Irish Water has opened a new state-of-the-art covered reservoir in Stillorgan in Dublin to ensure a safe, clean and resilient water supply to 200,000 customers.

It replaces one of Europe's last remaining uncovered treated-water reservoirs located there for the past 150 years.

In recent years falcons and other scare-tactics have been used to keep seagulls away from the reservoir but now these practices are no longer required.

Trevor Roche of Dublin Falconry explained how he and his birds went about the job of scaring away the seagulls, over the past four or five years, before the project got under way.

"We needed to scare the seagulls off the water to stop the birds from mucking into the water and causing contamination with cryptosporidium bacteria," he said.

The peregrine falcons Mr Roche used at the reservoir are among the fastest birds of prey in the world, with some capable of speeds more than 300 kilometres per hour.

It worked well, but was not 100% sufficient so other methods of scaring the seagulls away were also used including bird callers, distress callers, kites, lasers and other loud bearing sources.

Mr Roche even used to fire blank cartridges which he said tended to scare the seagulls off the water very quickly.

Of course, timing was everything when it came to the use of these alternative tactics.

He had to avoid periods when there was a lot of traffic or people moving about the area.

"It was a 'frightening' exercise, not a killing exercise, and so the peregrines were used to scare rather than to kill," explained Mr Roche.

Once released, the falcons would soar about 400 to 500 feet into the air.

Spotting a bird of prey flying so high above them caused the gulls to worry about an attack and so fly off to nearby rooftops away from the reservoir for safety.

The original Stillorgan Reservoir site comprised three open reservoirs where treated drinking water was left exposed to the elements

Some gulls were difficult to shift as they had been born and reared on the reservoir and felt safe in the water where peregrine falcons would not survive.

"Some of the gulls know that certain birds mean business and so soon as we released them, they would be gone, and they would stay gone for the entire period that we were there," he said.

"But when we left the gulls would come back. What Irish Water has now done, by replacing the open reservoir with the new covered reservoir, has cleared up the problem completely.

"But now the falcons are out of work. They have been sacked."

Irish Water said the new covered reservoir in Stillorgan brings a big improvement to Dublin's water supply.

Over 200,000 Dubliners will now enjoy a much safer and more secure water supply, according to Minister for Housing, Local Government and Heritage Darragh O’Brien.

He said it represents a huge leap forward in the provision of a more secure and resilient water supply for Dublin and is a landmark project.

The new reservoir will store over 160 million litres of treated drinking water, replacing three open reservoirs that were no longer fit for purpose as they were uncovered and presented a risk of contamination by birds, animals or human activity.

This project represents an investment of over €50 million by Irish Water and is the latest in a number of major upgrades of water supplies in the greater Dublin area designed to future-proof the supply to cater for increasing demand, population growth and the challenges that are likely to be presented by climate change.

Falcons are no longer needed at Stillorgan reservoir

Niall Gleeson, Irish Water Chief Executive, added: "We are committed to building a world class public water infrastructure, carrying on the legacy of the committed local authorities that have developed and operated these sites for generations, while applying cutting-edge technology and expertise in the development of solutions for the future.

"We all recognise the need to improve our ageing water infrastructure and the completion of this project is another important step along the road to building a secure and sustainable water supply for the people of Dublin for generations to come."

The original Stillorgan Reservoir site comprised three open reservoirs where treated drinking water was left exposed to the elements, with consequent risk of contamination.

The construction of the new covered reservoir will eliminate that risk and enable better management of the supply of water to customers.

Construction work began on the upgrade project in 2018 with the draining down of the Gray Reservoir, which had not been fully drained since it was built in the late 1800s.

The new covered reservoir was then constructed within the footprint of the Gray Reservoir.

The new reservoir is a key component of Dublin’s strategic water infrastructure, which links the supply from five major water treatment plants through an integrated network of trunk mains and reservoirs.

It is supplied with drinking water from water treatment plants at Vartry in Co Wicklow and Ballymore Eustace in Co Kildare.

The completion of the reservoir marks the culmination of a total investment of €150 million in the upgrade of the Vartry Water Supply Scheme, which also delivered the replacement of the old Vartry to Callowhill tunnel in 2018 and the construction of the new Vartry Water Treatment Plant which was completed in 2021.

The reservoir and associated infrastructure will have the capacity to support future water demand through 2031 and beyond.