WINNIPEG, Manitoba (Reuters) - Manitoba will tighten rules on expanding hog farms and ban manure spreading to cut the flow of phosphorus into the world's 11th-biggest freshwater lake, as Lake Winnipeg deteriorates from algae growth.
The western Canadian province, which has the country's third-largest pig herd, will also protect wetlands that filter out pollutants and force the capital Winnipeg to build a sewage treatment plant, Premier Greg Selinger said on Thursday.
The buildup of nutrients like phosphorus from sewage, farms or natural sources is a major environmental problem for the world's lakes and rivers, including Lake Winnipeg.
It causes growth of blue-green algae that can produce toxins that sicken humans and animals, and use up the water's oxygen. "The objective is to save the lake from going dead on us," Selinger told reporters.
Canada is the world's third-biggest shipper of pork. But changes in Manitoba are not likely to impact markets because hog production has been falling for several years in the province.
The 24,000-square-kilometre (9,000 square mile) Lake Winnipeg collects water from a farming area across four Canadian provinces and the northern U.S. Plains. The lake ultimately drains into Hudson Bay.
Fertilizer use on crops and Manitoba's expansion of its livestock herds since the 1990s are key causes of blooming algae on Lake Winnipeg, according to a five-year study commissioned by the province, which called for a 50 percent reduction of phosphorus into the lake.
Selinger said that is the province's goal, but he gave no timeframe.
He said Manitoba will block hog farm expansions that don't use environmental practices to protect water, such as chemically treated lagoons. From 2013 it will also ban the spreading of pig manure on fields in winter to fertilize soil.
Karl Kynoch, a hog farmer and chairman of the Manitoba Pork Council said the government was already planning to ban winter manure spreading, which few hog farmers still do.
He said the province is unfairly blaming the hog industry for Lake Winnipeg's problems, which have worsened even as Manitoba's hog numbers have shrunk.
"(It's) extremely disappointing to see the government attack the industry and accuse it of dumping hog manure in the lake," he said.
Selinger called his plan a starting point and said the province may later consider restrictions on commercial fertilizers for crops as well.
Some of Manitoba's most popular beaches are on the lake, along with a commercial fishery.
Spring floods in Manitoba have added to algae build-up as standing water soaks up nutrients from fields before flowing into the lake.
The lake's algae problem is on the verge of worsening dramatically, said the provincial study's author, Peter Leavitt of University of Regina.
Diverting nutrients such as municipal sewage and runoff from specific factory farms has improved water quality in other parts of the world. But regulating the problem from broader sources has been more difficult, the study said.
Editing by Janet Guttsman