As per CPCB report, 46 percent of the 603 Indian rivers are polluted based on indicator of organic pollution i.e. Biochemical Oxygen Demand (BOD) (3mg/L) with the discharge of untreated industrial affluents as one of the major reasons.

Industrial pollution of river water is a significant environmental issue:

1. Impact river water quality:  According to the CPCB, the Ganges and Yamuna often exceed permissible limits for pollutants such as biological oxygen demand (BOD), fecal coliform, heavy metals, and other toxic substances.
2.  Impact on Aquatic Life:  High levels of toxicity in the Ganges has severely affected the population of the endangered Ganges river dolphin.
3.  Public Health Concerns: According to the World Bank, water pollution is responsible for around 1.5 million deaths annually in India due to preventable waterborne diseases.
4.  Socioeconomic Impacts: Irrigation with contaminated water affects crop quality and yields, Declining fish populations, and diminishing the aesthetic and cultural value of rivers that are vital to India’s heritage.

Mitigation Measures to deal with this problem:

1. Stringent Enforcement of Environmental Regulations: E.g. the Water (Prevention and Control of Pollution) Act, 1974, and the Environment Protection Act, 1986, which set standards for effluent discharge from industries.
2. Effluent Treatment Plants (ETPs) and Common Effluent Treatment Plants (CETPs): Mandating industries to set up on-site ETPs to treat wastewater before discharge into rivers. 
3. Zero Liquid Discharge (ZLD) Policy: Encouraging industries to adopt ZLD technologies, which ensure that all wastewater is treated and recycled within the plant.
4. Green Chemistry and Cleaner Production Techniques: This includes using environmentally friendly raw materials and energy-efficient processes to minimize the generation of pollutants at the source.
5. Riverbank Buffer Zones and Monitoring: Establishing buffer zones around rivers where industrial activities are restricted and setting up real-time water quality monitoring systems

Government Initiatives in this regard:

1. Namami Gange Programme: Over 150 sewage treatment plants (STPs) have been sanctioned under this program to improve the water quality of the Ganga.
2. National Water Mission: Under the National Action Plan on Climate Change, it focuses on water conservation, pollution reduction, and promoting efficient water use in industries.
3. National Green Tribunal (NGT): The NGT has mandated the closure of 123 industries for non-compliance with pollution standards in various river basins.
4. Pollution Control Boards (CPCB & SPCBs): Central and state pollution control boards regulate industrial discharges and set water quality standards. Regular inspections and pollution audits are conducted to ensure compliance.
5. River Rejuvenation Programs: The Narmada Seva Mission launched by the Madhya Pradesh government focuses on afforestation and pollution control to restore the Narmada River’s health.

Therefore, stronger enforcement and technological upgrades such as Denmark’s wastewater treatment model, can aid in mitigating the river pollution sustainably.