During the 1970s Lake Rotorua was becoming eutrophic under heavy nutrient loadings, leading the Ministry of Works to propose diverting some sewage flow into the Kaituna River.
In 1990 however, the Rotorua Land Treatment Scheme saw an upgrade to treatment facilities to remove 80% of nitrogen and phosphorus from the effluent,[REF] and land application to reduce eutrophication and satisfy Māori cultural wishes.