Alarm bells sound in Kinki region as Lake Biwako continues to shrink


OTSU, Shiga Prefecture — Water levels have dropped to alarming levels in Lake Biwako, the water source for around 14 million people, prompting the prefectural government to consider emergency measures.

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 prefectures , Kyoto and Hyogo.

For the first time in 14 years, Shiga Prefecture established a Liaison and Coordination Council on November 17 to study the impact of the dry weather wave on ecosystems and other possible consequences.

An electric notice board in Otsu, Shiga Prefecture on November 17 shows that the water level in Lake Biwako has fallen into alarming territory. (Hirokazu Suzuki)

The lake water was on average 36 centimeters below baseline at this time of year. It was 65 cm shallower on November 17.

The prefectural capital of Otsu received just 43 millimeters of rainfall in October, about 30 percent of the average, while the monthly rainfall for Hikone was 30 mm, about 20 percent of the average, according to data from the Hikone local weather office.

“There has been no significant precipitation (in October) this year, with no approaching typhoons and no stationary fronts,” said an official from the meteorological office.

If the good weather continues to undermine the water in Lake Biwako, restrictions could be placed on water intakes in areas downstream of the Yodogawa River, which flows into Osaka Bay, officials said.

The Biwako office of the Kinki Regional Development Office in Otsu currently discharges 15 cubic meters of water from the lake per second, causing Biwako to lose about 1 cm of water per day.

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

If the level drops to about 90cm below the baseline, a Biwako-Yodogawa Drought Response Board is set up with other actors in the region, including the Ministry of Lands and the Prefecture Government. Osaka, to discuss possible water restrictions.

Shiga Prefecture government officials said if water levels remained low until spring, the lakeside reed plots could dry up and ruin spawning grounds for fish. Exposed algae could rot, creating a foul odor.

Receding shorelines could also prevent firefighters from drawing water from the lake to put out fires along coastal areas, officials said.

Shiga Governor Taizo Mikazuki expressed his concerns about the development at a press conference on November 16.

“I have a feeling that (the area of ​​the lake) is steadily decreasing,” he said, adding that he was considering calling on the public to reduce water consumption.

Falling water levels have already affected the operations of the Otsu-based Biwako Kisen Steamship Co., which organizes boat trips to the popular island of Chikubushima on the lake.

The receding waters made the usual gate near the center of the vessel unsuitable for embarkation and disembarkation on the island, which falls under the jurisdiction of Nagahama, Shiga Prefecture.

Instead, passengers used a narrower door near the stern of the boat, which does not accommodate wheelchair users and cyclists, company officials said.

However, the drop in the water level 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, emerged above the water’s surface.

“I had this wonderful opportunity to see the real thing,” said Masafumi Yamamoto, the 80-year-old general secretary of a local group of Sakamoto Castle lovers, who also serves as a volunteer guide for tourists.

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


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