Trevor James, the TDC’s Senior Resource Scientist, a specialist in aquatic ecology and water quality, presented his latest research to the MDCA’s October meeting.
The Health of Streams in the Moutere
Streams draining the Moutere Hill geology (including Mapua-Moutere-Tasman areas) have a particular character with distinct water quality and aquatic ecology issues. The hydrology is distinct in the region with very low low-flows in summer and high peak flows. This is due to low permeability ground conditions, a dominance of pasture land use and low prevalence of wetlands. As a consequence, streams in summer are particularly vulnerable to overheating, low dissolved oxygen and high cover of slime (filamentous algae) in unshaded sections of stream in summer. These issues are serious enough to affect invertebrate and fish life in many Moutere streams.
The other big issue in the Moutere is fine sediment discharges from forestry and land development. A recent report by NIWA (see link below) attributed the source of much of that sediment to forestry land use as well as “bank erosion” which also includes erosion of subsoil from land developments such as what occurred when the Carter Holt forests were redeveloped for rural-residential land use. Examples of erosion risk activities in this area were shown, e.g. root raking of stream banks after forest harvest, hill country cultivation and winter cropping and grazing without grass filter strips. On the positive side there are generally low levels of nutrients and disease-causing organisms and reasonable water clarity in base flows in these streams. For more information on fine sediment in our waterways, see the December 2016 report at: http://www.tasman.govt.nz/environment/water/rivers/river-water-quality/fine-sediment-in-our-waterways-and-coast
Where the habitat is poor there are typically 3-4 species of native fish in Moutere streams (inanga, shortfin and longfin eels, and common bully). Where the habitat is good you typically get these plus: banded kokopu, smelt, giant bully and in rare occasions you can find koaro, torrentfish and redfin bully. No longer do you find giant kokopu as too many wetlands have been drained and streams straightened. Dominion Stream has had giant kokopu, but it hasn’t been found in the last couple of surveys. Redfin bully is also rare in Dominion Stream, but no smelt, koaro or torrent fish.
Around NZ these rare fish are getting rarer. The main reasons for this include: fine sediment discharges, water temperature, increasing aquatic weed growth and decreased flows. Most of these issues are associated with agricultural intensification and urban development. In Tasman we have found in-stream structures creating a barrier to fish passage to be a major effect on native fish. For example, you find fewer fish species upstream of the rock riprap weir on the Moutere River 500m downstream of Old House Road. Attempts to address this have failed due to the unstable nature of this structure.
There are many opportunities for restoration, particularly by “joining the dots” of existing remnants of native forest and riparian restoration. Council would like to work with the Tasman Environment Trust and the wider community to develop catchment improvement plans. The TDC now has a fund available to organised landowners and community groups, principally to provide plants for riparian restoration. Plus, the latest Land Development Manual that directs developments will hopefully deliver some better environmental outcomes for our streams.
Q- What do you see as the biggest opportunity for improving stream health within this region?
Trevor: To improve ecological health, we should start with small streams close to the coast draining into estuaries – e.g. the Moutere catchment area. Then involve young researchers to map out critical areas.
Q- If streams flowing into rivers/estuaries were to be fenced, how much of a difference will it make?
Trevor: If the catchment has a source of sediment coming from uphill, it will impact lower down. Best intervention to improve water quality is to plant trees next to streams as it cools down streams, feeds with natural seeds etc.
Q – Are you optimistic about water health in our district?
Trevor: With funds becoming available, it does increase optimism. Fortunately, we don’t have such a big a job to do as in more intensive farming areas elsewhere in New Zealand.
In Other News
Active Transport Survey
Drew Bryant, TDC Activity Planning Advisor, spoke of an online Active Transport Survey on walking/cycling transportation. The questions are to discover how you undertake everyday travel and what is stopping you from walking or cycling as a mode of transport. The TDC looks to support more of this type of healthy transportation and is interested in hearing the thoughts of those that would not normally walk or cycle, not just those that are enthusiasts. A greater representation from the Moutere/Waimea ward is desired, as they represent only a small percentage of the responses so far. Take the survey at this link: https://www.surveymonkey.com/r/YQCDQ65
Community Social Seating
David Mitchell spoke about the importance of cultivating a social community and highlighted the campaign for greater mental awareness. Spaces that people commonly occupy in their daily life are: 1st space – home, 2nd space – work, 3rd space – public space. David felt that greater attention should be given to seating and configuration of seating in our community public spaces. Social seating around our community encourage more people to get out of their homes, especially the elderly. Should any one like to get involved, please email David at: email@example.com.
Mapua Community Care Project
The Trustees of the Mapua Community Care Project (formerly Dale Vercoe Community Care Charitable Trust) are establishing a community consultation group to advise on the project. The Project’s Ron Oliver asked the MDCA to provide a representative to the group. The membership discussed and passed a motion to have Chairperson Marion Satherly as the MDCA rep.
Dominion Flats Reserve
Helen Bibby reported that $2000 was received from Greenwood Trust for tree planting. And that the MDCA has applied to Pub Charities for $13,750 for further planting at Dominion Flats Reserve.
It was agreed that the Association would sign a Memorandum of Understanding with NZTA taking responsibility for maintenance (typically clean and repaint as required) of the Mapua School mural to be painted in the Coastal Highway underpass.
MDCA Social Media Report
In September, the MDCA posted 7 different news items on our Facebook page. Topics ranged from an invitation for nominations for Chairperson of the Waterfront Area Working Group to a notice of the McKee Reserve re-opening on Labour Day weekend. Our most viewed posts were the announcement of a new start for the Dale Vercoe Community Care Charitable trust (as the Mapua Community Care Project) with 1,103 views. And, of course, anything to do with pets: a post that “Sala, the lost pup, was found” had 2,273 views, 5 comments and 16 shares. In total, our posts in September attracted 6,677 views – about the same as our average views in July and August.
Be sure to attend our next monthly meeting: Monday, 12 November at 7 PM, Mapua Hall.