Stage one of this catchment management plan provided the background information for the Kaipara Catchment. The purpose of stage two is to identify the key issues within the catchment, look at the causes of them, analyse the current management of it and think of the management that should continue. After that, it identifies to the management and then it looks at monitoring indicators for each of the issues.
Key Issues
The following issues have been identified in the main catchment of the Kaipara/ Kumeu River and some have been identified in the sub catchment areas. The following issues are the priority for the Catchment Management Plan and needs to be addressed immediately to recover the river back to its natural state.
General Kaipara River Catchment Issues:
• Increased sedimentation
• Water Quality
• Hydrology/Flooding
• Land Use
• Low Biodiversity (Flora and Fauna)
The conflicts that can be identified within the catchment are the following:
• Land use v Biodiversity
• Land use v Flooding
• Economic value v Environment
• Cultural v Environmental
• Urban sprawl v Natural environment
All these conflicts within the study area contribute to the issues stated and will be discussed in this report. The issues have been discussed in the priority that they should be addressed as it will be of beneficial to the next issue as they all inter-relate with each other.
Sedimentation
Increased sedimentation has been evident in the upper parts of the Kumeu River in the Kumeu sub-catchment area behind the Kumeu shops. Large earthwork operations are taking place which is involving removing the top soil leaving clay which is washing into the river and creating blockages due to the high sedimentation levels. This is causing even more disturbances to the natural ecology of the place as the river is already being polluted by the residential, commercial and industrial areas present in the catchment already. Large earth work projects block the river and by doing so when the clay gets deposited into the river, it then covers small invertebrate species up and they could possibly die. This also affects the whole river because whatever happens in the upper part of the river affects the river downstream. Therefore, the sedimentation will travel downstream and it will affect the biodiversity in the whole catchment in the river and outside due to the fact that if there are birds that feed on certain invertebrates in the river and if they are not present there then the birds will migrate. High sedimentation is also caused by live stock getting into the river. High sedimentation levels affect the atheistic quality of the river especially when it rains the water becomes murky.
Current Management:
Auckland Regional Council has plans for sedimentation such as Regional Plan for Sediment Control and the most suitable ways of protecting and enhancing the area.
-Rodney District Council and Auckland City Council are working together by monitoring the sedimentation levels in the river and they are trying to re-vegetate the backs to reduce erosion of them.
-Resource Management Act
Future Management Regulatory:
That future development in the catchment be undertaken in such a manner as to avoid, or mitigate the erosive effects of earthwork discharges.
-Work within the driest seasons
-Fencing of waterways to prevent erosion from stock.
-Encouraging the community to re-vegetate along the banks of the river to reduce erosion.
-Educate the public about the effects of high sedimentation
Future Management Non-Regulatory:
-Provide incentives for the earthwork workers to minimize the area exposed at any one time.
-Encourage the community to help with the planting of vegetation along the river banks.
Constraints:
-urban sprawl demand is increasing as the Auckland Region is growing. However in saying that developers can adapt the Low Impact Urban D to decrease environmental impacts.
-Large amounts of the river are in private property therefore we have to encourage the residents to fence parts of the river from stock. Also we have to encourage them to replant the backs in their property.
Monitoring Indicators
Measuring water quality and turbidity
Look out for Visual effects such as clouding of waterways
Monitor sedimentation levels in the river
Water Quality
Water quality varies in the catchment depending on the land use around it. The part of the river that is surrounded by farmland, commercial, residential, and industrial use tends to have poor water quality; this is mainly along the main river. The cause of poor water quality in the catchment is erosion, nutrient levels and surface runoff. There has been an increase in farming, this increases the diffusion of pesticides, and fertilizers that contain nitrogen, and phosphorus chemicals in them, (Rodney District Council, Waitakere City Council, 2007). Surface runoff is at its peak off State Highway 16 where approximately 20,000 vehicles per day use the highway south of Kumeu and approximately 12,200 between Huapai and Waimauku, (Rodney District Council, Waitakere City Council, 2007). Erosion is high around the banks of the river where there is low numbers of vegetation and when it floods or animal stock gets into the river the bank erodes creating murky water. Also the tributary streams that flow off the Kaipara River had low dissolved oxygen levels.
Current Management:
-Kingett Michell and Auckland Regional Council provide water quality, temperature levels and pH level monitoring and they have done so for the last 20 years.
-Auckland Regional Council and Rodney District Council have got water quality surveyors working in the Kaipara Catchment to provide information on the river and how to improve it.
-National quality monitoring network which is done by NIWA
- s69 RMA Water Quality, ensuring the bottom line
Future Regulatory Management:
-Do not build impervious surfaces around the river.
-Regulate how much pesticides farmers use, and put restrictions on it.
-Houses should have storm water catchers that catch the water off the roof so the chemicals do not get into the river.
-Try increase the water quality by 50% by cleaning it up and this will increase the biodiversity in the catchment too.
Improve the drainage systems within the catchment region.
Future Non-Regulatory Management:
Educate the residents about water quality.
-Get the community involved in cleaning up the river and re-planting to increase the riparian corridor which in return will decrease the erosion
Constraints: -Hard to get farmers to stick to the restrictions as they may want to use more and it is hard to identify which farmer is using more pesticides.
-2050 the population is predicted to reach approximately 180,000 in the whole Rodney Region, this means more impervious surfaces which will cause more runoff and worsen the water quality.
-The cost of improving the drainage system may be too much and the council won’t be able to do it without increasing things like the rates of the land owners which would cause conflict.
Monitoring Indicators:
Monitor sedimentation levels in the river
Assess the different nutrient levels and see if they are reducing
Check water quality and how much oil and other chemicals get enters the river via street network
Hydrology/Flooding
Flooding is a major issue in the catchment including the river and the small streams during high rainfall and it is caused by the land use around it and also the high rainfall. Large amounts of impervious surfaces increases the flooding as the water cannot infiltrate, therefore it runs off into the river increasing the water level. Agricultural land is present around the river however there is a small amount of vegetation present therefore the rainfall infiltrates through the soil and gets deposited into the river. This causes flooding as the water has nowhere to go. Stream overflow presents a risk, both physically and economically to stakeholders in the catchment as the farmers are affected and cannot grow their crops, (Rodney District Council, Waitakere City Council, 2007). Flooding causes contamination of the river due to the fact that when in overflows it collects all the surface runoff from the roads and the pastoral land and deposits it into the river. This will have a negative effect on the fish species present there.
Current Management:
-Storm water drainage is primarily via open drains to the tributaries, which in turn discharge into the Kumeu or Kaipara Rivers.
-The Kaipara River ultimately discharges into the Kaipara Harbour. At road and rail crossings, flows are generally directed through bridge or culvert structures. There are currently 840 existing consented discharge points into the Kumeu/Kaipara Rivers.
-Stormwater treatment devices in accordance with ARC guidelines (ARC TP10,2003) to remove at least 75% of total suspended sediments on a long-term average basis.
-Monitoring the rainfall flooding patterns this is done by NIWA.
Future Regulatory Management:
-Land use intensification through urban development (whether reticulated or not) should only occur where adequate provision is made to mitigate the increase in storm water runoff, (Rodney District Council, Waitakere City Council, 2007).
-Re-vegetation along the banks of the river to reduce the flooding as it will absorb the water.
-Preserve the flood plains in Kumeu by not allowing development.
-Taupaki is a natural floodplain and no further development should be permitted.
Future Non-Regulatory Management:
-Educate general public
-Provide incentives for farmers to replant on their land to reduce flooding
Constraints:
-Hard to change the lifestyle of the people living on the farmland as they may not want to plant vegetation.
-Impervious surfaces that are present there now such as State Highway 16 cannot be moved and it will continue to flood because it is hard to change the water flow of the river.
Monitoring Indicators:
Continue monitoring the rainfall and flooding patterns.
Ask residence if they are noticing any differences in peak flooding periods if its decreasing or not.
Land Use
The land use in the Kaipara Catchment is mainly rural consisting of agricultural land. This causes soil erosion, ground water contamination, faecal contamination from the stock, pesticide runoff and infiltration which makes the river nutrient rich as it all ends up in the river. This all causes chemical changes within the water body as the oxygen levels decrease, nutrients are enriched and the pesticides are accumulated (Van Roon and Knight).
Oxygen depletion is caused by when the bacteria is breaking down the waste and also during the night plants respire. Most agricultural waste have a high biochemical oxygen demand therefore if there are high amounts of contaminants flora and fauna will not have enough oxygen.
In addition, there are large pine forests within the catchment where felling occurs. This causes large disruptions to the natural environment as the business operating the large areas of pine are constantly cutting them down and replanting them however the trees do not grow fast therefore the top soil gets washed down and causes sedimentation in the river. This is an issue that effects the catchment both on land and inside the river. The reason being is it effects the terrestrial species present there as they need to migrate when the trees have been cut down, and it effects the micro-invertebrates inside the river as the high sedimentation decreases the oxygen levels.
Current Management:
-S 70 (1) RMA discharges
-Farmers using pesticides must be in accordance with the Code of Practice for the Management of Agrichemicals.
-monitoring of pesticides inside the river by NIWA.
Future Regulatory Management:
-Create buffer zones between sections of the pine forest so it reduces the amount of sedimentation getting into the river.
-Set strict rules about the amount of stock each farmer can have on their land.
-Minimise tillage, mulch, plant on contour lines.
-Apply fertilizers during appropriate seasons
-develop alternative pest management techniques including biological controls.
Future Management Non-Regulatory:
-Providing incentives to farm owners to reduce the amount of pesticides they use or to develop alternative pest management such as biological controls.
Constraints:
-People do not like change, especially if it is going to cost more.
-The current management has not worked as we can tell by looking at the present state of the river.
-RMA is going to get changed therefore we do not know if it is going to be for the better or worse.
Monitoring Indicators:
Measure water quality and turbidity
Biodiversity
In the Kaipara Catchment there has been a huge decline in the flora and fauna. The reason for this is that biodiversity loss is being driven by private property rights and they override wildlife protection. There has been a huge decline in indigenous forests as they have been cut down and replaced by pine for economic purposes such as pine production. This has a flow on effect on the fauna such as birds, and reptiles that are present in the area. Once there habitats have been destroyed they migrate elsewhere. There has been a loss in micro-invertebrates within the main Kaipara River and also the small streams. This is due to the high sedimentation levels and poor water quality within the river and these small species cannot survive in such conditions. Forest loss has occurred due to the fact that pastoral and agricultural farming has increased over the years.
Current Management:
-The Royal Forest and Bird Protection Society set out rules of protecting our indigenous forest and birds.
-There are conservation management plans and strategies that are incorporated into the Regional and District Planning documents.
-Department of Conservation is trying to restore and protect the area.
-Rodney District Plan has a specific section on biodiversity that states to protect and preserve it.
-Resource Management Act is used as it states to “Protect and preserve the natural and physical environment”.
Future Management Regulatory:
-There needs to be a much better understanding on biodiversity and planning.
-There needs to be more emphasis on monitoring such as plan monitoring, consent monitoring, and state of the environment monitoring.
-Monitoring the number of micro-invertebrates in the river.
-Rodney District Council needs to create set guidelines on biodiversity and stick to it. Such as no cutting down native trees.
Future Management Non-Regulatory:
-provide incentives for the private property owners to plan indigenous plants which will attract different birds.
-re-vegetate along the banks of the river to attract more nesting places for birds and also it will stop erosion of the bank which in turn will allow micro-invertebrates to survive.
-educate the community about the importance of indigenous fauna and flora
Constraints:
- Not enough support from central government to help with the restoration of native fauna and flora in the area.
-Biodiversity loss is being driven by private ownership because the residence are destroying the indigenous vegetation and they may not want to stop doing that.
-Money is a major constraint as there isn’t a lot of funding for replanting.
-Hard to change the current situation due to human impact
Monitoring Indicators:
See what fauna and flora have adapted to the area that has been restored.
Count the number of micro-invertebrates are present in different areas.
