UK wins key case on sewage nutrient removal

The government has won a long-disputed case with the European Commission over whether several large UK coastal and estuarine waters are eutrophic. The decision obviates the need for expensive and energy intensive sewage treatment to remove nutrients.

The UK has resisted a challenge from the European Commission over its interpretation of the 1991 EU Urban Wastewater Treatment Directive. At stake was billions of pounds worth of investment in nutrient stripping for sewage discharges into the Irish Sea and Thames and Humber estuaries, which would have increased water prices and companies’ greenhouse gas emissions.

The commission maintained the UK had failed to designate several coastal and estuarine waters as sensitive to over-enrichment or eutrophication, and secondly to provide advanced wastewater treatment facilities, such as nitrate and phosphate removal, at sewage works discharging to those waters. The directive required that works serving populations of 10,000 or more and discharging to these "sensitive waters" be fitted with such facilities by 1998.

The case dates back to a Commission report in 2001 which found that the UK had not designated the Humber, the Wash, the Deben and Colne estuaries in East Anglia, the outer Thames Estuary, Southampton Water and the north east Irish Sea, or provided the necessary level of treatment (ENDS Report 323, pp 9-10 ).

The lengthy judgment, delivered on 10 December, considered the evidence for whether each of these waters could be classified as eutrophic, or liable to become so, between 1993 and 1997.

The directive sets four criteria for defining eutrophication: that the waters are enriched by nutrients, that these are causing accelerated growth of algae or other plants, that this is undesirably disturbing the balance of aquatic organisms or water quality.

In most cases, there was no question that there were high levels of nutrients in the waters in question, or that algae levels were elevated. But it could not be demonstrated that there were consistent disturbances to the balance of organisms and the water quality related to eutrophication.

However, the court did find abundant instances of marine algal blooms, mats of algae covering the foreshore of estuaries, problems with diarrhetic shellfish poisoning, loss of eel grass beds and wide fluctuations in dissolved oxygen levels. But in no case did the court find that these were so frequent, extensive and persistent to prove eutrophication.

The outcome comes as a relief to the water industry and government. In 2003, Yorkshire Water researched consequences of having to remove nutrients from sewage discharges to the Humber (ENDS Report 336, pp 12-13 ). It concluded the cost would run to £1.4bn over 20 years and result in "little or no environmental benefit".

The process would also use 118 gigawatt hours of energy per year, 1.3% of the water sector’s energy use, and boost CO2 emissions by nearly three million tonnes over 20 years. It would generate 86,000 tonnes of sewage sludge a year requiring three incinerators to be built.

If similar impacts are assumed for other major areas which would have been affected, such as London and Merseyside, the ruling might have avoided £5bn of investment and a 5% increase in the sector’s energy use. Greenhouse gas emissions would also be substantially increased.

A spokesman for the environment department (DEFRA) said: "We’re pleased with this decision. Water quality in England and Wales is better than at any time since the industrial revolution, and we are still working on improvements."

DEFRA said it reviewed sensitive areas designations every four years, as required by the directive, and would decide where tertiary treatment was required.

Water UK, water companies and NGOs approached by ENDS refused to comment, although one industry insider did say it was "refreshing to see the courts taking a pragmatic view".

While more energy-intensive sewage treatment might not be an appropriate response to the water quality problems in UK coastal and estuarine waters, government and the industry would be ill advised to ignore the writing on the wall.

The evidence suggests there are real eutrophication issues which need to be addressed, and the most appropriate and sustainable approach will be through catchment management approaches under the Water Framework Directive. Restoration of floodplains and controls on diffuse urban and agricultural inputs should be the first choice for controlling nutrient levels.

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