulations go some way to addressing this problem by requiring cities to develop an action plan to reduce their overflow effluent within a 30-year timeframe.

There are other sources of phosphates that the government's initiative does not address.

In rural areas, phosphates can seep into the lakes from leaky or overflowing septic tanks.

Phosphates can also enter waterways in runoff from lawns and farms, especially when there is no buffer-zone of natural vegetation protecting the banks of the rivers or lakes. Both the Yamaska River and Lake Winnipeg suffer from an excess of phosphates from agricultural sources.

"No plan to deal with cyanobacteria can succeed unless it has a very strong agricultural element to it," said NDP environment critic Thomas Mulcair.

Mr. Mulcair plans to table a private member's bill before Christmas that would encourage provinces to legislate

10-metre buffer zones separating farm fields from rivers and lakes. He said only three provinces currently have legislated buffer zones: three metres in Ontario and Quebec and 10 metres in P.E.I.

Under the NDP's proposal, the federal government would compensate farmers for the loss of their productive land. Mr. Mulcair estimates the compensation would cost about $1,500 per hectare.

Mr. Baird said he'd be willing to look at the NDP proposal, but dealing with agricultural runoff is not a component of his sewage-treatment plan.

Mr. Mulcair's bill would also ban phosphates in dishwasher detergent, a proposal that is already contained in a private member's bill tabled by Bloc Québécois environment critic Bernard Bigras. Liberal MP Francis Scarpaleggia has also tabled a bill that would limit the phosphate content of detergents to 0.5 per cent.

The province of Quebec has already announced it will ban phosphate in detergents. And the industry association has come out in favour of a Canada-wide 0.5-per-cent limit. But Mr. Baird will not say whether he supports banning or limiting phosphates in detergents.

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Rating our waterways

Scientists measured water quality at 395 sites across Canada between 2003 and 2005

What do the ratings mean? % of total sites

95-100: Excellent. Virtual absence of threat or impairment;

conditions very close to natural/desirable levels. 6%

80-94: Good. Minor degree of threat or impairment;

conditions rarely depart from natural/desirable levels. 39%

65-79: Fair. Occasional threats or impairments;

conditions sometimes depart from natural/desirable levels. 33%

45-64: Marginal. Frequent threats or impairments;

conditions often depart from natural/desirable levels. 18%

0-44: Poor. Almost constant threats or impairments;

conditions usually depart from natural/desirable levels. 4%

Not all 395 sites are plotted on map

What is the Water Quality Index?

The WQI is a rating system that describes, in lay terms, the ability of a freshwater river or lake to sustain aquatic life.

How does it work?

Scientists measure levels of different substances at monitoring stations in lakes and rivers, taking several samples over an extended period of time. Substances can include pesticides, organic nutrients, metals, and bacteria. Acidity (pH) and concentrations of dissolved oxygen can also be measured. Each measurement is then compared to the ideal for that substance for that body of water. The actual and ideal measurements are plugged into a formula that yields a number between 1 and 100.

Who measures it?

The ratings were compiled by Environment Canada and Statistics Canada based on data collected between 2003-2005 by federal and provincial environment departments.

What are the strengths of the WQI?

The WQI shows non-experts, in simplified terms, how healthy a lake or river is. It combines many measurements into a single, overall rating that is consistent across Canada. It allows, to some extent, comparison between different bodies of water.

What are the weaknesses of the WQI?

The WQI provides a general overview, not a detailed analysis. Contaminants that are not measured (such as pharmaceuticals) do not show up in the rating. Time and location where the samples are taken can affect the rating. Also, comparisons between different bodies of water may not always be accurate, since different monitoring agencies may test for different substances in different bodies of water.