Stopbanks

We require good access to the banks so that we can undertake regular inspections and maintenance. There are places where fences inhibit activities like mowing, gates have been blocked off or the Council has been locked out. There are also lengths of bank that are too narrow for safe access.

We do not encourage stock on Council-maintained banks. Unfortunately most of the Council’s stopbanks have been constructed with steep side slopes and most types of grazing will compromise them. This is particularly so in wet conditions or with larger animals such as cattle and horses. Where we own the land, we are progressively removing grazing rights to prevent further damage.

Large logs, debris or farm waste can direct flows into the stopbanks in flood conditions, they can mobilise and cause blockages, or cause damage directly to the stopbanks.

Regular crossing by vehicles or animals wear the stopbank crest down, creating a low point and weakness where the bank can potentially breach or fail in flood conditions. Track locations should be rationalised and surfaced using gravel or similar material to guard against this.

We need to approve any new or modification of existing structures on Council-owned stopbanks. Irrigation pipes, tracks, fences, etc., that can weaken the bank or hinder access need to be discussed with us.

Trees and shrubs can shade out the grass growing on the banks, hinder access and reduce bank performance in flood  conditions. If they are planted too close, tree roots create pathways for water to enter the stopbank. They can also blow over in a storm creating a breach as the root ball up-ends and tears a hole in the bank. Large trees should be planted a minimum of 15m from the base of any stopbank.

The Council’s contractor needs to spray and control weeds on or adjacent to our stopbanks to ensure a healthy grass sward can be maintained. Grass is considered to be the best cover on stopbanks to resist scour in flood events.

• Don’t put stock on stopbanks unless it is light sheep grazing outside of wet periods (or you are shifting them).
• Don’t feed out on stopbanks.
• Ensure that you consult the Council before installing any new irrigation pipes, fencing, track crossings, etc., that may penetrate or lie on or over the bank.
• Notify the Council of any damage or obstructions you are aware of.
• Keep water troughs or feed dispensers, etc., that animals congregate around, well away from the bottom of the bank.
• Ensure any crossings have a minimum layer of 150mm of gravel or crushed stone to protect the bank from wear and have gentle approach and departure ramps.
• Ensure that materials or waste are not stored on or against the bank both for access and flood damage and so we can maintain a healthy grass sward.
• Ensure that access is not restricted along the crest or flanks and that all gates are in good working order.

• Talk to lessees/landowners about improving access and bank condition along their section of bank.
• Mow the banks at least once a year in spring. The purpose is to create a dense, healthy sward of grass with full coverage of the bank sides to protect the banks from scour and piping (water tracking though the bank and flowing out at a weak point in the outer edge).
• Control weeds growing on or immediately adjacent to the banks.
• Check and maintain flapgates and culvert outlets associated with the banks.