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Published: 2002-05-16 00:00:00

Environment Waikato wants to establish a Care group to help improve the condition of Lake Waikare, east of Rangiriri.

Lake Waikare is a large natural lake with high sediment levels, which is significantly environmentally degraded. It is part of the Lower Waikato Waipa Control Scheme, and provides flood storage in conjunction with community control gates.

A resource consent to continue operating the control gate was granted in June 1999 and included requirements for 20 km of riparian planting and various monitoring. Auckland Waikato Fish and Game and Ducks Unlimited appealed these consents in relation to the condition of the lake.

To resolve the issues, Environment Waikato’s asset management group commissioned an investigation by NIWA to find out why the lake was declining and options for improvement. The report identified that the situation was complex with a number of factors involved. There was no simple solution, and management of the wider catchment was the key to achieving improvements to the lake.

The average water level of the lake was lowered about a metre during construction of the flood control scheme to provide additional flood storage and a level of protection for land around the lake.

Environment Waikato has met with the appellants to find a way forward, and decided to establish and support a Care group for the lake to identify practical actions and help with their implementation. The Lake Care Group would need to involve all key interest groups, including landowners and environmental interests.

Freshwater scientist Grant Barnes said the lake had shown significant deterioration since 1960 and again since 1993 and was now too turbid to support aquatic plants and was likely to have algal blooms of water quality improved. The area had gone from 1700 hectares of wetland surrounding the lake in the 1960s to 560 hectares in 1995.

Pressures on lake health included catchment development in the 1940s, intensified land use, lowering of the lake level, urban sewage discharge from Te Kauwhata and a variety of aquatic pests.

Options for improvement included riparian protection and enhancement of inflows, soil conservation in Matahuru, protection of lake each marginal wetlands, improvement of lake level fluctuations and treatment of discharges. Enhancement and restoration of other lakes in the Lower Waikato would also be worthy of consideration.