Urban sewage, hospital waste, and pesticide residues are polluting kole lands, the ecologically fragile wetland ecosystems in Malappuram and Thrissur noted for the integrated farming of rice and fish.

An expert committee appointed by the State government has found that sewage pollution from urban areas was being directly discharged into the main canals in the kole lands. This, it observed, often led to mass mortality of fish. Organic waste from urban areas, hospital waste, and pesticide residue from paddy fields were identified as other sources of pollution.