In News:

The Central Ground Water Board (CGWB) report on groundwater quality reveals alarming levels of contamination in India's groundwater, with a focus on nitrate, fluoride, arsenic, and uranium. The report highlights the impact of agricultural practices, poor waste management, and urbanisation on water quality.

Key Highlights:

Nitrate Contamination:

• 440 districts in India report excessive nitrate levels in groundwater, with 20% of samples exceeding the permissible nitrate limit of 45 mg/L (WHO and BIS standards).
• High-risk regions: Rajasthan (49%), Karnataka (48%), and Tamil Nadu (37%) are the top states with high nitrate levels. Other affected states include Maharashtra, Telangana, Andhra Pradesh, and Madhya Pradesh.
• Causes: Nitrate contamination is mainly due to excessive use of nitrogen-based fertilizers, over-irrigation, and poor management of animal waste. Urbanisation and improper sewage systems exacerbate the problem.

Other Groundwater Contaminants:

• Fluoride contamination: A significant concern in Rajasthan, Haryana, Karnataka, Andhra Pradesh, and Telangana.
• Arsenic contamination: Elevated arsenic levels found in several states, especially in floodplains of the Ganga and Brahmaputra rivers (West Bengal, Jharkhand, Bihar, Uttar Pradesh, Assam, and Manipur).
• Uranium contamination: 42% of uranium-contaminated samples are from Rajasthan, and 30% from Punjab. Chronic exposure to uranium leads to kidney damage.

Groundwater Extraction and Availability:

• 60.4% of groundwater is being extracted across India.
• 73% of groundwater blocks are classified as in the ‘safe’ zone, an improvement from 67.4% in 2022.

Monsoon Impact:

• Nitrate contamination increases post-monsoon, with 32.66% of samples exceeding safe limits during the rainy season.

Health Implications:

• High nitrate levels, particularly dangerous for infants, can cause blue baby syndrome (methemoglobinemia).
• Long-term exposure to contaminants like fluoride and arsenic can lead to fluorosis and increase the risk of cancers and skin lesions.

Sources of Contamination:

• Agricultural practices: Excessive use of fertilizers, pesticides, and improper irrigation.
• Waste disposal: Leaking septic systems, sewage, and hazardous waste sites contribute to contamination.
• Urbanisation: Increased wastewater and sewage, along with poor waste management, worsen the issue.

Measures to Address Contamination:

• Jal Shakti Abhiyan (JSA) and Atal Bhujal Yojana (ABHY) aim to conserve and manage groundwater resources.
• National Aquifer Mapping and Management Program (NAQUIM) to assess and map aquifer systems.
• Pollution control programs: Under the Water (Prevention & Control) Act, 1974, and initiatives like sewage treatment plants and effluent treatment plants to manage wastewater.
• Public awareness: Campaigns like Swachh Bharat Mission and Catch the Rain educate communities on the importance of groundwater conservation.

Key Statistics:

• 56% of districts in India report groundwater nitrate levels exceeding the safe limit of 45 mg/L.
• Monsoon effects: Post-monsoon data shows a significant increase in contamination levels (32.66% vs. 30.77% pre-monsoon).