OTSU, Shiga Pref. — The sustainability of the world’s lakes will increasingly depend on private investment and closer cooperation between scientific and governmental agencies, according to the keynote speaker at the ninth International Conference on the Conservation and Management of Lakes.
The opening session Monday of the five-day conference was attended by some 900 people from more than 100 nations. Held biennially, this year’s conference is the second to be held in Otsu, Shiga Prefecture, on the shores of Lake Biwa. Otsu hosted the first conference in 1984.
Keynote speaker Margaret Catley-Carlson said the world’s growing population, accelerated urbanization and rapid changes in socioeconomic structures around the globe have put severe stresses on lakes and rivers.
In developing and developed countries alike, lakes have long been used as dumping grounds for waste water, she said.
“We will have to look to scientists and experts for the research on how to reduce adverse impacts on lakes and the best techniques for conservation,” said Catley-Carlson, who is also chair of the Global Water Partnership.
“But we have to go further,” she said. “We also need financial experts. We need to start looking at innovative ways of attracting the private sector into particularly those increasing urban areas in order to solve some problems using new investment funds not currently available.
“Lakes store 90 percent of the globally available fresh water, but constitute only 0.07 percent of the water on the planet.”
Of the water available, 70% is used for agriculture, she said. “Agriculture is very much a matter of making the best use of green water, which is rainwater, and the blue waters of rivers and ground water.
“But we are going to have to change agriculture around the world. At the moment, we tend to think in terms of yield per hectare or yield in terms of ground or industrial input. More and more, we’re going to have to think of each cubic meter of water being applied at just the right time.”
Regarding Lake Biwa, those in attendance, including Prince and Princess Akishino, heard from Hiroya Kawanabe, director of the Lake Biwa Museum. Kawanabe said Japan’s largest freshwater lake is about 4 million years old and was once situated 50 km southeast of its present location.
It now provides drinking water for 14 million people — about 11 percent of the Japanese population.
In the 1960s, the transparency of the water in the middle of the lake extended down eight meters. However, by the late 1970s, algae, caused in part by industrial pollution, had spread throughout the lake and has been observed during the summer months every year. This has reduced transparency to less than 6 meters.
“When this began to occur, the communities around the lake voluntarily began to use soap instead of synthetic detergents, and the Shiga Prefectural Government enacted an ordinance to prevent eutrophication (the phenomenon of proliferating of algae) of the lake,” Kawanabe said.
“In terms of the levels of nitrogen and phosphorous, the lake has now leveled off.”
At the same time, the population around the lake has increased by 20 percent, so it is thanks to the efforts of local people that water quality has been somewhat stabilized, though it is still not what it should be, he said.
Kawanabe said a more serious problem now is that at the deepest levels of around 100 meters, the amount of oxygen becomes almost zero in summer.
This gives rise to sulfur bacteria, which then spreads to 50 meters from the surface. Shiga Prefecture has set a goal of returning the water quality to 1965-1970 levels over the next 20 years, Kawanabe said.
The international conference was initiated by former Shiga Gov. Masayoshi Takemura.