In December 2015 the TEER Program launched the TEER Water Quality Improvement Plan. This Plan will be the blueprint for NRM North and TEER to work together along with the community and key stakeholders to manage water quality throughout the TEER catchment. The Executive Summary is provided below along with a link to download a full copy of the Plan.
The Tamar Estuary and Esk Rivers (TEER) catchment area covers 10,000km2 (approximately 15 percent of Tasmania). It supports urbanised areas, agricultural activities, industrial operations and recreational pursuits as well as having rich and diverse aquatic ecosystems. The estuary supports a diverse range of use and environmental values, including a large industrial area at Bell Bay, salmon farming operation, fishing, swimming, tourist boats and highly valued waterfront commercial and residential areas.
This Water Quality Improvement Plan (WQIP) has been developed for the greater Tamar Estuary and Esk Rivers (TEER) catchment area to:
- Provide a comprehensive whole-of-catchment picture of water quality in the Tamar River estuary and its tributaries;
- Develop an understanding of the drivers of any water quality issues and the levers that can be used to address these; and
- Identify priority activities to address water quality issues.
It is recognised that the WQIP will need to be implemented by a range of key stakeholders for water quality improvement so catchment stakeholders have been engaged throughout its development. This plan aims to provide direction to all catchment stakeholders on the role they can play in protecting and improving water quality in the Tamar Estuary and Esk Rivers catchments. It provides a framework and processes to report on progression towards achieving these targets and for updating them. Development of the plan has involved substantial consultation and engagement with the community and key stakeholders where those engaged could provide suggestions and feedback on the direction and content of the WQIP. Stakeholders were engaged through community forums, key stakeholder workshops, presentations to councils and industry, one-on-one meetings, emails and the TEER Program committees.
Current Loads, Condition and Sources of Pollutants
A major component of the TEER WQIP has been the development of a computer based decision support system, the TEER CAPER DSS, which allows the potential impacts of a range of management actions and possible land use changes on catchment loads and estuary water quality to be modelled. This DSS has been used throughout the plan to develop understanding of current sources of pollution, as well as the potential impacts of adoption of best management practice, dairy expansion and urban development under the Greater Launceston Plan. Unless otherwise stated, all loads, concentrations and estimated impacts in the plan are derived from this DSS.
Pollutant inputs into the Tamar River estuary are from both diffuse and point sources. Diffuse sources are pollutant loads carried by rainfall runoff from the land surfaces. In the greater TEER catchment, point sources include sewage treatment plants (STP), combined system overflows (CSO) from Launceston and aquaculture. Combined system overflows refer to discharges of a mix of sewage and urban stormwater that occur during high flow events from the combined sewage and stormwater system that services Launceston. At other times the combined sewage and stormwater is directed to the Ti Tree bend STP and is treated before being discharged to the estuary.
Diffuse sources are the dominant supply of flows and pollutants to the Tamar River estuary:
- Close to 100% of the flow and TSS loads can be attributed to diffuse sources with a very small proportion of loads coming from point sources;
- For Total Nitrogen (TN), diffuse sources contribute approximately 70% of the total load with STPs and aquaculture making up the majority of remaining portion (22% and 6% respectively);
- For Total Phosphorous (TP), diffuse sources contribute to a lesser extent but are still a main source (~55%) of loads. STPs contribute approximately 35% and aquaculture 7% of loads, with a marginal portion (<1%) resulting from CSO; and
- Enterococci loads result mainly from diffuse sources (70%) with CSO contributing approximately 26% and STPs 4%.
Dominant land uses in the greater TEER catchment by land area are greenspace (~25%), grazing (~45%) and native production forest (~20%) with other land uses covering less than 5% of the total land area each.
- Flows to the Tamar River estuary mainly come from native production forest (~45%) and greenspace (~35%) with smaller but significant contributions from grazing (~5%), hardwood plantations (~5%), softwood plantations (~5%) and urban areas (<5%). The dominance of green space and native production forests in producing flows is due to their position in the catchment. These land uses tend to occur in high slope, high rainfall areas at the top of the catchment and so produce high flows relative to their areas. This higher relative contribution of flows also leads to a greater contribution of pollutants than for well covered lower rainfall and slope areas, particularly in terms of TP and TSS.
- Grazing areas represent a significant source of other diffuse pollutants, in particular enterococci. They produce only 4% of flows due to the relatively low rainfall in these areas, but 32% of TN, 13% TP and 50% enterococci.
- Dairy is a very small land use in the catchment, covering less than 1% of the land area but is estimated to contribute approximately 2% of the TN, 4% of the TP and over 20% of the enterococci load in the catchment
- Urban areas are a very small land use in the catchment, covering only 1% of the land area. They contribute substantially higher proportions of the total load than this relative area, ranging from 14% to 18% of nutrient and sediment loads.
- Cropping areas are a small land use in the catchment (3%) and produce a very small proportion of total loads (approximately 1% of nutrients and sediments). This is generally due to the lower rainfall and flows that occurs in these areas.
Pressures and Opportunities
Land use change can present both a threat and an opportunity to improve water quality. Two major land use changes are foreseen over the next 20 years: dairy expansion and urban development.
Dairy is currently a relatively small land use in the catchment covering less than 1% of the land area, but it is expected that this area will double in the medium term bringing with it an additional herd of nearly 40,000 cows.
The Greater Launceston Plan has been developed to guide urban development through to 2036. This plan envisages an additional 3.7% of the catchment under urban development.
Both these land uses could potentially lead to declining water quality, were they to occur without substantial adoption of best management practices (BMP). However, modelling presented in the plan shows that if these changes occur with high levels of adoption of BMP, then water quality can be protected. In some cases it may even be possible to improve water quality. These results demonstrate the importance of sustainable development and using change as an opportunity to improve environmental outcomes.
Load and Condition Targets
The WQIP develops a set of load and condition targets for the catchment and its estuary. Targeted load reductions presented in the plan are:
- 17% for Total Nitrogen
- 27% for Total Phosphorous
- 6% for Total Suspended Solids
- 24% for Enterococci.
These targets are based on analysis assuming future land use and population and feasible levels of adoption of best management practices outlined in the plan. The estimated potential impact of the current preferred option (as at May 2015) for the Launceston Sewerage Improvement Plan is also included in the target. Decreases in nutrients are largely due to decreases in point source loads while decreases in TSS and enterococci occur largely as a result of decreases in diffuse source loads.
Achieving targeted load reductions scenarios can be expected to lead to:
- Very substantial decreases in nutrient concentrations in the upper estuary, with changes in Zone 1 (Launceston to Legana) of 40% to 50% and 50% to 60% for TN and TP respectively; Relative changes in nutrient concentration decrease down the estuary until decreases in Zone 5 (Kelso to Low Head) are effectively zero;
- Smaller and more even changes in TSS down the estuary, with decreases of 12% to 13% in summer and 15% to 18% in winter; and
- Slightly greater in Zone 1 but relatively constant decreases in enterococci concentrations down the estuary at approximately 20%.
The greater TEER catchment covers a substantial proportion of the state and contains a very broad ranges of land uses and other point sources. Managing such a complex system to improve water quality means it will require action by a very broad section of the community. Recommended management actions to reduce pollutant loads in the catchment are summarised below.
- A major focus of management should be on improving groundcover management in the identified high and medium priority catchments emphasising productivity benefits to landholders.
- In the short term emphasis should be placed on getting those landholders not yet meeting median groundcover levels to improve to this level before trying to improve the groundcover on other farms.
- Actions to reduce stock access to streams should focus on lower cost solutions that are flexible to physical constraints on specific farms as well as the needs and preferences of individual farmers:
- In subcatchments where riparian revegetation is not a priority action or where there are significant physical constraints, simply excluding stock from the stream with narrow fenced buffers should be considered.
- Options where the stock are restricted from entering most of the stream while still having limited hardened access for stock watering should be considered where this is the preference of the landholder to increase the adoption and lower the overall cost of this action.
- The specific design of fencing (e.g. single wire fencing versus six wires fences) should be determined on a case by case basis with landholders depending on their preferences so long as the fencing adequately restricts stock access to the stream.
- Incentives should focus on compensating for the initial costs of fencing out streams.
- The primary focus of efforts to revegetate the riparian zone in order to improve water quality (not including biodiversity outcomes) should be on establishing broadscale adoption of narrower buffers (5m). For example, it would be substantially more effective for a landholder to create a 200m long, 5m wide buffer than a 100m long 10m wide buffer. Where landholders are happy to establish wider buffers on the same length of stream this should be encouraged.
- Limited stock access to riparian zones (e.g. crash grazing to keep weeds out) should not be actively discouraged except in sensitive areas where excluding stock has been identified as a priority.
- Incentives for revegetating riparian zones should be developed to address both upfront and ongoing maintenance costs for at least the first five years of establishment.
- Sufficient effluent storage should be provided for on dairy farms. This storage should be well-designed and placed to ensure effluent can be applied to an adequate area of the farm, and storages are unlikely to leach or overflow effluent.
- Stock should be restricted from all streams on dairy farms wherever it is feasible. The inclusion of riparian buffers is likely to have very small benefits for water quality, however could be expected to benefit stream health through shading, increased bank stability, increased connectivity between vegetation remnants and provision of wildlife corridors. Creation of riparian buffers should be encouraged for these reasons, however the most important outcome for water quality in most cases is that stock are removed from streams. Therefore management should be flexible to allowing for this with either minimal or no buffers where this is likely to achieve greater adoption of this action.
- Irrigation scheduling should be managed to match irrigation to soil infiltration rates and pasture growth rates, and irrigation water reused to reduce drainage losses where possible.
- Drains need to be managed to minimise the transport of pollutants off the farm. This presents some practical challenges for dairy farmers and more consultation is needed to develop practical solutions for best management practice.
- Fertiliser management is a key action in reducing nutrient losses from cropping areas. Adoption of enhanced efficiency fertilisers should be strongly encouraged as these are likely to have the greatest impacts on nutrient runoff.
- While fertiliser management is very effective for reducing nutrient runoff, improving water quality off cropping areas will require a more holistic approach to ensure sediment loads are reduced. Both improving groundcover and adoption of riparian buffers can improve water quality in terms of sediment loads, as well as having impacts on nutrient runoff. Narrow riparian buffers can be expected to have greater impacts than low levels of adoption of groundcover management.
- While the magnitude of impacts of riparian buffers are similar to those of groundcover management, groundcover management is likely to be significantly more cost effective than riparian buffers which achieve load reductions at a much greater cost per kg than the other management options. This emphasises the importance of focusing on these low cost options even where they are not very effective at a catchment scale at reducing pollutant loads as they represent economically efficient options for achieving some improvements in water quality.
- Narrower buffers have the potential to improve water quality at a catchment scale by more than wider buffers where these are seen as more adoptable. A flexible approach should be used in encouraging farmers to adopt riparian buffers with an emphasis on broadscale adoption of narrow buffers likely to be more effective than lower adoption of wider buffers. Greater incentives for farmers willing to adopt wider buffers may need to be provided. An emphasis on adoption of narrow buffers in the short to medium term with long term encouragement to expand these to wider buffers is likely to be more effective in terms of producing water quality benefits.
- Focusing extension efforts to emphasise the long term benefits of buffers in reducing streambank erosion and subsequent losses of productive land are also expected to be more effective in increasing the adoption of buffers rather than a focus on the environmental benefits, given that the loss of productive land to buffers was identified as a key impediment to their adoption. Upfront incentives are required for any level of adoption of buffers. Maintenance incentives shouldn’t be a focus of programs given feedback that these are unlikely to have any impact on the adoption of buffers.
- The Forest Practices Code has been essential in improving water quality from production forest areas. It is important that this continues to be implemented in the future.
- Any areas that are pre-code in the catchment should be identified and, where possible, streamside reserves should be created in these areas prior to harvesting activities.
- Household scale WSUD devices such as plumbed in rainwater tanks and rain gardens should be encouraged using a combination of incentives and education focused on both environmental benefits and those directly experienced by the householder. In particular, these devices have the potential to be very effective at reducing overflows from the combined system in Launceston. It is recommended that City of Launceston and TasWater look to household scale devices such as these to assist in the management of combined system overflows.
- Large scale retrofit options are much more difficult to adopt broadly across the catchment. Opportunities should be sought by councils to identify ‘win-win’ opportunities for retrofitting WSUD – for example as a feature of green space areas, or by including quality management in existing flow detention systems.
- The Northern Stormwater Working Group should continue to work together to build the capacity of councils to develop and maintain large scale WSUD systems. Opportunities should be sought to fund ongoing maintenance of systems as this is a key impediment to broad scale retrofitting of WSUD identified by stakeholders.
- Councils should work proactively with the community, in particular local businesses, to identify small scale WSUD options that can be incorporated in refits and redevelopments, for example, to treat or reduce pollutant exports from commercial car parks and other hard surfaces.
- The NRM North Stormwater and Catchments Officer and councils should engage with the community and provide education about the sources of pollutants in urban areas, the role and advantages of WSUD and actions they can take to improve stormwater quality. This may include but not be limited to school education programs, workshops with developers and builders and education of home owners on the potential benefits of household scale WSUD options.
Urban expansion in the Greater Launceston area
- Water sensitive urban design should be broadly adopted in all new development areas where on-site constraints allow this to occur. Specific treatment trains will need to be designed subject to site specific constraints using expert assistance to ensure they provide the greatest benefit at the lowest cost. In order to be effective, WSUD devices need to be properly maintained.
- While erosion and sediment controls can be seen to have a relatively small impact catchment wide, they still represent an important action in preserving and improving water quality. These controls should be used and properly managed on all new development sites to minimise soil erosion from new developments.
- The Northern Tasmanian Stormwater Program should facilitate the development of templates for incorporating WSUD into Development Control Plans (DCPs) and Local Environment Plans (LEPs) for new developments to assist councils in their efforts to implement WSUD in future developments.
- TasWater should continue to investigate and refine options for improving sewage discharges in the Launceston area through the Launceston Sewerage Improvement Plan.
Heavy metals were raised by the community as a serious water quality concern. These were not modelled in the CAPER DSS because: diffuse loads are unlikely to be a major source of metals – these are likely to be sourced primarily from historic mine sites and urban areas; and insufficient information was available to model these at the catchment scale. Management options outlined in this plan for improving stormwater quality in terms of nutrients, sediments and pathogens are likely to also produce benefits in terms of reducing heavy metal exports from these areas. Resuspension of contaminated sediments in the estuary is also an issue that needs to be considered in managing pollution from metals.
- Historic mine sites leaching metals should be identified and where possible remediated to manage potential future discharges of heavy metals.
- The impacts of resuspension of contaminated sediments particularly in Zone 1 of the estuary should be investigated.
Scientific investigations, modelling and monitoring
This plan relies on the best available science to evaluate the potential benefits of proposed management actions. In collating and integrating this information, several weaknesses in current data and information were identified. Priorities for scientific investigations, modelling and monitoring to fill these gaps are:
- The TEER Tamar Estuary Ecosystem Health Assessment Program (EHAP) should continue to collect monitoring data for the Tamar River estuary. This data is essential to understanding the current condition of the estuary and identifying changes into the future.
- Further agricultural trials should be conducted to collect more locally sourced data on the impacts of management actions such as improvements to groundcover, impacts of fertiliser management and the impacts of drain management on dairy farms. Costing actions and identifying barriers to their adoption as part of these trials would also be useful.
- Collection of disaggregated data on the adoption of management actions. In most cases current rates of adoption of various management actions have been obtained either through state-wide surveys of land holders, or in discussion with key stakeholders. Very little data is collected to help quantify the current rates of adoption of specific management actions within regions of the state or catchments.
- Continued monitoring of pollutant concentrations and flows in stream systems in Tasmania is vital to understanding current condition and pressures on water quality in these systems. Monitoring of instream water quality, collocated with flow measurements should be continued and where possible expanded in areas where land use and management is likely to be having impacts. Ideally, other ecological monitoring such as AUSRIVAS data collection should be conducted where stream monitoring is available to allow linkages between water quality, flow and ecological health to be investigated.
- Monitoring of overflows from the combined system should be undertaken, including locations, flows and concentrations of overflows. These should be collected to allow comparison with rainfall and antecedent conditions.
- The Source Catchments model used to underpin the CAPER DSS has been calibrated to flow, nutrient and sediment data. Literature values are used to model enterococci loads. Ideally, the Source Catchments model will be refined and calibrated to include pathogens in future revisions.
The CAPER DSS should be updated as new information and modelling becomes available. This includes: revised versions of the Source Catchments and receiving water quality modelling; improved land use data; improved information on adoption rates of current practices; improved information on the effectiveness and costs of proposed management actions; and additional MUSIC modelling of WSUD options which are based on local data, including for household scale options such as raingardens and rainwater tanks.
For further information please contact:
Ph: 03 6333 7777