The sampling was carried out jointly collected by the Maharashtra Pollution Control Board (MPCB) and non government organisation Vanashakti two weeks back, where on four days, water and effluent samples from various outlets near Phase-I and Phase-II of MIDC were collected to check the levels of oxygen and alkalinity. The Central Pollution Control Board (CPCB) directed the MPCB to conduct a joint analysis based on independent tests by the NGO which showed oxygen levels had depleted in the Ulhas creek and alkalinity was high. Effluents from Dombivli MIDC flow into the Ulhas river which in turn enters Thane creek.
The latest results show that the highest bio-chemical oxygen demand (BOD) level for the samples from Phase-I was more than 840 milligrams/litre, while the average of samples taken at Phase-I was 560 mg/l. Per CPCB standards, 100mg/l is the standard limit and BOD above 500mg/l is “highly above prescribed limit”. BOD measures the deficiency of oxygen in water. Depleting oxygen levels cripple survival of aquatic life forms.
The chemical oxygen demand (COD) levels were as high as 3,000 mg/l, while the standard limit is 250mg/l. While high alkalinity levels — highest pH of 14 — were found near Phase-I, the average pH was around 10. The standard alkalinity level should be between 5.5 and 9.
Residents living around MIDC Phase-I and Phase-II said that the test results aren’t a surprise because of the stench from the 450-odd industries, many of which manufacture chemicals. “Recently, we filed a police complaint because complaints of a stench were coming in from as far as Dombivali station area. Respiratory disorders and sore eyes are common because the MIDC’s drainage has leakages that spill effluents into the city’s drains, eventually mixing with Ulhas creek,” said Raju Nalawde, secretary, MIDC residents’ apex body.