They had discussed with the Castlereigh security officers and had inspected the main tributaries to the reservoir, the Keselgamu-Oya and Dik-oya and had ruled out the possibility that the oil had flown to the Castle reservoir through these channels.
They suspect that the oil had been put into the reservoir from the surrounding areas. Hence, the Central Environmental officials had taken measures to test the samples of deposited oil.
After the Castlereigh water is used for hydro power generation, it is released into the Kelani river.
Pics by Ranjith Rajapaksha- Hatton Corr.