The Environment Agency (EA) has published its biennial report on reservoir safety for 1 January 2019 to 31 December 2020 - the report is a comprehensive review of reservoir compliance and enforcement over the last 2 years.

Photo:Toddbrook Reservoir - damaged spillway in August 2019

Legislation covering reservoirs is contained in the Reservoirs Act 1975 - Parliament amended this act to create the Flood and Water Management Act 2010.

Currently 2,097 large raised reservoirs (LRRs) in England are covered by the Act - LRRs are those that can hold at least 25,000 cubic metres of water above ground level. Of these, the EA operates 219 and water companies operate 663.

Of the 219 operated by the EA, 17 are under the supervision of a construction engineer, the rest are in operation.

Introducing the report, the Agency said it had seen improvements in many areas of non-compliance over the last 2 years. Main improvements include:

• maintaining high compliance of engineer appointments
• taking quicker, firmer enforcement action
• closer collaboration with reservoir undertakers on safety measures to drive improvements and maintain compliance
• maintaining high standards of safety and compliance during the coronavirus (COVID-19) pandemic

According to the Agency, the data and results provided in the report should be considered in light of COVID-19 which affected all regulated sectors, including reservoir safety. This “tested the resilience” of the regulatory regime and the role of reservoir undertakers and engineers, the EA said.

However, despite COVID-19, the EA kept non-compliance in England low and developed a temporary Local Enforcement Position (LEP) to account for the potential difficulties – the EA commented:

“This combination of advice and adjustments to compliance and enforcement has been well received. The approach is now used by several European countries.”

Over the period of the review most reservoir incidents were “limited in scale and ..well managed by the undertakers”. None of the incidents resulted in a complete failure of the dam or reservoir.

The highest profile incident during the period took place at Toddbrook Reservoir in Derbyshire at the beginning of August in 2019 where the dam was under threat of collapse after heavy rainfall caused serious damage to the spillway at the reservoir in Whaley Bridge.

In July 2020 Arup were appointed as the design consultants for the Toddbrook Reservoir repair.

After the Toddbrook incident report was published, ministers appointed Professor David Balmforth to carry out a further independent review which focussed on the wider legislative and regulatory framework.

The EA says in the latest biennial report:

“The events at Toddbrook Reservoir, recent flooding and the threat posed by a changing climate show that we cannot be complacent. It is crucial for all infrastructure to be fit for the future.”

The EA will continue to work with all those involved in reservoir management to improve safety and compliance by using:

• intelligence from these reports
• learning from incidents
• international collaboration
• research and development (informed by climate science)

The measures will help:

• mitigate the impact of climate change
• the growing role reservoirs will play in wider water management
• secure more climate resilient places

“We will work with Defra and its stakeholders to complete Professor Balmforth’s recommendations. This will be a significant piece of work which will take several years,” the EA says.

In July 2021 the Environment Agency published updated inspection and operator guidance for owners of large reservoirs - Defra will issue a new ministerial direction later this year requiring undertakers to prepare and maintain emergency on-site flood plans.

Click here to access the EA Biennial report on reservoir safety: 1 January 2019 to 31 December 2020