Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 274

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 274
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 sum to the indicated total due to rounding. Figures below have been rounded to the nearest million m 3.

| Year ended Dec. 31                   |     | 2024 |     |     | 2023 |     |     | 2022 |     |
|:-------------------------------------|:----|:-----|----:|:----|:-----|----:|:----|:-----|----:|
| Water withdrawal                     |     |      | 237 |     |      | 273 |     |      | 233 |
| Water discharge                      |     |      | 212 |     |      | 239 |     |      | 207 |
| Total water consumption (million m3) |     |      |  25 |     |      |  34 |     |      |  26 |

Dam Safety Our dam safety programs include all hydroelectric developments, constructed ponds and fluid retaining structures such as ash lagoons and canals, as well as associated equipment and structures and the personnel required to operate, maintain and inspect these items. They are governed through our Dam Safety Policy and Dam Safety Management System, which includes requirements on design, modification and decommissioning, operation, maintenance and surveillance, public safety, emergency management and risk management. TransAlta’s Board and its President and CEO oversee the effectiveness of our dam safety programs and receive regular updates. In 2022, a member of the Board was designated as the Company’s Dam Safety Advisor to assist the Board in fulfilling its oversight role in regard to the Company’s dam safety practices given the unique and technical aspects of dam safety. In addition, TransAlta engages an external Dam Safety Review Panel to provide external review of the

program and its management, including overall assessment and benchmarking against other national and international programs. Our monitoring programs include:

| • |     | Regular operations and engineering inspections; |

| • |     | Testing critical equipment; |

| • |     | Numerous instruments in the dams monitoring water level, temperature, movement, earthquake 
 detection;                                                                                 |

| • |     | Use of drones and satellite remote movement monitoring; |

| • |     | Emergency plans and exercises with internal and external stakeholders; and |

| • |     | Regular third-party reviews that are shared with the regulators. |

We work closely with local stakeholders including conservation authorities and public agencies on watershed management, emergency planning and flood response. In 2022, we started decommissioning the Keephills Ash

| M120 |