Pollution ‘killing’ major Goa rivers



PANAJI: Almost all the rivers in the state are polluted and water availability is increasingly being threatened due to rampant pollution from untreated domestic sewage and industrial effluents flowing into the rivers making the water unfit for drinking or any other purpose, according to a recent study by the Goa State Pollution Control Board (GSPCB).

The pollution of rivers has been caused because of the presence of faecal coliform bacteria on account of the disposal of untreated/partially treated domestic sewage and open defecation. Faecal coliform is a type of bacteria whose presence indicates that the water has been contaminated with faecal matter of human or other animals.

The GSPCB study checked the water quality with respect to indicators such as biochemical oxygen demand (BOD), dissolved oxygen (DO), which is the amount of free oxygen found in water, faecal matter of humans or other animals (faecal coliform) and total dissolved solids (TDS). It was found that the water quality was gradually deteriorating thus making the river waters unfit for any use.

According to the water quality criteria prescribed by the Central Pollution Control Board (CPCB), faecal coliform most probable number (MPN)/100 ml should be 30 or less in river water without conventional treatment but after disinfection. But the study report of GSPCB found the level of faecal coliform in River Sal to be in the range of 13,000-54,000 MPN per 100 ml with dissolved oxygen level not meeting the standards in most of the study period. This being the condition of River Sal at Khareband, one can well imagine the quality of the river waters in other parts of the state.

The analysis report of GSPCB found the level of faecal coliform to be in the range of 330-11,000 MPN per 100 ml at six sites of River Mandovi. The analysis indicated that the water quality met the desired criteria of various parameters except for the levels of faecal coliform at all the six locations. The analysis further indicated that the level of turbidity at two locations, that is near Hotel Miramar and at IFFI Jetty exceeded once during monsoon.

Samples collected from River Sinquerim at two locations – Candolim and near Ganapati temple – showed faecal coliform to be in the range between 450-7,000 MPN per 100 ml. Dissolved oxygen was higher than the limits indicating it to be a better sign for the marine life.

In Chapora and Zuari rivers, faecal coliform exceeded as high as 3,300 and 7,900 MPN/100 ml, respectively, during monsoon.

River Bicholim is the most polluted river and unsafe for human use due to the high level of faecal coliform bacteria in it, according to the GSPCB study. The observation has revealed that there is heavy discharge of raw sewage along its stretch and during low tide, the polluted river emanates an unbearable stench. The GSPCB has reported higher volumes of faecal coliform in this stretch with a reading of 11,000 MPN/100 ml.

Biochemical oxygen demand (BOD), one of the most important indicators of oxygen depletion in a water body, was observed to be within the permissible limit of less than 3 mg/L in River Bicholim. It was between 0.7 to 2.3 mg/L. However, it had depleted compared to the previous year’s data wherein the reading was between 1.2 to 4.2 mg/L. A high BOD in water means that the water has a great amount of microrganisms, mainly aerobic bacteria. This is common in areas contaminated with waste water.

The report further states that River Tiracol at Keri in Pernem taluka and River Talpona in Canacona are the two water bodies where faecal coliform is very low when compared to other rivers. The readings were 33 and 23 MPN/100 ml in River Tiracol and River Talpona in April, respectively.

River Kushawati in Sanguem, River Khandepar at Codli and River Madei in Valpoi have also been affected by sewage discharge and the faecal coliform levels are quite high.

According to the GSPCB annual report, the Mapusa river is also badly polluted as the faecal coliform count ranged between 3,300 and 7,900 MPN/100 ml, which clearly indicates that the river receives a lot of sewage and effluents along its course. The dissolved oxygen level in the river had also depleted thrice in different seasons.

According to a soon-to-be-released report by the Goa State Urban Development Agency on defecation sites, at least 177 spots identified in 124 municipal wards are used by people as open-defecation grounds. Most of these spots are open fields and spaces or slums along the water bodies.

Among the 14 municipal bodies, Margao, Mapusa, Bicholim, Mormugao, Ponda, Valpoi, Canacona, Sankhali and Quepem were leading with sizeable number of open defecation areas in wards which accounts for 50 to 80 per cent of the wards. The survey was carried out by municipal bodies to provide real time data on the problem of open defecation.