Lake Waikare


General Information

Lake Waikare is the largest lake in the Waikato Region and regularly suffers from algal blooms. The lake was lowered in 1965 for flood control and is extremely turbid, being very shallow for its large surface area. Due to the low light environment it is difficult for aquatic vegetation to establish, which would help stabilise the sediments.


Lake Waikare photo by Wendy Paul

Wetland area surrounding the lake has declined by 67% since 1963 (Barnes, 2002). Lake Waikare receives discharge from the Te Kauwhata wastewater treatment ponds. The Trophic state of lake Waikare has worsened since 1993, with increased N and P and suspended sediment loads and decreased secchi depth. Chlorophyl a concentrations have remained stable, and this has been attributed to light limitation of algae due to the high suspended sediment concentrations.

Restoration Action

Lake Waikare is a difficult case for restoration due to its large catchment and surface area, shallow depth and continued inflows from wastewater treatment ponds. Macrophyte re-establishment would help reduce high suspended sediment loads and internal nutrient loading. However, macrophytes would be extremely difficult to establish due to 1) high suspended sediment loads restricting light penetration for macrophyte growth, 2) high wind exposure resulting in an unconsolidated lake bed, 3) risk of Egeria densa becoming dominant and collapsing due to high nutrient availability.


Lake Waikare Statistics

Area3442 ha
Maximum depth1.5 m
Trophic stateHyper-eutrophic
Catchment8.6 km2 of associated wetlands (1982), pastoral
RecreationGame bird hunting, eel fishery and yachting
Restoration progressWater level lowered by 1m and weir to control water levels established in 1965.
Peat influenceLow-none
Reserve statusImportant role in Environment Waikato's flood control scheme. 25% of the lake is managed as a wildlife reserve.
Submerged vegetationNone currently, but has supported populations of the native species: Nitella hookeriRuppia polycarpRanunculus limosella,Zannichellia palustris and introduced Egeria densa,Potamogeton crispus and Myriophyllum triphyllum (Champion et al. (1993).
Harmful algae 
Invasive fishKoi carp


Images

 

References

Barnes G. (2002). Water quality trends in selected shallow lakes in the Waikato region: 1995-2001. Environment Waikato Technical Report No. 2002/11.

Champion et al. (1993). The Vegetation of the Lower Waikato Lakes. Volume 2: Vegetation of thirty-eight lakes in the lower Waikato. NIWA Ecosystems Publication No.8 August 1993.

Stephens et al. (2004). Rehabilitation of Lake Waikare: Experimental investigations of the potential benefits of water level Drawdown. Environment Waikato Technical Report 2004/25.

Town J.C. (1982). Lake trophic status and water quality 1982 survey. Waikato Valley Authority Technical Report No. 22.