Research study flags pollution hotspots along Indrani River in Udupi

Research study flags pollution hotspots along Indrani River in Udupi 

Prakash Samaga 

Coastal Talk News | Manipal 

A research published by Springer Nature has flagged serious pollution and flood-related concerns along Indrani River, which flows through Udupi city, warning that unchecked sewage discharge, waste dumping and altered river flow are degrading one of the region’s water bodies. The study, conducted by researchers from Manipal Institute of Technology (MIT), Manipal and published in Scientific Reports journal, examined water quality at 15 locations along the 14 km river stretch from Manipal Lake to Malpe. 

According to the findings of the study, dissolved oxygen (DO) levels- a critical indicator of river health-fell below safe limits at nearly 40 percent of the river stretch. According to Water Quality (WQ) standards, the permissible threshold for DO is 5 mg/L or higher. The most alarming DO level reading was recorded near Kodavoor at 0.16 mg/L, where stagnant water and untreated sewage discharge were observed. Similarly, at Matadabettu area the second-lowest DO value (0.89 mg/L), was attributed to the discharge of inadequately treated effluent from a nearby sewage treatment plant. 

Researchers also noted rising electrical conductivity (EC) and salinity levels downstream, pointing to sewage inflow, accumulation of inorganic waste and seawater intrusion near the river mouth. EC is measured in microSiemens per centimetre (µS/cm) which should be below 800 µS/cm. The study observed the pH level and salinity value is within the threshold limits, while total dissolved solids (TDS) was also within the threshold limit along the river path, but in Malpe it was 17,290 mg/L (acceptable TDS threshold -500 mg/L). 

While most upstream locations of the Indrani River path met drinking water standards, several downstream points were classified as moderate to high-risk pollution zones. The study showed that pollution intensifies after the river enters densely populated urban stretches, where residential wastewater, plastic waste and runoff from roads flow directly into the river. Encroachments along the riverbanks are also found to obstruct natural water flow, worsening both pollution and flooding during monsoon. This writer in the past had written ground level reports on the pollution caused to Indrani River and the flash floods during the monsoon. This research now holds the mirror to the burgeoning issue of contamination of Indrani River.