The Ngāti Kahu Rūnanga and Northland Regional Council say people washing cars and trucks at Lake Waiporohita is putting the ecological state of the far north lake at risk.
The dune lake is one of just 12 in Northland that has officially been classed as being in an “outstanding ecological state.”
The Rūnanga and Council are 2 of a number of partners working to protect Lake Waiporohita.
Ngati Kahu and its marae hold the 6.9 hectare lake in especially high regard and in September last year the regional council approved a $52,850 project via its Environment Fund project to improve water quality and ecology there, as well as in Lakes Rotokawau East and West on the north-western corner of the peninsula.
Anahera Herbert-Graves, Chief Executive for Te Runanga-a-Iwi o Ngati Kahu, says dune lakes are under already multiple stresses, including nutrient runoff, invasive pest fish and water weeds, and cumulative effects from use by the wider public.
However, Lake Waiporohita has an added threat in that it is one of only several dune lakes in Northland that are easily accessible to the public.
“Unfortunately, this means that the lake is all-too-often used as an unofficial car wash by passing 4WD vehicles that have used nearby beaches or boat-ramps.”
Peter Wiessing, the regional council’s Kaitaia Area Manager, says this puts the lake at increased risk of transfer of water weeds and pest fish (which it is currently largely free of) as well as exposing it to oil and other lubricants from the vehicles and trailers themselves.
“This practice is very detrimental to lake environments as it disturbs both the marginal reed beds and native plants in the lake bed. Sediment is re-suspended, adding to nutrients which feed algal blooms.”
Mr Wiessing says vehicle owners should use public carwashes or wash down their vehicles and trailers at home.
Anahera Herbert-Graves says, in a bid to better protect the lake, the next phase of the improvement project will see the project’s partners working to landscape the riparian strip in the open area along Inland Road where 4WDs tend to access the lake.
“This area will be landscaped shortly using locally sourced materials, native plantings and signage to let the public know that vehicle and boat access will no longer be tolerated in the lake.”
“Lake Waiporohita is a treasure not just to local tangata whenua, but to all Northlanders.”