Photo/Illutration The usually submerged stone walls at the ruins of Sakamoto Castle partly appear along the coast of Lake Biwako in Otsu, Shiga Prefecture. (Hirokazu Suzuki)

OTSU, Shiga Prefecture—Water levels have receded to alarmingly low levels in Lake Biwako, the water source for about 14 million people, prompting the prefectural government to consider emergency measures.

A further shrinkage of Japan’s largest lake could cause serious damage to the environment and the tourism industry and force restrictions on water use in the Kinki region, including Osaka, Kyoto and Hyogo prefectures.

For the first time in 14 years, Shiga Prefecture set up a liaison and coordination council on Nov. 17 to study the impact of the dry weather spell on ecosystems and other possible consequences.

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An electric bulletin board in Otsu, Shiga Prefecture, on Nov. 17 shows Lake Biwako’s water level has fallen into alarming territory. (Hirokazu Suzuki)

The water in the lake has been on average 36 centimeters below the reference level at this time of the year. It was 65 cm shallower on Nov. 17.

The prefectural capital of Otsu received only 43 millimeters of precipitation in October, about 30 percent of the average, while the monthly rainfall for Hikone was 30 mm, about 20 percent of the average, data from the Hikone Local Meteorological Office showed.

“There was no sizable rainfall (in October) this year, with no typhoons approaching and no stationary fronts,” an official with the meteorological office explained.

If fine weather continues to sap water from Lake Biwako, restrictions could be imposed on water intakes in downstream areas of the Yodogawa river, which flows into Osaka Bay, officials said.

The Kinki Regional Development Bureau’s Biwako Office in Otsu currently discharges 15 cubic meters of lake water per second, causing Biwako to lose about 1 cm of water a day.

The prefectural government customarily sets up a drought response headquarters when the water drops to 75 cm below the reference level.

If the level falls to around 90 cm below reference, a Biwako-Yodogawa drought response council is set up with other stakeholders in the region, including the land ministry and the Osaka prefectural government, to discuss possible water restrictions.

Shiga prefectural government officials said if the water levels remain low through spring, lakeside reed-grown plots could dry up and ruin the spawning grounds for fish. The exposed waterweeds could decay, creating a foul stench.

Receding shorelines could also make it difficult for fire engines to draw water from the lake to douse fires along coastal areas, the officials said.

Shiga Governor Taizo Mikazuki expressed concerns about the development during a news conference on Nov. 16.

“I have the impression that (the lake surface) is shrinking steadily,” he said, adding that he is considering calling on the public to reduce water usage.

The falling water levels have already affected the operations of Otsu-based Biwako Kisen Steamship Co., which runs boat tours to the popular Chikubushima island in the lake.

The receding water has rendered the usual gate near the center of the vessel unsuitable for boarding and disembarking at the isle, which falls under the jurisdiction of Nagahama, Shiga Prefecture.

Instead, passengers have been using a narrower gate near the boat’s stern, which does not accommodate wheelchair users and bicycle riders, company officials said.

The decreasing water level, however, has had a rather positive effect elsewhere.

In Otsu, part of the stone walls of the ruins of the lakeside Sakamoto Castle, built by 16th century warlord Akechi Mitsuhide, has emerged above the water’s surface.

“I have been given this wonderful opportunity to have a look at the real thing,” said Masafumi Yamamoto, the 80-year-old secretary-general of a local group of Sakamoto Castle amateurs, who also serves as a volunteering guide for tourists.

(This article was written by Shinya Okudaira and Hirokazu Suzuki.)

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