The construction of skyscrapers and a new subway line highly attributed to the lake leak that recently took place in the southern capital, Seoul officials said Thursday. 

According to the Seoul Metropolitan Government, large-scale constructions of Lotte World Tower, Subway Line No. 9 and eight other skyscrapers in Songpa-gu contributed to the decrease in the water level of the Seokchon Lake by over 0.5 meters over just a few years.

The city government launched a probe after the lake level dropped from 4.68 meters to 4.17 meters between 2011 and 2013. Located at Jamsil, the 5-meter-deep lake is artificially made with its lakebed composed of well-drained silty sand. 

The lake leak coincided with the construction around the region, and the isotope probe also showed that the lake water was highly similar to the leaked underground water from the Lotte World Tower and Subway Line No. 9, officials said.

The water flow also changed direction to those two sites after the construction began, they added.

The city, however, projected that the water level will rise again once the construction of the Lotte skyscraper and the subway wraps up.

Several sinkholes in Jamsil were found to be not related with the lake leak, they added.

As part of its efforts to prevent further lake leakage, the city vowed to run a lake monitoring team and obligate construction workers to report it immediately should an underground water leak be spotted, the authorities said.

By Lee Hyun-jeong (rene@heraldcorp.com)