Manganese shoots up in Selaulim reservoir

Flows into reservoir from uncovered mining dumps 

Increase is five times higher than normal

Affects production of treated water

TEAM HERALD

teamherald@herald-goa.com

PANJIM: Even though this monsoon, Goa is yet to witness heavy rains, the uncovered mining dumps and lack of precautions have once again resulted in manganese content in the raw waters of Selaulim reservoir shooting up by almost 5 times. The result – overworked pumps, larger turnaround times, increased costs and finally restricted water supply to Salcete and Mormugao yet again. 

Following the last instance of rise in manganese content in July 2012, the government had directed the PWD and Forest department to clear all the dumps, but both departments failed to act, resulting in the present situation.

The manganese content in Selaulim water has risen beyond the permissible limit of 0.3 mg per litre touching 2.8 mg per litre. The reservoir normally produces 214 MLD of treated water.  

According to State government records, 13 mining leases are located within 500 mts radius from the Selaulim reservoir, of which three mining leases are located within 200 mtr radius.

Speaking to Herald, PWD Executive Engineer S R Paranjape, said that the manganese content has gone up from the normal 0.1 mg per litre to 2.8 mg per litre as a result of heavy rains that hit the State last week. 

“As a result, the rejects from dumps located in the surrounding areas are being washed into the reservoir,” he said adding that efforts are on to treat the water.

PWD has said that due to increase in manganese content in the raw water, production of treated water is affected. 

Paranjape said that chemicals such as lime and alum have been used to reduce the manganese content as per the recommendation by the National Environmental Engineering Research Institute (NEERI). 

This is the second incident in the last two years when the manganese content in the reservoir has gone up as a result of washing of dumps. In July 2012, the manganese content had gone up to 3 mg per litre. Earlier this year in April, the manganese content in the reservoir had gone up to 0.8 mg per litre due to decrease in water level during summer.  

“The manganese content in the Selaulim increases thrice every year. Once in the month of May when the water level decreases, another in July-August due to heavy rainfall which washes iron ore dumps stacked along the side of the rivers into the reservoir and in November-December when the canal is opened,” Paranjape explained.