The present study published in Current Science deals with water quality assessment of rivers in Uttarakhand using biomonitoring assessment. 60 stretches of 19 rivers have been examined.
Background:
Ritual bathing accompanied by the ceremonial imbibing of water on auspicious days is an important event. Mass bathing has the potential to pollute the rivers. Organic matter contribution in the form of body secretions, offerings of milk, curd, ghee, flowers, hair etc. Frequently, these offerings are carried in plastic bags which are disposed off in the river.
Biological assessment is based on monitoring changes to the ecological balance to the system due to changes in the physico-chemical parameters of a water body due to pollution.
Presence of total coliforms is used as an indicator of aesthetic water quality of freshwater bodies such as:
(a) 50 MPN/100 ml for drinking water sources after disinfection,
(b) 500 MPN/100 ml for outdoor organized bathing
(c) 5000 MPN/100 ml for drinking water source with conventional treatment followed by disinfection.
Earlier studies carried out on the deterioration of water quality at mass bathing places are referred to.
Results of the assessment:
The paper lists the clean water stretches (class 'A'), slightly polluted stretches (class 'B'), moderately polluted stretches (class ‘C’), heavily polluted (class ‘D’) and severely polluted stretches (class ‘E’) of the surveyed rivers and tributaries in Uttarakhand. Average physico-chemical water quality levels at various biological water quality classes of the rivers are also presented, as are the average, minimum and maximum heavy metal and pesticide residues. Total and faecal coliform counts for the various sites are also given.
Material and methods:
60 locations on 19 rivers in Uttarakhand were selected for the survey based on the various human activities carried out in the area. The Biological Water Quality Criteria (BWQC) developed by CPCB were used.
Results and discussion:
Biological water quality:
Most stretches of the various rivers surveyed have clean water with acceptable diversity of benthic invertebrates. However, stretches of the rivers Bhagirathi, Dhauliganga and Ramganga, downstream and upstream of hydroelectric projects are degraded with a total absence of benthic invertebrates.
Physico-chemical water quality:
The various parameters surveyed are presented in the paper. The BOD ranges from less than 1.0 to 1.675 mg/l.
Heavy metal and pesticide residues:
Traces of chromium, copper, iron and zinc have been detected in sediments. Pesticide residues have been observed in the water but not in the sediments.
Bacteriological water quality:
This study reveals the paradox that clean stretches of the rivers may be the most bacteriologically contaminated as these stretches are used for domestic purposes.
A copy of the paper can be downloaded from below: