Lake Level Graphs
The hydro lakes - Aratiatia, Ohakuri, Atiamuri, Whakamaru, Maraetai, Waipapa, Arapuni and Karapiro - that formed behind the dams have, over the years, become part of the natural environment of the Waikato River, supporting a wide variety of flora and fauna and providing a broad range of opportunities for community recreational uses.
The main source of water for the Waikato River and the hydro lakes is Lake Taupo. Water flowing out of the lake takes some 18 hours to arrive at Karapiro, the last station on the Waikato hydro system.
Because each of the hydro lakes has only a limited capacity to store water the Waikato Hydro system is reliant on regular inflows into Lake Taupo, which holds up to 93% of all water stored in the system. The lake is operated within a range of 1.4m, (equivalent to just one percent of the total volume of the lake), to closely mimic natural fluctuations in the lake level.
Like all lakes, Taupo experiences water level fluctuations, which reflect the hydrological conditions in the catchment. Periods of sustained low inflows into the lake can affect storage levels, particularly if this occurs when demand for electricity is high. The level of the lake is also affected by the regulatory requirement to maintain set flow volumes down the Waikato River, irrespective of rainfall in Lake Taupo's catchment.
The Waikato hydro lakes also experience fluctuating water levels as a response to hydrological conditions. However, they are also affected by changes in patterns of supply and demand for electricity, how much water is stored in the lake and the efficient operation of power stations.
Daily fluctuations in the hydro lake levels are usually the result of changes in demand for electricity, which is generally greatest in the morning and evening when household electricity consumption is high.
Not all of the water in a hydro lake at any given point in time is available for generation. Hydro power stations operate most efficiently when they have a full "head" of water, as this produces the water pressure necessary to drive the turbines at optimum efficiency. Because of their limited storage the Waikato hydro power stations can only generate at full capacity for a short time before water levels must be replenished, resulting in daily level fluctuations.
Click on the individual lakes on the menu to find information on their location, history, levels and usage by Mighty River Power.