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the unseenthreat towater quality

Diffuse water pollution in Englandand Wales report – May 2007

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Environment Agency The unseen threat to water quality1

Foreword

Clean rivers, lakes, groundwaters, estuaries and coastal waters are essentialfor a healthy water supply, recreation, fisheries and wildlife. Great strideshave been taken in cleaning up major discharges from sewage treatmentworks and industry, and salmon have returned to our major rivers like theTees and the Mersey. This work is not finished, but the progress is nowhighlighting the impacts of diffuse sources of pollution. These are pollutantsfrom many small-scale sources carried into water bodies by rainwater run-offfrom urban and rural land.

Diffuse pollution is one reason why improvements in river quality are levelling off.One in seven urban rivers is still of poor quality. Eroded soils carrying surplusfertilisers and livestock manure are degrading many rural rivers and lakes.Underground water supplies are contaminated with fertilisers, pesticides and otherchemicals, and this pollution flows into estuaries, bathing waters and the sea. Thecosts, in terms of treating drinking water supplies or lost wildlife and amenity, aresubstantial.

The Water Framework Directive, which is new legislation, has put diffuse pollutionin the spotlight. Diffuse sources must be tackled if we are to achieve the objectivesset. Some of the problems are complex and will take decades to resolve, but manyof the solutions are known and could be put into practice now. Failure to do so willallow the problems to get worse and increase the future costs.

This report sets out the evidence for the impacts of diffuse pollution and what needsto be done about it. We will work with other organisations to gain a betterunderstanding of the problem and to arrive at cost-effective solutions. Farmers andfarm advisors, the water industry and businesses can make important contributions,but we all have a part to play. It is in everyone’s interests to tackle diffuse pollution,and new ways of managing river catchments need to be embraced if the harm tothe water environment is to be put right.

Tricia Henton Director of Environment Protection


ContentsExecutive summary 3Introduction 5

What is diffuse water pollution? 5The scale of the problem 6Sources of diffuse water pollution 7

The impact of diffuse pollution 9Rivers and lakes 9Groundwaters 11Coastal waters 12

Initiatives to control diffuse water pollution 14Conclusions 17References and endnotes 18


Executive summaryDiffuse water pollution is a serious problem in some parts ofEngland and Wales. It is caused by many small or scatteredsources. It represents a widespread and long-term threat tothe ecology of lakes, rivers and coastal waters, and to thequality of groundwater and the costs of water supplies.Tackling diffuse pollution is essential if we are to ensure thesustainable use of this vital natural resource. It is importantthat diffuse water pollution features in major forward-lookingexercises, such as the implementation of the WaterFramework Directive and the water strategies beingdeveloped by Governments.Our main concerns are:• high levels of nutrients in rivers, lakes,

estuaries and coastal waters, which cancause eutrophication;

• nitrate contamination of water used fordrinking water;

• hazardous chemicals leaking into rivers,lakes and groundwater from industrialsites;

• pesticides and sheep dip from agricultureentering rivers, lakes and groundwater;

• oxygen depletion in water due to organicpollution from livestock manure;

• sediments from soil erosion smotheringhabitats in rivers, lakes and estuaries;

• bacteriological contamination of bathingwaters and shellfish waters from farmwaste and illegally connected sewers.

We need to take concerted action acrossmany sectors. The European WaterFramework Directive (WFD) is a significantnew piece of environmental legislation thatwill help us do this. It requires all inland andcoastal waters to be of good status by 2015.We are establishing river basin districtswithin which demanding environmentalobjectives will be set, including ecologicaltargets for surface waters. As part of this, weare refocusing our monitoring to providebetter information on the impacts of diffuse

pollution so that we can develop targetedmeasures to improve water quality.

We need to tackle both urban and ruralsources of pollution. In urban areas run-offfrom roads and other surfaces, foul drainswrongly connected to surface drains, leakingsewers and spilled chemicals, oil and fuelpollute rivers and groundwaters. We wantsustainable drainage systems (SUDS) thatintercept pollutants and reduce flood risk tobecome a common feature of urban design.We will work with central and localgovernment to promote SUDS and reducediffuse water pollution through land-useplanning and remedial measures.

We are working with businesses to promotepollution prevention, for example through ourOil Care Campaign. We want to see allindustry sectors take straightforward steps toprevent diffuse pollution.

Investment and regulation have improvedsewage discharges and water quality overthe past decade. The further measures thatare needed include the safe storage ofchemicals, better maintenance of pollutioncontrol equipment and more staff training toraise awareness about the risk of causingpollution. We also ask the general public totake care in disposing of used oil andchemicals, and to make sure that their foul


drains are correctly connected. We wantbuilding inspectors to check that fouldrainage is not illegally connected into cleanwater sewers at new housing developments.

The Department for Environment, Food andRural Affairs (Defra) and the WelshAssembly Government (WAG) are reviewingnon-agricultural sources of diffuse waterpollution. They are working with us, industrysectors and others to prioritise the mosturgent problems to address. They will assessthe effectiveness of existing measures anddetermine what changes and additionalmeasures are needed. An expert steeringgroup has been set up to take the workforward and both governments have recentlygone to public consultation on the issue.

Farming can be a significant source of diffusepollution. Inorganic fertiliser use issignificantly higher than 50 years ago andhas contributed to elevated levels of nutrientsin water. Run-off from agricultural landdepletes oxygen in the water if animalmanure or silage effluent are present.Bacteria washed out of manure spread toland can adversely affect bathing waterquality. Soil erosion can be caused byinappropriate cultivation, trampling ofriverbanks by livestock, construction andother land disturbance leading to sedimentbuild-up in rivers and lakes.

We will work with farmers, the NaturalEngland Partnership, Defra, WAG andothers, to protect the water environment,using targeted advice, incentive schemesthat reward good practice and regulationwhere it is necessary. Agri-environmentschemes such as EnvironmentalStewardship projects in England and TirCynnal and Tir Gofal in Wales are nowpaying land managers to adopt resourceprotection measures such as nutrient and soilmanagement and to introduce buffer strips.Special advisors are working with farmers in40 river catchments in England and two inWales to share advice and knowledge toreduce water pollution under the CatchmentSensitive Farming Delivery Initiative. As wellas running workshops and farmdemonstrations, advisors are working on aone-to-one basis with farmers, advising on,for example, the use of fertilisers andlivestock densities. The catchment sensitivefarming initiatives in England and Walesfocus at the local level and pull togetherfarmers, farm advisors, government agenciesand other organisations.

To reduce urban and rural diffuse pollutionfurther, we are likely to need new orimproved legislative powers, for example toimprove land management practices, and acombination of voluntary, regulatory andeconomic measures.


IntroductionOur rivers and bathing waters have become a lot cleaner overthe last decade, mainly thanks to the efforts of watercompanies and industry working under our regulation. Butmuch remains to be done and diffuse pollution is haltingprogress. We think it is now a bigger threat to river waterquality than point source pollution (see Table 1). Together withDefra, the Welsh Assembly Government (WAG) and otherswe have devoted significant efforts to understanding the scaleof the problem.

In this report we summarise the impact thatdiffuse pollution has on rivers, lakes,groundwater and coastal waters. Wedescribe the various sources of diffusepollution and identify the main actions thatare needed to tackle the problem. Diffusepollution is sometimes complex so manyorganisations and individuals have animportant part to play in reducing it. We aimhere to help everyone reach a commonunderstanding of the issues and what can bedone to achieve a clean and sustainablewater environment.

We start with a short account of what diffusepollution is and then discuss the scale of the

problem. We look at the impacts on waterquality and wildlife for each of the main typesof water body. We discuss the sources ofdiffuse water pollution and finally we saywhat initiatives are needed to address diffusepollution. We identify where more actionneeds to be taken.

What is diffuse water pollution?Water pollution can come from either diffuseor point sources. An example of point sourcepollution is treated sewage effluentdischarged from a sewage treatment works.Point source pollution is controlled byregulation.


Diffuse source pollution typically comes fromunlicensed sources and dispersed land-useactivities (Figure 1). It often occurs afterrainfall and its composition is extremelyvariable. Common examples of diffuse waterpollution include:• contaminated run-off from roads• drainage from housing estates• accidental chemical and oil spills from

transport and industrial sites• surplus nutrients, pesticides and eroded

soils from farmland.

Emissions of gases into the air fromtransport, industry and agriculture can alsoeventually cause diffuse water pollution.

On its own, each source of diffuse pollutionmay be of little significance. But when theyoccur together, for example in an urban area,they can create significant problems. By itsnature, this kind of pollution is difficult tocontrol.

The pathways by which pollutants reachsurface and groundwater are often complex.Soluble pollutants, such as nitrate, can leachthrough the soil to the water table, eventuallyreaching rivers, groundwater, lakes orcoastal waters. Other pollutants stay on ornear the ground surface and can be washedoverland or on soil particles into water. Theseprocesses are usually driven by rainfall butcan take hours, days or years depending onlocal factors.

The way land is used and how it is managedis critical to the risk of water pollution. Soildisturbance near to watercourses increasesthe chance that erosion will cause pollution.

The timing of work such as ploughing andharvesting, for example in relation to rainfall,is important. In many circumstances reducingthe risk of diffuse pollution can be achievedat little or no cost by adjusting the timing ofthese activities

The effects of diffuse pollution can be verylong-term. Contaminants can persist ingroundwaters or sediments for decades orcenturies. Nutrient-enriched lakes andacidified waters may take many years torecover. It is far better and more costeffective to deal with the problem at sourcerather than try to treat the water once it hasbeen polluted. The main solutions weadvocate aim to stop pollutants reachingsurface and groundwaters in the first place,by reducing the use of potential pollutants,storing and using chemicals safely, andmodifying land management and drainagetechniques.

The scale of the problemThe impacts of diffuse pollution depend onthe amount of pollutants released, how easilythese substances can reach water bodiesand how sensitive the water environment isto pollution.

Our risk assessments for the WaterFramework Directive (WFD) show thatdiffuse pollution is now a bigger risk thanpoint source pollution for rivers, lakes andgroundwaters (Table 1). These are estimatesof risk, not proven impacts, but it is clear thatdiffuse pollution could be affecting asignificant number of waterbodies (Figure 2).1We will refine these assessments andconsult on our new findings.


Table 1Percentage of waterbodies at risk of not achieving WFD objectives2

Pressures Rivers Lakes Estuaries Coastal waters GroundwaterDiffuse pollution 87 50 35 20 68Point discharges 39 38 84 24 3Abstraction 14 1 53 Not applicable 29Physical changes 58 52 88 91 Not applicableAlien species 34 20 87 61 Not applicable

Our main concerns are:• high levels of nutrients in rivers, lakes,

estuaries and coastal waters, which cancause eutrophication;

• nitrate contamination of water used fordrinking water;

• hazardous chemicals leaking into rivers,lakes and groundwater from industrialsites;

• pesticides and sheep dip from agricultureentering rivers, lakes and groundwater;

• oxygen depletion in water due to organicpollution from livestock manure;

• sediments from soil erosion smotheringhabitats in rivers, lakes and estuaries;

• bacteriological contamination of bathingwaters and shellfish waters from farmwaste and illegally connected sewers.

Diffuse pollution also has social and indirecteconomic costs. Cleaning up rivers can turnthem into natural focal points for businessand leisure.3 The poor quality of many urbanrivers adds to social deprivation and detersbusiness investment. Diffuse pollutionimpacts on fisheries and bathing waters,reducing angling opportunities and limitingrecreation and tourism. The costs are difficultto measure but are likely to be substantial.

It costs the UK Water Industry several millionpounds a year4 to remove nitrates fromdrinking water abstracted from river andgroundwater sources. In the mid 1970sgroundwater required only minimal treatment;now almost half of groundwater used forpublic water supply requires fuller treatmentdue to pollution and tighter standards.5

In many areas, closing the gap betweenpresent and good water quality will requirechanges to activities that we do not directlyregulate. This has been given fresh impetusby the WFD, which introduces new ways ofassessing and managing the impacts ofdiffuse pollution.

Sources of diffuse water pollutionCommon sources of diffuse pollution include:• vehicle and plant maintenance in many

small industrial areas leading to spills ofoil and fuel;

• industrial sites storing and handling fueland chemicals with leaking tanks andpipes;

• road surfaces and railways that arecontaminated with lubricants, products ofcombustion, vehicle debris andherbicides;

• industrial and transport emissions into airleading to acid rain in upland areas;

• agricultural activities and constructionsites releasing sediments to surfacewater;

• surplus inorganic nutrients, animalmanure and pesticides washed offagricultural land;

• faecal or other pathogenic bacteria fromlivestock and wild animals;

• overloaded, leaking or wronglyconnected sewerage systems.

Urban pollutionIn urban areas run-off from roads and othersurfaces, foul drains wrongly connected tosurface drains, leaking sewers and spilledchemicals, oil and fuel pollute rivers, coastalwaters and groundwater.

Towns and cities have a major impact ongroundwater and surface water qualitybecause of current or historical pollution. Forexample, in Nottingham up to 15 per cent ofthe nitrate in groundwater comes from theleaking sewerage system. There are over300 sites in England and Wales that havecontaminated land due to their industrialpast. These sites can pose risks to health,and the pollutants may leak into groundwaterand surface waters. The contamination hasto be treated or contained, which isexpensive, and is often only carried out whenthese sites are redeveloped.


Pesticides used by local authorities,households and others to control weeds arefound in surface water downstream of urbanareas. River water quality can deterioratefollowing rainfall that washes bacteria fromboth urban and rural areas into rivers. Urbanrun-off contains oil, organic matter such asdog faeces, metals like lead and cadmium,and a wide range of chemicals from businessand household use. After or during rainfall,the first flush of water carrying accumulateddust and dirt is often highly polluting and canbe similar in strength to raw sewage,depleting rivers of oxygen.

Rural pollutionFarming is a major source of diffuse waterpollution. The use of inorganic fertilisers andthe spreading of animal manures to land canincrease nutrient levels in water. Run-off fromagricultural land depletes oxygen in the waterif animal manure is present. Bacteria presentin the manure is also having a significantimpact on our efforts to improve bathingwater quality. Soil erosion caused byinappropriate cultivation, trampling ofriverbanks by livestock, construction andother land disturbance can lead to sedimentbuild-up in rivers. Agricultural sourcesaccount for most of the silt entering water inEngland.6

Losses from agricultural land are estimatedto account for 61% of nitrate which enterssurface waters in England and Wales withsewage and other discharges accounting forthe rest.7 Nitrate concentrations in rivers arelinked to the proportion of arable land in thecatchment upstream (Figure 3).8 Intensivelivestock production is also a significantsource.

Farming accounts for up to 40% of thephosphate load in rivers, although this variesbetween catchments.9 Phosphate inputs toboth lakes and rivers in England and Walesrose over the last century mainly as a resultof expansions in cereal crop production andthe increasing use of artificial fertilisers.Between the 1930s and 1990s, estimatedphosphate losses to water from agriculturedoubled.

Losses of agricultural pesticides to water areaffected by the type of crop, the timing andquantity of applications and the weatherconditions.

Sheep dip chemicals have caused pollutionin upland streams in Wales and other uplandareas and reduced levels of aquatic life. Themarketing authorisation for one of thesechemicals has been temporarily suspendedto allow the manufacturers time to developways to manage the risks better.

Other sources of diffuse pollutionTributyl tin (TBT) from anti-fouling paints isstill being released from the hulls of largermarine vessels. Its use will be banned from2008. We are concerned about TBT becauseof its direct effects on certain marineorganisms. For instance, it has the potentialto cause dog whelks to change sex.

Anodes that are made from zinc andsuspended underneath boats and alongmarinas to reduce metal corrosion act as adiffuse source of zinc and have been shownto cause water quality problems in someestuaries.10

Oil discharges in UK waters from productionplatforms, refineries and other sites havebeen greatly reduced but illegal oil pollutionfrom passing ships remains a concern.

The main source of pollutants that form acidrain are gaseous emissions of sulphur andnitrogen from transport, industry and the landspreading of animal manure. These enter theatmosphere but ultimately affect the waterenvironment in certain sensitive locations.Usually upland areas with base-poor soils.


The impact of diffuse pollutionThis section describes key impacts on each major type ofreceiving water (rivers, lakes, groundwaters and coastalwaters).

Rivers and lakesOver two-thirds of all rivers are now of goodor very good biological and chemical quality11

(Figure 4). However, 87 per cent of rivers areat risk from diffuse pollution and this islimiting further improvements. Half of alllakes are at risk from diffuse pollution.

In urban areas one in seven rivers was ofpoor or bad chemical and biological quality in2005, frequently made worse by inadequatesewers and private drainage. About one infive properties have foul drains illegallyconnected into surface water sewers thatthen discharge untreated sewage effluentinto rivers.12

Over 22,000 hectares of Sites of SpecialScientific Interest in England are in anunfavourable condition due principally todiffuse water pollution from agriculture. Thisincludes rivers, lakes, ditch systems,freshwater and coastal wetlands, estuariesand coastal waters.13

NutrientsForty-five per cent of rivers are at risk fromhigh14 nitrate concentrations and 50 per centare at risk from high15 concentrations of

phosphate. High concentrations and risingtrends in nitrates are causing extra costs inthe supply of drinking water for a number ofwater companies and local abstractors,particularly in England.

In fresh and coastal waters high levels ofnutrients can cause excessive plant growth(for example, algal blooms) that harms otherwildlife, a process called eutrophication. Infreshwater systems the amount of phosphateis usually the limiting factor for plant growth,although nitrate may be important in somesituations. This is a greater problem inEngland than it is in Wales.

In 2005 just over half the rivers in Englandhad high concentrations of phosphate, 12 percent less than in 1990 (Figure 5). In 2005 28per cent of rivers in England had high nitrateconcentrations, much the same as in 1995(30 per cent). Nutrient pollution is much lessevident in Wales but there is a need toprotect the ecology of sensitive low-nutrientWelsh water bodies.

Our assessments for the Water FrameworkDirective indicate that a significant number ofour lakes are at risk of not achieving goodecological status due to elevated phosphate


concentrations. In 2002 there were 30 majorfish kills caused when the die-off of algalblooms led to a lack of oxygen in the water.16

A study of 129 lakes in England and Walesfound that 69 per cent had elevatedconcentrations of phosphate, indicating thatmost were nutrient-enriched.17

In Slapton Ley, the largest freshwater lake insouth west England, the resulting eutro-phication made the water turbid and reducedthe abundance of higher water plants. Otherlakes have also been affected (Box 1).18

Box 1Eutrophication of Bassenthwaite Lake

Relatively high levels of phosphate inBassenthwaite Lake are causing a heavygrowth of algae that smothers other plantsand threatens animal life, including a rarefish, the Vendace. Since 1995 the localsewage works has had a phosphate removalplant, but phosphate including that containedin agricultural run-off has built up in the lakesediment and is still a problem. To tackle theproblem the Lake District Still WatersPartnership has set up the BassenthwaiteLake Restoration Programme. Options tocontrol eutrophication are being assessed.

PesticidesA fifth of rivers are at risk of failing the WaterFramework Directive (WFD) standards frompesticides. Pesticides can harm aquatic lifeand must be removed from surface water orgroundwater used for public supply if theyexceed the drinking water standards. TheWFD requires the concentrations ofpesticides in water to at extremely low levels.

In 2005 commonly used pesticides werefound above the threshold value in about 8%of samples taken from rivers (Figure 6).19

Pollution by sheep dipping chemicals hasreduced aquatic life in small upland rivers,particularly in parts of Wales (Box 2).

Box 2Sheep dip pollution in upland Wales

Sheep dip has caused problems in Wales inrecent years. We have investigated andextensively monitored areas at high risk suchas private drinking water supplies andsalmon and trout nursery streams. Thisrevealed that poor operational practices werewidespread, including sheep having directaccess to watercourses shortly aftertreatment, and occasionally the use of anarable formulation of a chemical for treatingsheep instead of approved products.Targeted monitoring has revealed that similarproblems exist in England as well. Suchchemicals are highly poisonous to insect lifesuch as stoneflies and mayflies, protectedspecies such as crayfish are also affected.Surveys show that there were signs ofpollution damage to 30km of the Afon Teifi.Recovery may take many years.

SedimentsTwenty-three per cent of rivers are at riskfrom high levels of sediment. Too muchsediment blocks river-bed gravels andreduces the supply of oxygenated water toaquatic plants and animals. In 2004 half ofrivers with salmon action plans20 were at riskof missing their egg deposition targets, withsiltation of spawning gravels a major factor.Across southern England in 2000, 28 out of31 trout spawning beds studied containedenough fine sediments from soil to kill halfthe eggs and larvae.21 Chalk streams areparticularly at risk (Box 3).


Box 3Chalk stream malaise

Chalk rivers are especially valued for theirrich communities of plants and animals.There are 161 chalk rivers and streamsacross England but only 37 per cent achieveboth very good biological and chemicalquality. Excess silt is smothering river-bedgravels, harming aquatic plants andinvertebrates as well as fish eggs. Only 23per cent meet the guideline standard forphosphate concentrations (set for chalkrivers designated as Special Areas forConservation). High phosphate inputs arecausing algal growth to smother gravelhabitats and plants such as water crowfoot,which is a feature of chalk rivers. Thisgeneral deterioration caused by diffusepollution from soil erosion and phosphatefertilisers, and made worse by low riverflows, is known as ‘chalk stream malaise’.22

Acid rainAbout 16 per cent of lakes and 3 per cent ofrivers are at risk from acidification. In someupland areas with sensitive geology, such asmid-Wales, the Pennines and Cumbria,thousands of kilometres of small streams andlakes have been affected by acid rain.23

Acidified soils can release aluminium andother metals that are toxic to trout, salmonand other aquatic life.

Acid rain is caused by sulphur and nitrogenemissions. Since 1990 the emissions fromindustries we regulate and from roadtransport have declined substantially (Figure7). Agricultural releases of nitrogen asammonia, largely from animal waste spreadto land, have fallen less sharply. The qualityof upland waters is improving, but substantial

recovery will take decades unless waters aretreated (Box 4).

Box 4Treating an acidified river

In some cases it is possible to treat acidifiedwaters. The Afon Tywi in Wales is a majorsalmon and sea trout river that suffers fromacidification. Since 1991 the fishery has beenrestored by dosing the water with powderedlimestone at an initial capital cost of £90,000and £30,000 per year running costs. This hassuccessfully restored river quality andincreased fish populations, although it is not apractical or affordable solution for all rivers.

GroundwatersOver two-thirds of groundwaters are at riskfrom diffuse pollution and that diffusepollution is the main cause of groundwatercontamination. Diffuse pollution includesnutrients from fertilisers and manure,pesticides, oil and fuel.

Groundwater supplies one-third of drinkingwater in England and Wales; in parts ofsouth-east England it is the only source ofdrinking water. It is also an important watersource for industry. Water levels and flows inlakes, wetlands and rivers are maintained,especially in dry weather, by groundwater.Groundwater is particularly vulnerable topollution. Contaminated groundwater maytake decades or centuries to recoverbecause chemicals can degrade very slowlyand groundwater is flushed through at a veryslow rate.

NitrateForty-five per cent of groundwaters are atrisk from high nitrate concentrations. In 2005about 14 per cent of sites had an averagenitrate concentration that exceeded the50mg/l threshold value for the NitrateDirective. Nitrate is the most widespreadpollutant in groundwater, particularly in thesouth, east and midlands of England (Figure8).


PesticidesMore than a fifth of groundwaters are at riskof failing their environmental objectives underthe WFD as a result of pesticidecontamination.

We detected pesticides in nearly a fifth of allthe groundwater we monitored - in somecases the levels exceeded the limit fordrinking water (Figure 9). There is someevidence in certain areas that pesticideconcentrations in groundwater aredeclining.24 This improvement may be theresult of a shift to pesticides that are used atlower application rates, and safer use anddisposal in response to tighter legislation.

Atrazine has been a major problem, but sincethe non-agricultural use of it was banned in1994, concentrations in groundwater havegradually declined. In some areas Atrazinelevels in groundwater will continue to be amajor problem for a long time. The use ofatrazine will be banned completely after2007.

Coastal watersThe main impacts of diffuse pollution areseen in estuaries and nearshore areas wherecontaminants are less diluted. Over a third ofestuaries and a fifth of coastal waters are atrisk from diffuse pollution.

NutrientsNine per cent of estuaries and five per centof coastal waters are at risk from high nitrateconcentrations due to diffuse pollution. Highlevels of nutrients can increase the size,frequency and persistence of algal blooms. Inextreme cases algal blooms discolour largeareas of th sea and may deoxygenate water.These are sometimes called ‘red tides’. Thisis not a common problem in coastal waters inEngland and Wales, but smaller-scale algalblooms do occur from time to time. Thegrowth of green seaweed mats in shallowestuaries is more of a concern and canreduce the number of seabed invertebratesand prevent birds from feeding on them (Box5). Toxins released from algal blooms in thewater can lead to the closure of shellfisheriesto avoid the risk to people of shellfishpoisoning. The links between nutrientenrichment and algal blooms are not entirelyclear.

Box 5Coastal impacts of nutrients atLindisfarne

At Lindisfarne (a Special Protection Areaunder the Wild Birds Directive) the heavygrowth of the seaweed Enteromorpha hascovered the intertidal mudflats, reducing thesuitability of the site for feeding birds. Amajor factor is the supply of nutrientsentering coastal waters from diffuseagricultural run-off into major rivers such asthe Tweed.25 The changes may also be dueto a combination of other factors: changes insedimentation and turbidity, a reduction ingrazing invertebrates due to tributyl tin (TBT)pollution and milder winters. We are lookingat all existing licences we issue to make surethat they comply with the Directive and thosethat are found to be causing damage tohabitats will be amended or revoked.


With regard to nitrate inputs to UK coastalwaters direct inputs from discharges havefallen significantly since 1990 but inputs viarivers show no such falling trend to date.

An assessment of eutrophication is underwayfor UK waters and other sea areas coveredby the OSPAR Convention, an agreement toprevent pollution of the North East Atlanticseas. Ten estuaries in England and two inWales have been found to be eutrophic orlikely to become so.

Pesticides and other hazardoussubstancesOver 30 per cent of estuaries and 15 per centof coastal waters are at risk from pesticides.Pesticides, other organic pollutants andheavy metals have accumulated in someestuarine sediments and are a source ofdiffuse pollution released by tidal movement.Concentrations of PCBs (polychlorinatedbiphenyls), PAHs (polycyclic aromatichydrocarbons), mercury, cadmium and otherheavy metals in sediment are above levels ofconcern for the protection of bottom-livinganimals in some areas. Estuaries like theTees and Mersey are among the worstaffected due to the legacy of industrialpollution. In some of these areas musselscontain high levels of contaminants and fishshow signs of contamination.26

Our pesticides monitoring shows there is awidespread failure to comply with thestandards for TBT. Paints containing thechemical TBT were used as an antifoulingagent on leisure and commercial craft untilthey were banned in 1987. We areconcerned about TBT because of its effectson marine organisms. It can cause adverseeffects in molluscs, including dog whelkschanging sex and oyster shells thickeningabnormally. The use of TBT on smallervessels led to a serious decline in dog whelkpopulations around the coast in the 1980s.27

In many areas dog whelk populations arenow starting to recover, but full recovery willtake many years because TBT remainswithin the sediment. Larger vessels can stilluse TBT leading to continuing pollutionparticularly around docks.

Some waters that supply scallops, oystersand other shellfish are affected by metals,principally copper and zinc, and bacteria fromdiffuse sources. In 2005 about 13 per cent of

shellfish sites failed to meet chemicalstandards for water quality.

Microbiological pollutionBathing waters are the cleanest on record,but can be affected by diffuse pollutionparticularly from livestock farming.28 Forexample, in South West England over ahundred bathing waters, about half of theregion's total, are affected by diffusepollution.29 In 2006, a quarter of Englishbathing waters and one in nine Welshbathing waters failed the strictestmicrobiological standards (Figure 10). In2005, 90 per cent of shellfish beds achievedat least Class B30 compared to just 72 percent of beds in 2000. Reducingmicrobiological contamination is also neededto meet the Government’s aim that alldesignated shellfish waters achieve at leastClass B for shellfish hygiene31 and toendeavour to meet guideline microbiologicalstandards under the Shellfish WatersDirective.

OilPassing ships and urban run-off can causeoil pollution in the marine environment. Oilslicks in the sea around our coasts and inestuaries are a risk to wildlife. About 60 percent of dead and dying sea birds washed upon UK beaches are oiled, although somemay have been oiled after death fromanother cause.32 There were almost 600 oilpollution incidents in 2004, of which themajority occurred in the open sea.33 Althoughmost of this oil is naturally dispersed anddegraded, oil slicks are a risk to wildlife.


Initiatives to control diffuse waterpollutionDiffuse pollution must be dealt with if the water environment isto be improved and the UK is to meet its existing nationaltargets and international commitments.

These targets and commitments include:• the Water Framework Directive (WFD)

that requires all water bodies (with someexceptions) to achieve good ecologicaland chemical status;

• commitments to bring Sites of SpecialScientific Interest into favourablecondition;

• the Nitrate Directive that aims to reducenitrate pollution from agriculture;

• the Groundwater Directive that aims toprevent or limit pollution from hazardoussubstances;

• the Bathing Water Directive that setswater quality standards which arecurrently being tightened;

• the Habitats and Birds Directives, andUK Biodiversity Action Plan, that requireaction to protect habitat quality;

• commitments under the North SeaConference and OSPAR Convention thatset targets to reduce marine pollution.

Reducing rural and urban diffuse pollution islikely to require a combination of voluntaryand economic measures, and new regulatorypowers such as the development of GeneralBinding Rules (GBRs) to ensure that goodpractice in undertaken to reduce the risk ofwater pollution. A wide range of actions totackle diffuse pollution is already being takenforward by Defra, WAG, ourselves andothers.

The main initiatives to control diffuse sourcesare outlined below. Controlling the productionand use of certain hazardous chemicals tostop the pollution at source is a key part ofthe approach.34 Soil protection is also centralto reducing diffuse water pollution becausesoils are the route by which many pollutantsreach water.35

A new approach to water protectionTo deal effectively with pollution and otherenvironmental problems we need to lookacross whole water catchments at all thefactors affecting water quality.36 This is theapproach set out in the WFD, which requiresall inland and coastal waterbodies to reachgood status by 2015. We are looking at theimpacts and risks to all water bodies todevelop a programme of measures wherechange is needed to meet environmentalstandards in England and Wales. The WFDsets out to reduce and eventually to eliminatepollution from priority hazardous substances;limits are currently being set by the EuropeanCommission. New environmental qualitystandards will be introduced for thesechemicals and to achieve them we will haveto control diffuse pollution. We are alsorefocusing our monitoring to provide betterinformation on the impacts of diffusepollution.

Defra will consult on the measures needed tomeet the WFD’s objectives. The methodsused to reduce diffuse pollution are likely toinclude negotiated agreements, economicinstruments, educational projects andpromoting more environmentally friendlypractices (such as those described below),as well as regulation. We will be combiningthese measures into action plans by 2009,with the aim of meeting the demandingenvironmental objectives by 2015.

Preventing urban pollutionIn urban areas the problems of diffusepollution are complex and are only justbeginning to be measured. Defra and WAGhave published a consultation document onnon-agricultural diffuse water pollution. Theyare working with us, industry sectors,


local authorities and others to prioritise themost urgent problems. They will assess theeffectiveness of existing measures anddetermine what additional measures andchanges are needed. An expert steeringgroup has been set up to take work forwardin this area.

To stop pollutants reaching watercourses inbuilt-up areas we want to see run-offmanaged by a range of techniques known assustainable drainage systems (SUDS) (Box7). This approach recreates a more naturalpattern of run-off, slowing down the flow ofrainwater so that more passes through thesoil where pollutants are retained and brokendown. Relatively clean water is then returnedto rivers or groundwater. SUDS includerainwater re-use, soakaways, permeablesurfaces, ponds and wetlands. Toincorporate SUDS into urban design,developers, planners and the water industryneed to work together.37

Box 7Sustainable drainage systems: theBourne Stream Partnership

At Bournemouth beach, bathing water qualityused to be badly affected by diffuse pollutionfrom the Bourne Stream, particularly after dryweather when the first flush of rain led to highlevels of bacterial contamination. The 7kmstream flows through built-up areas andenters the sea near the pier.

The Bourne Stream Partnership is tacklingdiffuse pollution by sustainable methods,including pollution prevention and promotingSUDS. Features such as ponds andwetlands have been installed to slow thestream’s flow, allowing sediment to settle outand pollutants to degrade naturally. Thepartnership is working to raise awareness ofwater pollution and good environmentalpractice. Bathing water quality has improvedand meets the requirements of the BathingWater Quality Directive.

Tackling other sources of diffusepollutionIn both urban and rural areas preventingpollution at source depends to a large extenton simple precautions being taken bybusinesses and individuals. Many of theseactions are explained in our pollutionprevention guidance notes and voluntarycodes of good practice (available fromwww.environment-agency.gov.uk). Usingregulation, advice and campaigns such as Oil

Care, our strategy for small and mediumsized businesses and NetRegs, we areworking with businesses to promote pollutionprevention. Examples include:

• using oil and chemicals safely, withbunded storage and handling areas;

• disposing of waste oil and chemicalssafely;

• using minimal volumes of herbicides tocontrol weeds in public areas;

• choosing chemicals with a lower impacton the environment;

• disposing of wash water to the foulsewer, not to surface drains;

• avoiding the illegal connection of foulsewage to surface water drains (Box 8);

• cleaning up dog fouling.

Box 8Are you well-connected?

One in five properties have incorrectlyconnected drains. Resolving the problem offoul drains wrongly connected to surfacewater sewers requires homeowners, buildersand plumbers to take more care, and thebuilding regulations to be enforced. Wrongconnections are dealt with by the water andsewerage companies, with our support, buttracking them down is extremely timeconsuming. If the proposal to include checksfor wrong connections in the new houseseller’s pack is accepted, this would help toraise awareness of the problem and reduceits impact.

All sectors will have to make further cuts inemissions to air to meet the targets of theNational Emissions Ceilings Directive by2010 and the WFD.38 Diffuse sources of airpollution will need to be tackled. Emissions ofgases into the air from a large number ofsources such as transport, industry andagriculture can also eventually cause waterpollution through being washed out in rainfall.

Reducing pollution from farmingAgriculture is changing. The latest reform ofthe EU Common Agricultural Policy (CAP) in2003 broke the link between financial supportand production. CAP support is now tied tocompliance with EU standards for theenvironment, public and animal health.Farmers will also have to maintain land ingood agricultural and environmentalcondition. In addition, new agri-environmentschemes in England and Wales will rewardfarmers for actively maintaining andimproving the environment. Farmers will be


encouraged to select these options in prioritycatchments. Environmental Stewardship inEngland and Tir Cynnal and Tir Gofal inWales are now paying land managers toadopt resource protection measures likenutrient and soil management, and theintroduction of buffer strips.

Direct regulation also has a part to play inreducing diffuse pollution from agriculture. Toreduce inputs of nitrate from agricultureNitrate Vulnerable Zones (NVZs) have beendesignated across 55 per cent of Englandand 3 per cent of Wales. The rules thatgovern the application of manure andfertilisers to land in these areas have been inplace since 2002. As yet there is no evidencethat nitrate levels are declining. Forgroundwater we expect any changes to taketime but we would expect to see somereduction of nitrate levels in rivers. Thecurrent rules are being revised and bothDefra and WAG are going to publicconsultation on revised proposals thissummer.

Further action will be needed in manycatchments to achieve national objectives forsurface and groundwaters.39 These are beingdeveloped by Defra and WAG under theCatchment Sensitive Farming Programme,which will tailor solutions to localenvironmental circumstances through farmplanning (Box 9).

We have been working successfully withfarmers to control the diffuse pollution of

bathing waters, for example as part of theGreen Seas initiative in Wales.

We visited nearly 10,000 farms last year, toadvise farmers how to comply with controlson fertilisers and manure. We have signed anaccord with the National Farmer’s Union andWater UK, committing us all to working inpartnership to tackle diffuse pollution.

To bring about effective change we alsobelieve that new approaches such as co-operative agreements and economicinstruments should be considered. Forexample, the Voluntary Initiative is analternative to a tax on pesticide use. It aimsto minimise the environmental impacts ofpesticide use and achieve environmentalimprovements. The programme is led by theCrop Protection Association with the supportof other agricultural industry bodies includingthe National Farmers Union, conservationbodies and ourselves. The initiative has hadsome success but there is still much to do.

Box 9Catchment Sensitive Farming Delivery Initiative

Catchment sensitive farming requires a partnership between farmers, regulators (such asourselves and Natural England) and others. Farmers and their advisers will need to increase theirunderstanding of pollution risks and prevention. At problem sites they may have to improve dirtywater storage and manage soil and chemical use to limit losses of pollutants to water. Thisapproach will be promoted through advice, incentive schemes, and regulation where it is needed.

With Defra, we are funding a network of catchment officers to help farmers reduce diffuse pollutionin priority river catchments. Local projects, like Landcare on the Hampshire Avon, have shown thatthis approach can work.


ConclusionsDiffuse water pollution is an increasingly important issue. Wewant to reduce the social, economic and environmental costsof contaminated water sources, degraded urban rivers, anddeclining biodiversity and fisheries. High quality waters arevital to rural economies and are at the centre of urbanregeneration.

The Water Framework Directive (WFD)requires much better control of diffusepollution in order to improve water quality.Our initial assessment for the WFD showsthat many groundwaters, rivers, lakes andcoastal waters are at risk of not achievinggood status. We will refine this assessmentand consult on our new findings.

Adjusting land management and taking stepsto prevent pollution can often be inexpensive,although changing habitual practices will taketime. We will be working with farmers to bringabout catchment sensitive farming. We willbe working with planners, architects anddevelopers to design diffuse pollution out ofurban waterways. In some cases, furtherresources will be needed. It is not always

clear who should pay, but the potentialbenefits are likely to greatly outweigh thecosts.

To tackle diffuse pollution we all need toexplore new ways of managing both land andwater. We should look at potential pollutantsfrom cradle to grave. Finding the bestsolutions for the environment will require newthinking, better information and action. Byworking with other organisations andinterests we can agree cost-effectivesolutions. By looking at whole river basins wecan target the main problems. Much can beachieved through voluntary measures andthe right advice based on local knowledge.Regulation can then be directed to where it isneeded most.


References and endnotes 1 Environment Agency website, www.environment-agency.gov.uk/business/444217/444663/9555732 Percentage of the total length or area of each waterbody type. Waterbodies can be at risk from more than one pressure.3 Environment Agency (2002) Our urban future. Environment Agency, Bristol. 25pp.4 2004/05 prices including investments between year 1989/90 and 2004/05 for all nitrate reduction costs.5United Kingdom Water Research Limited (UKWIR) (2004) UKWIR news, Issue 33, November 2004. London.6 Defra (2004) Developing measures to promote catchment-sensitive farming. A joint Defra-HM Treasury consultation.Defra, London, 77pp.7 Defra (2004) Updating an estimate of the source apportionment of nitrogen to waters in England and Wales - phase 2report to the Department for Environment, Food and Rural Affairs. London, 34pp.8 European Environment Agency (2004). Signals: A European Environment Agency update on selected issues. TheEuropean Environment Agency, Luxembourg, 36 pp.9 Defra (2004) Developing measures to promote catchment-sensitive farming. A joint Defra-HM Treasury Consultation.Defra publications, London. 77 pp.10 National Rivers Authority (1995) Zinc in estuaries. National Rivers Authority, Bristol. 48pp11 As shown by our general quality assessment.12 Petts, G, Heathcote, J and Martin, D (2002) Urban rivers: our inheritance and future. IWA Publishing, UK. 117 pp.13 English Nature website. www.english-nature.org.uk/special/sssi/report.cfm?category=N14 Above 30 mg NO3/l.15 Above 0.1 mg P/l.16 Environment Agency (2004) Our nation's fisheries. The migratory and freshwater fisheries of England and Wales - asnapshot. Bristol. 51pp.17 Foy RH and Bailey-Watt AE (1998) Observations on the spatial and temporal variation in the phosphorus status of lakesin the British Isles. Soil management 14, 131-138.18 Johnes P, Curtis C, Moss B, Whitehead P, Bennion H and Patrick S (2000) Trial classification of lake water quality inEngland and Wales: a proposed approach. Environment Agency, Bristol, R&D Technical report E53, 80pp.19 Environment Agency (2006) Pesticide report 2005.www.environment-agency.gov.uk/yourenv/eff/1190084/business_industry/agri/pests/20 The Government requires Salmon Action Plans for all 63 principal salmon rivers to implement the National SalmonStrategy.21 Milan DJ, Petts GE and Sambrook H (2000). Regional variations in the sediment structure of trout streams in southernEngland : benchmark data for siltation assessment and restoration. Aquatic Conservation: Marine and FreshwaterEcosystems 10, 407–420.22 Environment Agency (2004) The state of England’s chalk rivers: summary report by the UK Biodiversity Action PlanSteering Group for Chalk Rivers. Environment Agency, Bristol. 16 pp.23 National Expert Group on Transboundary Air Pollution (NEGTAP) (2001) Transboundary air pollution: acidification,eutrophication and ground-level ozone in the UK. Centre for Ecology and Hydrology and Defra, London. 314pp.24 Worrall, F, Besien, T, and Garthwaite, D (in prep). Pesticides in the groundwater of Southern England 1992-2000. Journalof hydrology.25 Covey, R and Laffoley, D d’A (2002) Maritime state of nature report for England: getting onto an even keel. EnglishNature, Peterborough. 48 pp.26 Marine Environment Monitoring Group (2004) UK National Marine Monitoring Programme – second report (1999-2001).CEFAS, Lowestoft. 136pp.27 Environment Agency (1999) The state of the environment of England and Wales: coasts. Bristol. 201 pp.28 Defra (2005) Press release 9th November 2005.29 Environment Agency pers comm.30 A measure of shellfish quality. Class B shellfish can be sold for human consumption after treatment in a purificationcentre. Class A shellfish needs no treatment.31 Defra (2004) Developing measures to promote catchment-sensitive farming. A joint Defra-HM Treasury Consultation.Defra publications, London, UK. 77 pp.32 Marine Conservation Society (2004) Factsheet on marine oil pollution. MCS, Ross-on-Wye.33 Advisory Committee on Protection of the Sea (2005) Annual survey of reported discharges attributed to vessels andoffshore oil & gas installations operating in the United Kingdom pollution control zone 2004. ACOPS, Maritime andCoastguard Agency, London. 48pp.34 Environment Agency (2003) Managing chemicals for a better environment. The Environment Agency's strategy.Environment Agency, Bristol. 41pp35 Environment Agency (2004) The state of soils in England and Wales. Environment Agency, Bristol. 32 pp.36 Environment Agency website, www.environment-agency.gov.uk/business/444217/444663/95557337 National SUDS Working Group (2004) Interim code of practice for sustainable drainage systems. National SUDS WorkingGroup for ODPM, Defra and Welsh Assembly Government, 58pp, www.ciria.org/suds/icop.htm38 National Expert Group on Transboundary Air Pollution (NEGTAP) (2001) Transboundary Air Pollution: acidification,eutrophication and ground-level ozone in the UK. Centre for Ecology and Hydrology and Defra, London. 314pp.39 GFA-RACE Partners Ltd & IEEP (2003) The potential environmental impacts of the CAP reform agreement. Defra,London.

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