How Does Tees Barrage Work?

The Tees Barrage is a complex feat of engineering that balances a multitude of variables to ensure it operates as effectively and efficiently as possible to maintain a safe and vibrant environment on the river.

Sitting alongside the Barrage is the International White Water Course which is popular destination for visitors to enjoy a wide range of watersport activities. Both the Tees Barrage and the white water course (Archimedes screws), are monitored, controlled and operated by Canal & River Trust (CRT) independent of Tees Active who only deliver the watersport activities.

Course Operations and River Conditions

So how does the white water course work? Here comes the technical bit….

The white water course can be operated in three ways:

• GRAVITY mode (this is our preferred option) – when there is a low tide it means fresh river water from upstream of Tees Barrage can naturally flow down the course, where it escapes through an outlet pipe into the river downstream of Tees Barrage and continues its journey out to sea, hence this is called Gravity mode.

• PUMPED mode – when the tide is high the course can’t operate in gravity mode as the outlet pipe needs to be closed to prevent sea water from flooding the white water course, which is a fresh water habitat. Instead, water flows naturally down the course and is then transported back to the top of the course via the Archimedes screws. The water then continues to flow down the course creating a constant loop of water.

• GENERATION mode – in the same way gravity mode can only be operated when there’s a low tide, Generation mode is when the fresh water from upstream is diverted to the Archimedes screws, instead of flowing down the course. The water from the screws escapes through the outlet pipe and out to sea in the same manner as Gravity mode. It is within this mode that we can generate electricity.

Can the course just run on gravity all the time?

Unfortunately, it cannot and there are several factors that influence this which are beyond Tees Active’s control…

1. Firstly, as highlighted in the above illustration, the ability to run the course on Gravity is determined by the tide level downstream of Tees Barrage – the level of the tide, and its highest and lowest points, varies day to day and hour to hour.

2. The Canal & River Trust have the very responsible, and often complicated, role of managing the river upstream of Tees Barrage at all times. They must follow an extensive hierarchy of criteria that they have to adhere to when it comes to river management. This is known as the Scheme of Operation.

So how does this affect the operation of the course?

The Canal & River Trust need to maintain water levels within a predefined range upstream of the Barrage.  So, when there’s very little rainfall in the dry summer months and river levels start to drop, they need to ensure an adequate level is maintained. Unfortunately, this means that they can’t let any water down the white water course and downstream to the sea meaning the course cannot operate in its preferred Gravity mode. This is why you will sometimes visit and there will be no water flowing down the course – the white water course is a very small component in this much bigger ecosystem.

To provide some context on how much points 1 and 2 affect the white water course…

In 2019, during our peak months, April to September, there was approximately 13 days when the course could be ran in gravity during our opening hours. That’s only 7% of days available over a 6 month period!

3. Other criteria on the Scheme of Operation, such as flood risk, fish passage to aid migration and spawning, and lock operations, also mean the course cannot operate in Gravity mode on some occasions. However, points 1 and 2 are the main reasons why the white water course cannot operate in Gravity mode as often as Tee Active would like.

The Archimedes Screws and Power

Archimedes screws are an amazing invention that transport water uphill, or upstream in our case. Each of the 4 Archimedes screws weighs a huge 14 tonnes, and when they are operating, each one transports around 3.8 tonnes of water every second. So, as you can imagine, it takes an enormous amount of energy to move the weight of the screws and shift the water to operate in Pumped mode.

Don’t the Archimedes screws generate electricity to pay for the energy the course needs to operate in Pumped mode?

Sadly not! It’s a common misconception and has never been the case unfortunately! As mentioned earlier, the Archimedes screws can generate electricity when the conditions are favourable, meaning only when the tide is out and river levels upstream are sufficiently high enough to allow water to pass through them and downstream – Generation mode.

With ever changing and more erratic climate conditions over the past few years it has meant there has been a steady decline in the amount of electricity that can be generated. The Canal & River Trust computers at the Barrage automatically determine if the conditions are suitable to allow the Archimedes screws to generate power, a process that works independently of Tees Active.

The power that is generated is then used by the Canal & River Trust to operate the entire Tees Barrage operation, excluding the watersports centre. It is only after this that any surplus can then be sold back to the national grid, which then provides a fraction of income to offset the cost of operating the screws. Anyone who has solar panels at home will be aware that the amount of energy companies pay you for the electricity you’ve generated is significantly less than the cost to purchase it back – such as when we need to operate the Archimedes screws to operate in Pumped mode.

What does all this mean for energy costs and how does it affect the operation of the course?

Faced with fewer opportunities to operate in Gravity and Generation modes means the costs to operate the course have increased, and our ability to obtain income from Generation mode have diminished further. If that wasn’t bad enough, just like every business and homeowner in the UK, we have seen energy costs triple and further rises are anticipated.

That means the cost to operate the course in Pumped mode is constantly being reviewed to create an affordable and balanced programme to provide opportunities for watersport activities so we can all keep enjoying this amazing facility!

As you can see, the Tees Barrage is a complex site! From flood risks, wildlife and tides, to fish migration, rainfall and watersports, there is a huge amount of work that goes into running this facility!

Follow us on social media for all the latest on what’s going on at Tees Barrage @teeswhitewater.