Page 57 - Freshwater-Biology-and-Ecology-Handbook

There are no European standards for High status represents only very minor changes to the
hydromorphology, physico-chemistry and biology of a water body.
ecological status; each Member State has to Good status requires no more than slight changes to the biology of the
develop its own ecological assessment method water body and compliance with quality standards for pollutants. The
other status classes are defined according to the level of impact upon
and ecological standards. A consequence their biology. The aim is to restore quality and to prevent deterioration.
of this is that the only difference between a
Change
priority substance and a specific pollutant is from Natural
that standards for priority substances are set Ecological Status Condition
HIGH
No or
at European level and standards for specific minimal
pollutants are set nationally. Many specific
pollutants are elevated to priority substances
GOOD*
when Europe-wide standards are set. Slight

‘Ecological potential’ replaces ‘ecological status’
in artificial and heavily modified waters. Ecological MODERATE Moderate
potential takes account of the reduction in biological and
morphological status caused by a desirable physical
modification that we do not want to remove in order
to restore biological status. Physical modification in RESTORE POOR Major
this context includes structures such as dams or flood
defences; it does not include chemical, physico-chemical,
or hydrological elements. Ecological potential can be
either good or not good. BAD Severe

Chemical and ecological status or potential are combined Key
to produce an overall water body status. The class given
to a particular water body will represent an estimate of Chemistry Hydromorphology
the degree to which the structure and functioning of the Prevent Deterioration
aquatic ecosystem have been altered by the different Biology
pressures to which that water body is subject. Figures 1.14 *Good status also requires good water quality
and 1.15 provide a description of the five status classes.
High ecological status
Each of the relevant biological, hydromorphological and physico-
chemical quality elements match their reference conditions.
General Hydromor-
Biological Other Good ecological status
Priority quality physico- phological specific
substances chemical quality
elements pollutants
substances elements The relevant biological quality elements are only slightly changed
from their reference conditions as a result of human activities.
Environmental quality standards are achieved for the relevant
physico-chemical quality elements.
Moderate ecological status
Chemical Ecological status
status
The relevant biological quality elements are moderately changed
from their reference conditions as a result of human activities.
Poor ecological status
Final status surface water quality The relevant quality biological elements show major changes from
their reference conditions as a result of human activities (ie there
are substantial changes to the reference biological communities).
Figure 1.14
Individual WFD status classifications contributing to the overall Bad ecological status
WFD Surface Water Status. (Torenbeek, 2007, translated)
The relevant biological quality elements are severely changed
from their reference conditions as a result of human activities (ie
large portions of the reference biological communities are absent).
Figure 1.15
Graphic representation and text summary
of the five stage classification system

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