Our last post elicited a response from Genesis Energy. This clarified the situation
1) The price rise was in Waitemata only (West and North Auckland).
2) The particularly low night rate (that affected 850 people) was actually a rate that should not have existed. It appears we were wrong in suggesting it was the rate of a neighboring lines company.
Also they made a mention that no fish would have floated to the top of the Waikato river. They said they employ a person full time to ensure that the temperature of the river doesn't reach over 25 degrees.
They actually adjust production of electricity on a half hour basis depending on what the projected temperature of the river is likely to be.
So apparently there are controls in place to prevent fish from dying, and we must have misunderstood our information. Perhaps our source of information meant that if the turbines weren't taken off line the fish would have floated to the top of the river.