ide range of chemicals are often produced in the proximity of
fresh-water systems. The resulting breakdown and by-products
from the production process finally end up into the water. Environmental
concerns arise on whether the residual concentrations of
these compounds represent a risk to human and biota, and
whether fresh-water systems meet water quality requirements
for society in terms of water supply for human consumption and
other activities (e.g. fishery, aquaculture and tourism). A combination
of physical, chemical and biological indicators is frequently
used to assess water quality