Contact on Monday announced a major new initiative to improve the quality of the water discharged into the river following submissions from river users and communities on Contact's application to renew Wairakei resource consents.

Company chief executive Steve Barrett said that as well as substantially removing hydrogen sulphide from the plant's cooling water discharge, Contact was now proposing to remove or reduce other trace elements, including arsenic, found in small quantities in the separated geothermal bore water.

"We will be reducing Contact's discharges to the maximum extent practicable and will consider the feasibility of various options including treatment or reinjection techniques.

"We will be exploring the best options to reduce discharges over the next few months, with the most likely options being water treatment and further outfield re-injection, where water is returned underground but away from the geothermal field.

This initiative was expected to take several years to fully implement and would require the construction of new treatment facilities, Barrett added.