Lake Okaro is located south of Rotorua near the Waiotapu Geothermal area and is accessed off Okaro Road. Lake Okaro/Ngakaro is the smallest of the Rotorua lakes under public management. and is appreciated for its quiet rural setting, it is surrounded by farms and is also a popular water-skiing spot. The lake has a total area of 31 Ha and the total catchment area is 367 Ha. The lake has an average depth of 12.5 m and at its deepest point is 18 metres.
The meaning and origin of the name has been lost over time, but Lake Okaro is considered to be of significant taonga to Ngati Whaoa / Ngati Tahu.
Lake Okaro occupies a small basin surrounded by volcanic materials formed by explosive activity, and is in an area buried by up to 1 metre of Rotomahana Mud during the AD1886 eruption. The lake was formed around approximately 700 years ago, simultaneous with a late stage of the Kaharoa eruptive phase at Tarawera. The lake has had a significant algae problem due to the levels of nitrogen and phosphorus nutrients which have increased over several decades. The nutrient-rich deposits over the catchment from the 1886 Tarawera eruption also have an ongoing effect on the lake's water quality.
Water quality in Lake Okaro has fluctuated over the last 10 years. Historically the lake has suffered from regular seasonal algal blooms. Over the 2014 and 2015 years the lake has complied with its TLI target of 5.0. This has been largely as a result of actions to reduce nutrients coming from the mainly agricultural catchment and targeted alum dosing to lock up phosphorus in the sediments. All actions in the action plan have been completed.