Lake Rotoma

Lake Rotoma

Lake Rotoma

Lake Rotoma means "lake of exceptionally clear water". The lake currently has the best water quality of all the Rotorua lakes.

Lake Rotoma is the cleanest of all the Rotorua lakes, with water clarity of around 11 metres. The clarity makes fly fishing more challenging. Four buoys near the centre of the lake mark a submerged Maori pa site.

At a glance  
Lake size: 1110 ha
Catchment area: 2810 ha
Elevation: 316 m
Average depth: 37 m
Deepest point: 83 m
Formed: 8500 years ago
Drains by subsurface outflow  







Water Quality Status

An Action Plan is being implemented with the key action of sewerage reticulation.  This sewerage reticulation is scheduled to be completed along with the remaining Lake Rotoiti reticulation in 2018-2019. However, there have been increasing phosphorous levels in the lake over recent years. The level of phosphorus that will be removed by reticulation is being evaluated and there is some science work required to determine whether some further marginal reduction in phosphorus will be required from land use.

Catchment Map

Click here to view image of map

Target and Results

To meet community expectations for Lake Rotoma nitrogen inputs need to reduce by a total of 1320 kg and phosphorus to reduce 250 kg per year.

Water Quality target


2017 result


2016 result








The 2015 TLI for Lake Rotomā was well above the target TLI due to a long hot summer. However, lake water quality needs to be considered by a rolling average rather than annually to get a true picture of water quality conditions. This is because annual readings can be influenced by one off climatic conditions. The 3 year rolling average TLI for Lake Rotomā is around is target of 2.3.


Nutrient information

  Nitrogen Phosphorus

Total load 

18 Tonnes

736 Kilograms 


16.7 Tonnes 

486 Kilograms


Action Plan

Lake Action Plans direct what steps need to be taken to improve lake water quality to meet communitys' expectations

Read Lake Rotoma Action Plan