Local activists say phosphates from industrial scale poultry farming upriver in Powys and Herefordshire are killing the river’s eco-system.
And by buying and selling “cheap chicken”, the retail giant is contributing to the problem, they claim.
The march came as the plight of the Wye was highlighted on a BBC2 documentary series Our Troubled Rivers presented by Paul Whitehouse, which aired last Sunday night and is available on iPlayer.
And BBC1’s Countryfile also examined the issue on Sunday night (March 19), when Matt Baker and Anita Rani met the volunteers going to the Wye’s rescue, from the cider maker-turned citizen science champion to the volunteers creating a 30-acre wetland to harbour wildlife.
Protestors who took to the streets of Chepstow armed with placards saying ‘Tesco! Stop killing the Wye’ and ‘Wye, oh Wye Tesco?’ included members of Save the Wye Coalition, Extinction Rebellion Forest of Dean, Foresters against Fowling and Friends of the Lower Wye.
The Forest XR Rhythms Samba band also played, while the march was led by ‘the Lady of the Wye’ and an activist dressed as a chicken .
SWC’s Rachel Bomford said: “The systemic pollution of the Wye has many sources but the prime driver is manure spreading from intensively reared livestock, in particular intensive poultry units in the Upper Wye catchment.
“We are asking Tesco to live up to their environmental promises and to stop selling food which is killing the River Wye.”
That was backed by Forest of Dean and Gloucestershire Green councillor Chris Mcfarling, who added: “Unfortunately, it is a stark choice between cheap chicken or losing the River Wye.”
Campaigners claim that unless large commercial firms like Tesco and Hereford-based poultry supplier Avara change their ways now, there will be a “complete ecological disaster”.
Marchers handed out leaflets urging people to avoid buying produce which contributes to the problem of Wye pollution, with a reported 20 million birds farmed and reared in the river’s catchment area.
A spokesperson for Tesco said: “Protecting and maintaining water quality and biodiversity in our supply chains is an important priority within our supplier partnerships, and we’re committed to playing our part in ensuring the protection of the River Wye, alongside other actors across the food industry.
"We continue to engage with suppliers and stakeholders across all agricultural sectors in the region as part of the Wye Agri-Food Partnership and have encouraged all of our suppliers to sign up to the Water Roadmap as part of the Courtauld Commitment 2030, which looks to reduce water pollution in key sourcing regions, including the Wye & Usk catchment.
“In partnership with WWF, we have funded some of the work of the Wye & Usk Foundation to tackle water pollution in the area.
"They work directly with a number of our suppliers on implementing nature-based solutions, including tree planting, as well as supporting farmers to test soils and implement on-farm best practice that all help reduce pollution in the River Wye.”