The vigorous exploitation of groundwater has severely impacted its levels and quality in Maharashtra, with nearly 20 districts showing presence of heavy metals in excess of the maximum acceptable concentration. The intake of such metals can cause serious damage to health. The Central Ground Water Board (CGWB) carries out groundwater monitoring four times a year on a regional scale through a network of observation wells in the country.
Comparison and analysis of pre-monsoon water levels in 2017, collected by the CGWB, with the average water level seen in the decade between 2007 and 2016, indicates a decline in about 57 per cent of observation wells in the state. While the decline is less than the national average of 60.7 per cent, experts say it is still a matter of concern.
A total of 1,487 such wells were selected in Maharashtra for observation. Of these, 667 – 43 per cent – showed a rise in water levels, but 887 – 57 per cent – showed a decline. Eight monitored wells showed no change.
What is more worrisome is that nearly 20 districts in Maharashtra recorded groundwater contamination by different chemical constituents.
The levels of heavy metals, including lead, cadmium and chromium, were found to be exceeding the maximum acceptable concentration.
The districts with a higher-than-permissible concentration of these metals in water include Ahmednagar, Akola, Aurangabad, Beed, Buldhana, Dhule, Gadchiroli, Jalna, Kolhapur, Latur, Nagpur, Nanded, Osmanabad, Parbhani, Pune, Sangli, Wardha, Washim and Yavatmal.
The deterioration in groundwater quality is mainly blamed on geogenic reasons, because of the inherent characteristics of aquifers or man-made reasons such as domestic and industrial effluents or excessive use of fertilisers.
Maharashtra’s rivers and canals have a total length of 16,000 kilometres. Its water bodies are spread over 3.83 lakh hectares. There has also been severe over-extraction of groundwater in the state. The fourth Minor Irrigation Census conducted in 2006-07 shows that there were over 21.5 lakh wells and borewells across Maharashtra. The number of such wells recorded in the first census was 5 lakh, suggesting a four-fold increase in a period of less than 30 years.
To tide over this problem, new rules were formulated under the Maharashtra Groundwater (Development and Management) Act 2009. The law has stringent provisions to check unregulated extraction of groundwater from areas where there is severe water scarcity. Officials claim that under the aegis of the central government, there is a plan to build 1.11 rain water-harvesting and artificial recharge structures in the country at an estimated cost of Rs 79,178 crore to harness 85 BCM (Billion Cubic Metres) of water.