Water Quality Improvement Plan Douglas Shire Far North Queensland December 2006 Prepared by Douglas Shire Council, Far North Queensland Funds provided by Natural Heritage Trust, an Australian Government Initiative Compiled by Richard Davis, 2006 This publication may be cited as Richard Davis (2006): Douglas Shire Water Quality Improvement Plan. Douglas Shire Council Executive Summary Background 1. In late 2003 the Queensland and Australian Governments agreed to the Reef Water Quality Protection Plan (RWQPP), the objective of which is to halt and reverse the decline in water quality entering the Reef within 10 years. The RWQPP identifies nutrients and sediment as pollutants impacting on the inner reefs and seagrass areas of the Reef. Under the auspices of the RWQPP, Water Quality Improvement Plans (WQIPs) are being developed and implemented as the primary management vehicle for achieving long-term ecologically sustainable pollutant loads to Reef waters. 2. Douglas Shire was chosen for the initial WQIP and associated projects, which commenced prior to release of the RWQPP, because of (a) the willingness of the Douglas community to accept and adopt change to protect its environment, and (b) the relative small size of the Douglas catchments and therefore likelihood of demonstrating effective water quality management over a shorter period. 3. WQIPs, prepared through the NHT Coastal Catchments Initiative (CCI), are environmental management plans that codify and implement Australia’s National Water Quality Management Strategy (NWQMS) and the National Principles for the Provision of Water for Ecosystems. 4. This WQIP: • identifies current status of pollutant loads; • identifies the Environmental Values (EVs) of water bodies in Douglas Shire, and the Water Quality Objectives (WQOs) that will protect the EVs; and • commits to a set of management actions to achieve and maintain those EVs and WQOs, and which will take the first steps to reducing the current pollutant loads towards the achievement of sustainable pollutant loads. • derives estimates of pre-European and current loads of nutrients and sediments from Douglas Shire; • develops modelling and monitoring systems, and adaptive implementation strategies. 5. Implementation of the WQIP will require sustained partnerships between the Douglas Shire Council, FNQ NRM Ltd, relevant Queensland Government agencies, and industry bodies such as Canegrowers and Agforce (see Table 1) 6. The Wet Tropics NRM Board (FNQ NRM Ltd) has developed a natural resource management plan for the region under the NHT’s regional NRM programme. The Australian Government considers implementation of WQIPs a core deliverable of the regional NRM programme. Therefore the Douglas Shire WQIP will be integrated into the Wet Tropics NRM Plan and its implementation accorded a priority for investment under the regional NRM arrangements. Environmental Values and Water Quality Objectives 1. Douglas Shire contains parts of two World Heritage Areas – the Wet Tropics and the Great Barrier Reef World Heritage Areas (WHAs). The Environmental Values (EVs) of the freshwaters, estuaries and near-shore waters of Douglas Shire have been established by the Queensland Government, through consultation with the Shire community. These have now been scheduled under an amendment to the Queensland Environmental Protection (Water) Policy 1997. The EVs are the waterway values and uses to be protected for these areas. A census conducted by CSIRO found widespread community support for retention of the natural values of the Shire’s waterways. 2. Total suspended sediments (TSS), and the nutrients - total nitrogen (TN) and total phosphorus (TP) are the three parameters of concern in this WQIP. Water Quality Objectives (WQOs) were established for these parameters to protect the EVs. Subsequent work by QEPA has expanded the WQOs to other parameters and to the whole Shire. These added parameters and waterways have not been included in this plan. 3. Comparison of the WQOs with an ambient water quality monitoring program showed that water quality in the Daintree River and the upper Mossman River meets the water quality objectives for all pollutants of concern. Forms of nitrogen exceed the WQOs in the lower reaches of the Mossman River, while phosphate exceeds the WQO in the lowest reach of the Mossman River and Cassowary Creek. The turbidity WQO is also exceeded in Cassowary Creek. Lower Mowbray exceeded turbidity, total nitrogen and phosphorous. 4. The principal point sources of the three parameters of concern in this WQIP in the Shire include the sewerage treatment plant at Mossman, unsewered residential areas, tourist resorts, boat discharges (polluter can be isolated, but discharge is diffuse) and aquaculture. Principal diffuse sources include nitrogen losses from sugarcane production, sediment loss from shire’s modified drainage pattern, and streambank erosion. 5. There has been no long-term monitoring suitable for calculating pollutant loads, (the amount of pollutant eg suspended solids delivered over a period of time). Using CSIRO modelling and expert opinion, TSS, TN and TP loads are estimated to be 134,000 tonnes, 2,250 tonnes and 179 tonnes per annum. Uncleared land, principally in the WHA, is by far the major source of all three pollutants due to the dominant share in area within the catchments. 6. The same models were used to calculate pre-European settlement loads as 72,800, 1,980 and 122 tonnes p.a. for TSS, TN and TP respectively. These values are used as the interim long-term Aspirational targets for the WQIP. These values will be reviewed with further information generated during the 7-year life of the WQIP. Pollutant Loads 1. Sugar cane is the principal crop grown in the Shire. There is some beef grazing in the mid- Daintree catchment and small pockets within the other catchments. Tourism, based on the two WHAs, is a major activity in the Shire with Port Douglas the centre of this activity. 2. The principal point sources of nutrients in the Shire include the sewerage treatment plant at Mossman, unsewered residential areas and tourist resorts, boat discharges and aquaculture. 3. Principal diffuse sources include nutrient and sediment losses from sugarcane production, cattle grazing, and streambank erosion. There has been no long-term monitoring suitable for measuring current pollutant loads. Using CSIRO modelling, TSS, TN and TP loads are estimated to be 134,000 tonnes, 2,258 tonnes and 179 tonnes per annum respectively. Land which is relatively undisturbed, principally in the World Heritage Area, is by far the major contributor to all three pollutants, due to its much higher area than other land uses. Further water monitoring data inputted into the modelling will improve these estimates. 4. Pre-European settlement loads of TSS, TN and TP are estimated from modelling to have been 73,000 tonnes, 1,980 tonnes, and 122 tonnes per annum respectively. These values are used as long term aspirational targets for the WQIP, as it is believed that achievement of these targets will protect the EVs of the Great Barrier Reef. These values equate to a reduction of 45% for TSS, 12% for TN, and 32% for TP. However, there are very high uncertainties associated with these modelled pre-European and current day loads. These uncertainties will be addressed through this WQIP’s adaptive management strategy. 5. In the absence of precise information on impacts of land based pollution from Douglas Shire on the Reef, it is proposed to set a 25 year load reduction target of half the Aspirational targets; that is, 22.5% reduction of TSS, 6% of TN and 16% of TP for protection of the GBR. These targets are effectively Resource Condition Targets (RCTs), and equate to half the anthropogenic (human-induced) loads of these pollutants. Both the Aspirational and Resource Condition Targets will be reviewed during the life of this WQIP. Environmental Flows 1. Aquatic life in the rivers and estuaries of Douglas Shire depends on the continuation of long term flow patterns as well as good water quality. Flow patterns can be modified through barriers across rivers; extractions of water; discharges of water; changes in land use; and climate change. 2. There are no barriers across Shire rivers, with none planned. There are some small irrigation and town water supply abstractions under licence to the Queensland Department of Natural Resources and Water. The abstractions may have local effects; water supply to Mossman and Port Douglas does not constitute a major component of river flows. 3. There have been major changes to land use, altering runoff patterns in the lowlands. Although there are no monitoring data available, runoff is believed to have become more immediate as a result of vegetation clearance, drainage works and wetland reclamation. The CSIRO modelling shows that 87% of runoff originates in the high rainfall coastal ranges where vegetation is relatively undisturbed. 4. The volumes and patterns of flows in the rivers are not believed to have changed significantly since pre-European times, although there may be some changes in the immediacy of runoff in the lowlands as a result of land use change. 5. The Douglas Shire Council and the Queensland Department of Natural Resources and Water have drafted an MoU containing draft flow objectives. This Plan recommends the following objectives, consistent with the MoU: • Maintain current flow volumes; • Maintain inter-annual and intra-annual natural flow variability; • Prevent barriers to wetland and floodplain inundation;