No.05 2004

Algal bloom monitoring service
Blooms of hazardous blue-green algae in rivers, lakes, and reservoirs can cause problems for both animal and human health. How can you find out if an algal bloom is potentially toxic? NIWA is now operating a laboratory specialising in the analysis of blue-green algae. The new service provides a one-stop shop for algal counts and toxin testing, with the toxin testing provided by NIWA and AgResearch.

Aquatic plants indicate lake condition
Submerged plants in Lake Waikaremoana.
Aquatic plants are valuable indicators of lake health, and through LakeSPI – a new management tool using ‘Submerged Plant Indicators’ (SPI) – they can be used to assess lake condition.

Groundwater aquifers of Christchurch
Model of the geology in the top 100 metres under Christchurch.
The resource
Christchurch (population 340 000) has one of the best water supplies in the world. The supply comes from groundwater, is of extremely high quality, and requires no treatment.
The groundwater system that provides this water is dominated in the west by gravels (possibly up to 350 m thick) and sands deposited by the Waimakariri River. Beneath Christchurch, and to the east, is a succession of alternating gravel and marine deposits.

Outlook for water resources January–March 2004
Average summer air temperatures are expected in many areas, with average or above average temperatures likely in eastern areas of both islands. More anticyclones than usual are expected across the North Island, and more westerlies across the South Island. Settled weather, especially if warm, is likely to create the sort of stable, strongly stratified and warm conditions that favour algal bloom development in North Island lakes, similar to the blooms of autumn 2002.

Water allocation planning: guidance note on the Quality Planning website
Planning for water allocation from rivers and groundwater resources is a crucial part of water management. Water allocation plans can provide vital frameworks for managing the taking and use of water from rivers, lakes, and aquifers, and enable councils to address the cumulative environmental effects of water take and use. Water allocation planning is a multidisciplinary process that requires diverse skills and detailed information.
Salmon anglers at the mouth of the Waimakariri River.

Water resources in spring 2003
River flow
River flows for spring were normal or above normal for most of the North Island, the top half of the South Island, and Fiordland.