Catchment Issues

  • The main water resource pressures in the Cam and Ely Ouse management catchment come from public water supply through groundwater sources, from river abstractions and from the spray irrigation of agricultural land.
  • The catchment suffers from diffuse agricultural pollution which causes siltation and high nutrient levels. Discharges from sewage treatment works, private sewage systems and misconnections further intensify these problems which can be compounded at times by low flows.
  • Invasive non-native species pose a significant future threat in the catchments. For example, signal crayfish are now present in the River Lark disturbing banks and predating on native life. This has led to increasing amounts of fine sediment in rivers and alterations to the ecology.
  • The extent of historic river modification, such as heavily embanked or re-sectioned rivers, has decreased habitat diversity. Furthermore, weirs and flood defence structures create obstacles to fish.
  • Diffuse nitrate quality issues are a significant problem for ground water and as a result, eleven Safeguard Zones have been designated within the Cam and Ely Ouse management catchment.
  • Pesticides including metaldehyde are also a threat to public water supplies. Further information on Metaldehyde can be found at

CamEO Failure

The large proportion of heavily modified water bodies will prevent good ecological status from being achieved across the catchments (See Water Framework Directive). Significant improvements have begun on many of these water bodies.

Phosphate stripping from sewage treatment works remains the most productive means of removing high phosphate loads in water, whilst targeted agricultural campaigns to reduce the impacts of pollution from rural areas also play an important role.Pressures_Key_(3)

Balancing the requirements of abstractors, the environment and the recreational users of water resources is essential to the success of catchment level water management.

The table below outlines the reasons for failing to achieve good status, as represented by the coloured bar charts on the catchment maps.

Catchment Issues

Physical ModificationsChanges made by people to the rivers, lakes and estuaries - for example: flood defences, weirs, land drainage and navigation modifications.
Pollution from Water RecyclingTreated water may still contain substances, such as nutrients (phosphates and nitrates), ammonia and other chemicals.
Pollution from Towns, Cities, and Transport including Urban Diffuse PollutionPollutants, such as oil, chemicals and organic debris are carried into the water environment by rain water draining off hard surfaces (roads, pavements and yards). Chemicals from contaminated land; sewage/liquid wastes from homes and commercial premises wrongly connected to surface water drains rather than foul sewers.
Changes to the Natural Flow and Level of Water including AbstractionToo much water taken from rivers, canals, lakes and groundwater, leads to less water available to create flow, required to support the riverine ecosystems.
Invasive Non-Native SpeciesThe impact of non-native plants and animals introduced to UK waters (particularly the competitive effects of these organisms on local wildlife).
Pollution form Rural Areas including Rural Diffuse PollutionThe effects of agricultural practice and rural land management on the water environment.
OtherFailures that occur naturally, are unresolved or are due to suspect data.