NMCG rolls out framework to monitor plastic pollution in rivers

India generates approximately 4.13 million tonnes of plastic waste annually, according to the Central Pollution Control Board (CPCB)'s Annual Report. Pic: iStock

The National Mission for Clean Ganga (NMCG) has prepared a protocol for monitoring plastic pollution, specifically macroplastics that are visible to the naked eye, in rivers, with the framework seeking to generate comparable data, identify pollution hotspots and support targeted interventions.

During major religious, cultural and mass gatherings such as the Kumbh Mela, Chhath Puja, Durga Puja and Kanwar Yatra, special monitoring will be undertaken to assess additional plastic loads entering or accumulating in rivers. The data generated during these events will be recorded and analysed separately from routine monitoring.

The protocol is significant as the government has separate frameworks for monitoring water quality, hydrology, sediment, fisheries and biodiversity, but the document says there has been "no prominent framework" for assessment of riverine plastic pollution.

The absence of a unified methodology for sampling, analysis and reporting has resulted in fragmented and non-comparable data across agencies.

India generates approximately 4.13 million tonnes of plastic waste annually, according to the Central Pollution Control Board (CPCB)'s Annual Report on Implementation of Plastic Waste Management Rules, 2016 for 2020-21.

A significant proportion remains uncollected or improperly managed, contributing to leakage into river systems.

The protocol has specifically chosen macroplastics -- plastic debris larger than 25 mm -- for initial monitoring because they are visible to the naked eye and can be reliably collected and assessed through field-based methods.

Macroplastics are also the most visible and manageable form of riverine plastic pollution and are generally associated with identifiable sources such as packaging, carry bags and fishing gear.

The protocol has prescribed three complementary monitoring methods -- collection through fishing operations by local communities, monitoring at artificial barriers such as barrages and trash interception structures, and scientific net-towing surveys by boats.

The Protocol for Riverine Macroplastics Monitoring was released by Union Jal Shakti Minister C R Patil during the valedictory ceremony of the India International Water Week at Bharat Mandapam here on September 25.

Prepared under the aegis of NMCG through a multidisciplinary Plastic Pollution Task Force, the protocol has received technical inputs from the CPCB, Central Water Commission (CWC), National River Conservation Directorate, State Missions for Clean Ganga and academic and research institutions.

In his message accompanying the protocol, Patil had said plastic debris entering rivers from cities, industries, fisheries and mass gatherings had remained a largely unaddressed dimension of river pollution in a standardised manner.

While the protocol focuses on macroplastics, smaller plastic particles are not excluded from the broader pollution problem.

The document notes that riverine plastic occurs in different sizes, forms and polymer compositions, but field-level identification of different polymer and packaging types can pose practical difficulties.

It therefore adopts a simplified system that can be consistently implemented by field staff, fishermen and community participants.

The monitoring framework presently focuses on macroplastics at the water surface, with provisions to progressively expand assessment to the water column, sediments and biota.

The fishing-based method uses routine fishing operations to collect visible plastic trapped in nets and provides continuous, community-based information.

The artificial barrier method measures plastic accumulating at fixed locations such as barrages, bridges and trash interception structures, while boat-based net towing provides standardised estimates of floating plastic abundance and transport.

The protocol prescribes five categories for collected macroplastics -- bottles and containers; bags, wrappers and packaging; fishing and utility plastics; thermocol products; and other plastics and composite items.

The material will be segregated, weighed and recorded, including the number of filled fixed-volume bags.

Fishing-based and artificial barrier monitoring will be conducted monthly, according to the protocol.

Boat-based sampling will initially be undertaken monthly for six months to establish baseline data and may subsequently be revised to quarterly to capture seasonal variations, including pre- and post-monsoon conditions.

Major drain outfalls discharging into rivers may also be monitored, preferably daily, by urban local bodies or designated agencies using suitable collection nets or screens.

The collected material will be segregated and weighed, with the data integrated into the basin-wide monitoring system to identify plastic leakage hotspots and prioritise source-control measures.

The protocol also specifies that collected plastic will be sent to authorised facilities for recycling, co-processing or environmentally sound disposal.

Non-plastic material will be disposed of as per applicable waste-management rules and excluded from the dataset.

For the Ganga, the protocol uses existing CPCB monitoring stations, major barrages, trash skimmers, interception structures and fish landing and fishing locations.

The initial network can be reviewed, expanded or refined based on monitoring results, site suitability and identified gaps.

NMCG will coordinate the programme and manage the centralised data system, while CPCB will provide technical guidance and State Pollution Control Boards or NMCG-nominated agencies will undertake periodic monitoring.