A recent study by a city-based private ecological research organisation, Shrishti Eco-Research Institute (SERI), shows that Mutha, Ramnadi and Pavana rivers have turned into gutters. The Mula is on its way to degradation, while the Indrayani is comparatively clean. However, the dissolved oxygen (DO) levels are fast depleting in all rivers.
SERI experts have also pointed out that the Pune Municipal Corporation’s (PMC) sewage treatment plants (STP) have been unable to arrest this damage to the city’s water bodies.
This study, comparing the toxicity of all the rivers in the Pune Metropolitan region, was conducted under the River Health Analysis programme. Students from classes V, VI and VII of city schools assisted the researchers in collecting river water samples from four spots as part of their class project. These showed DO levels of less than 1PPM in city limits.
For the Mutha, only the sample taken from Vitthalwadi showed DO at 1 PPM. Those from Mhatre Bridge, Bhide Bridge and Sangamwadi did not show any presence of oxygen. Turbidity of the Mutha was 70 JTU (Jackson Turbidity Unit) at Vitthalwadi, and at the other three spots, it crossed 100 JTU.
The samples of Ramnadi were collected at Bangalore bypass culvert, behind Ramnagar Colony, at Pashan lake and Baner. No trace of DO was found at the first two spots. DO shot up to 9 PPM at Pashan lake and went down to 1.3 PPM at Baner due to polluted water and plastic waste mixing into the river from Pashan and Baner.
The DO level in Pashan lake was high because of the quantity of water in the lake. For the Pavana, DO was at 6.5 PPM near Punavale Bridge, but it dipped to 3.9 PPM at Morya Gosavi temple in Chinchwad. Near the Mahalakshmi temple, the sample had no DO, but it rose to 0.8 PPM at Sangavi crematorium.
The Mula recorded DO level of 3.8 PPM at Aundh, which plunged to zero near Harris bridge. The river breathes again near CME, BEG and other military establishments, which are sparsely populated and the DO increases to 1.8 PM near Holkar Bridge. Finally, near Westin Hotel, due to Bhairoba Nala discharge, the DO turns nil again.
The Indrayani, which flows along pilgrimage spots of Dehu and Alandi fares a little better. Its DO count is 8.4 PPM near Indori Bridge in Maval taluka and continues to be the same at Dehu. However, it reduces to 4.2 PPM at Moshi and dips to 1.8 PPM at Alandi. Plastic waste was spotted floating in the river at this point. The Indrayani’s water near Moshi stinks a lot, due to discharge from Chikhali nullah and other city drainage.
Near Alandi, the river has become very dirty. Vinod Bodhankar of SERI said, “When the DO level dips below 4 PPM, the water body starts dying. The chemicals mixed in the water start killing organisms in water. When the DO level reaches ‘0’, the water body is declared dead.
This is what is happening with the rivers in our city.” The researchers observed that rivers continue to be in a dismal condition despite the PMC having installed 10 sewage treatment plants across the city. This means that the PMC is treating sewage water, but not implementing any changes in the city.
If PMC treats water and releases it for irrigation to villages downstream, it could lift more water from reservoirs. Currently, it is not getting additional water from the reservoirs. The city generates about 9.5 TMC sewage every year and the irrigation department has asked it to treat and release 6.5 TMC for irrigation.
For the last 50 years, PMC has been getting water from the state irrigation department on the condition that it will treat 6.5 TMC water annually for agricultural use.
Due to PMC’s failure to do so, it has been asked to pay Rs 6 crore as compensation. Sandeep Joshi, director, SERI, said, “PMC has installed heavy machinery for treating water, but that does not seem to be happening.
Also, purified water and pollutants are both released in the rivers at the same time. The current system of purification is not effective as the water treated here cannot be used for irrigation due to its high chlorine content.
Also, earlier research had found that water directly lifted from Mutha and sent to Purandar for irrigation created health problems for people consuming the produce grown there.”
►►► When the DO level reaches ‘0’, the water body is declared dead
- Vinod Bodhankar, SERI