10. Surface Water Quantity

A Northland lake.

Summary

RPS Objectives

· The maintenance of the flows and levels in significant streams, rivers, lakes and wetlands to preserve their natural character and to protect high ecological, cultural or scenic values.

· The maintenance of water flows and levels in natural water bodies that are sufficient to preserve their life-supporting capacity, natural character, intrinsic values and associated or dependent values.

· The efficient use and conservation of water resources.

· To protect property and other values from adverse effects due to the diversion of water from its natural drainage pattern.

Pressures

· Northland's water resources are under increasing pressures to meet demands from a variety of consumptive users – including agriculture, horticulture, public and private water supply and industry sectors and the effects of land use change.

· Surface water takes, both consented and permitted, affect water flows. There is an increase in the number of permitted takes in Northland, as well as a large number of ‘permitted' takes that are likely to exceed the volume allowed in the permitted activity rules.

· Currently there are 381 consents allocated up to 500,000 m3/day of water from streams, rivers and dams in Northland (excluding diversions). A review of consented water takes indicates many catchments in central and southern areas of Northland are highly allocated.

State

· Annual rainfall ranges from 900mm in low-lying coastal areas to over 2,900mm at higher altitudes.

· Flows vary greatly between catchments, which can be largely attributed to rainfall patterns, catchment size and catchment geology. In Northland, catchment geology greatly influences low flows during drought conditions.

· Northland's climate is such that it will experience a regional drought, on average, once every three years at east coast and inland locations, and once every four years at west coast and high altitude locations.

Doing well

· The Regional Water and Soil Plan contains policies relating to the maintenance of flows and levels in water bodies.

· The Northland Regional Council (NRC) operates a hydrometric network consisting of 60 sites throughout Northland, which collects continuous data for 30 river level sites, six tidal monitoring sites and 24 rainfall sites.

· During periods of drought, water levels are monitored and when a low threshold is reached a low flow-gauging programme is undertaken in affected rivers. The NRC holds more than 11,700 flow-gauging records for 1,503 Northland sites.

· New flow measuring equipment, an Acoustic Doppler Current Profiler has improved the council's ability to gather more accurate information on Northland rivers, in both low flow and flood conditions.

Areas for improvement

· Ensure accurate water metering of consented takes and water use analysis to enable a better understanding of the volume of water abstracted within catchments and the effects on water resources.

· Encourage all water users to register their ‘permitted takes' with the Council to enable greater understanding of the ‘actual' water taken in catchments.

· Establish design minimum flows (minimum flow required to be maintained) for a greater number of catchments.

· Include in Northland's plans maximum total volumes allocatable for water bodies in Northland, to provide water use securities for users and sustainable allocation of water resources. Also include rules to ensure assessment of cumulative effects of subdivision on water resources.

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Published: 03 Apr 2008