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Time called on river pollution from runoff

Pollution from microplastics, toxic metals and hydrocarbons washed into rivers by surface water runoff must be tackled with consistent monitoring and widespread regulatory control if water quality failures are to be successfully reduced, experts are demanding.

The contribution of pollution from urban and transport runoff to water quality failures is reported in the Environment Agency (EA)’s “The State of the Environment: Water Quality” update (WWT 22.2.18) which admits that overall 86% of England’s water bodies fail to meet ‘good’ status.

Yet the report sidesteps the need for action to prevent pollution from urban and highway runoff, warns Jo Bradley, who spent more than 20 years working for the Environment Agency before joining SDS as a specialist advisor on water quality last year.

“Pollution from brake and tyre erosion, exhaust fumes and oil spills is known to contain chemicals which are toxic to the aquatic environment and to inhibit reproductive success in aquatic invertebrates,” says Bradley.  “This pollution is, therefore, highly likely to be a major contributor to the water quality issues responsible for 38% of all fish test failures and 61% of all invertebrate failures recorded in the report’s Key Findings.

“The report also calls out the threat to water quality from microplastics pollution including from urban runoff.  Sub-5mm plastic particles from tyre abrasion provide a host to which toxic pollutants can adhere, in the same way as they bind to silts and sediments in runoff.”

A study published by a team at the University of Manchester (as reported in WWT this week) has brought further attention to the high levels of microplastics contamination in river catchments and how they can be washed into the oceans during peak flooding.  Microplastics pollution comes from a range of sources, not just microbeads and synthetic fibres, but also broken-down fragments as a result of tyre abrasion from transport activity, says Bradley.

Shortcomings

She continues: “The Environment Agency report estimates that the urban and transport sector accounts for 13% of all activities preventing water bodies from achieving ‘good status’, yet it singles out farmers and Water Companies for action to reduce polluting discharges into rivers, without naming one single measure to tackle diffuse and point-source discharges from urban and transport runoff.

 “These shortcomings highlight the imbalance between the investments rightly made in wastewater treatment to prevent pollutants including Polyaromatic Hydrocarbons (PAHs) and toxic metals from being discharged into rivers, while highway outfalls that are part of the very same catchments remain completely uncontrolled.”

Bradley says a significant proportion of water bodies are classed as ‘Do Not Require Assessment’ (DNRA) and given ‘good’ status, even though they are not monitored at all. 

“The Environment Agency’s own figures state that of the 4,679 waterbodies in England, 133 did not achieve ‘good status’ for chemicals.  However, only 1,075 were monitored and found to achieve ‘good’ status. A further 3,471 were not monitored and were simply assumed to be ‘good’ and recorded as DNRA2,” she added.

One Million Highway Outfalls

“There are estimated to be around one million highway outfalls to waterbodies in England, many of which are not officially considered to be known discharges of significant quantities of priority hazardous substances.  Yet, road runoff has been shown to contain polyaromatic hydrocarbons, particularly the hydrocarbon benzo[a]pyrene, well in excess of the European Environmental Quality Standards (EQS).

“To stand a chance of achieving the country’s environmental water quality targets in future, there is an urgent need for greater monitoring and greater use of the existing regulatory powers to reduce polluting discharges from urban and road runoff. These are actions both for the Environment Agency itself, as well as for the highway authorities and other high-risk sources of urban runoff.

“A wide range of tools and techniques, including Sustainable Drainage Systems (SuDS), are available to treat stormwater runoff and they effectively target harmful pollutants by removing solids and filtering out toxic metals.   At high risk locations manufactured devices, such as hydrodynamic vortex separators, can target problem pollution and can also be deployed successfully alongside vegetative features to prevent pollution from entering river water bodies. 

“With a growing body of knowledge, best practice, guidance and regulation, the industry is ready and able to act on surface water pollution – but we expect our environmental regulator to take a much stronger lead to monitor and enforce.”

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