The board of inquiry into the Ruataniwha dam enters its second week on Monday and will focus on how much damage the intensification of farming resulting from the dam will do to rivers.
Hawke's Bay Regional Council, which is developing the $600 million water storage project, is at loggerheads with environmental groups and Maori over the impact the dam will have on the environment.
Environmental groups are worried the increased level of nitrates from intensive dairying could kill off native fish life in the rivers and pollute drinking water supplies.
Council experts have argued a computer modelling shows nitrates do not need to be managed, and it is phosphorous that should be controlled. They will continue giving evidence to that effect.