Water levels at the Castlereagh and Maussakelle reservoirs are declining rapidly as extreme dry weather persists in the catchment areas on the western slopes of the Central Hills, engineers said Friday.
As of Friday, the Maussakelle reservoir had fallen to 50 feet 11 inches below spill level, despite receiving 12 mm of rainfall the previous day. Castlereagh had dropped to 40 feet 10 inches below spill level after 14 mm of rainfall on Thursday.
As water levels continue to decline, several islands and archaeological ruins submerged during the original construction of the reservoirs have begun to re-emerge, engineers said.
The drop has direct consequences for electricity generation. The two reservoirs supply the Wimalasurendra, Laxapana, New Laxapana, Canyon and Polpitiya hydropower plants. Reduced hydro availability typically forces the grid to rely more on expensive thermal generation, adding pressure to tariff-setting discussions already underway at PUCSL.
The decline marks a sharp deterioration from the early-April warning when Maussakelle stood at 47 feet and Castlereagh at 43.8 feet below spill. In just over two weeks, both reservoirs have fallen further despite intermittent rainfall, with the situation now described as “declining rapidly” by engineers.
The Department of Meteorology has previously forecast normal rainfall for May and June, but the inter-monsoon window in April has left the system exposed. The National System Operator has already asked PUCSL for a further 15% tariff hike on top of the 10% applied from April 1, citing revised generation costs partly driven by lower hydropower availability.
