The Centre for Biodiversity and Ecology Research was requested by Environment Bay of Plenty (EBoP) to present model results that demonstrate the water flow implications of four different water level operational regimes in Lake Rotoiti. The aim was to quantify the proportion of nutrient-enriched Lake Rotorua water being transported from Ohau Channel around the diversion wall and into Lake Rotoiti. Environment Bay of Plenty did not wish to compromise the effectiveness with which the wall diverted this nutrient-enriched water from Rotorua directly to the Kaituna River.