The Water Framework Directive is a piece of European legislation that states that all UK waterbodies (rivers, lakes, seas) must be in ‘good ecological status’ by 2027.

The ‘ecological status’ of a stretch of river is measured by looking at a number of things which affect the health of a river, including:

  •        Flow level (i.e. is it enough to sustain the river’s ecology?)
  •        Invertebrate populations
  •        Fish populations
  •        Macrophytes (link to glossary)
  •        Phytobenthos (link to glossary)
  •        Diatoms (link to glossary)
  •        Morphology (link to glossary)
  •        Pollutants (e.g. phosphate or ammonia)
  •        Oxygen content
  •        pH
  •        Temperature

For each category, the river is graded either Bad, Poor, Moderate, Good or Excellent.  The entire stretch of river takes its classification from the worst result in these categories; for example, if the river is achieving ‘Good’ status for everything except its fish populations, which are classed as ‘Bad’, the entire stretch will be classified as ‘Bad’.  This ensures that work can be targeted towards tackling the reason (or reasons) a river is failing to meet Good Status, e.g. its fish populations.

The table below shows the most recent Water Framework Directive classifications for the (upper) Lower Lea, and the reasons for these.  The projects outlined in this Catchment Management Plan will help to move the river into Good Ecological Status.

Section of river


Ecological status

Criteria failing to meet Good Ecological Status

River Lea Woolens Brook to Tottenham Locks Poor Macrophytes
Small River Lea and tributaries   Moderate Invertebrates 
Nazeing Brook   Poor





Cobbins Brook   Bad Fish
Cuffley Brook to Turkey Brook   Poor Fish
Dissolved oxygen

Design by LTD Design Consultants and build by Garganey Consulting.