Agenda item

The Executive Member for Planning and Growth presented a report that supported the Overview and Scrutiny Committee’s consideration of concerns about the cumulative impact of sewage discharge on rivers in East Hertfordshire, following a Motion agreed by Council on 22 October 2025.

The Executive Member for Planning and Growth said that she was presenting the report jointly with the Executive Member for Wellbeing as the issues impacted upon both portfolios. The report supported the committee’s consideration of an issue of significant concern to residents - the cumulative impact of sewage discharge on rivers across East Hertfordshire.

The Executive Member for Planning and Growth said that a motion was approved at Council in October 2025, which recognised both a responsibility to protect rivers and the growing evidence of declining water quality, driven in part by the frequency and scale of wastewater discharges.

The Executive Member for Planning and Growth said that senior representatives from Thames Water and the Environment Agency were in attendance, and this provided an important opportunity for Members to better understand the scale of the issue, the data behind it, and the respective roles and responsibilities of those organisations in managing and regulating our water environment.

Members were advised that the session was primarily about information gathering and constructive scrutiny. It was an opportunity for Members to ask questions, test the evidence, and explore how the cumulative impacts of sewage discharge were being addressed, particularly given concerns that such events were no longer exceptional, but becoming increasingly frequent.

Members were advised that it was also important to be clear about the role of the planning system in this context. The Executive Member said that where there was clear evidence that wastewater infrastructure was inadequate, this may constitute a material consideration in planning decisions, particularly where development could lead to unacceptable environmental impacts such as deterioration in water quality.

The Executive Member for Planning and Growth said that where Members should, however, be aware that the delivery of sewage infrastructure rests with the statutory undertaker, and national policy generally assumes that the necessary upgrades will be delivered. She said the adopted District Plan policies WAT6 (Wastewater Infrastructure) and DEL1 (Infrastructure and Service Delivery) already provided a robust basis for managing this.

The Executive Member for Planning and Growth said that the insights gained from the session would be important in informing future work, including the preparation of the new Local Plan. The council was currently commissioning a Water Cycle Study to strengthen the evidence base and ensure the council fully understood infrastructure capacity and its impact on river health, so that future growth was properly planned, aligned with capacity, and environmentally sustainable.

The Executive Member for Planning and Growth encouraged Members to use the session to engage openly and constructively with the guests from the Environment Agency and Thames Water.

The Chairman thanked representatives from Thames Water and the Environment Agency (EA) for attending and invited questions from Members.

A Member questioned whether the frequency of sewage discharges indicated that storm overflows had become an operational feature of Thames Water's network rather than exceptional emergency measures. A representative from Thames Water did not accept that characterisation and stated that storm overflows remained part of the designed operation of wastewater systems during periods of heavy rainfall and groundwater infiltration. He emphasised that treatment works did not discharge continuously and that EDM monitoring data showed a clear relationship between rainfall events and storm overflow operation.

Members sought clarification on the proportion of Thames Water's recently raised capital that would be invested in reducing sewage discharges. They were advised that investment would be prioritised across the region in accordance with regulatory obligations and environmental performance requirements. A detailed breakdown of local investment could be provided to the Committee.

Questions were raised regarding the impact of climate change and increasingly frequent extreme weather events on the sewerage network. Thames Water acknowledged that greater resilience would be required in the future and that the key challenge was reducing the volume of surface water entering the sewer system. The importance of sustainable drainage systems was highlighted, together with improved surface water management and planning controls to minimise additional pressures on existing infrastructure.

The Committee heard that storm overflows had always formed part of wastewater system design. Thames Water explained that discharges occurring during storm conditions were generally highly diluted and followed treatment and storage processes before entering watercourses.

Members were advised that forthcoming continuous water quality monitoring would provide a more detailed understanding of the environmental impacts of discharges.

The Environment Agency representatives advised that increased inspection activity was enabling greater regulatory oversight of storm overflow operation. Members were informed that inspections were being undertaken to ensure storm tanks were only used during storm conditions and that the Agency had also carried out specific work to investigate and reduce dry-weather spills.

Members expressed concern that responsibility for pollution was frequently attributed to factors outside of Thames Water's control. Questions were raised regarding groundwater infiltration and whether this reflected deteriorating infrastructure. Thames Water acknowledged responsibility for infiltration occurring within its network and advised that significant investment was being made in sealing manholes, relining pipes and undertaking wider network improvements to reduce groundwater ingress.

The Committee discussed customer bills, shareholder returns and investment in infrastructure. Thames Water acknowledged Members’ concerns but advised that its current owners had not taken external dividends since acquiring the company in 2017. Members were advised that recent increases in customer bills reflected the need to fund substantial investment programmes required by regulators and environmental improvement schemes.

A Member raised concerns regarding the transparency of Thames Water's reporting systems and the extent to which residents were able to see what action had been taken following reports of pollution or operational issues.

The Committee discussed the importance of the River Lea catchment and the capacity of Rye Meads Sewage Treatment Works. Members expressed concern regarding the impact of future housing growth on the facility and sought reassurance regarding this future capacity. They were advised that it would obtain further information from its Developer Services Team, and they would provide a response to the Committee.

Questions were also raised regarding the effectiveness and timeliness of environmental enforcement. The Environment Agency representatives acknowledged historical concerns and advised that recent legislative changes had strengthened its enforcement powers.

Members were also advised that provisions within the Water (Special Measures) Act 2025 intended to strengthen accountability within water companies. Members discussed the causes of pollution incidents and the distinction between permitted storm overflow discharges and pollution resulting from sewer blockages or asset failures.

Questions were asked on the role of water companies in the planning system and Members questioned whether Thames Water's status as a non-statutory consultee limited its ability to influence development proposals.

Thames Water representatives advised that while it would welcome a stronger role within the planning process, it currently provided advice and recommendations to planning authorities where capacity issues were identified. Representatives confirmed that they could recommend planning conditions or development phasing where infrastructure constraints existed.

A Member asked the Environment Agency to comment on "Rights of the River" policies adopted by some local authorities and whether a national approach might strengthen river protection. Members were advised that Officers would look into this matter.

In response to further questioning regarding Rye Meads, Thames Water representatives acknowledged concerns raised by Members regarding historic discharge issues affecting nearby land.

The Chairman thanked representatives from Thames Water and the Environment Agency for their attendance and their responses to Members' questions. Thames Water offered to provide contact details to Members and encouraged direct engagement regarding future concerns about investment programmes, network capacity and environmental performance.

Councillor Andrews proposed, and Councillor Nicholls seconded, a motion that Overview and Scrutiny Committee welcome the attendance of representatives from Thames Water, and the Environment Agency and Members note the presentations delivered, acknowledging the information and evidence presented and the responses provided to Members’ questions.

After being put to the meeting and a vote taken, the motion was declared CARRIED.

RESOLVED – that (A) Overview and Scrutiny Committee welcome the attendance of representatives from Thames Water and the Environment Agency; and

(B)   Members note the presentations delivered, acknowledging the information and evidence presented and the responses provided to Members’ questions.