SHILLONG, Dec 29: As another year comes to an end and the will to start anew remains at sixes and sevens, the plight of the dying rivers in the state remains the same.
According to a recent report of the Meghalaya State Pollution Control Board (MSPCB) on water quality of rivers in the state, bacteria were among the main pollutants in the water bodies. This was mainly due to direct discharge of waste water in an untreated form from the residential and commercial centres.
The amount of waste received by the two rivers viz., Umkhrah and Umshyrpi rivers, was much beyond their assimilative capacity and thus has deteriorated the water quality to the extent that the water in these rivers cannot be put to any beneficial use.
In all the monitored locations, the pH level was observed to be in the normal range of 6.5 to 8.5.
The dissolved oxygen was found to be very low in Umkhrah and Umshyrpi rivers with the minimum value 0 mg/l recorded at Umshyrpi river at Law College and Umkhrah river at Slaughter House Mawiat during the dry winter months of February and March, whereas its concentration in other rivers was always above 4mg/l, which was the minimum oxygen requirement for propagation of wildlife, fisheries etc.
The bio-chemical oxygen demand was observed to be above 3mg/l in Ward’s Lake, Umkhrah and Umshyrpi rivers. The total coliform count was observed to be above 5000mpn/100 in Umkhrah and Umshyrpi river.
The monitoring results indicated that the water quality of Ward’s Lake meets the criteria for propagation of wildlife and fisheries. The water quality of other water bodies was relatively good as and can still be put for various beneficial purposes although it was not recommended to use directly for drinking purposes unless treated and disinfected by an organised water supply system.
According to the water quality reports of rivers in West Khasi Hills and South West Khasi Hills, the pH level in all the monitored locations was observed to be in the normal range of 6.5 to 8.5.
The dissolved oxygen content in all monitored rivers was always above 4mg/l, which was the minimum oxygen requirement for propagation of wildlife fisheries etc.
The bio-chemical oxygen demand was observed to be above 3mg/l and total Coliform count above 500mpn/100ml in Nanbah river at Nongstoin. Located in the centre of the district headquarter of West Khasi Hills, this river is also subject to pollution arising out of direct disposal of solid and liquid waste from residential and commercial areas, automobile workshops and servicing centres and agricultural runoff.
However, the water of this river can be used for propagation of wildlife and fisheries and irrigation purposes. The water from other water bodies could still be used beneficially although it was not recommended to drink it unless treated and disinfected by an organised water supply system.
In Ri-Bhoi, the pH level of monitored water was observed to be in the range of 6.5 to 8.5, which is normal, and the dissolved oxygen content in all the stations was found to be above 4mg/l, which was the minimum oxygen requirement for propagation of wildlife fisheries etc. The bio-chemical oxygen demand stood above 3mg/l in Umiam Lake and Umtrew river at Byrnihat. The total Coliform count in these water bodies was also observed to be high. The Umiam Lake received the waste that was generated in Shillong through the two rivers viz., Umkhrah and Umshyrpi, whereas the Umtrew river was subject to pollution originating from the residential, commercial and industrial areas.
The water in Umiam Lake and Umtrew river is fit for propagation of wildlife and fisheries and irrigation purposes. The water quality of other water bodies too was relatively good and could be put to use for various beneficial purposes, but not recommended to be consumed directly.
As many as 12 rivers in East and West Jaintia Hills have turned acidic due to effluent from coal mines located on the catchment areas and upstream.
The pH level in water bodies of the region including rivers such as Myntdu, Lunar, Lukha etc., was observed to be very low with the minimum value of 2.3 recorded at Lunar river at Myndihati during the dry months of April.
Low pH indicates that the water is acidic in nature mainly due to acid effluent from coal mines located on the catchment and upstream.
The dissolved oxygen in all monitored rivers was always above 4mg/l.
The bio-chemical oxygen demand was observed to be above 3mg/l at Myntdu river, Jowai, Kyrhukhla river, Khliehriat, and Lunar river, Myndihati. The total coliform count was observed to be above 500mpn/100 ml in Myntdu river in Jowai mainly due to contamination from the domestic waste water/sewage. The water quality of other water bodies was relatively good and it could be used for various purposes but not drinking.
In Garo Hills, the pH level was observed to be in the normal range of 6.5 to 8.5 except in Nongal river, where the average pH was 4.5.
The dissolved oxygen content in all the monitoring stations was found to be above 4mg/l, which was the minimum oxygen requirement for propagation of wildlife fisheries etc.
The bio-chemical oxygen demand was observed to be below c3mg/l in all the monitored water bodies. The Coliform count was observed to be moderately high in Simsang and Ganol river. The water quality of all monitored water bodies was relatively good.
