Page 141 - Freshwater-Biology-and-Ecology-Handbook

Ballinderry River Black Burn
Ballinder r y River
Cru mlin River
COOKSTOWN
LOUGH NEAGH
Killymoon River
Pomeroy
STEWARTSTOWN

Cappagh
COALISLAND
Aghalee
Donaghmore
River Torrent
DUNGANNON
Castlecaufield
MOYGASHEL MOIRA
lygowley Water River Rhone CRAIGAVON Magheralin
Ballygawley LURGAN
Oona Water Eglish
Moy River Tall
Waringstown
PORTADOWN
River Ban n
Blackwatertown
AUGHNACLOY
Ballybay River Lawrencetown
Loughgall
River Blackwater
GILFORD
Richhill
BANBRID
Caledon ARMAGH TANDRAGEE
GOOD (Unstressed Fauna)
MODERATE (Slightly Stressed Fauna)
POOR (Highly Stressed Fauna)

BAD (Extremely Stressed Fauna)

NOT CLASSIFIED

Figure 3.3
Map showing biological quality status – example is an extract from the 1991 survey of

Northern Ireland(DoENI, 1993) based on the 5M classification with river stretches
belonging to different classes in contrasting colours (40) – compare with Figure 3.6

The key objective of achieving Good Ecological Status and existing High status sites should not be allowed to
places significant emphasis on ensuring that the class deteriorate. The process of setting the river invertebrate
boundaries (particularly between Moderate and Good) are status boundaries is described in Section 4.2.
correct and equivalent across all Member States, which is
ensured by intercalibration. Biological metrics are complex because they describe
complex processes. The classification metrics model the
The criteria for choosing appropriate river invertebrate normative definitions, but like all models they have their
classification metrics and the classification metrics adopted limits, and they cannot cover every unusual condition.
in the UK are described in Section 4.1 and Section 2.2. An understanding of the classification metrics is needed
If class boundaries are set too low, the environmental to fully interpret the reliability of the classification results
improvements that the WFD aims to achieve will not be (Section 5). In cases beyond the limits of the model, the
met. If class boundaries are set too high, the costs will be final classification has to be based on other information.
excessive. The emphasis on setting the Good/Moderate
status boundary correctly is crucial because Good status The classifications are inevitably simplifications that
is the ultimate objective for most water bodies, so it is the need to be understood by politicians and the general
boundary that determines compliance or non-compliance public, to allow programmes of measures to be chosen,
with environmental objectives. Other boundaries are also funded and undertaken.
important: lower standards may be set as interim standards

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