The Annual Sustainability Report 2024/25 highlights work that Sizewell C is doing to promote jobs, skills and economic growth; supporting employees; investing in local communities; improving biodiversity; and mitigating greenhouse gas emissions.

Its section on "nature and the environment" covers enhancing local biodiversity, embedding circular economy principles, managing its water supply and sustainable infrastructure.

Meanwhile, the report's chapter on "climate" covers powering net zero technologies, greenhouse gas emissions and adapting to the changing climate.

Multiple new sources of water planned, under construction or in operation

Sizewell C has already started using significant volumes of water for construction activities. In the 2025 financial year, the project used 19,151m tankered to the site from Anglian Reservoir and and 6,603m of water from on-site boreholes. A volume of 5,091m of foul water was discharged from the site.

"We recognise that construction is taking place in a region of water stress and that the development will need large volumes of water -- both during construction and when the plant is up and running," the report says.

"Acknowledging this, we have established a clear approach to ensure we do not affect the local community's supply."

Water demand during construction will be driven by tunnelling, cut off wall construction and dust suppression. The report caveats that drinking water would only be used for domestic facilities and welfare.

"Non-potable water for dust suppression is being sourced from two local river abstractions located to the north and south of the construction site within the Sizewell Estate," the report says.

"Up to 1M litres per day is available between the two abstraction licences, which have been granted by the Environment Agency. Water is pumped to the construction site via short-supply pipelines and is stored in a lined reservoir to provide resilience.

"The northern abstraction point came online in September 2024 and the southern point in March 2025.

"We have also applied for a new licence to install a temporary groundwater borehole on the Sizewell C site. If approved, the borehole will provide up to 0.6M litres per day of water."

Multiple additional supplies are either planned or being worked on, highlighting how water-intensive the construction and operation of the plant is expected to be.

Sizewell C has applied for a new mains construction supply from Essex and Suffolk Water.

Additionally, a "new water storage and distribution facility is available at Orwell Logistics Park" is under construction and expected to be completed in 2025, "work is progressing at pace to design and construct Sizewell C's temporary desalination plant," and "long-term permanent water supply will be established by Essex and Suffolk Water" by 2032.

Sizewell C aiming to achieve 19% biodiversity net gain

The Sizewell C sites span a significant proportion of the area between the town of Leiston and the Suffolk coast. NCE previously covered the state of groundworks at the main construction area (MCA), temporary construction area (TCA) and the ancillary construction area (ACA) based on aerial images and official updates.

"Sizewell C's Main Development Site sits largely within the Suffolk and Essex Coast and Heaths National Landscape, with a small section overlapping the Sizewell Marshes Site of Special Scientific Interest (SSSI)," the report says.

"It is our priority to protect and enhance this beautiful stretch of coastline throughout every phase of the Sizewell C lifecycle. As part of our long-term approach, we are also creating new, connected habitats across the landscape -- designed to support local wildlife and deliver a 19% net gain in biodiversity."

Addressing the issue of pursuing development at the site of special scientific interest (SSSI), the report says: "Where land-take is unavoidably required from the Sizewell Marshes SSSI, we have developed strategies to deliver compensatory habitat at ratios agreed with Natural England, our regulator."

Sizewell C will permanently take 5.29ha from the SSSI, but "this impact will be more than compensated for by the habitats we have already created and plan to create", the report adds.

"We have been investing in nature and local biodiversity for well over a decade," it says. "More than 170ha of former low-grade arable farmland have been put under conservation management, much of it voluntary, going 'above and beyond' what is required in the planning process."

Read the full Sizewell C annual sustainability report here.

Plant's legacy 'will be measured' in benefits brought to people and nature

Sizewell C joint managing directors Julia Pyke and Nigel Cann said: "This first Annual Sustainability Report is a landmark for Sizewell C and shows how big infrastructure can deliver lasting social benefits.

"We are already creating thousands of jobs, supporting local communities, and protecting Suffolk's environment. While construction does bring temporary disruption, we are determined to ensure that our project delivers lasting change for the better for East Suffolk.

"Sizewell C will power six million homes with clean energy for 60 years, but its legacy will be measured just as much in the opportunities and benefits it brings to people, communities, and nature."

Local authority to make sure plant sticks to responsibilities set out in DCO

An East Suffolk Council spokesperson told NCE: "This report highlights the critical importance of working closely with local partners and communities to deliver a scheme of this magnitude.

"Every effort must be made to minimise the impacts of construction activities on residents and the surrounding area.

"Therefore, we will continue to ensure that the developer meets all its responsibilities set out in the Development Consent Order, as well as the commitments made under the project's Deed of Obligation."

Benefits from plant ultimately paid for by the public - campaigner

Stop Sizewell C executive director Alison Downes told NCE: "Much is being made of the legacy aspects of Sizewell C, in areas the region is under provided for, especially education.

"But the vast majority of Sizewell C's funding comes from the British public - from our taxes and the 'nuclear tax' on our energy bills - so the reality is we are paying for these projects ourselves.

"It remains our view that the government will learn well before Sizewell C is completed that there were better ways to spend our money.

"Besides, how can we take Sizewell C's promises seriously when they won't even go public with a target completion date that is a little more specific than 'mid to late 2030s'?'"