Vijayanagara: The Cauvery Water Management Authority (CWMA) has admitted through a Right to Information (RTI) reply that it lacks updated information on siltation, live storage loss and sediment management in Karnataka’s four major Cauvery reservoirs — Krishna Raja Sagara (KRS), Hemavati, Harangi and Kabini — after 2009, environmental activist Sadananda Heggadadalmath of Kottur said.Heggadadalmath said he sought the information through an RTI application filed on June 20, 2026. In its reply dated July 23, the CWMA’s central public information officer stated that no updated hydrographic or remote-sensing survey reports on live storage capacity loss in the four reservoirs had been received after 2009.The RTI reply also stated that the authority had no year-wise siltation survey data for the reservoirs from 2010 onwards.According to the reply, CWMA had no information on whether siltation-induced storage loss was considered while regulating water releases under the Water Year concept and distress-year provisions following the supreme court’s Feb 16, 2018 order.It further stated that no information was available on communications, notes or decisions regarding siltation loss and its impact on inter-state water sharing since 2018.The authority also said it had no information on whether it had directed or proposed a joint survey by the Central Water Commission (CWC) and Karnataka Engineering Research Station (KERS) to assess current live storage loss.The RTI response added that CWMA had no information on whether it assessed excess monsoon spills from Karnataka reservoirs reaching Tamil Nadu due to reduced storage capacity.It also stated that no information was available on measures taken to implement sediment management and reservoir maintenance in the Cauvery basin in line with the National Water Policy.Further, the authority said it had no information on the status of making reservoir siltation data, storage loss figures and inflow-outflow data publicly available on the CWMA dashboard.Referring to the RTI reply, Heggadadalmath alleged that the absence of updated surveys meant the actual storage capacity of the reservoirs remained unknown.He claimed that continuing water releases without such data was unscientific and undermined transparency and accountability in inter-state water management.In a separate letter to the CWC, Heggadadalmath urged the agency to address the issue. He said water-sharing and drought-management decisions were being made using outdated design capacities.He sought immediate collection of the required data, assessment of live storage loss in major reservoirs, and ensuring that future water allocation and drought-management decisions are based on actual live storage capacities. He also urged the CWC to place updated reservoir data in the public domain.
