Namoi River
Water Quality and River Flow Objectives
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At a Glance |
This section gives the Water Quality Objectives (WQOs) and the River Flow Objectives (RFOs) for the Namoi River catchment, which should be used by the Namoi River Regulated, Unregulated and Groundwater Management Committees and others to develop plans and actions affecting water quality and river health. Only the priority RFOs are listed in this section, but the remaining objectives still need to be considered when developing flow management plans or dealing with particular local river conditions.
Town water supply subcatchments
The streams in town water supply subcatchments typically feed into a town water supply storage. In some cases the catchment may be declared specially protected to minimise the effects of land use on water quality.
Map: This category applies to streams running through areas coloured light blue on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- This category includes the catchments of Dungowan, Chaffey and Connors creeks and Quipolly Dam.
- Raw water sourced from these catchments will need to be of a high enough quality in the long term for available treatment to be effective. Existing land management programs aimed at maintaining or improving drinking water catchments should continue and be reviewed; for example, the work of the Chaffey Dam Catchment Advisory Committee. These programs include efforts to reduce erosion in the catchments, the frequency of algal blooms in the dams, and other pollutant sources that limit drinking water quality.
- Not all parts of large river systems can be protected from human activities that degrade drinking water quality. See 'Uncontrolled streams' and other river categories, below, for objectives that apply to drinking water offtakes.
- Local factors to be considered include maintaining natural flows from springs (groundwater); effects of land management on volumes and times of runoff, particularly in droughts; flow needs of ecosystems and people within the area and downstream; and reliability of the town water supplies.
- Protection of freshes and high flows does not currently require action but is essential for town water reliability and ecosystems. Minimising any adverse effects of weirs should continue to be a priority.
Mainly forested areas
Streams in mainly forested areas are often valued for their conservation or recreational values. They usually have relatively natural flows and water quality. Many are in national parks or state forests. Other forests are generally in the upper areas of catchments.
Map: This category applies to streams running through areas coloured green on the map (state forests, national parks and nature reserves); and through other forested areas, if any are defined locally.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- Where the whole catchment of a stream is naturally vegetated (e.g. above Dungowan Dam, which is also a drinking water catchment), WQOs and RFOs are generally achieved. High-level protection should be given to flows and water quality in these least affected streams and in other streams with high conservation values. Existing management practices in national parks or other reserves may already aim to achieve this. In some streams, local circumstances restrict achievement of objectives. For example, the use of streams in state forests by cattle may conflict with the achievement of water quality suitable for swimming and can degrade aquatic ecosystems.
- Some of the state forests and other reserves marked on the map contain streams that start in largely cleared land, such as along parts of Baradine and Bohena creeks. The water quality and flow patterns through these vegetated areas generally reflect any upstream effects. The public accessibility of these areas, particularly for recreation, leads to a high public expectation for good water quality.
- Some streams flowing from disturbed vegetation, plantations or regrowth may meet most WQOs and RFOs, but streams below and within recently disturbed sites may have increased turbidity and downstream sedimentation. Extensive areas of rapidly growing trees may reduce low flows in adjoining streams. Thick groundcover may absorb storm peaks and increase the duration of some flows.
- Vegetation on stream banks and floodplains can provide good habitat for native fish, other animals and plants. The effective value of these habitats is likely to be limited if the water quality is poor or if flow patterns are not sufficiently close to natural to provide correct cues for breeding and survival of the offspring. Returning water quality and flow patterns as close as possible to natural is therefore desirable.
- Waters flowing out of naturally vegetated areas, including private forests, can provide clean water for downstream use by, for example, homesteads or livestock. These downstream benefits may be defined locally for specific protection.
- Aboriginal people have identified the consumption of raw aquatic foods as a traditional and existing use within the catchment. NSW Health recommends against the consumption of raw shellfish harvested on a non-commercial basis and local communities should be made aware of the risks involved.
- If the catchment or river management committees consider that a high level of protection should apply to streams with high conservation value outside reserves, they may seek local views and make recommendations to the Government.
Waterways affected by urban development
Waterways within urban areas are often substantially modified and generally carry poor-quality stormwater. Local communities are often keen to see these waterways returned to more natural conditions.
Map: These areas are shown as orange dots on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- This category includes creeks and minor waterways within the towns of Tamworth, Gunnedah, Boggabri, Manilla, Barraba, Werris Creek and Narrabri.
- In some urban waterways, aquatic ecosystems are considerably modified. A return to pristine aquatic ecosystems in these areas is unlikely and impractical, but water quality conditions for existing ecosystems can be improved greatly for the benefit of local species and broader catchment health. Data from other local aquatic ecosystems of similar type, in areas that are not urbanised, may provide achievable criteria for these ecosystems.
- Action is needed to reduce the effects on surface and groundwater quality of stormwater and sewerage discharges and unsewered villages.
- Under the Urban Stormwater Management Program, local councils are required to produce stormwater management plans for urban centres with more than 1000 people. Stage 1 of the Program includes a grant to Tamworth City Council of up to $307,500 for 'Heritage Estate Stormwater Quality-Remediation Wetland.'
- The tendency for urban developments to cause rapid rises in storm runoff should be minimised.
- See supporting information under 'Uncontrolled streams', below
Uncontrolled streams
These include all uncontrolled waterways that are not in the other categories. Their flow patterns are largely natural. Flows can occur in these streams from local runoff. They are typically ephemeral (flowing only during floods and freshes). Frequently, they open into or flow through wetlands and billabongs.
Map: Uncontrolled streams are shown as blue lines on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- This category includes unregulated effluent creeks (e.g. Shepherds Warrambool) and anabranches (except Pian Creek), which are common on the Western Plains, where high flows in the main rivers flow away from the river in natural channels.
- Water taken at point of supply must be kept at a high enough quality in the long term for the available level of treatment to be effective. Towns on uncontrolled streams that extract drinking water are Bendemeer and Walcha (McDonald River), Barraba (Manilla River), Nundle (Peel River), Werris Creek (Quipolly Creek) and Quirindi (bores).
- In some areas where there are more intensive agricultural industries and rural residential developments (e.g. around Tamworth), the water quality in streams is often poor. Primary contact recreation objectives are not currently being achieved at some locations. High bacterial levels have been found downstream of major urban centres. Pesticides have been detected in some uncontrolled streams, particularly Coxs Creek.
- Local factors to be considered in sharing river flows in dry seasons and protecting inundation patterns of flood-dependent ecosystems include:
- strong demand during low flows from some streams; for example, the Mooki and Upper Peel rivers and Coxs and Quirindi creeks
- occasional reduction of higher flows in some streams; for example, in effluent creeks west of Narrabri
- identified conservation values; for example, native fish
- environmental worth and natural inundation patterns of small wetlands, river red gums, and other riparian or floodplain vegetation; for example, in effluent creeks.
- Managing land-use practices to limit groundwater recharge above areas with existing or potential dryland salinity is important. Management would continue to be on a case-by-case basis, aiming to avoid a rise in the watertable, threatening agricultural production, streamwater quality or terrestrial or aquatic ecosystems. (Local action is under way in the Liverpool Plains).
- Minimising adverse effects of weirs is an important issue throughout the catchment. Local factors include the wish to restore native fish populations; and the filling of natural waterholes by sediment, which causes increased dependence on weirs to secure stock and domestic supplies.
Major regulated rivers
These rivers have large dams supplying irrigation water (and some town and industrial water) for substantial distances downstream. Flows are typically supplemented during the irrigation season, resulting in fairly stable and unnaturally high water levels. River flow is substantially reduced during non- or low-irrigation seasons. At any time of year in periods which would normally have high or very high flow, flows may be substantially reduced by the trapping of water in a large dam.
Map: These rivers are shown as yellow lines on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
No RFOs were recommended in 1999, because Environmental Flow Rules had been adopted for the regulated river. In 2004, a Water Sharing Plan (WSP) commenced for the regulated Namoi River, including environmental water provisions. In general, the RFO framework should be considered when the WSP is reviewed under the Water Management Act.
Supporting information
- These rivers extend from Split Rock and Chaffey dams to Walgett and include parts of Pian and Gunidgera creeks.
- Walgett obtains part of its water supply from the Namoi River and Pian Creek. The water quality is often poor owing to blue-green algae. Other places that draw water associated with regulated rivers include Manilla and Tamworth (Peel River), and Gunnedah, Boggabri and Narrabri (bores).
- Where there are more intensive agricultural industries and rural residential developments, the water quality in streams is often poor.
- Recent monitoring data suggest that the Namoi River at and downstream of Gunnedah, and Narrabri Creek at Narrabri, would usually fail the criteria for primary contact recreation. The monitoring identified human sources of bacteria, such as sewerage and septic systems, and animal sources, pointing to problems throughout the catchment. (See Bacterial Water Quality of the State's River System for 1996-97, prepared by DLWC). Pesticides have been commonly detected at several sites on the Namoi River and Pian Creek, downstream of Gunnedah.
- The quality of water (e.g. its temperature) released from Keepit, Chaffey and Split Rock dams has been identified as a problem. Opportunities to modify the outlet works should be taken.
- DLWC's Integrated Monitoring of Environmental Flows Project incorporates important indicators of water quality and river health that can be improved with flow management.
- The RFOs Protect pools in dry times and Mimic natural drying in temporary waterways will not normally be applicable. There may be some locations where specific actions related to these objectives are feasible and appropriate.
- Alluvial aquifers adjoining regulated rivers will need to be managed in association with the rivers. Groundwater levels may affect ecosystems. Action is needed to maintain groundwater within levels critical to ecosystems and streamflows, and to deal with other local concerns such as the reliability of bore water supplies for stock.
Controlled rivers with reduced flows
This category covers two cases:
1. River reaches downstream of the regulated sections where the water is extracted or diverted. Flow is generally reduced throughout the year. Water is delivered from the main stream for stock, domestic, some irrigation, and town water supplies several times a year.
2. Sections of rivers immediately below town water supply dams, where water is diverted directly from the dam. Flows can be substantially reduced throughout the year, though special environmental releases may be possible.
Map: These rivers are shown as red lines on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- These rivers include Pian Creek (case 1) and river sections below Dungowan and Quipolly dams (case 2).
- Where flows have been reduced, water quality can be affected by the loss of diluting or flushing flows.
- Water quality problems, usually associated with blue-green algae, are common in Pian Creek.
- Flows in much of Dungowan and Quipolly creeks are often substantially reduced by diversion of water to meet urban and industrial needs. Landholders downstream depend on the remaining flow and may contribute to further reductions. Augmentation of town water supplies will not be required, but the management of these storages should be reviewed, along with the conditions on water licences along these streams. Local factors include support for protection of native fish and landholders' needs.
- Flows in Pian Creek have been substantially altered by regulating works upstream and large-scale irrigation extraction. Developments on the floodplain have also significantly altered the natural patterns of flow. There are numerous weirs along Pian Creek. At some times, partially regulated flows are diverted to Pian Creek between Rossmore and Dundee weirs.
This page was published 1 May 2006
About the Objectives
