A dam fine idea to check first | Rural

Digging into wetlands, and diverting or damming streams are not good farming practice so before cutting loose with a digger or bulldozer, it's best to check what is allowed under the Regional Water and Soil Plan (RWSP) for Northland.

This plan - developed under the Resource Management Act (RMA) and operative since August 2004 - was adopted after extensive consultation and testing before the Environment Court.

Farming groups, environmentalists, forestry companies, iwi authorities, other local authorities and a large number of Northland individuals participated in the preparation of the plan.

The final document is a contract between all of these parties and the Northland Regional Council as to the environmental standards we, together, want for current and future generations.

The RWSP - along with other district and regional plans - contains policies and rules that affect how land is managed and, in particular, controls activities that are likely to have an adverse effect on other people's land, water quality, the quantity of water flowing in streams, and native bush, scrub, wetlands and dune systems.

Many of these are not new rules. Even under 1000-year-old common law, it was not permitted to dam a stream and deprive downstream landowners of water. This common law prohibition was included in the Water and Soil Conservation Act 1967, requiring land owners to seek a water right to dam a stream.

Under the RMA, conditions of the early act became a resource consent - the damming of a permanently flowing stream requires a resource consent from the regional council.

Straightening streams can also cause all sorts of problems, the most common being erosion of the stream bed and, eventually, its banks.

When a stream is straightened, it is shortened and the grade or slope of its bed increases. The increased slope causes the waterway to scour or erode its bed.

The sediment or gravel dislodged by this erosion builds up on the inside of bends, where the water flow is slower, causing the stream to erode away the outside of the bend and meander.

The more the bed and stream erode, the more it meanders, causing the loss of land and structures such as fences, bridges and culverts.

A resource consent is required before any straightening or realignment of a stream.

Blockages may need to be removed from streams to control erosion, including trimming or removing trees that have fallen into or, like willows, have grown in the stream channel.

This work is a permitted activity under the RWSP so it can be done as of right - subject to some common sense environmental performance standards. However before starting this type of work, it's good to check with the regional council as to what can legally be done.

When doing any work in a stream - whether it is a permitted activity or consented - let downstream neighbours and the Northland Regional Council know what the work is and when it will be done.

Someone downstream may well draw water from the stream. (By letting the regional council know on Freephone 0800 002 004 we will be able to respond to any inquiries or complaints we receive on our Environmental Hotline).

Draining "significant indigenous wetlands" is not permitted under the RWSP.

The definition of "significant indigenous wetlands" is set out in an appendix to the plan, including photographs of the various types. Draining of anything that fits these descriptions is an offence and the penalties can be severe.