Page 61 - Freshwater-Biology-and-Ecology-Handbook

Do the estimated values Yes Yes Do the hydro- Yes
for the biological quality Do the physico-chemical morphological Classify as
elements meet reference conditions meet high conditions meet high high status
conditions? status? status?
No No No

Do the estimated values Do the physico-chemical
for the biological quality Yes conditions (a) ensure Yes
elements deviate only ecosystem functioning Classify as
slightly from reference and (b) meet the EQSs good status
condition values for specific pollutants?

No No

Is the deviation of the Yes
values for the biological Classify as
moderate
quality elements
moderate or less? status
No

Yes
Is the deviation major? Classify as
poor status

No
Figure 1.17 Yes
Decision-tree illustrating the Is the deviation severe? Classify as
bad status
criteria determining the different
ecological status classes

The five-stage classification is used to define environmental the UK. The WFD approach sets out the principles of
status or potential of the water environment and water management across all EU and UK River Basins
environmental quality objectives. It is also used to assess for the near 30 year lifespan of the Directive and for the
progress towards achieving environmental objectives and foreseeable future.
the effectiveness of measures to restore quality.
Implementing the WFD means that expensive regulatory
Biological status or potential is supplemented by and infrastructure investments are now focused on meeting
assessments of various supporting physico-chemical biological objectives. This required significant improvements
elements that are necessary to support the biota to biological and ecological monitoring and assessment. It
(such as oxygen, inorganic plant nutrients and pH) and has accelerated research and the development of biological
hydromorphological quality elements (such as flow methods and guidance across the EU to improve accuracy,
requirements, connection to groundwaters, residence time, quality assurance and equivalence of assessment methods.
and nature of the substrate). These are combined to define This handbook provides background to this development
ecological status. In addition, certain toxic chemicals are and gives open access to the wealth of technical information
included for which standards to protect biological status available to water managers.
are set at national level, and these are known as ‘specific
pollutants’. Chemicals that are to be severely limited or A further key principle of biological and ecological
eliminated, with standards set at European level and assessment is management at river basin or catchment
specified in WFD or subsequent amendments, contribute management level (sometimes referred to as watershed
to a chemical classification. (See previous section on management). This also underlies the WFD and has been
chemicals.) The ecological and chemical classifications a core element of water management in the UK for the past
are combined into an overall status classification. 50 years, since the establishment of the UK Regional Water
Authorities in 1974. In Western Europe, this approach has
Development and implementation of the WFD focuses facilitated the successful clean-up of many river systems and
on biological and ecological outcomes in the aquatic the rivers Rhine, Danube and Thames are examples of how
environment and has brought a step change in our this restoration has progressed.
approach to water management across the EU and

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