ESTONIAN ENVIRONMENTAL REVIEW 2009

6.4.2. Evaluating the status
of surface water bodies
Ensuring water quality and ecological balance is
important on both the local and the international level.
The primary objective of the EU’s framework policy is thus
to ensure that the status of water bodies and groundwater
is good in all EU countries. In order to learn which are
the problematic water bodies, what causes them to be in
poor condition, and how to improve the situation, first
the status of water bodies is evaluated. The assessment
of the state of water bodies is the basis for preparing the
programme of measures for water management plans to
bring water bodies that are in moderate and poor condition
into good condition. If necessary, restrictions are
established to prevent the condition of water bodies that
have a good and high status from becoming worse.
The assessment of the state of water bodies set out in
this overview covers the period from 2004–2008 and is
based on the relevant regulation of the Minister of the
Environment I .
The evaluation of the ecological status of rivers, lakes
and coastal waters is based on three groups of quality
elements: biological, hydromorphological and physicalchemical
quality indicators. The main emphasis is on the
aquatic biota – evaluating biological quality elements
which depending on the type of body of water are phytoplankton,
phytobenthos, macrophytes, zoobenthos
and fish. Hydromorphological conditions include water
regime, flow rate, weirs and other obstacles on rivers and
depth and width of the body of water. Physical chemical
indicators are water temperature, oxygen content,
transparency and nutrient content.
Besides the ecological status, the chemical condition
of the water is also evaluated – i.e. pollutant levels
are determined (such as heavy metals, plant protection
products, hazardous substances) and whether they exceed
the established limits or not.
In evaluating the status of the body of water, the body
of water being studied is compared to quality indicators
for a similar comparison body of water that is in a natural
condition unimpacted by human activity. The combined
rating is for the most part assigned based on the worst
biological quality element.
The rating is expressed on the basis
of a five-level classification:
• high status – lack of or minimal human
impact, biological quality element elements
conform to the comparison criteria with
minimum deviation;
• good status — human impact is low, biological
quality element values indicate minor deviation
due to human activity from comparison conditions;
• moderate status — human impact is moderate,
biological quality element values vary moderately
from comparison conditions and indicate more
major disruption than in the case of good status;
• poor status —human impact is strong, and the
biological quality element values deviate strongly
from the comparison conditions or a large share of
conventional biological communities is lacking;
• bad status — human impact is very strong,
biological quality element values deviate strongly
from the comparison conditions or biota is lacking
altogether.
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I
The Minister of the Environment Regulation no. 44 of 28 July 2009, “Procedures for establishing surface water bodies, list of surface water bodies whose status class is to be
determined, status classes for surface water bodies and procedures for determining quality indicator values corresponding to the status classes”.