Filling the Reservoir with Artificial Rain is Considered Cheaper, BMKG Claims the Cost is Only One Tenth of the Benefits

JAKARTA - BMKG assesses that weather modification operations to maintain water supplies for reservoirs and lakes are much cheaper than the economic benefits generated.

Head of BMKG Teuku Faisal Fathani said one example was carried out in Lake Toba from May to June 2026 with Perum Jasa Tirta I.

The operation is aimed at maintaining the water level so that it is still able to supply hydroelectric power plants, agricultural needs, and raw water.

"The investment is about 10 times smaller than the value of the water benefits used for the PLTA," Faisal said at the Presidential Palace Complex, Jakarta, Tuesday, July 28.

According to Faisal, the water surface of Lake Toba can drop by about one centimeter per day during the dry season. Therefore, artificial rain is carried out to maintain water discharge.

BMKG also conducts scientific studies before determining the location of weather modification operations. Indonesia has 699 seasonal zones and 240 reservoirs with different characteristics so that each operation is adjusted to the conditions of each region.

Faisal emphasized that the seeds used in weather modification operations were natural materials so as not to endanger the environment.