The Poutō peninsula includes nearly 50 dune lakes of a hectare or more in size, and is the focus of Northland Regional Council's efforts to better manage fresh water in Northland.
The regional council has worked with science providers to improve our understanding of the quality and management of lakes, rivers, aquifers and wetlands in the region. Although monitoring records are available continuously back to 2005 from which to look for changes in lake quality and better understand why changes have occurred, this is a comparatively short period of time relative to Poutō dune lakes that can data back over 50,000 years and have experienced marked change in catchment land use over the past century.
DairyNZ and the University of Auckland reconstructed the past water quality of three Pouto lakes (Humuhumu, Rotokawau, and Rototuna) over their record of extensive land use (100-200 years). They found that changes to erosion preceded changes to lake level and water column mixing, as well as later changes to nutrient availability. From this, we have been able to inform our knowledge that lake level and clarity appear to be critical constraints on aquatic macrophytes, key to healthy dune lakes, with reductions in water quality occurring as far back as 1930 with greater algal growth since in two of the three lakes tested. The report is also available as a Masters thesis from the University of Auckland (Rip, 2016 – School of Environment).