Degradation Case

STATUS AND TRENDS OF WATER QUALITY IN RIVER AND LAKES

Only four major river basins out of 23 are perennial while the remaining may go dry

during summers leaving no water for dilution of waste water discharged in them. This problem

has been compounded by many water regulating structures. The water quality monitoring

programme of CPCB revealed that the organic (BOD) and bacterial contamination emanting

from urban areas are critical in these water bodies.

The monitoring results (1994-2004) revealed that BOD values were less than 3.0 mg/l

in 58-67% observations and between 3-6 mg/l in 19% and it exceeded 6.0 mg/l in 15%

observations. There is a gradual decrease in number of observations having BOD between 3-6

mg/l. The coliform and faecal coliform conformation of < 500 MPN was in 40-67%

observations where as it exceeded 5000 MPN in 9-35% cases.

The rivers in hilly regions of the country are not affected significantly by such

pollution. The rivers Narmada, Mahanadi, Brahmini, Baitarni, Subarnrekha, Beas and Chambal

maintained a DO level of 4.0 mg/l or above throughout the year. Ganga, Yamuna, Krishna,

Sabarmati, Tapi, Sutlaj however, go as low as 0.3 mg/l DO. The critical stretch of Ganga in

1994 was from Kannauj to Varanasi which has now being restricted to Kannauj to Allahabad

(2004) and while that of Yamuna, downstream of Delhi upto Udi.

The lake waters indicated that deterioration was not as much as in rivers but yet

significant in the lakes of Andhra Pradesh, Tamil Nadu, Gujrat, Madhya Pradesh, Himachal

Pradesh. The nitrates were high in lakes of Andhra Pradesh, Karnataka, Kerala indicating

eutrophic conditions.

The ground water quality also in many places exceeds limits of nitrates,