River management

• Mowed twice with an extra mow as required, generally once before Christmas (the stopbanks on the Brooklyn Stream are not mowed being too steep and narrow).
• Weed spraying in summer/autumn to control establishing woody weeds such as blackberry, broom, gorse, Old Man’s Beard etc.
• Regular inspections of all flap gates on drainage pipe outlets under the banks – on a three or six monthly cycle depending on risk assessment.

These are inspected monthly to check they are operating as intended.

Little Sydney Tide Gate - the screens on this gate are removed ahead of any significant wet weather as they become clogged and impede the water flow.

• Ground based spraying in X&Y river rated river lengths as required to control woody weeds for maintaining flood conveyance, and to manage specific pest weeds (generally vines that are threat to existing vegetation or weed species that are not widespread so that elimination from particular river or reach of river is feasible).
• The Waimea/Wairoa is being done over the current growing season, as it has not been done for three years and is showing quite a lot of woody growth on the beaches.
• We plan to get the remaining Chocolate vine (Akebia sp.) from the mid-Wai-iti in hard to get places typically on top or behind bankside vegetation (this will be the third time we have targeted this species in this area).
• We will monitor the Sherry for follow-up control of Asian Knot weed and OMB (Old Man's Beard). This work is undertaken during the growing season (November – April inclusive) and is governed by a separate consent.
• It’s likely that we will have a larger programme next growing season.
• No need for aerial control identified to date.

• Layering - aging willows are lopped or layered to rejuvenate them and to protect sections of bare bank. Layering is typically used for the smaller willow varieties such as basket willows, and involves pushing the willows down to partially sever the trunk at the base with an excavator. We generally don’t layer over summer due to the risk of killing the willows with the hot dry conditions.

• Focus on continuing to maintain and expand existing sites along with development of several new sites.
• Around 15,000 natives are planted each year through the river maintenance contract with up to 40,000 being maintained at any one time.
• Maintenance involves removal of covers from the grass related species (flax, toe toe, cabbage trees) when they become tight, weedeating and spraying within and around the site to keep weeds down in the first 1-2 years following planting.
• We are intending on switching 100% to cardboard planting guards this winter after trialling a new product to the market in 2018.
• We have scaled back our maintenance effort this season. This saves on resources but means that sites will look ‘scruffier’. Once plants are above waist height then we only need to control larger or climbing weeds, as the plants grow they will shade out grasses and herbaceous weeds.
• We plant a fairly small list of colonising/edge species natives that are hardy and fast growing (flax, toe toe, cabbage trees, mānuka, kānuka, ribbonwood and lacebark, pittosporums, hebes, ngaio, coastal tree daisy, ake ake ). Coastal species are only planted in the lower reaches as they are frost sensitive.
• Now that we have multiple established sites we are planting the longer lived forest ‘giants’ into these such as rimu, kahikatea, miro and mataī.
• Landowners wishing to establish native vegetation outside the fully maintained network are now supported through the Environment and Planning departments Environmental Enhancement Fund.

This work is to correct undesirable river alignments and protect banks and adjacent infrastructure and land from river erosion following a flood or high flow event.

It may include relocation of river gravel within the channel to realign the low flow channel, incorporation of tied or buried willows, bank reshaping and placement of rock either as discrete structures (such as groynes) or longer lengths (termed rip rap).

• Gravel extraction may also be carried out as part of this work, but no sites have currently been identified for this.
• We are currently still predicting a need for these works to continue with potential flood events during the year.

Historically gravel extraction from river beds was the main source of aggregates.

Studies carried out by the Council and Landcare Research Ltd have shown that in general there is limited sustainable replenishment of gravel in our main rivers. Consents to extract gravel are now focused on land-based sites such as quarries and open pits.

Some river management projects are required to relocate gravel within sections of a river particularly where single stream channels are controlled by rock work. Typically you'll see these around meandering bends. The huge cost of maintaining the rock work necessitates training works to stabilise the active channels and minimise the need for additional rock works.

Historically gravel extraction from river beds was the main source of aggregates. However, local studies have shown that in general there is limited sustainable replenishment of gravel in our main rivers. Consents to extract gravel are now focused on land-based sites such as quarries and open pits.

Some river management projects are required to relocate gravel within sections of a river particularly where single stream channels are controlled by rock work. Typically you'll see these around meandering bends. The huge cost of maintaining the rock work necessitates training works to stabilise the active channels and minimise the need for additional rock works.

A few gravel extraction and relocation projects and standards are outlined below:

• Several extractions are planned for the Motueka and Tākaka Rivers.
• We plan to undertake river bed monitoring surveys of the Y rated sections of the Waingaro and Anatoki Rivers in Tākaka.
• Other surveys will only be undertaken following significant flood events (twenty year flood or greater) in one of our rivers where this type of monitoring is already carried out.

We maintain a number of modified waterways/drains in the Riuwaka area such as the Little Sydney, that require silt and vegetation removal from time to time. Also some smaller waterways like Eves Valley Stream and the Redwood overflow on the Waimea plains.

Generally we don’t spray these smaller waterways to control vegetation, but use physical removal or mulching to keep them open. Over time and especially following flood events these waterways can silt up significantly so require excavation.

• Hamilton’s drain in Riuwaka currently requires vegetation and silt removal, at most times this drain is dry so has little to no aquatic value.
• We have a number of jobs programmed in Powelly (Pauley/Pawley) Creek in Lower Moutere involving willow maintenance, widening and rock bank protection to alleviate localised flooding and erosion issues.

The Waimea and lower Wai-iti Rivers have a high incidence of illegal dumping. The Motueka highway bridge and the river bank behind Tākaka township are other areas where this activity periodically takes place.

• We maintain signage at known dumping hotspots.
• We aim to remove this on the ‘fly’ waste within five days of notification.
• Waste includes abandoned cars

NOTE - The solid waste budget pays for this work but it is carried out under the river maintenance contract.

Outside of the X & Y rivers we have a policy to subsidise landowners up to 50% of the value of agreed river control or flood protection works. We are currently working to complete a number of jobs still outstanding from the ex-Gita event and from subsequent smaller events in catchments such as Wai-iti, Dove, Mārahau, Otūwhero, Westbank/Lower Motueka, Riuwaka and the Buller.

Other than the creation of new river control assets through planting or rock work, no capital works have been identified other than works to improve the performance of the Little Sydney tidal gates (details of which have yet to be finalised, to do with the inlet screens which require frequent removal due to heavy rain warnings).

There is the potential to include some minor stopbank upgrades i.e. repairing stock damage or fencing improvements into the programme should there be a lull in flood events.