The naturalist, broadcaster and national treasure paid tribute to the public water company and environmental organisations who worked in partnership to create a new storage capacity of 41 billion litres of water.
Sir David said: "I can remember a time when nature conservation and development were seen to be in opposition - you either developed or conserved - and that led to confrontation. Here at Abberton this is fundamentally, extraordinarily and wonderfully different."
"This development has been constructed hand-in-hand to create a wonderment for people and wildlife who live and visit here and a godsend for people who depend on it for water,"he said.
Abberton Reservoir is important to wildlife and wildfowl and has some of the highest environmental protection designations including, Ramsar site and SSSI status as well as being a Special Protection Area.
Essex & Suffolk Water has enlarged Abberton Reservoir by 58 per cent and the additional water will bolster supplies to the Chelmsford, Basildon, Brentwood, Southend and Thurrock areas and also to the London boroughs of Barking, Dagenham, Havering and Redbridge.
Construction began in 2010 and the major works were completed last year.
Heidi Mottram OBE, Chief Executive Officer of Essex & Suffolk Water, hoped the project will leave a lasting legacy for Essex – the driest county in the country.
She said that the 1995 drought – which left the reservoir empty – changed the way the company thought about future planning and encouraged it to launch into a comprehensive programme to drive down leakage (Essex & Suffolk Water has the lowest leakage levels in the country), encourage greater efficiency by its customers, improve the operation of its waste water treatment plant, and expand Abberton.
Ms Mottram said that knowing you are right doesn’t mean you automatically take the people with you and with a project on this scale – at one time Abberton was the largest construction site in Europe – the company needed to talk differently.
She said that Essex & Suffolk Water was able to build into its plans the feedback it received from a programme of stakeholder meetings that resulted in a reservoir that is designed for the benefit of birdlife and will secure the water supply for future generations of local people.
Watch and re-live the day with Sir David Attenborough at the official opening of the Abberton Scheme visit Essex & Suffolk Water’s YouTube Channel: