Impact case study database

The tools developed through this research has revolutionised the way that the UK plans and invests in improving water quality; for the first time, all significant polluters can be identified at waterbody scale across the entire country and their contribution to the issue quantified. No other country in the world has a chemical source apportionment model of equivalent range of sources, chemicals or scale. Comber’s on-going research [5.1 & 5.2] has driven the development of the model to better predict nutrient sources and chemical fate in rivers, thereby allowing the regulators to confidently predict the impact of planned investment on improving water quality. Water pollution in the UK has historically been attributed to point sources from sewage and industry. However, as polluting heavy industry inputs have declined and sewage treatment technology has improved, other sources of pollution have become increasingly important, particularly those from diffuse sources such as agriculture where climatic events (rainfall) and hence climate change plays a significant role. Diffuse sources of pollution include nutrients such as phosphate and nitrate from agricultural runoff from fields and farm infrastructure. In recognition of this changing emphasis in the distribution of pollution entering UK waters, the UK Government enacted a ‘fair share’ policy within the “polluter pays” philosophy set by the WFD, which has driven state of the art research to quantify the loads of pollutants entering the water environment from all the main point and diffuse sources. SAGIS has for the first time, enabled the regulators to target the significant sources of pollution and, for the first time, demand investment of £billions to upgrade sewage works as well as to provide grants to relevant farmers, safe in the knowledge that the desired water quality improvements are going to be achieved.

This ground-breaking collaboration between UK’s Water Industry [5.3], Environment Agency [5.4], Natural England [5.5], UK Water Industry Research [5.6] and Scottish Environment Protection Agency [5.7] has ensured a unique combination of academic rigour, thorough validation and the acceptance of the SAGIS model to be used for all water quality planning within the UK.

The development of the SAGIS model by Comber has led to the further development of the holistic catchment-based approach to improving water quality [5.8] rather than addressing individual inputs; an initiative driven by Government, via the Environment Agency, in adopting and complying with the EU’s Water Framework Directive [5.9]. The use of an accurate predictive model such as SAGIS allows the impact of investment in mitigation measures to improve water quality to be predicted, thereby allowing the most cost-effective solutions to be implemented. Prior to the development of SAGIS, the financial burden of water quality improvements in the UK fell largely onto the water industry. The development of SAGIS has enabled the regulators (EA and SEPA) to confidently identify and apportion the sources of pollution (particularly phosphate) between agricultural and sewage effluent sources within the UK river system.

Between 2015 and 2020, the use of SAGIS modelling was used to justify the following spend on water quality improvements largely to reduce the amount of phosphorus entering rivers:

• £2.3bn of water industry infrastructure improvements including upgrades to sewage treatment works to meet tighter phosphorus permit conditions through enhanced flocculation or ultrafiltration technology;

• £0.4bn investment in agriculture through the Countryside Stewardship scheme to better manage runoff from farm infrastructure, put in buffer strips adjacent to watercourses, fence of rivers from livestock, bund silage pits etc;

• £50m in farmer match-funding via Catchment Sensitive Farming which includes advice to farmers on fertiliser management and use, and

• £110m of Highways England investment to tackle flood risk and polluting outfalls as part of the Designated Environment Fund where reed beds and other mitigation technologies have been installed.

The fact that SAGIS provides funders with an unprecedented level of confidence in identifying appropriate programmes of measures to tackle water pollution has allowed more targeted and effective investment in environmental improvements to be planned and implemented. This has included using the SAGIS model during the second cycle of the Water Framework Directive (2015-2021) to identify sites for farm interventions such as improved management of slurry, silage, on-farm surface water runoff, stock control to prevent fertilisers and manures polluting rivers. Furthermore, the continued development of the SAGIS model in the last 5 years by Comber and co-workers has refined outputs, provided decision support tools, improved forecasting accuracy and enriched existing databases. This has provided the improved accuracy, precision and usability required to justify an increasing amount of investment made by the water industry (and agriculture) through future cycles of the WFD (2021-2027) via River Basin Management Plans [5.4], with the confidence that the predicted outcomes in improved water quality will be achieved. For example, working with the Water Industry and Ofwat, the EA have used SAGIS to develop the Water Industry National Environment Programme (“All of the WFD P permits in PR19 for rivers have been calculated using the SAGIS models and our internal optimisation tool” – Paul Simmons, Principal Water Quality Office, EA, [5.3]. This programme delivers the Asset Management Plan cycle 7 (AMP7) which is a £4bn investment in Water Company programmes of measures to deliver river quality improvements between 2020 and 2025 [5.6]. This includes projects planned to upgrade sewage treatment plants using latest technologies to more efficiently remove phosphorus from effluent discharged to rivers.