Environmental Engineering Reference
In-Depth Information
The knowledge of taxonomy is required with respect to each region;
They reflect environmental changes after the damage has been implied;
They are not specific with respect to pollution sources and causes;
There is a danger that classification of sampling sites and habitat types may be
subjective.
Down stream catchment areas are usually vast and situated in gently sloping fertile
valleys, whichare ideal for settlement and agriculture. The choice of control sites in
such conditions is difficult, as usually the whole area has been affected by human
activities. Upstream sites could not serve as controls because of the different site
conditions and stream morphology. The definition of pristine implies the “natural
state” of the aquatic ecosystem, which is a rare occurrence in downstream sites,
thus, a compromise of “the best attainable ecosystem” would need to be
done.(Hohls 1996).
Resh et al. (1995) points out that there is a difficulty in defining thresholds of
variation, such as: howmuch is due to sampling inaccuracy or natural variation,
what are the limits of change in species composition, if any?
3 REGULATORY ASPECTS
The evident difficulty to monitor and control diffuse pollution requires an objective
orientated approach, where the main goal should be to control and maintain natural water
quality in a sustainable manner. The development of regulatory instruments play a key
role in this process and would lay the foundation for a sustainable practice. These
documents should be able to allow a comparison with actual measurements, the detection
and assessment (quantification) of pollution levels, as well as the possibility to penalize
polluters.
3.1
The regulatory approach
The Water Quality Objective approach should be implemented in order to provide a
wider range of protection of the water resources and to specify the natural (surface and
groundwater) background quality for each specific region, as well as to include the
detection, assessment and regulation of diffuse pollution sources. The formulation of
sustainable and practically implementable objectives would require:
• A sound estimation of the present status of the natural water quality in the catchment
basin, or sub basin,and its corresponding beneficial use;
• A good knowledge of treatment and disposal methods for wastewater and storm water
at local andinternational level and a choice of the best alternative (BA), related to local
conditions;
• A consideration of the conditions for implementation of BA in the light of the economic
status of the region and availability of financial, technical and human resources.
The implementation of this approach does not necessarily mean that it should lead to a
conflict for cases where the effluent discharge regulations are in place. It should be
viewed as a broader approach to the regulation of water quality, which could include
