Rising Nitrate Levels in India’s Groundwater

Source: This post on Rising Nitrate Levels in India’s Groundwater has been created based on article “India, cross-border insolvency and legal reform ” published in The Hindu on 4^th January 2025.

UPSC Syllabus topic: GS-3- Conservation, Environmental Pollution and Degradation, Environmental Impact Assessment

Context: India’s groundwater quality is facing a significant threat, as highlighted by the latest annual assessment from the Central Ground Water Board (CGWB). The report indicates a worrying increase in districts affected by excessive nitrate contamination in groundwater, rising from 359 districts in 2017 to 440 in 2023. Rising Nitrate Levels in India’s Groundwater

What does the CGWB’s annual assessment reveal about nitrate levels in groundwater?

1. The Central Ground Water Board’s (CGWB) 2023 assessment shows that the number of districts with excessive nitrate in groundwater has risen from 359 in 2017 to 440 in 2023.
2. This means over half of India’s 779 districts now have nitrate levels exceeding the safe limit of 45 mg/L.

Why is excessive nitrate in groundwater a concern?

1. Health Impact:
   1. High nitrate levels can cause methemoglobinemia or ‘Blue Baby Syndrome’ in infants, which reduces red blood cells’ ability to carry oxygen.
2. Environmental Impact:
   1. Excess nitrates in surface water, such as lakes and ponds, contribute to algal blooms, which harm aquatic ecosystems.

What proportion of groundwater samples were found with excessive nitrate levels in 2023?

Out of 15,239 samples analyzed, 19.8% contained nitrates above the safe limit. This is a slight improvement from 2017 when 21.6% of 13,028 samples were unsafe.

Which states report the highest nitrate contamination?

1. Rajasthan (49%), Karnataka (48%), and Tamil Nadu (37%) showed the highest percentages of samples exceeding safe nitrate limits.
2. Rajasthan, Madhya Pradesh, and Gujarat face perennial nitrate issues due to geological factors, with relatively stable contamination levels since 2017.
3. Regions in central and southern India are witnessing a rise in nitrate levels, which is an emerging concern.

 What causes elevated nitrate levels in groundwater?

1. Intensive agriculture has been consistently linked to high nitrate concentrations.
2. Over-exploitation of groundwater exacerbates contamination, as evidenced in states with severely depleted groundwater blocks.

What other chemical contaminants affect groundwater quality?

1. Apart from nitrate, fluoride and uranium were identified as major concerns.
2. High fluoride levels are problematic in Rajasthan, Haryana, Karnataka, Andhra Pradesh, and Telangana.

 What is India’s current rate of groundwater extraction?

1. The degree of groundwater extraction stands at 4%, consistent with levels observed since 2009.
2. About 73% of the blocks analyzed are in the safe zone, meaning they are adequately replenished to offset water extraction.

What measures are in place to monitor groundwater health?

1. India now has a robust, scientific system for annual assessment of groundwater quality and levels, providing valuable insights for action.
2. Strong awareness programs and policy interventions, driven by leadership at the highest levels, are essential to contain the crisis.
3. States need to act on CGWB findings and implement measures to curb nitrate contamination and over-extraction.