MEXICO CITY (Reuters) - Mexico's environmental prosecutor said it had kept regular oversight of the country's largest gold mine, days after a Reuters report on a prolonged leak of contaminated water there prompted activists to accuse the agency of failing its mandate.
Environmental prosecutor Profepa said that since 2013 it had completed five "administrative proceedings" on the Penasquito mine in Zacatecas state, which is owned by Canada's Goldcorp Inc.
It did not say whether the proceedings were related to the leak.
Reuters reported on Wednesday that levels of the potentially toxic mineral selenium rose in groundwater in a monitoring well on the mine property in October 2013. Goldcorp reported the rise to authorities a year later.
After the report, anti-mine activists in Zacatecas accused Profepa and other Mexican environmental agencies of bias toward the miner.
Profepa said in a statement released on Saturday that the company told it in October 2014 about a rise in selenium and sulphates in two wells. The agency said the incident did not pose a risk to the environment.
It said selenium levels had been stable since September 2015 "at the original level" of 0.01 mg per liter, the maximum allowed in Mexico.
Data Goldcorp showed to Profepa in a presentation this month and seen by Reuters shows that before the incident, selenium levels were actually at 0.005 mg per liter. Profepa did not respond to a request for comment on the discrepancy.
High concentrations of selenium in water can damage human health and cause deformities in wildlife.
Profepa also said trenches were being built at the site because of possible leaks to the south of the dam in which waste from the mine is stored.
A village called Las Mesas, home to about 90 families, is just south of the dam.
The Goldcorp presentation to Profepa this month, which was dated March, confirmed there was indeed leakage on the southern side of the waste facility. Both Goldcorp and Profepa say the leak was controlled before it went beyond the limits of the mine property.
(Reporting by Noe Torres and Frank Jack Daniel; Writing by Christine Murray; Editing by Bill Trott)