GUWAHATI, Feb 10 - As part of the Centrally-sponsored National Water Quality Monitoring Programme (NWMP), being implemented throughout the nation, the Pollution Control Board, Assam (PCBA) has been regularly monitoring the quality of water at various water sources in Assam with specific frequencies, i.e., monthly, quarterly and half yearly.
Prior to April 2008, monitoring was done for 41 monitoring stations only, but since April 2008, 60 new monitoring stations were included under the NWMP, raising the total number of stations to 101.
�Out of these, 10 sampling points are in the River Brahmaputra, 32 are in the tributaries of the Brahmaputra, and two are in the Barak river and its tributary. 27 sampling points are in ponds/tanks, while 32 ground water stations have been included in the programme,� PCBA sources told The Assam Tribune.
Stating that action plans for restoration of water quality of polluted stretches were being worked out, sources added that one of the prerequisites for formulation of action plans was to monitor water quality on a continuous basis.
The PCBA had submitted two DPRs under the Centrally-sponsored National River Conservation Plan (NRCP) for Bharalu and Kolong rivers for control of pollution and restoration of the river stretch to the Union Ministry of Environment and Forests.
�Rectifications, as suggested by the MoEF, have already been incorporated in the report, and the decision of the government is awaited,� sources said.
The Central Pollution Control Board (CPCB) had identified 29 river stretches at 42 locations as polluted in Assam under three categories � Priority I, IV & V, based on values of Biochemical Oxygen Demand (BOD) parameters.
Both the Bharalu and Kolong rivers are recorded as most polluted under Priority � I (BOD: greater than 30 mg/l).
Among the rivers identified as polluted stretch under Priority � IV (BOD: 6-10 mg/l) are the Digboi river at Lakhipathar Reserve Forest, Desang river at Gudamghat, and Brahmaputra river at Kherghat.
�The BOD values of the river during the period from 2008 to 2013 exceeded marginally greater than 3 mg/l in four out of 24 observations. On three occasions, out of 24 observations, the BOD remained in the range of 6-7 mg/l. These three occasions out of 24 may be regarded as incidental and hence three out of four observations could be well managed,� sources said.
In the river Desang at Gudamghat, the BOD value exceeded 3 mg/l on four occasions when it remained in the range 3.1 � 5.0 mg/l. �This is well within manageable limits,� sources said.
At Kherghat also, the water of the Brahmaputra exceeded the BOD value on only one occasion, which was recorded at 4.2 mg/l. On other occasions, it mostly remained within 3.5 mg/l of BOD.
�All these three monitoring stations under NWMP could be recorded as non-polluting where the BOD value exceeded marginally on a few occasions out of 24 observations during the period 2008-2013. These excess can be regarded as incidental and do not indicate regular pollution,� sources said.
As per CPCB record, 24 river stretches fall under Priority-V, where the BOD value lies between 3-6 mg/l. The average BOD values at Maijan (i.e. upstream of Brahmaputra) out of 72 observations and at Dhubri (i.e., downstream of Brahmaputra) out of 24 observations under NWMP are 2.0 mg/l and 1.7 mg/l respectively.
�On the basis of the above observations, it may be concluded that the excess of BOD values (>3 mg/l) is occasional only, not on continuous basis,� sources said.
Sources said that PCBA had already directed all the local bodies for compliance of the Municipal Solid Wastes (Management and Handling) Rules 2000 to safeguard the environment from pollution.