Dr John Iwan Jones                            WQR0034

Written evidence submitted by Dr John Iwan Jones, Research Leader at Queen Mary University of London


What are the best indicators for river water quality that could be used as targets being developed under the Environment Bill?

Biological indicators, especially aquatic invertebrates, provide an excellent indicator for river water quality and should be used to develop targets for the Environment Bill. The tool for assessing ecological status using aquatic invertebrates (RIVPACS/RICT) is the most robust and best developed of the biological indicators, where the uncertainty associated with assessments is fully included (Pilgrim et al. 2018).

In addition to providing an integrated assessment of ecosystem condition, biological indicators offer other advantages.

Many pollutants, particularly those arising from diffuse sources, are delivered to watercourses as episodic events, often associated with peaks in precipitation (e.g. storms: Ockenden et al. 2017) or accidental discharges (e.g. Thompson et al 2016). Whereas detection and characterisation of episodic events requires intensive physical and chemical sampling through time (Lloyd et al. 2014), such events cause lasting changes to biotic communities. Hence, a single biological sample can reflect pollution problems over a substantial time period: one invertebrate sample is capable of determining mean pH with a precision comparable with a year of fortnightly direct measurements of water chemistry (Ormerod et al. 2006). For well-developed biological tools (such as RIVPACS/RICT, the precision in assessing condition is comparable with or better than water chemistry. Hence, the use of biological indicators is more cost effective than technological advancements such as automated chemical monitoring (which require frequent maintenance to achieve adequate precision: Collins et al. 2015).

The relationships between changes in the aquatic invertebrate community and major pollutants (e.g. organic pollution: Jones et al. 2008) are well described. Furthermore, biological indicators are sensitive to a range of potential pollutants, and will indicate damage irrespective of the cause, whereas chemical monitoring techniques can only return information on the determinant being assessed.

How adequate are the monitoring and reporting requirements around water company discharges? How can technology improve and assist with transparency and enforcement?

Monitoring budgets for the statutory agencies have been under pressure for some time, whilst many CSOs are discharging regularly (The Guardian, 2020). Monitoring and reporting requirements need to be sufficient to detect where unlicensed discharges are causing environmental damage, and statutory agencies given sufficient resource to achieve this.

Budgets for strategic monitoring by the statutory agencies should be increased the ability to detect long-term and widespread change in the environment is critical for assessing the success of the Environment Bill. It is also vitally important to link monitoring data to potential causes of change, to help Government develop and deliver effective policy.


What is the impact of plastic pollution and other materials on drainage and water quality in rivers and what should be done to mitigate it?

Larger plastic items (macroplastic) in surface water and wastewater can cause blockages to drains and outfalls. Such blockages cause problems with water flow and will need to be cleared manually to avoid flooding. Blockages in sewers can result in discharge of raw sewage via CSOs or can cause sewage to back up and flood homes and businesses. Wet wipes and other plastic items disposed of inappropriately can contribute to the build up of fatbergs, which cause significant blockages in sewers.

Raw sewage can be discharged into the environment where larger plastics cause blockages in sewers. This will result in damage to the environment through organic pollution, and the release of contaminants directly into the environment including microplastics.

Whereas larger plastics are known to impact wildlife, through entanglement, false satiation, etc., the extent to which microplastics (particles < 5mm) cause environmental damage to freshwater and estuarine ecosystems is equivocal (Jones et al. 2020). Nevertheless, research into this field is relatively new and the precautionary principle should be applied, due to the ubiquitous and increasing presence of microplastics in the environment. Sub-lethal effects on invertebrates and fish may be possible at some sites (Jones et al. 2020), and the long-term impacts are not yet fully understood. Further work is needed to understand better the impact of microplastics on aquatic and terrestrial environments.

Significant amounts of macroplastic enter watercourses from surface run off which mobilises plastic particles from sources such as urban litter, landfill, the road network, agriculture and wastewater. The relative importance of these different sources is not known, but is being quantified by studies such as the Preventing Plastic Pollution Project. Efforts to change behaviour are likely to produce substantial reductions. Macroplastic may fragment into microplastics.

Inappropriate disposal of plastic (and other) items into the sewage system by the public causes issues where plastics cause blockages, especially the discharge of untreated sewage to watercourses via CSOs. Campaigns to raise public awareness about appropriate disposal of plastic (and other) products should be supported to address this. Regular monitoring of CSOs by statutory agencies should be supported: reduced monitoring budgets have had an impact on the ability of Government to prevent CSO failures and prosecute those responsible.

A reduction in the dependence on single-use plastics and a move to a circular economy will be hugely beneficial. Policy to drive this change will be of fundamental importance. Public awareness campaigns coupled with policy to drive change in marketing and advertising are essential. Public education campaigns on the impacts of plastic pollution and to address littering behaviour are also essential and should be supported by government.


Collins, AL, Haygarth P, Barker P, Hiscock K, Lovett A, Lloyd CEM, Freer JE, Johnes PJ & Jones JI (2015) Summary of emerging evidence from the Demonstration Test Catchments (DTC) Platform. Defra.

The Guardian (01/07/2020) Exclusive: water firms discharged raw sewage into England's rivers 200,000 times in 2019.

Jones JI, Davy-Bowker J, Murphy J, Keller V, Williams R & Davies C (2008) Review of the evidence for organic pollution thresholds to protect rivers with special designations for wildlife. Natural England NECR023

Jones JI, Murphy JF, Arnold A, Pretty JL, Spencer K, Marjus AA, Vethaak AD (2019) Evidence Reviews on Analysis, Prevalence & Impact of Microplastics in Freshwater and Estuarine Environments Evidence Review 3 What is/are the impact(s) of microplastics on freshwater and estuarine biota? (Defra project WT15112)

Ockenden, M.C., Tych, W., Beven, K.J., Collins, A.L., Evans, R., Falloon, P.D., Forber, K.J., Hiscock, K.M., Hollaway, M.J., Kahana, R., Macleod, C.J.A., Villamizar, M.L., Wearing, C., Withers, P.J.A., Zhou, J.G., Benskin, C.M.H., Burke, S., Cooper, R.J., Freer, J.E., Haygarth, P.M., 2017. Prediction of storm transfers and annual loads with data-based mechanistic models using high-frequency data. Hydrology and Earth System Sciences 21: 6425-6444.

Ormerod, S.J., Lewis, B.R., Kowalik, R.A., Murphy, J.F., Davy-Bowker, J., 2006. Field testing the AWIC index for detecting acidification in British streams. Archiv für Hydrobiologie 166: 99-115.

Pilgrim E, Jones JI, Collins AL, Stirling M, Hodgkinson R (2018) DTC Policy and Practice Note 3. Assessing the impacts of pollutants on freshwater ecology. Defra

Thompson, MSA, Bankier, C, Bell, T, Dumbrell, AJ, Gray, C, Ledger, ME, Lehmann, K, Mckew, BA, Sayer, CD, Shelley, F, Trimmer, M, Warren, SL, Woodward, G. (2016) Gene-to-ecosystem impacts of a catastrophic pesticide spill: testing a multilevel bioassessment approach in a river ecosystem. Freshwater Biology 61: 2037-2050


February 2021