NEW DELHI: The phased opening of the five sluice gates over the past week at the Okhla Barrage by the Uttar Pradesh irrigation department has sent more silt, sludge and froth cascading into the Yamuna at Kalindi Kunj. The silt and sludge have also created additional problems in the stretch immediately downstream of the barrage. Delhi Jal Board set up a temporary lab there to monitor the water.Taking one other measure beside the usual spraying of chemicals from boats to prevent foam forming, DJB has also installed green nylon nets at Kalindi Kunj to stop the foam from accumulating near the riverbank.
"Seven anti-frothing automatic sprinklers have been installed under the bridge over the river. These spray the de-frothing liquid to suppress the foam and we have achieved the target of producing a clean water surface," a DJB official claimed on Thursday. According to officials, additional silt from the barrage has not only increased the pollution levels exponentially but also made it difficult for boats to move around for sprinkling the anti-froth chemicals.
"Due to the additional silt and sludge, around 100 metres of the river downstream has become lifeless. There is no dissolved oxygen there and the water has high turbidity and high total suspended solids," the official said. Experts from DJB said that the sudden spike in pollution extended their responsibility to monitor the river's quality downstream of Okhla, and their task is not just limited to frothing, which they have controlled to some extent by spraying anti-surfactants, but also the pollution.
"At the makeshift lab, we are testing water sample three times a day for chlorides, dissolved oxygen, turbidity, total dissolved solids, conductivity, pH, ammoniacal nitrogen and algal analysis," said an official at the lab, which will remain till Chhath Puja. "Back in our main lab, we are testing for the remaining parameters, including biochemical oxygen demand, total suspended solids, chemical oxygen demand, phosphates, surfactant, oil and grease, heavy metals, and total organic carbons, etc."
Officials also pointed out that there was no water remaining upstream of the barrage. Due to the sludge flowing downstream into the main river course, the total suspended solids shot up to 2500 units on Wednesday against 32 units in September. "Upstream silt is settling downstream, even making boat operations to spray the defoamer difficult," said an official. "Since the silt was flushed out from beyond the barrage, the dissolved oxygen is nil for a 100m stretch. Around 250m from the barrage, the oxygen level is 0.5mg/l, improving to 1mg/l after 500m. When we started monitoring the water downstream of the barrage in Sept, the oxygen was 4mg/l, biochemical oxygen demand 9mg/l, chemical oxygen demand 36mg/l and dissolved solids, 32mg/l."
The UP irrigation department said that the sluice gates were opened to allow maintenance of the Agra Canal. "At this time of the year, the canal is closed. While most barrages divert water for drinking or irrigation, the Okhla Barrage feeds the Agra Canal," said an irrigation department official. "Between Dussehra and Diwali, we clear the silt from the canal and carry out repairs to ensure irrigation for the rest of the year. Since the canal is closed, the upstream water had to be released."
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