Reservoir Jobs: 4 of the world’s most ambitious water management engineering projects

In 2018, Patricia de Lille, the mayor of the South African city of Cape Town, was forced to make a panicked announcement.

Successive years of drought and an ageing infrastructure unable to keep up with population growth meant that Cape Town was on course to become the first modern major city to switch off its municipal water supplies, requiring residents to collect a daily ration of 25 litres. 

People queue to collect water from a spring in the Newlands suburb as fears over the city’s water crisis grow in Cape Town, South Africa, January 25, 2018. Photo: Reuters/Mike Hutchings

“We have reached the point of no return,” De Lille told an emergency news conference. “The chance of reaching Day Zero on April 21 is now very likely.”

The apocalyptic-sounding Day Zero to which De Lille was referring was the day when the water level in the majority of reservoirs supplying the city was projected to fall to 13.5% of capacity.

Fortunately for Capetonians, strict water saving measures from residents and heavy rains in June 2018 averted the crisis and Day Zero never actually arrived. Since then, the city has implemented a programme of clearing alien invasive plants, infrastructure maintenance, and drawing more ground water from aquifers. The city has also announced plans to build a desalination plant which could generate between 50 and 70 million litres of drinking water a day from sea water.

The crisis in one of Africa’s biggest and most prosperous cities has highlighted the need for better water security measures at a time of rapid urbanisation, climate change and frequent under investment in public utilities.

And Cape Town is not the only city facing a water crisis. In 2014 São Paulo in Brazil came within 20 days of running dry when the city’s main reservoir dipped to just 3% capacity, and in February this year Mexico City, home to 22 million people, said it could face Day Zero by June - a crisis averted by just-in-time rainfall.

With more and more cities under pressure to safeguard water supplies for drinking, transport or tourism, a growing number of developers, water companies and governments are investing in ambitious new water security infrastructure projects.

Construction Briefing looked at some of the most ambitious.

1) The Sites Reservoir, California

An artist’s impression of the Sites Reservoir Project. Image: Sites Reservoir Project

First proposed in the 1950s as part of California’s ambitious State Water Project, which collects water from rivers in Northern California and redistributes it to water-scarce populous cities, the Sites Reservoir project would, if built, be the largest new reservoir in California since 1979.

Located west of Colusa in the Sacramento Valley, the new US$4.5 billion reservoir, would inundate Antelope Valley, stretching 13 miles from north to south and 4 miles from east to west, becoming California’s eighth largest.

The project is being masterminded by the Sites Project Authority, a collection of government agencies. The project would require building two main dams on a pair of streams that typically only appear during extreme storms and also diverting water through existing canals from the Sacramento River.

The State of California plans to raise US$875 million to pay for some of the cost of the reservoir but the remainder of the costs will be footed by the water agencies which will eventually be able to receive water from the project.

The project has been supported by California Governor Gavin Newsom, who exercised his power, under a new package of legislation designed to cut red tape, to fast track a lawsuit filed against the project by environmentalists which eventually was not successful. The project is also opposed by a number of Native American tribes.

In September, the project suffered a setback when the California State Water Resources Control Board refused to grant the project the right to take the river water needed to fill the reservoir because it said the Sites Project Authority had not yet submitted enough information to the Army Corps of Engineers about how the project would comply with endangered species, clean water and historical preservation laws.

2) Trojena Lake, Neom, Saudi Arabia

Digital render of Trojena (Image: Neom)

Saudi Arabia is ranked the world’s third driest country. Its arid climate means the country has no permanent natural rivers or lakes. However, the country is investing much of its huge oil wealth providing plentiful fresh water in the desert – both as drinking water for its growing population, for agriculture, and also for leisure and tourism projects.

One of these ambitious projects is the Trojena tourism project in the mountains close to the Gulf of Aqaba. The project is designed as a ski resort which will open for three months of the year, while the rest of the year it will focus on hiking, biking and watersports.

The project is planned around a 1.5 square kilometre artificial lake which is expected to be filled via a desalination plan powered by 100% renewable energy.

In January, Italian contractor Webuild signed a US$4.7bn contract to build the lake, constructing three dams. The main dam will be made of roller compacted concrete and will be 145 meters high, 475 meters long and will hold a volume of approximately 2.7 million cubic meters of water.

3) Río Indio dam, Panama

In late 2023, a severe drought in Panama led water levels in Lake Gatún to decline to unprecedented levels.

For the small South American country this was doubly bad. Not only does the artificial lake provide drinking water to around half of Panama’s 4.5 million people, but it is also the main source of water used in the lock system of the Panama Canal – the shipping thoroughfare which handles nearly 3% of all maritime trade (roughly US$270 billion of cargo each year).

The water shortage forced the Panama Canal Authority, the body which administers the canal, to restrict the number of ships passing through. By February 2024, transits had been reduced to around 18 a day, from a typical 36 a day, leading to global shipping delays and forcing some companies to look for alternatives.

In a press conference in July, Panama Canal officials announced that in order to avoid a repeat of the situation, the authority has revived a controversial megaproject to invest US$1.6 billion in damming the nearby Indio River and then drilling a tunnel through a mountain to pipe fresh water 8 kilometres into Lake Gatún.

Officials said the project would allow 15 more ships per day to pass through the canal and ensure a reliable water supply for Panama City.

4) Havant Thicket Reservoir, Hampshire, UK

A visualisation of Havant Thicket when completed. Image: Portsmouth Water

In the UK, a country well known for its drizzly, grey weather, water security has seldom been anywhere near the top of the political agenda.

Yet, here too concerns about climate change, increasing urban populations and ageing infrastructure are prompting water companies to invest in the country’s first new reservoirs in 30 years.

Last year, the National Infrastructure Commission (NIC), the government’s independent advisor on infrastructure challenges, published a report calculating that by the mid-2030s the country will require at least 1,300 megalitres per day from new infrastructure.

In response, water companies have come up with proposals for nine new large reservoirs, two reservoir enlargements, three large intercompany transfers. 11 water recycling schemes and nine new desalination plants.

Due to open in 2029, the planned new Havant Thicket reservoir, which lies around ten miles from the city of Portsmouth, will be the first to complete. It will eventually provide customers with up to 21 million litres of water a day, supplying 160,000 people and reducing the amount of water which needs to be taken from chalk streams the River Test and the River Itchen.

The project is being built jointly by water companies Portsmouth Water and Southern Water. They plan to build underground pipelines from the nearby Havant and Bedhampton springs to fill the reservoir, constructing a 3 kilometer long, 20-meter-high dam at one end of the valley to keep it in and using the site’s existing clay to create a watertight base.

Mackley, a member of the Van Oord Group, together with North Wales-based jones Bros Civil Engineering, signed a £167 million (US$221.7 million) contract with the water companies last year following a detailed tender process.