On 2 August, a citizen detected and documented by photographs that the water of the Arkaitzerreka stream was not clean when leaving under the incinerator. It seems that this is a structural problem for the incinerator, since some discharges have also occurred through this channel. GuraSOS has denounced that there has been "another serious spillage" from the incinerator of Zubieta to Arkaitzerreka and that it has contaminated "the Oria and its surroundings". Even though the photos are on Friday, you can't tell when the spill started.

GHK has denied what GuraSOS has denounced and called the position of the Abertzale left as "hoax". "The extraction of reddish iron fines is a natural phenomenon that occurs every year, during the months of heat and water scarcity," GHK reasoned, according to Naiz. According to ARGIA, the members of the URA agency went to Arkaitzerreka, and GHK indicated that, following the verifications carried out by URA, the situation of the river was a consequence of the said natural phenomenon.

Discharges and pollution of the incinerator have long been reported. On the occasion of the pollution caused by the incinerator of Zubieta in May 2020, the GuraSOS Association disseminated a number of information on the report prepared by the Civil Guard. GuraSOS stated that the report concludes that pollution caused the deaths of hundreds of fish and fifteen sheep, that a laboratory found that an eel had a high rate of chloroalkane – according to Guardia Civil experts, “a banned and highly carcinogenic component”, with incineration origin – and that since November 2019 the illegal operation of the incinerator was verified, without continuous measurements. The association complained that the incinerator poses "a real and serious risk to health and the environment", that "economic interests prevail" and that "the incinerator pollutes".

In 2022, in another spill in the Arkaitzerreka stream, ARGIA collected several images and videos. On 13 July, a citizen noticed that the pipe coming from below the Zubieta incinerator was polluting the Arkaitz River. ARGIA collected that the river carried clean water when it reached the incinerator, below which it was dirty. The City Council of Usurbil and EAM reported on the results of the contaminated water tests received in Arkaitzerreka and sent to the laboratory, and noted that the contamination found in that year was higher than that detected in May 2020. “Then there were hundreds of fish and eels. On this occasion, no such photos have been seen, probably because the river has been “burned” since then” without fish,” they pointed out in reference to the contamination of 2020. In the 2022 analyses, abnormal levels were found in chlorides, ammonium, conductivity, and COD (Chemical Oxygen Demand) in the analyses.

In November, the Environment Minister of the Basque Government, Arantxa Tapia, acknowledged that the Zubieta incinerator did not comply with the pollution regulations of the Basque Government and in December imposed a fine of EUR 160,000 on GHK for failing to comply with the orders of the administration to channel the landfill detected in Arkaitzerreka.

Disagreement before incinerator construction

Prior to the construction of the incinerator in 2016, a group of parents organised the Gelditu Incinerator initiative, and the signature was collected to paralyse the incinerator project. “We never want and will never accept, we will fight until we leave the skin, because the health of our sons and daughters is in danger,” said the members of the initiative. They denounced that it was "potentially serious" for those living in an area of less than ten kilometers, and that they wanted to build the plant in a hurry, without informing or consulting about the risks.