The Basque Government has named the company Verter Recycling 2002 SM as the principal responsible for the environmental damage caused by the Zaldibar landfill. The Basque Government issued a statement on 20 January in which it stated that the company Verter, as manager of the plant, was responsible for damage to surface and underground water. The Basque Government has given the company a period of ten days to submit its "environmental damage repair" project.

The Basque Government, in cooperation with the Basque Water Agency, has confirmed the existence of "serious signs". With regard to groundwater, and as explained in the note, "some analytical results exceeding standards and threshold values" have been determined. Surface water, for its part, has been affected by landfill activities in an area of "at least" 300 metres in length. In addition, "concentrations of benzopyrene and fluoranthene have been recorded in the Aixola canal, which exceed the limits established by the current regulations".

In addition, hazardous waste has been detected in impermeable soils, which, as the Basque Government has pointed out, prevent the quality of the soil and do not allow any use of it. Economic Development, Sustainability and Environment Counselor Arantxa Tapia has reported that an asbestos-containing cell was "broken", so this toxic material spread to all areas of the landfill contaminating the entire land.