BAKUN HYDROELECTRIC PLANT
Controlled Release Plan
A controlled release is necessary to ensure the safety of the dam, river users and downstream communities. Bakun HEP Controlled Release (CR) Procedure is prepared for the operation stage as a guideline for the operation staff of the HEP. The procedure stresses mainly the communication requirements to obtain the necessary permission from the relevant authorities for the operation of the spillway gates and the dispersion of necessary information to alert downstream river users and downstream communities on the controlled release.
Bakun’s full supply level (FSL) is at EL 228m and its minimum operating level (MOL) is at EL 195m. The normal operating range for Bakun HEP should be maintained within the range of EL 221.0m to EL 227.5m. For the optimum operating level, the reservoir shall be maintained within the range of EL 225.0m to EL 227.5m. By keeping the reservoir below the FSL, larger flood storage is available, and the flood discharges and downstream flow fluctuations can be minimised.
Bakun HEP is installed with a gated chute spillway on the left abutment with four radial gates and two chutes each ending in a flip bucket which will project the flow into a plunge pool in the river, downstream of the powerhouse. Each radial gate is equipped with a small flap gate to assist in the removal of logs. To meet the requirements of routine maintenance, the spillway gates shall be tested (open and close back) periodically. The spillway was designed to withstand a Probable Maximum Flood (PMF) of 15,000 m3/s.
During a controlled release, the spillway gates will be conducted in interval opening steps to avoid a fast rise of the downstream river level. Similarly, during the closure of the gates, gradual lowering is required to avoid a drastic drop in the downstream river level. This is to ensure minimal risk to the downstream communities.
The aerial overview of Bakun HEP
Number of Controlled Releases from 2020 to 2024
Year | Controlled Release (CR) |
2020 | CR 1: 9 March - 29 March (3 weeks) |
| CR 2: 3 May – 6 June (5 weeks) |
| CR 3: 12 July – 22 Aug (6 weeks) |
| CR 4: 23 Dec 2020 -22 Jan 2021 (4 weeks) |
2021 | CR 1: 8 Sept – 9 Oct (5 weeks) |
| CR 2: 3 Dec - 31 Dec (4 weeks) |
2022 | CR 1: 30 May - 13 June (2 weeks) |
CR 2: 28 Sept – 19 Oct (3 weeks), with extension until 3 Nov (2 weeks) | |
CR 3: 19 Dec 2022 – 12 Jan 2023 | |
2024 | CR 1: 13 July - 25 July 2024 |
Riverine Notice
- Controlled release of water from Bakun HEP Reservoir to commence from 13 July to 3 August 2024
Sarawak Energy’s Notices of Bakun HEP Controlled Release
Sarawak Energy will cease the controlled release of water from Bakun HEP reservoir as water levels have normalised. The seasonal controlled release to manage reservoir levels effectively started on 13 July 2024 and will end on Thursday, 25 July 2024. We thank our neighbouring community for their cooperation and advise residents downstream to stay alert to changing water levels and currents.