Lake Horowhenua restoration work continues under a modified work programme

During Horizons Regional Council meeting yesterday, councillors recommended the continuation of Horizons’ lake restoration via a modified work programmes under the Lake Horowhenua Accord.

These work programmes include water quality and flow monitoring of tributaries, increasing groundwater monitoring as part of Horizons contribution to the Freshwater Improvement Fund project, pest animal and plant control, and working with local horticulture growers.
Work also includes maintaining and monitoring the sediment trap, which was installed in 2017 and is designed to remove 50 per cent of coarse sediment during heavy rainfall events.
Council also recommended the continuation of ongoing science and monitoring programmes, and to progress the building of an access road and boat ramp to enable lake weed harvesting to improve water quality and aquatic health of the lake.
Horizons chair Bruce Gordon says some beneficial owners of the lake have actively challenged restoration work, which has considerably slowed progress.
“Work has also been hampered by aggressive and threatening behaviour towards Horizons’ staff and trustees working at the lake,” says Mr Gordon.
“Without the actions of these individuals, restoration work would have advanced much further. Costs have also significantly increased as some funds have been diverted from restoration initiatives to legal costs.
“Perhaps the most frustrating thing has been the inability to get the weed harvester on the lake.
“The lake weed harvesting project is viewed as a key intervention to address the in-lake process that lead to toxic conditions - including elevated pH, ammonia toxicity and cyanobacteria blooms.
“To advance the lake weed harvesting project further, legal processes around Court injunctions and archaeological permissions need to be advanced and Council has endorsed progressing with this work.
“While work directly around and on the lake has been held up, Council has still been able to carry out other non-regulatory work, including fencing and planting, re-establishing a monitoring and science programme, and working with Horowhenua horticulture growers to implement drainage and erosion management plans.
Following lake restoration option reports commissioned by Horizons and completed by NIWA, the Lake Horowhenua Accord was signed in 2013. Led by the Lake Horowhenua Trust, the other Accord signatories are Horowhenua Lake Domain Board, Horowhenua District Council, Department of Conservation, and Horizons.
In 2014 the Lake Horowhenua Action Plan was launched and included 15 key lake restoration actions such as fencing and planting, the installation of a sediment trap, remediation of two fish barriers, and weed harvesting.
Lake Horowhenua is below National Policy Statement – Freshwater Management (NPS-FM) national bottom lines for a range of water quality indicators.
Mr Gordon says the Accord interventions have been predicted by Dr Gibbs from NIWA to likely move four of the five key indicators out of the bottom line category.
“Modelled improvements are for parameters that included toxicity measures of ammonia and cyanobacteria that can impact on aquatic life, and in the case of cyanobacteria (toxic algae) have an effect on the lake for recreational use,” says Mr Gordon.
“Lake restoration collaboration has extended to involve central government, horticulture growers, and the dairy industry across three large work programmes financially supported through the Lake Horowhenua Freshwater Clean-up Fund, Te Mana o Te Wai, and Freshwater Improvement Fund projects.
“The Lake Accord celebrated its fifth anniversary in August.
“Investment in restoration is estimated at more than $7 million over the first decade of the Lake Accord  programmes. This excludes some costs such as landowner and agencies’ contribution, as well as policy development, and some regulatory and consent processes.
“The ongoing regional rate contribution is funded through a targeted Lake Horowhenua Restoration rate of 80 per cent paid by Horowhenua District ratepayers, with the remaining 20 per cent rated across the region, and some as a general rate funding for monitoring, research, and some implementation work.”
Mr Gordon says ongoing delays and increasing costs are of concern to Council, Accord partners, the community, ratepayers, and funding partners.
“We all want the same thing. To restore the lake. Today’s recommendations gives staff the mandate to progress the work programme in collaboration with the other Accord Partners.”

The full council item can be found at It includes the Lake Horowhenua Report Card, rationale for weed harvesting, sediment legacy project results, kakahi (fresh water mussel) monitoring project results, pest fish survey results, water quality state and trends, health and safety considerations.