Wainono Lagoon is a 480 hectare shallow coastal lagoon and wetland in the South Canterbury region. A number of rivers flow into the lagoon, including the Hook River from the north and the Waihao River from the south. The lagoon hosts over 50 species of waterfowl and fish, including threatened Canterbury mudfish/kōwaro and longfin eel/tuna. Its importance derives from the lagoon’s size, diversity of habitats and location in a chain of coastal wetlands. The lagoon and its tributaries are highly significant to Waihao rūnanga as a mahinga kai source and a cultural site. Once an important mahinga kai (food gathering) area for Ngāi Tahu hapū, it is now a metre deep in mud and silt and saturated with farm run-off.
Further European settlement and farm development released large volumes of sediment into the Lagoon and since the 1970s, more intensive farming practices and use of fertilisers have left the Lagoon cloudy and saturated in phosphorus and nitrogen with frequent algal growth and blooms. Ngāi Tahu rūnanga in the area are extremely concerned at the degradation of this important mahinga kai. In 1999 farmers, residents of the area and Ngai Tahu rūnanga formed the Waihao-Wainono Water Users Group, which adopted a ground-breaking plan for environmental protection along with development. In 2011, Wainono restoration became a flagship project under the Canterbury Water Management Strategy, promoted by the Lower Waitaki-South Coastal Canterbury Zone Committee established the previous year by Environment Canterbury. The Department of Conservation, Central South Island Fish and Game, Forest and Bird South Canterbury and Waihao-Wainono Water Users Society are all involved, together with Te Rūnanga o Waihao and Te Rūnanga o Ngāi Tahu.
Farmers have willingly joined the restoration project, fencing off and sometimes covenanting land around the Lagoon and working towards reducing sediment and nutrient runoff. Further up the Waihao river farmers are removing willows to give greater access to the walkway from McCulloughs Bridge to the Black Hole.
The Wainono Lagoon is a taonga to tangata whenua, treasured for its place in their history as well as its abundant fish and bird species. The name Waihao refers to the hao eel, a life-stage of the short-fin eel which has been a delicacy to generations of whānau who have gathered here. The name was given by the daughter-in-law of Waitaha ancestor Rakaihatu, renowned for digging out the lakes of the South Island. In the late 1800s Wainono Lagoon fed up to 240 permanent residents of the Waihao Pā. Generations enjoyed a diet of fish including eels-tuna, flounder-pātiki, whitebait-īnanga and birdlife including moa. This was a nohoanga-camping place where food was gathered and preserved for the winter.
Before European settlement the Lagoon was mostly freshwater. The last 170 years have seen significant change, with development of its catchment into fertile farmland. Land drainage, vegetation clearance and stock in waterways have dislodged large volumes of sediment which washed into the Lagoon. Recently, more intensive cropping and dairy conversions have increased fertiliser use and farm runoff.
Protecting farmland from flooding is the Waihao Box, built in 1910 to replace an 1896 structure. The box opens when a big flow comes into the Waihao River, shifting shingle and creating enough pressure for water to flow out to sea. When it is closed, the river flows along a coastal channel into Wainono Lagoon. Draw-off of irrigation water has reduced flow into the Lagoon, in drought years leaving the riverbed dry for longer periods where it meets State Highway 1.
Mudfish, eels, weeds and willows have been the recent focus of the team working at Wainono Lagoon on Te Rūnanga o Waihao’s Te Mana O Te Wai Project. The project, funded by the Ministry for the Environment with contributions from Environment Canterbury and the Department of Conservation, is led by the rūnanga and aims to improve the water quality of the lagoon through a range of measures.
The majority of the physical work carried out has focused on controlling weeds and willow trees that have an impact on the water quality and biodiversity of the lagoon. This has included working with the Department of Conservation to control the weeds on the gravel bar and completing willow control on important wetlands on the lagoon margins. The Wainono Lagoon restoration project aims to feed more and better freshwater into this freshwater lagoon near Waimate, separated from the coast by a shingle bank. The project involves fencing of the wetland and waterways to stop stock access, traps to catch sediment and earthworks to prevent erosion such as bank reshaping, as well as farm environment plans for farmers in the contributing Hook catchment. These plans take an overall look at each farm, making small changes which across the catchment can make huge improvements to water quality in the lagoon and habitats for fish and birds. Improving water quality in the lagoon is the long-term aim. The main tactics being used to improve water quality are fencing off streams, reshaping, grassing and planting their banks and building sediment traps and bunds.
Two new native mudfish populations have been found in small streams that run into the Lagoon and habitat protection and enhancement is being carried out to protect these sites. Fish barrier work to help prevent other fish species from predating the mudfish is being undertaken on Buchanan’s Creek by the Working Waters Trust.
Annual eel monitoring was also undertaken by rūnanga and Environment Canterbury biodiversity staff to better understand eel populations as an indicator of overall ecological health in Wainono Lagoon and its catchments.
At this stage the public will not notice a lot of the work going on in the area but eventually, in addition to the parking area recently established towards the mid section, there will be signage and landscaping. Work at the Waihao Box recreation area has been done in the past year.
A walkway goes along the coastal side of the lagoon. You can start at either end but will need to return the way you came (see the map). Access to the cache is along a road that is fine in an ordinary car if the road is not wet. It might be challenging if greasy. Also watch travelling over the bridge near the parking area especially if wet.
Please bring a pen!