The Northland Regional Council engaged NIWA to update the Wells and Champion 2011 Northland Lakes Status report by providing the following assessments of lakes and water bodies:
Endangered species identification, wetland extent and species composition, submerged vegetation abundance and composition including LakeSPI assessment, water bird, fish and aquatic invertebrate presence and abundance, and processing findings to assign a Lake Biodiversity Assessment ranking.
Lake Kaiwai and Lake Omapere
Lake Humuhumu; Lake Kahuparere; Lake Karaka; Lake Mokeno; Lake Rotokawau; Lake Roto-otuauru / Swan; Lake Rotopouua; Lake Rototuna; Lake Whakaneke
Grass carp assessment - Lake Heather and Lake Roto-otuauru / Swan.
Weed surveillance - Lake Humuhumu, Lake Kai-iwi, Lake Ngatu, Lake Taharoa, Lake Waikere, and Lake Waiporohita.
Lake Kaiwai - ecological assessment was carried out for the first time.
Lake Omapere - margins have been found to support populations of two nationally critical plants.
Lake Humuhumu - remains ranked an “Outstanding” lake.
Lake Kahuparere - is ranked as a “High” value lake.
Lake Karaka - is a “High” ranked lake with an indigenous vegetation and fauna and much of the margin surrounded by wetland including nationally endangered plants, fish and birds.
Lake Mokeno - remains ranked as an “Outstanding” lake.
Lake Rotokawau - is a “High” ranked lake.
Lake Roto-otuauru / Swan - has a “Moderate” ranking.
Lake Rotopouua - is an “Outstanding” ranked lake.
Lake Rototuna - is a “High” ranked lake with retired margins.
Lake Whakaneke - is a “Moderate” ranked lake, near Lake Mokeno.
No new weed incursions were found in the six high-risk lakes monitored.
Grass carp results
Lake Heather - After 2 years of grass carp in the Lake Heather the egeria (Egeria densa) has nearly all gone and about 50% of the hornwort (Ceratophyllum demersum) has been removed.
Lake Roto-otuauru / Swan - Progress with hornwort and egeria eradication has been rapid with no traces of these weeds found (after 3 years of grass carp).