A RECENT seminar organised by the Environmental Protection Agency (EPA), Sindh, was informed that the Indus river is highly polluted. The levels of various parameters are high enough to classify the river as polluted. Even the coliform level, which should have not been present in water bodies at all, averaged 800 per 100 ml.

It is a fact that the Indus river is polluted due to indiscriminate discharges of untreated municipal and industrial wastewater, the Manchar Lake discharges make the pollution further distinct during periods of low flows (December-January). But the comparison of water quality of this river and other water bodies with the international standards made at the seminar, was not justified. The water quality of Indus river was compared with the WHO’s guidelines for drinking-water and the EU’s drinking-water standards.

The international drinking-water guidelines and standards do not apply to waters of the surface water bodies (Indus river, Phuleli Canal, Manchar Lake, Danistar Canal, Haleji Lake, Pinyari Canal, etc). It is just like comparing oranges with apples.

The surface water treatment revolves around pumping of water from a river and its treatment in a water treatment plant. Conventional water treatment plants (rapid-sand filters for major cities; and slow-sand filters for rural towns), depending on the quality of raw water, design and operation of the plant, remove conventional pollutants (fecal coliforms, turbidity, suspended and dissolved solids, colour and inorganic elements) to a varying degree. For example, coagulation and sedimentation are effective in removing colour and turbidity, slow-sand and rapid-sand filters are effective in removing bacteria, colour and turbidity, but have no effect on the hardness of water.

The statement that coliforms should not be present in water bodies reflects lack of understanding of water engineering.

There are eight rivers in North America, 10 in Central and South America, nine in Europe and 14 in Asia and the Pacific, which have fecal coliform levels ranging from 100 to 1,000 per 100 ml. There are three rivers in Asia and the Pacific region with fecal coliform levels of more than 100,000 per 100 ml.

Water pollution in the Indus results from three sources: municipal wastewater discharges, industrial wastewater discharges and, return-agriculture flows through drainage structures. Most cities and towns of Sindh discharge their untreated municipal wastewater into the Indus. With wherever treatment facility exists (e.g., at Tando Muhammad Khan), the wastewater does not receive the desired degree of treatment.

The parameter of major concerns is the discharge of organic matter. This causes depletion of dissolved oxygen in river water. In extreme cases, when the assimilative capacity of the river is exceeded, anaerobic (septic) conditions result. This could be a problem in the river, during the months of low dilution (December and January), or, when there is water shortages in the Indus river. Under anaerobic conditions, iron and manganese become more soluble and become a potential source of groundwater pollution. Due to high coliform content, use of water for drinking purposes without appropriate treatment, would result in water-borne diseases like malaria, typhoid, cholera and dysentery.

Industrial wastewater discharges, depending upon the nature of industry, comprise wide-ranging variables. These include organic matter; ions like sodium, potassium, calcium, magnesium, carbonates and bicarbonates, chloride; other inorganic variables like fluoride, silica, cyanide; metals like cadmium, chromium, copper, mercury, lead, zinc, nickel, etc. The return-agriculture flow characteristics include salinity, total dissolved solids, sodium adsorption ratio (SAR), nitrates, phosphates and pesticides.

In case of industries, like thermal power plants, the variable of major concern is temperature and mercury poisoning which results in death.

At Jamshoro, where power plants are also located, presence of mercury in Indus river water has been reported. Sudden increase in surface water temperature by three degrees Celsius is harmful for marine organisms. Required level of oxygen is usually not available, as the increased water temperature decreases solubility of oxygen in water.

Salinity, in case of return-agriculture flows, is an important property and, in the present case, is of major concern. Disposal of saline effluent in the Indus river degrades its water quality. The ground water quality in the Indus Basin is impacted by the water quality of the river.

According to a case study conducted by the United Nations Economic and Social Commission for Asia and the Pacific, Bangkok, titled “Desertification in Indus Basin due to salinity and water-logging, 1989”,...ground water is becoming increasingly saline making it less useful for agriculture. A large population in the area is also affected because they are using the saline underground water for drinking purposes.”

While the EPA, Sindh, has taken samples from various points, the water quality of the Indus river, at any given point, depends on (a) the proportion of surface run-off from catchment areas, and groundwater, (b) reactions within the river system governed by internal processes, (c) the mixing of water from tributaries of different quality (e.g. from Manchar Lake), and (d) inputs of pollutants from municipal and industrial sources (e.g., municipal wastewater from various towns and, power plants located at Jamshoro).

Water quality variability also depends on the hydrological regime of the river. Dissolved substances in the river are highly variable from one place to another, depending on their sources, pathways and interactions with particulates.

Monitoring water quality of the Indus river, conducted in isolation, would be inadequate if the pollutants are put to true perspective. It is customary in environmental engineering field to conduct biological monitoring along with physiochemical monitoring to have a complete pollution scenario.

Physiochemical monitoring may classify a river as good, when pollutants, not specifically tested for (e.g. pesticides), are present; or where the sampling points do not detect intermittent pollution events. Unlike water quality monitoring which examines the water itself, biological monitoring looks at the abundance and diversity of the tiny creatures (macro-invertebrates) that live in the river. Biological monitoring can reveal the effects of pollution not detected by physiochemical monitoring.

There is a serious water shortage at the Sukkar Barrage. As a result, less water is supplied to the off-taking canals, which in turn, is affecting Rabi crops. The water shortages are further expected to aggravate in the coming days. Despite being the lifeline of Sindh, it seems the Indus river water quality is being taken for granted, with no control over it. No department seems to be responsible for the water quality of the Indus river.

The wake-up calls given by environmental engineers, from time to time, to stop pollution of the Indus river and degradation of the river ecosystems, need to be heeded by the Sindh government. There is a need to set up an Indus river authority to control the discharge of all municipal and industrial wastewater effluents into the river including discharges from other sources (e.g., Manchar Lake).

Polluted Indus threatens the livelihoods of people, affects the agricultural produce and, makes water treatment for drinking purposes increasingly difficult.