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The National State of the Environment report (Australian State of Environment Committee 2001) provides an approach for assessing land use pressures and effects on inland waters by classifying land uses and management practices in relation to the land use pressures:
The effects of these land uses and management practices on the State's surface and groundwaters must be considered, because of the intrinsic links between inland waters and their catchments. The effects have significant implications for the State's environment, society and economy. The effects of water extraction and storage may include:
Land use activities within catchments can result in:
Essentially the impacts of water extraction and storage and catchment land use activities can result in changes to the quality and quantity of Tasmania's inland waters across varying spatial and temporal scales. Both water quantity and quality are essential requirements for the habitat and life cycle requirements of Tasmania's inland aquatic flora and fauna communities and are important for human use and consumption. More detail about the effects of water extraction and storage and catchment land use activities on inland waters in Tasmania is provided in the 'Assessing and Measuring' section of this report. Many of the implications of water extraction and storage and catchment land use activities on Tasmania's inland waters are discussed in the 'Assessing and measuring the current situation' section within this Issue Report. Further information on how these have influenced the condition of the State's waters can be accessed through the following links to relevant issue reports: Tasmania has an extensive network of rivers and streams, thousands of natural and artificial lakes, hundreds of swamps and wetlands, and significant groundwater resources. Reductions in water quality, changes to water quantity and a decline in aquatic health, generally reflect the results of water extraction and storage and more broadly, land use activities undertaken within both surface and groundwater catchments. This issue, therefore, is mainly orientated around areas of the State with significant urban, industrial or agricultural development, and other areas of land clearance or native vegetation conversion. Assessing and measuring the current situation Assessing the effects of water storage and extraction and catchment land use activities on inland waters in Tasmania can be achieved by directly measuring the condition or state of inland waters (e.g. water quality exceedences), as well as measuring the known pressures (e.g. land clearance) on inland waters. The assessment of land use pressures is important, particularly as it is generally the monitoring and adaptation of the land use practices that can be the most effective way in which to avert their impacts upon inland waters. The types of pressures and effects that water extraction and storage, and catchment land use activities have on the water quantity and quality of Tasmania's inland waters are described below. There is some limited information available in Tasmania that can support various indicators of these pressures and effects on inland waters. A brief summary of the types of assessments and measures being applied in the State is provided here, with further detail in the 'Indicators' section below and through links provided in the text to other relevant issue reports within the SoE Report. Water extraction and storage-implications for water quantity Water development in the form of extraction and storages has occurred to meet growing demands by society for greater quantities and more reliable sources of water. This pressure on Tasmania's water resources has implications for the environment and the long-term water supply for human use. Water extraction and storage (including the infrastructure-e.g. dams, weirs, etc) can lead to alterations in natural river flows, groundwater levels and catchment hydrological processes in general. Each of these alterations to water quantity can affect the geomorphology (e.g. river structure and karst), habitat and aquatic ecosystem health (including flora and fauna) of a water system. Downstream availability of water for different types of human use may also be a problem. Water storages (e.g. reservoirs, dams, weirs) or regulated rivers alter the natural flow regime through changes in the magnitude, timing and duration of flows. They commonly reduce downstream average annual discharge, lower the seasonal flow variability, reduce flood size, and release unnatural pulses of water (Petts 1984). These effects, however, vary between different types, sizes and number of storages along a river (e.g. the effects may be enhanced with bigger water storages, while cumulative effects result from numerous dams along a river). Recent mainland studies (e.g. ICAM/SKM 1999) have indicated that off-stream farm dams can also have significant effects on catchment streamflow, such as increasing the length and frequency of periods of low or no flow in downstream streams. Similar to in-stream dams, these effects vary between different types, sizes and number of storages within a catchment (e.g. the cumulative effects resulting from numerous dams within a catchment may enhance periods of low or no flow downstream). Despite their important role in irrigation and water supply, regulating structures such as weirs can have considerable impact upon in-stream physical and biological environments (Walker 2000 and Bednarek 2001). Under natural conditions variations in water surface level and associated wetting and drying regimes of stream banks are important for the creation of channel form (e.g. pools, riffles, bars, benches) and habitat attributes (e.g. large woody debris transport and placement). Regulation can result in an accelerated rate of scour at the base of the bank that, in turn, may lead to bank slumping. Reduced flood flows can also have geomorphological impacts upon adjacent wetlands that may be dependent upon flood flows for inundation. The flow of a river or the inundation cycle of a wetland is also fundamental to its ecosystem, providing habitat for many organisms and supporting a variety of critical ecological processes. An aquatic ecosystem can be threatened when significant alterations to the natural flow regime occur. The relative threat is dependent upon the ecosystem being affected. For example, many ecosystems are threatened by an overall reduction in the magnitude of flows, while some systems are more susceptible to the unseasonal timing of the flow, or higher flows at certain periods (e.g. for irrigation extraction). In addition, constant flows can be detrimental to species that rely on a variable flow regime as triggers in their life cycle, for example recruitment in native fish can be affected by a constant flow regime. Overall there is recognition that the health of Tasmania's inland waters is intricately linked to the quantity of water that they receive. In-stream regulating structures such as dams, weirs and barrages can also act as a physical barrier to native fish movement and affect other aquatic organisms such as macroinvertebrates and larger crustaceans. If migratory movements of species are limited or prevented as a result of artificial barriers such as weirs, culverts and fords, the affected species may eventually become excluded from the entire waterway or part thereof, therefore impacting upon species abundance and overall biodiversity. The maintenance of a permanent body of water in an in-stream dam or weir pool, combined with clearance of remnant vegetation, can result in the raising of groundwater levels, and the creation of permanent hydrologic connections to adjacent wetlands. This can have an ecological impact upon the flora and fauna of that wetland if, under unregulated conditions, the wetland had a natural wetting and drying cycle. Shallow groundwater tables in adjacent floodplains to weir pools or in-stream dams can also restrict the root zone of riparian vegetation and make trees vulnerable to falling during high winds as they don't have the root zone to stabilise them. Falling groundwater levels can be indicative of over-extraction and could result in a decrease in baseflow in rivers, streams and wetlands, and contribute to salinisation. A summary of possible causes for and effects of rising or falling groundwater levels or pressure is available. Water extraction and storage - implications for water quality The impacts of water extraction and storage on water quantity can also lead to the alteration of the water quality of Tasmania's water resources. Water quality may be affected through changes in, for example, the natural sediment and nutrient fluctuation, turbidity and siltation levels, temperature, dissolved oxygen and salinity. The accumulation of pollutants (e.g. within a storage) can also contribute to reducing the water quality of a water system. Such alterations to water quality can affect ecosystem health and cause problems for human use and consumption. Artificial low flows resulting from, e.g. in-stream dams, river regulation, or a large off-stream storage capacity within a catchment, can potentially cause stagnation and a build up of sediments, nutrients and pollutants (e.g. heavy metals) within a waterway that are normally flushed. Accumulated sediments can result in increased levels of turbidity and siltation, as well has being a common source of nutrients. Additional nutrients may lead to eutrophication and algal blooms (e.g. blue-green algae outbreaks), which may impact on freshwater-dependent ecosystems or industries (e.g.natural ecosystems, recreational fishing, fish farms) and reduce water quality for drinking, recreational and agricultural purposes. The thermal and physical conditions within in-stream dams or weir pools more closely resemble a lake than a river environment. There is limited mixing of water as a result of reduced velocities of flow and this can contribute to temperature stratification with cooler temperatures maintained at lower depths, while the surface layers in the dam heat up. Water released downstream from the dam is often released through structures well below the dam's surface, therefore tapping the cold water layer. When these releases fall outside the 20th to 80th percentile of natural stream temperatures, cold water pollution is deemed to have occurred (ANZECC and ARMCANZ 2000). The ecological impacts of cold water releases can include: Thermal stratification can favour many exotic species such as Carp (Cyprinus carpio) as they are able to utilise lower water temperatures for breeding and the replacement of native 'warm water' fish species with 'cold water' species is a common occurrence downstream of large impoundments (Koehn et al. 1995). Temperature changes can also severely affect the composition of macroinvertebrate communities. The timing or occurrence of particular life history stages may be altered by very small changes in temperature. Thermal stratification can also lead to decreased dissolved oxygen in lower water layers and leaching of nutrients and accumulated pollutants from sediments. Reduced dissolved oxygen and the release of pollutants can affect aquatic fauna (e.g. fish), and there is potential for algal bloom development from the increased nutrient concentrations. An area that is less known about in Tasmania is the potential impacts of storage dams and groundwater abstraction on the levels and residence times of groundwater, and the resulting changes to groundwater quality (e.g. increased salinity from increased groundwater levels and residence time in relation to storage dams) (see Groundwater Issue Report). Water extraction and storage-assessing and measuring The following information outlines a number of programs being undertaken throughout Tasmania that facilitate the assessment and measurement of the impacts of water extraction and storage upon inland waterways. Information contained in this section includes linkages to more detailed information in the 'Indicator' section of this Issue Report and other issue reports across the SoE Report. The number of dams and river structures across the State has been listed on the Water Information Management System (WIMS) database managed by Water Resources in DPIWE (see Water Quantity and Water Use Issue Report). However, the WIMS database does not account for all types of in-stream dams and other structures, and dam capacities. The actual numbers of off-stream dams (e.g. agricultural dams) may also be under-estimated. Therefore, the database does not provide a complete picture of in-stream and off-stream structures. The National Land and Water Resources Audit (NLWRA) has consolidated a large amount of information on Australia's surface water resources. Through the NLWRA process Tasmania was divided into a number of Surface Water Management Areas (SWMA) for the purposes of assessing current condition and as a tool for future sustainable management. The water availability, development status and water use of Tasmania's surface water resources in relation to sustainable water management have been assessed (NLWRA 2002, NLWRA 2001 and DPIWE 2001) and is reported in the Water Quantity and Water Use Issue Report and in the 'Indicator' section in this Issue. The sustainable water yield was not measured for 6 out of the 19 SWMAs, because estimates could not be finalised for Hydro Tasmania's catchments. At a finer scale than the SWMAs, the Department of Primary Industries, Water and Environment (DPIWE 2001) provides information on the occurrence of water restrictions, which is one of the few 'measures' available to determine if rivers/regions are under stress through water extraction at this scale in Tasmania (see Water Quantity and Water Use Issue Report). However, there is little known about the hydrology of smaller catchments in the State. The NLWRA has conducted an assessment of changes in irrigation extent and usage per SWMA in Tasmania (see Australian Natural Resource Atlas and the Water Quantity and Water Use Issue Report). It is difficult to relate any irrigation changes to impacts on Tasmanian water resources, however, because changes may be due to a number of factors including climate conditions, changing irrigation methods, and changes in the types and numbers of crops grown. Information on irrigation methods and their efficiency, including changes in these methods is limited. Some water quality monitoring is being conducted by Hydro Tasmania and DPIWE in relation to the possible impacts from in-stream dams (see the Water Quality Issue Report). The Inland Fisheries Institute with Natural Heritage Trust funding has also undertaken a significant water quality study of Lakes Sorell and Crescent as part of the Lakes Sorell and Crescent Rehabilitation Project. Aquatic health has also been assessed in some locations across the State in relation to impacts from water storage and extraction by DPIWE as part of the nationwide AUSRIVAS program (2001) and the State of Rivers Reporting program (see Aquatic Health). There is limited information on groundwater use in Tasmania. Some data are available through Mineral Resources Tasmania Web Site and the NLWRA (see Groundwater Issue Report). The NLWRA presents the first consolidated Statewide assessment of groundwater extraction and therefore provides some baseline information on the current state of groundwater resources in Tasmania. Further programs are required to examine groundwater flow requirements to support environmental needs and to determine a formal allocation system for environmental groundwater use. Indicators that have been included in this Issue Report that provide some 'measure' of the pressures and effects of water extraction and storage on inland waters include 'Water Use' and 'Exceedences of Water Quality Guidelines: Inland Waters' (see 'Indicator' section). There is a lack of information available at a Statewide level to enable indicator measures of environmental flow objectives and water pricing. Catchment land use activities-implications for water quantity Land use activities within catchments such as urbanisation, forestry, agriculture, mining and other industry can each lead to impacts on water quantity in Tasmania's inland waters. Past and present actions associated with these activities including land clearance and changes in catchment and riparian vegetation, irrigation, and the physical alteration of drainage systems (e.g. channelisation), can result in changes to groundwater levels, surface water flows, and catchment hydrological processes in general. The introduction of pest plant species may also affect surface water flows and hydrological processes. Such alterations to water quantity can have follow-on effects that may impact the geomorphology, habitat and ecosystem health of a water system, as well as potentially cause problems for human water use and consumption. Land clearance and the replacement of deep-rooted native vegetation with shallow-rooted short-lived pasture and crop species within a catchment can increase the amount of water filtering into groundwater systems. In some areas, this has caused rises in groundwater leading to dryland salinity (see 'Catchment land use activities-implications for water quality' section below and Salinity Issue Report) and water logging. Irrigation also has the potential to increase groundwater levels and dryland salinity in a similar manner. Land clearance and changes in vegetation (e.g. native forest conversion) can also affect other catchment hydrological processes (e.g. the groundwater recharge dynamics of surface rivers, streams and wetlands). The hydrological effects of forest change are highly variable, however, and depend upon a number of catchment characteristics. As such it is difficult for hydrologists to forecast the change in water yield resulting from altered forest cover (Vertessy et al. 1998). Mainland studies indicate that the conversion of native forest vegetation to plantation forests such as pine can alter catchment water balances by changing the amount and timing of catchment streamflow (Vertessy 1999). The amount of water available within a forest system depends on evapotranspiration rates and the leaf area and rainfall interception capacity. Pines (Pinus radiata) have a higher leaf area index and greater rainfall interception (Vertessy 1999). Plantations of either pines or eucalypts (when replacing pasture) will result in a reduction in streamflow due to increases in evapotranspiration and rainfall interception. The main changes to water yields during a plantation's life-cycle include (Vertessy 1999): Effects upon catchment hydrology of long-term plantation rotations within the same area are not known in Tasmania. The effects of land clearance and vegetation change (e.g. through forestry land use changes) on catchment hydrology could result in downstream consequences for potential power generation, irrigation and town water requirements (Fahey and Jackson 1997). The clearance of catchment and riparian vegetation can increase surface water run-off into inland waterways, increasing their flows above natural conditions. For example, urbanisation has resulted in changes to the surfaces within catchments from 'soft' vegetative surfaces to 'hard' impervious surfaces such as roads, buildings and roofs. The effect is higher volumes of run-off combined with a reduction in the time for run-off to occur and reach waterways, compared to an undisturbed catchment experiencing the same rainfall. This can cause intensive downstream flooding of waterways, and an altered flood regime. The changes in catchment hydrology (e.g. river flows, groundwater levels and recharge dynamics) from catchment land use activities, can have broadly similar effects upon the geomorphology, habitat and ecosystem health of a water system as previously discussed in the 'Water extraction and storage-implications for water quantity' section above. The physical alteration of surface drainage systems (e.g. channelisation and clearance of large woody debris out of waterways) can increase the flow velocity in many of Tasmania's inland waterways. In addition to the effects upon flow, important habitat for fauna species such as the giant freshwater lobster (Astacopsis gouldi) can be inadvertently disturbed or removed. Wetland drainage also alters the natural wetting and drying cycle often associated with wetlands, which can have significant effects upon the wetland flora and fauna dependent on this cycle. The introduction of pest plant species, such as willow trees, can have significant impacts on water quantity, including, altered run-off patterns due to lack of understorey, reduced low flows, and reduced drainage. These can lead to further problems for water quality, which are discussed in the section below. Catchment land use activities-implications for water quality Similar to water quantity, in many parts of Tasmania the water quality of the State's inland waters has been influenced by catchment land use activities such as urbanisation, forestry, agriculture and mining and other industry. The pressures from these activities include: These pressures have lead to many impacts upon water quality in associated water systems. Alterations in water quality can have significant effects upon ecosystem health and problems for human use and consumption. Land clearance and changes in catchment vegetation coverage types have been linked to increases in dryland salinity (see Salinity Issue Report and above discussion). Increased groundwater levels resulting from changes in the vegetation can lead to groundwater salinisation and potential inflow of this saline water into rivers, streams and wetlands. Run-off from saline land also contains higher salt loads than would naturally be discharged into inland waterways as a result of overland flow. Salinity problems may also be induced through irrigation. Any increases in the salinity of inland waters can cause significant stress on aquatic flora and fauna, riparian vegetation and result in fundamental changes in the water chemistry. The species composition of saline inland waters is significantly altered from that which would occur under natural conditions. Species which are more salt tolerant have a competitive advantage and can dominate over less salt-tolerant species. There is also potential for salinity problems to affect drinking water supplies and agricultural production (crop yields and types). The clearance of deep-rooted riparian vegetation can also contribute to increased water tables and groundwater salinity levels. Other impacts upon the water quality of inland waters associated with the removal of riparian vegetation for various land use activities (e.g. for stock access to waterways) include:
The Health and Extent of Native Riparian Vegetation Issue Report, provides further information. Each of these impacts on water quality can also lead to further impacts upon the habitat and ecosystems of inland waters, and potential problems for human use and consumption. Many fertilisers, pesticides, herbicides and other chemicals are used particularly as part of agricultural and forestry activities, but are also used in urban areas. The use of fertilisers is often linked to excess nutrients entering waters, disrupting the natural balance within the ecosystem and increased growth of algae and algal blooms. Many pesticides, herbicides and other chemicals used can be toxic to organisms other than those targeted. Their accumulation in the environment and subsequently the food and produce harvested from it, can have significant impacts on people, plants and animals (NSW EPA 2000). Physical alterations to drainage systems (e.g. channelisation, de-snagging and wetland drainage) can have detrimental effects upon water quality through increasing flow rates and therefore subsequently increasing erosion and sedimentation. Where alterations to drainage flows are conducted in areas containing acid sulphate soils, waterways can be subject to increased acidity and heavy metal pollution (see Disturbance of Acid Sulphate Soils Issue Report). Heavy metal pollution can have serious effects on the aquatic ecosystem and can make water unsuitable for human consumption. Some animals such as oysters can also 'bioaccumulate' metals, making them unsafe to eat. Pollution inputs from past mining practices in Tasmania have had a significant impact upon surface and groundwaters mainly in the form of acidification, heavy metal contamination, turbidity and siltation. Specific contaminants from mining include acid mine drainage and suspended solids (see Acid Mine Drainage and Water Quality Issue Reports). There are numerous ecological consequences of these pollutants that continue to have an impact, such as elevated levels of trace heavy metals being toxic to aquatic life and potentially resulting in fish kills. Further sources of pollutants into the State's inland waters include wastewater discharges from sewage treatment plants and intensive animal enterprises that can contribute nutrients (phosphate, ammonia, nitrite and nitrate), organic matter (measured as biochemical oxygen demand), and suspended solids. Water contaminants in surface and groundwaters are also associated with stormwater drainage, discharges from landfill sites, leaking fuel storage tanks and manufacturing plants. Polluted stormwater entering waterways can lead to: Introduced pest plant and animal species in Tasmania may also affect the water quality of inland waters. For example, willow trees within a waterway can influence run-off, stream flow and drainage processes, potentially leading to soil erosion, reduced dissolved oxygen levels, and increased sedimentation and organic loads (and therefore, increased nutrient levels). Although any one of these problems may originate from catchment land use activities, effects upon water quality can extend to estuary and marine environments (see the Coastal, Estuarine and Marine Chapter). Similarly the time-lags before any of the above effects manifest themselves range from almost immediately (e.g. a change in water chemistry due to a chemical discharge or spill into a river), to decades (e.g. water salinisation through dryland salinity), or even hundreds of years (e.g. reduced groundwater level in an aquifer). Other influences such as site geology and stream length can also have an influence over water quality pollution. A summary of some of the pathways for contaminants to enter waterways and potentially cause pollution is shown in the table. Catchment land use activities-assessing and measuring A number of programs and projects are being undertaken throughout Tasmania that facilitate the assessment and measurement of some of the land use activities and their impacts upon the State's inland waters. However, there are also significant gaps apparent in some areas of monitoring and assessment. This section provides a summary of some of the programs and gaps, with linkages to more detailed information in the 'Indicator' section of this Issue Report and other issue reports across the SoE Report. Fundamental to assessing and measuring the impacts of catchment land use activities upon the State's water resources is a classification of land use and land use change (e.g. land clearance). The Tasmanian Land Use Mapping Project funded by the Natural Heritage Trust, completed 200 maps of land use for the State in March 2003. This recent completion of the project has meant that the maps could not be used in this Issue Report, but will be incorporated as part of the future work program for the SoE Report. Alternatively, the SoE Report provides information based on a land use classification developed by Baxter and Russell (1994), as outlined in the National State of the Environment Report (Australian State of Environment Committee 2001). The classification provides an indication of the increasing intensity of land use that approximates the degree of transformation from an initial, 'unmodified' state, which is further described within the Land Tenure, Land Use and Land Cover Issue Report. Similar to the classification of changes in land use, assessing land cover change is another useful measure for assisting with the identification and monitoring of possible pressures upon inland waters across the State. Catchment land cover change has also been estimated by measuring woody vegetation change through satellite imagery, and by calculating the percentage area of a catchment under modified land cover classes (see Land Tenure, Land Use and Land Cover Issue Report). However, it is important to consider that not all woody vegetation loss may be 'bad' for the environment and not all woody gains may necessarily be 'good'. Alternatively, urban and suburban uses represent a substantial modification of land cover with significant flow-on impacts for catchment condition. There are five catchments within Tasmania with a high percentage area under urban and suburban land uses. Direct information on the extent of deep-rooted vegetation to indicate potential effects upon catchment hydrology and water quality is currently unavailable, but may be accessible with the completion of the TASVEG mapping project (DPIWE 2000) and Australian Greenhouse Office land cover reports (AGO 2002). Estimates of native vegetation clearance, however, have been conducted at different levels for Tasmania-Statewide (e.g. CARSAG APU), bioregion (e.g. FPB and Landsat imagery analysis) and vegetation type (FPB). These estimates are also limited due to inadequate information available on baseline data (i.e. pre-European vegetation cover) (see 'Indicator' section within this Issue Report). The area of riparian zone disturbance has been estimated from data obtained through the Wild Rivers Project (1998), and a more recent assessment of riparian condition by bioregion was conducted as part of the NLWRA (Dunn 2002) (see Health and Extent of Native Riparian Vegetation). There is still uncertainty, however, about the amount of change and the extent of reservation of riparian vegetation, due to a general lack of information on native riparian vegetation species and communities, including Statewide mapping. The potential consequences for inland water resources as a result of dryland salinity from vegetation clearance and conversion, have been recognised through the comprehensive assessment of the extent and impacts of dryland salinity in Tasmania by Bastick and Walker (2000) (see Salinity Issue Report). There has been some surface water salinity testing in half of the 48 planning and management catchment areas in the State. The ability to report on areas of rising watertables and groundwater salinity is restricted, however, due to the limited groundwater monitoring systems suitable for assessing Statewide groundwater levels and trends. Data from 2,903 production bores across the State provide some information on groundwater level (Mineral Resources of Tasmania), but do not represent a complete picture of Tasmania's hydrogeology (see Groundwater and Water Quality Issue Reports). Limited data are available for trends in watertable depth from salt affected areas of Longford-Cressy and the Coal River Valley. The NLWRA (NLWRA 2001) also provides a large body of information on Tasmania's groundwater resource (see 'Indicator' section below). There is uncertainty, however, as to whether measured salinity levels through these sources are background levels or have been influenced by anthropogenic pollution. Research into the 'Effects of Waste Disposal on Tasmanian Groundwater Quality' has been undertaken by Ezzy (2002) and is reported upon in the Groundwater and Solid Waste Issue Reports. This study of the effects of waste disposal on groundwater quality identified groundwater contamination at six of the ten sites that were investigated. If this percentage is extrapolated to the 176 sites identified around the State, potentially up to 100 waste disposal sites may have contaminated groundwater (Ezzy 2002). The actual number of past and present landfill sites across Tasmania is not known. The problem of soil erosion resulting from land use activities (e.g. vegetation clearance or physical alteration of a drainage system) that can lead to sediment entering waterways, has not been fully addressed in Tasmania. A study of private freehold land (Grice 1995) provided good information on soil erosion for the previous SoE Report, but there has been little additional information since that time (see Soil Erosion Issue Report). Cotching and Sims (2000), in a study in the north-west of the State, determined that intensively cropped catchments resulted in off-site environmental degradation involving high stream turbidity levels and suspended sediment loads. The highest turbidity levels came from run-off flowing over fallowed paddocks (see Soil Erosion Issue Report). The Normalised Difference Vegetation Index, obtained from Landsat remote sensing data, has been applied in estimating the potential areas of soil erosion across Tasmania. The south-west and Central Plateau are shown as areas susceptible to erosion as well as the intensively farmed areas in the north-west and Midlands (see Soil Erosion Issue Report). The monitoring of soil erosion is also important with respect to the potential for land use activities (e.g. drainage works) to exacerbate the disturbance of acid sulphate soils, risking acidification of the receiving waters (see Disturbance of Acid Sulphate Soils Issue Report). Understanding the scope of the problem of acid sulphate soils has improved considerably due to the survey, mapping and report prepared on acid sulphate soils in Tasmania by Shivaraj Gurung (Gurung 2001). However, insufficient information is available from the survey to identify priority areas with the potential to result in acid drainage from disturbance or land development activity. The environmental impacts from existing impacts are also unknown. There is at present no monitoring and assessment of land use changes in areas hosting acid sulphate soils. These areas are not systematically monitored for disturbance from land management activities. However, the recent preparation of a land use map of Tasmania could be applied to support this work in the future. The acidification of water resources is also considered through assessments of acid mine drainage in Tasmania. However, although it is recognised that new information has been published on acid mine drainage in Tasmania, it was unable to be reported on in this SoE Report within the time available (see Acid Mine Drainage Issue Report). It is hoped that it will be included in the future as part of the on-going work program. Wastewater treatment plant discharges have traditionally been a significant source of pollution into inland waterways. Historically it is estimated that approximately 11% of wastewater discharges have been into inland waterways in Tasmania (Dettrick, pers comm, 2003). The performance of wastewater treatment plants that discharge into inland waters is monitored through a DPIWE database. Monitoring data collected by Local Government and industry are collated within the database. The National Pollutant Inventory (NPI) provides data on substance emissions into the State's waterways and is one tool for measuring changes in emission substances between reporting years. Variations between reporting years in the reporting requirements and which facilities actually report, make it difficult at this stage to report on the impacts of pollution from activities on the State's inland waterways. NPI reporting has become mandatory through Section 43 of EMPCA and as such, data generated through NPI reporting in future may prove to be a valuable tool for assessing some pollution impacts upon inland waterways. The effects of land use activities upon inland waters are also measured through various programs that provide an indication of the current state of water quality within Tasmania's inland waterways and wetlands. Exceedences of the national surface water quality guidelines (ANZECC 2000) has been a key assessment for Tasmania based on available bacterial and chemical monitoring data (e.g. see the 'Indicator' section within this Issue Report and the Water Quality Issue Report). Data from the expanded network of water quality monitoring sites were not available in time to include within this SoE Report. The Waterwatch monitoring network also provides a set of regionally-based programs covering many areas across the State that provide information on water quality in relation to catchment land use activities. Information on how land use effects may well be influencing drinking water quality is also available through the number of boil water alerts issued by the local government authorities or the Department of Health and Human Services (see Drinking Water Quality Issue Report). Alert numbers in relation to bacterial problems in drinking water, often associated with land use activities, have been monitored between 1998 and 2000. The performance of the State's drinking water supply systems is reported upon annually in the Director of Public Health's annual report. Non-compliance can be attributed to a number of variables, but boil water alerts can be a useful indicator of the quality of the State's inland waterways. The effects of catchment land use activities (and associated entry of pollutants into waterways) upon aquatic flora and fauna communities are more difficult to measure than the effects on physical, chemical, and bacterial aspects of water quality. However, data on aquatic health have become available since the last SoE Report through the Tasmanian Program component of the Australian River Assessment System (AUSRIVAS) (see Aquatic Health Issue Report), the State of the Rivers reporting, current catchment and Rivercare Plans, and will become available through the proposed Natural Resource Management Plans. The use of AUSRIVAS in Tasmania has generated data on the ecological health of many of the State's waterways through sampling of macroinvertebrate communities (see Aquatic Health Issue Report). Data collected have provided useful baseline assessments of the State's waterways through the use of consistent methodologies. Continued macroinvertebrate monitoring of these river systems will, in the future, assist in the identification of links between land use effects and their resultant impacts upon river health. The National Land and Water Resources Audit has published The Assessment of River Condition (ARC), an Audit of the Ecological Condition of Australian Rivers, 2001; and the Australian Catchment, River and Estuary Assessment 2002. These documents include information on river condition at the reach and basin scales across Tasmania (see Aquatic Health Issue Report). State of Rivers reporting provides information on the condition of waterways and water resources at the catchment level. These reports also identify the likely causes of any impacts with respect to land use practices within the catchments. The primary focus to date has been on catchments subject to forestry, agriculture and river regulation. Catchments that have been studied are centred around the north-east of the State, with reports soon to be released on some catchments in the north-west and south-east of the State. Currently, the limited number of catchments that have been reported on hinders a Statewide assessment of land use impacts on waterways and water resources by catchment. There is no apparent information available on the nutrient loads within inland waters that can lead to algal blooms and Tasmania does not currently have a program specifically targeting the monitoring of inland waterways for algal bloom outbreaks. However, water quality monitoring undertaken at local and regional scales by a variety of organizations provides data of relevance to identify outbreaks when they do occur. The Rivers and Water Supply Commission, however, regularly monitors the Craigbourne Dam for algal blooms. Information is also available on the number and type of pest plant and animal species there are in Tasmania (Plant Pests (Weeds) and Diseases and Animal Pests Issue Reports). However, little monitoring of the direct impacts these have upon water quality in Tasmanian inland waterways has been able to be reported on within this SoE Report, although there is information available for some species. For example, information on the impacts of willow trees is available through the Rivercare Unit within the Department of Primary Industries, Water and Environment. There is some limited information regarding fish kills as a result of altered water quality (e.g. pollution) available through the Environment Division of DPIWE, but due to time constraints, comment on the data could not be provided in this SoE Report. A comprehensive assessment of what monitoring there is for pesticide and herbicide exposure or pollution of inland waters and aquatic ecosystems in Tasmania was also unable to be completed for this SoE Report. It is hoped that any available information will be presented in the future as part of the ongoing work program. Indicators that have been included in this Issue Report that provide some 'measure' of the pressures and effects of catchment land use activities on inland waters include 'Water Use', 'Native Vegetation Clearing', 'Exceedences of Water Quality Guidelines: Inland Waters', and 'Groundwater Salinity' (see 'Indicator' section). |
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Water Use - at a glance
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Native Vegetation Clearing - at a glance
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Exceedences of Water Quality Guidelines: Inland Waters - at a glance
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Groundwater Salinity - at a glance
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There have been a number of management responses since the last SoE Report that are relevant to land use effects upon inland waters, many of which are also related to other issues described particularly within the Inland Waters and Wetlands, Land and Biodiversity Chapters. Some of the key responses, including water management legislation, policies and strategies, as well as other related programs, projects, frameworks and initiatives are listed below. Water management legislation Various key pieces of legislation have been enacted since the last SoE Report, which are relevant to the management of the State's water resources, including land use effects. These are listed below.
Water management policies and strategies A number of policies and strategies have been developed since the last SoE Report, which help to monitor, regulate and manage the State's inland waters, including land use effects. These are listed below.
Other Programs, Projects, Frameworks and Initiatives A range of other programs, projects, frameworks and initiatives have been undertaken since the last SoE Report that have contributed towards improving the management and use of Tasmania's inland waters, and helped to control some of the catchment land use pressures on water resources. Motivating forces have included both national and Statewide directives and participants have included all levels of government, private industry and the community. A summary is provided below of relevant programs, projects, frameworks and initiatives at a general level; a list of specific guidelines and codes; and management responses relating more specifically to river management, water pricing, allocation and metering, landcover and vegetation management. General
Guidelines and codes
River management
Water pricing, allocation and measuring
Modelling and monitoring
Land cover and vegetation management
This issue report has highlighted the significant impacts of water storage and extraction and catchment land use activities upon the State's inland waterways. Impacts have been broadly separated into those effecting water quantity and water quality in this report, but as has also been highlighted, 'flow-on' effects can also have significant environmental impacts upon the geomorphology (physical form and processes), hydrological processes, and aquatic ecosystem health of a water system. Impacts may also arise that cause problems for human use and consumption. While a range of programs and initiatives since the last SoE report have provided data on the condition of the State's inland waterways, significant changes to State legislation and policies will also have positive benefits for future management. Generally there is increasingly greater community ownership and corporate acceptance of everyone's role and responsibility to effectively plan for and manage catchment health. The following are some of the overall directions that have been identified as supporting management of land use pressures and their impacts upon inland waters in Tasmania. Irrigation
Dams
River Structures
Native Vegetation
Catchment/NRM Management
Urban Point-Source Pollutant Inputs
Tasmania Together and the RMPS Relevant Tasmania Together goals and standards for 'Inland Waters and Wetlands' are listed in the linked file. The Tasmania Together Progress Board reported on progress toward targets for benchmarks set (Tasmania Together Progress Board 2003). Indicators, targets and baseline data are available in the latest Progress Report June 2003. Further information, including progress report updates, is available from Tasmania Together. Involvement of the community, and the fair and orderly use of resources are also fundamental principles of the RMPS. The RMPS objectives have been developed to advance the principles of sustainable development.
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Contact the Commission on:
email: soe@justice.tas.gov.au Phone: (03) 6233 2795 (within Australia) Fax: (03) 6233 5400 (within Australia) Or mail to: RPDC, GPO Box 1691, Hobart, TAS, 7001, Australia
Last Modified: 14 Dec 2006
URL: http://soer.justice.tas.gov.au/2003/ilw/3/issue/96/index.php
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