This chapter deals with issues associated with the impacts of land and water users on our waterways and their associated values. The strategies developed suggest the need for an overarching Catchment Management Strategy to ensure that guidelines for improved management continue to be developed and adhered to.
Many of the issues associated with sustainable management of the waterways depend on information that has yet to be gathered. The uniqueness of each river system means it is difficult to transfer information from one location to another. The Ord is a highly regulated river with two dams creating very different environments along its length whilst other rivers such as the Negri and Pentecost are unregulated and subject to seasonal flows. The general lack of information about tropical river systems makes it challenging to proceed with sustainable management without significant research effort.
Waterways management cannot wait for the complete gathering and interpreting of research information but must proceed on the basis of the best existing knowledge while new knowledge is gained.
There are a number of agencies that have statutory responsibilities for managing waterways within the catchment. These include the Department of Water, the Water Corporation, the Department of Environment Regulation, Department of Parks and Wildlife, the Shire of Wyndham East Kimberley and the Shire of Halls Creek. Local residents, tourists and tour operators also have a responsibility for minimising the impacts they have while enjoying the waterways.
To protect, maintain and monitor existing fish stocks with a view to increasing specific species if required.
Fishing in the catchment is a popular pastime for local residents and it acts as a significant draw card for visiting anglers. The main target species for freshwater fishing are barramundi (Lates calcarifer), western sooty grunter (Hephaestus jenkinsi) and a number of species of catfish.
There are bag limits in place for two of these species with the barramundi possession limit being two fish per angler (size range 55cm–80cm) and western sooty grunter four fish per angler (minimum size of 25cm).
Since the construction of the Kununurra Diversion Dam and the Ord Dam the habitat range of barramundi in the catchment has been restricted to the area of the Ord River below the Kununurra Diversion Dam and its tributary the Dunham River. Western sooty grunter and catfish are distributed along the full length of the freshwater sections of the catchment.
The absence of adequate fish stock information prevents any firm conclusions regarding fish stocks in the catchment. Whilst there are seasonal variations due to the extent of annual recruitment, the current barramundi stocks, however, do not appear to be in decline. The general satisfaction levels for the recreational fishery and consistent anecdotal information supports this claim.
The Department of Fisheries are the lead agency involved in fish stock management and aquaculture development around the State of Western Australia. Currently, two Fisheries Officers are based in Kununurra. Recfishwest is the recognised peak recreational fishing body in Western Australia. This organisation is based in Perth but has an informal network in the Kimberley built on membership.
There is one known introduced species of fish present in the catchment, currently restricted to the Ord River and Lake Kununurra; redclaw crayfish (Cherax quadricarinatus) was accidentally introduced into Lake Kununurra sometime in 1999 or 2000, most likely as a result of commercial fish farming operations and trials in the Ord River Irrigation Area. This species has since spread downstream into the lower Ord. The full impact of this issue on the endemic aquatic species is not fully understood. No size, bag or possession limits apply for redclaw recreational fishers.
The Department of Fisheries manages a current project (2015) that has recently completed the stocking of 500,000 hatchery raised barramundi fingerlings into Lake Kununurra as a trial with the aim of determining if they will remain in the lake and create a viable recreational fishery. This initiative is subsequent to a program that ran from 2000 to 2007 and explored the possibility of establishing a fish ladder on the Kununurra Diversion Dam and the Lake Argyle spillway. The ladders would re-establish migratory pathways for fish into the upper Ord catchment. A number of studies carried out as part of this program showed a potential direct economic benefit to the local community of $2.1 million in 2002. A further study indicated that the stocking of the lake with barramundi may prove beneficial in the control of redclaw and that the reintroduction of barramundi to that section of the river would not adversely impact on the current fish fauna.
There are no current aquaculture operations in the catchment. However, previously a commercial barramundi caged fishery was temporarily established on Lake Argyle and some minor redclaw and western sooty grunter commercial trials were undertaken in the Ord River Irrigation Area. There is some interest in the potential of another caged barramundi fishery being established on Lake Argyle.
Commercial fishing within the catchment is currently restricted to a small fishery on Lake Argyle that targets silver cobbler (Arius midgleyi). There has been no commercial fishing in the lower Ord since the development of the Barramundi Accord in 2000 that placed the lower Ord and sections of Roebuck Bay in Broome off limits to commercial activities. The accord was due to be renegotiated in 2013 however, the recreational, commercial and charter sectors considered there was less need for an accord than previously and negotiations did not progress.
Currently, only one charter business operates in the Lower Ord River area. Barramundi is the focal fish of interest for this operation and the operator abides by the barramundi regulations regarding size and number of fish taken.
There is an absence of adequate fish stock information and therefore the impact that fishing (both recreational and commercial) is having on the fish stock is not fully understood.
It is not fully understood whether hatchery raised fish released into Lake Kununurra would reside in the lake or move out through the Diversion Dam gates.
The number of fish required to sustain the barramundi recreational fishery in Lake Kununurra is unknown.
The degree of fishing pressure actually placed on the catchment is unknown. This is including heavily fished areas such as downstream of the Diversion Dam and creeks flowing into Lake Argyle from the east that intersect the Duncan Road.
It is unknown whether the numbers of other fish species are increasing or decreasing in the catchment.
The impact of changed flow regimes in the lower Ord River on fish populations and associated habitat is unknown.
Protect the existing fish stock from overfishing by:
1. Understanding the carrying capacity of the various fisheries within the catchment.
2. Encouraging recreational fishers to become responsible for protecting the fishery.
3. Developing and promoting fishery management planning for high use areas within the catchment.
4. Preventing overfishing by individuals who do not comply with management guidelines through increased policing by the Department of Fisheries.
5. Researching the impact that all land and water users have on the capacity of the river to support a healthy fishery.
6. Encouraging the State Government to finalise and enact the draft Aboriginal Fishing Strategy.
Investigate proposals relating to fish stock management:
1. Continue to advocate for the construction of a fish way/ladder at the Kununurra Diversion Dam.
Promote a greater understanding of sustainable recreational fishing:
1. Conducting extensive publicity and education programs.
2. Involving recreational fishers, school students and the community in research, information gathering and monitoring processes.
3. Developing the log book/licensing concept to increase the information and understanding about the fishery.
Minimise the potential conflict between aquaculture and other land uses by:
1. Ensuring that small land based aquaculture ventures meet the required environmental standards.
2. Ensuring that planning schemes provide for the segregation of aquaculture and agriculture/ horticulture so as to minimise possible conflicts.
3. Supporting well planned aquaculture ventures.
The Department of Fisheries has statutory responsibility for the management of fish stock and aquaculture developments, in addition to conducting research and monitoring fish stock to inform improved management decision-making.
Recfishwest is the recognised peak recreational fishing body in Western Australia and has the responsibility of ensuring that recreational angler's interests, including stock management, are promoted to Government and its agencies.
The Shires of Wyndham East Kimberley and Halls Creek have responsibilities for town and rural planning that identifies areas for particular land use.
The general community, and in particular recreational fishers, have responsibilities to both participate in planning and observing the rules that apply to bag and size limits. Charter operators may be able to assist with monitoring fish populations, recording logbooks and conducting some research in conjunction with Universities.
1. Gardiner, H.G. (2000) Ord Land and Water Management Plan 2000. National Heritage Trust: AGWEST.
2. Western Australia Department of Fisheries. (2014) Recreational Fishing guide 2014 – Simpler Rules for Better Fishing (brochure): Government of Western Australia, Department of Fisheries.
3. Managing, Monitoring, Maintaining and Modelling Barramundi. (2005) Proceedings of the National Barramundi Workshop, 6-8 July 2005, Darwin, Northern Territory and overview of the Barramundi Modelling Workshop, 27 February - 3 March 2006, Perth, Western Australia: Editors: Grace, B., Handley. A., @ Bajhau. H.
4. Lake Kununurra Fish Stock Enhancement Committee. (2002) Lake Kununurra Economic Benefits Study: Corporate and Regional Enterprise Consulting.
5. Dupe, R., Morgan, D., Gill, H., Rowland, A. & Annandale, D. (2003) Ecological and Social Issues Concerning the Establishment of a Recreational Barramundi Fishery in Lake Kununurra. Lake Kununurra Fish Stock Enhancement Committee: Centre for Fish and Fisheries Research, Murdoch University.
6. West, L.D., Pepperell. J.G. &Waugh. G. (1996) Ord River Fishing Survey – Report to: East Kimberley Recreational Fishing Advisory Committee: Kewagama Research.
7. Fisheries Western Australia. (1999), Kimberley Aquaculture Development Strategy, Lake Argyle Barramundi Aquaculture Industry: Strategic Environmental Review: Fisheries Western Australia.
8. Makaira Pty Ltd. (1999) The Translocation of Barramundi: A Discussion Paper, Fisheries Management Paper No.127: Fisheries Western Australia.
9. Doupe. R.G. & Bird. C. (1999) Opportunities for enhancing the recreational fishery of Lake Kununurra using barramundi Lates calcarifer: A review: Proceedings of the Royal Society of Queensland. In Press.
10. Thorne, T. (1997) The aquaculture of non-endemic species in Western Australia – Redclaw Crayfish – Cherax quadricarinatus. Fisheries Management Paper No.100: Fisheries Department of Western Australia.
To support the continued development and implementation of ecologically sustainable, Commercial and Recreational plans for the Catchment’s waterways.
All the waterways within the catchment within easy travelling from communities are popular spots for recreational activities. These include waterholes, streams, lakes and rivers. Activities include swimming, fishing, water skiing, sailing, canoeing and general boating. High use areas include the lower Ord River, Lake Kununurra and to a lesser extent Lake Argyle.
Lake Kununurra Foreshore and Aquatic Use Plan
Currently, a section of Lake Kununurra between the Kununurra Diversion Dam and the Kununurra Racecourse, Lily Creek Lagoon and the Packsaddle wetlands are managed under the Lake Kununurra Foreshore and Aquatic Use Plan (2010). The Lake Kununurra Foreshore Reference Committee is a stakeholder represented group with the purpose of implementing the plan.
The main focus of the Lake Kununurra Foreshore and Aquatic Use Plan is to address land use issues affecting foreshore reserves and associated areas on both sides of Lake Kununurra, from the Diversion Dam up to and including the Kununurra Racecourse. The following areas are also covered by the Plan; Lily Creek Lagoon, the Packsaddle wetlands, the foreshore adjoining the Crossing Falls residential area, the Packsaddle/Jabiru Road agricultural area, the commercial canoe camps and tour boat day use areas.
An Aquatic Use Plan has been incorporated into the document to show synergies between land and water use and to ensure that these uses complement one another. The Aquatic Use Plan focuses on those activities that occur on the waterway.
The Ramsar Convention is an international treaty for the conservation and sustainable utilization of wetlands, recognising the fundamental ecological functions of wetlands and their economic, cultural, scientific, and recreational value. It is named after the city of Ramsar, Iran, where the Convention was signed in 1971.
The Ord River catchment contains two Ramsar sites; the Ord River floodplain and the Lakes Argyle and Kununurra Ramsar Site.
During the Ord River Fishing Survey conducted in 1996 (West et al, 1996), concern was raised by twenty three percent (23%) of the respondents in regard to rubbish along the river and many of the popular fishing and recreational sites. This rubbish is hazardous to native animals in addition to being unsightly and ruining the “experience” that can be gained by residents and visitors alike from the area. Currently, the Shire of Wyndham East Kimberley regularly collects rubbish from along the foreshore at Celebrity Tree Park, Lions Park, Swim Beach and other foreshore areas within the town boundaries. Once a year the Shire has a cleanup at the Mambi Island boat ramp prior to the tourist season.
Fishing line left in the water can have a significant impact on native wildlife, in particular water birds. Unfortunately its removal is hampered by the presence of crocodiles and fast flowing water. Lures and hooks still attached to the snagged line makes recovery from the shore difficult and often is not an effective option.
Since the construction of the Diversion Dam, as a result of the constant water levels and flows in Lake Kununurra and the lower Ord River, cumbungi (typha) has significantly increased in prevalence and density. Currently there are two species of cumbungi growing in these locations, Narrow leaf cumbungi (Typha domingensis) which is native to Western Australia and Broadleaf cumbungi (Typha orientalis) which is native to eastern Australia and other Pacific nations.
The management of cumbungi in Lily Creek, which is included in the Foreshore Plan, is challenged by the ability of the plant to colonise sections of waterways where depths are of less than two metres. Because of this shallow sections of Lake Kununurra are being converted to river bank as the cumbungi spreads and subsequent colonisation by trees, for example paperbarks and Leichhardt trees occurs.
Whilst cumbungi lines sections of the lower Ord River restricting access to shore based fishers, regular flooding does significantly restrict its spread along the river.
Freshwater crocodiles (Crocodylus johnstoni) also known as Johnston's crocodile are widespread across the freshwater sections of the catchment whilst saltwater (estuarine) crocodiles (Crocodylus porosus) have had their range and numbers restricted by the construction of the two dams across the Ord River to form Lake Argyle and Lake Kununurra.
Both lakes are crocodile control zones (CCZ), both have high numbers of freshwater crocodiles and occasionally saltwater crocodiles are reported and trapped in these lakes, in particular Lake Kununurra. If a saltwater crocodile is reported in the CCZ the Department of Parks and Wildlife will take measures to remove it. In the Ord River below the Diversion Dam crocodiles are trapped or controlled if they have been shown to be problem animals, particularly in areas that are regularly used by people, such as the River Farm Road rural blocks or Ivanhoe Crossing.
The Department of Parks and Wildlife updated its operational policy on the management and conservation of saltwater crocodiles in May 2014. Objectives of the policy are:
To reduce the risk of crocodile attack for those who work, recreate, visit or reside in or near areas where crocodiles are likely to be found.
To ensure the long term conservation of crocodiles in the wild.
To support the ongoing commercial farming of crocodiles in Western Australia.
Boating is generally restricted to the lower Ord River, Lake Argyle and Lake Kununurra where water levels and access are favourable. Increased powerboat activities may lead to greater leakage of oil and fuel residues into waterways. This may not cause problems in areas where the flow rates are high; however, it could have an impact in the shallow wetland areas where mixing and throughput is reduced.
Uncontrolled access to waterways can result in serious disturbances that include; crushing and trampling of native vegetation, increased weed growth, rubbish spills, soil compaction and accidental fires. This highlights the need for management of public access to the river.
Increases in canoeing and other outdoor activities that involve camping between the two dams may cause disturbances to wildlife breeding sites. Turtles, crocodiles and water monitors favour sand banks as areas for breeding sites. These sandy areas are also favoured by campers (Watkins et al, 1997). One commercial canoeing enterprise currently operates on Lake Kununurra and maintains four overnight stop points along the river for canoeists. Thes are in locations that have minimal impact on crocodile, turtle and water monitor breeding sites.
One commercial houseboat and several private houseboats operate on Lake Kununurra. The commercial houseboat is restricted from travelling upstream of the entrance to Carlton Gorge due to navigational restrictions and fast moving water. It is also subject to regulations regarding the disposal of grey and black water. These restrictions do not currently apply to private houseboats.
Who is responsible for ensuring rubbish collection at popular locations?
Should rubbish collection facilities be provided at popular locations or should the message be: "take your rubbish home/Leave No Trace"?
How many people actually use the river for recreational purposes and what pressures are they placing on the river?
The potential impact of more houseboats on Lake Kununurra and Lake Argyle.
Reduce rubbish and other pollution of waterways by:
1. Involving the whole community in the development of river management guidelines to include:
active rubbish management (a take your rubbish home campaign);
developed and serviced access points;
management of refuelling and sullage of all recreational and commercial vessels; and
encourage recreational anglers to use lure retrievers to regain snagged lures and line from the water.
Reduce the pressure on the river from recreational use by:
1. Encouraging the development and implementation of management guidelines for all types of recreational use of waterways, including boating, camping, swimming and fishing.
2. Managing high use areas such as boat ramps and other access points.Strategy 3
Improve the understanding of issues associated with recreational use of waterways by:
1. Conducting information and education programs, for example using a logbook as a source of information on native and feral species, fish species, rubbish management, and other items.
2. Involving recreational groups in planning for sensible sustainable recreational use.
3. Encouraging recreational user groups to manage the areas they use consistent with ‘Leave No Trace’ principles.
4. Developing and implementing best management practices for recreational use of waterways.Strategy 4
Improve safety on the water by:
1. Recognising boating codes of practice or ethics.
2. Implementing regulated speed limits at specific locations, launching areas and designated use areas.
3. Maintaining awareness of crocodile presence in waterways.
4. Encouraging the development of improved boat launching facilities on Lake Argyle.
5. Increasing awareness of designated ski areas.
Strategy 5Maintain separation between recreational and commercial interests by:
1. Encouraging all commercial boats to operate out of a commercial boating facility on Lake KununurraResponsibilities
Recreational use of waterways includes a number of areas of State agency jurisdiction including Department of Transport for boat licensing, the Department of Water for water abstraction and river health, the Department of Environment Regulation for pollution response, and the Department of Parks and Wildlife for Ramsar and crocodile control. The Shires of Wyndham East Kimberley and Halls Creek for amenity management and Visitor’s Centres for providing visitor information. The Department of Fisheries has responsibility for fish stock management, research, education, enforcement and monitoring associated with the recreational and commercial fisheries.
Tour operators have a responsibility to both avoid damage to the waterways and environs and to communicate the need for better management of recreational use.
The Lake Kununurra Foreshore Committee has expertise in managing natural resources and recreational use and should therefore be involved in the planning and execution of best management practices.
The general community and in particular the recreational user groups and sporting clubs need to be involved in ensuring sensible use of the waterways.
Traditional Owners and other Aboriginal groups also have a role in developing management plans and providing the necessary information and education links to Aboriginal people.References
1. Gardiner, H.G. (2000) Ord Land and Water Management Plan 2000. National Heritage Trust: AGWEST.
2. Department of Agriculture, Fisheries and Forestry Biosecurity Queensland. Fact Sheet Cumbungi.
3. Department of Parks and Wildlife. (2014) Operational Policy Science and Conservation Division Management and Conservation of Saltwater Crocodiles: www.dpaw.wa.gov.au/.
4. West, L.D., Pepperell, J.G. &Waugh. G. (1996) Ord River Fishing Survey – Report to: East Kimberley Recreational Fishing Advisory Committee: Kewagama Research.
5. Doupe, R.G. & Bird, C. (1999) Opportunities for enhancing the recreational fishery of Lake Kununurra using barramundi Lates calcarifer: A review: Proceedings of the Royal Society of Queensland. In Press.
6. Watkins, D., Brennan, K., Lange, C., Jaensch, R. & Finlayson, M. (1997) Planning for Ramsar Sites in the Kimberley Region of Western Australia:, Wetlands International – Oceania, Environmental Research Institute of the Supervising Scientist Consultant.
7. Water and Rivers Commission. (2000) Protecting Riparian Vegetation, Water Notes, WN10: Water and Rivers Commission.
To continue to provide input into the water planning processes within the Ord River catchment and influence enhanced outcomes in water allocation.
The Department of Water is responsible for ensuring the sustainable management of the State’s surface and ground water resources. In order to achieve this, water allocation plans are required for each “water management system” to define the amount of water to be made available for each use.
Water allocation plans define the amount of water that can be legally diverted from river systems and ground water aquifers. Water allocation plans must take into account: environmental water provisions, ecological water requirements, sustainability, irrigators, recreational users and other potential users.
Allocation plans are implemented through the Rights in Water and Irrigation Act 1914. Licenses formalise the allocations and are subject to conditions necessary for good management of the resource. The State’s water allocation system is evolving to meet the requirements of the Council of Australian Government’s Water Reform Framework Agreement and licensing is to become the means to identify water allocations and their holders (WRAP 2, 1999).
Each water allocation plan aims to provide strategic direction by identifying future development and associated demands for water while protecting the supply of water necessary for the environment. Environmental approval of developments is subject to the determination of an acceptable amount of water to support the ecological and environmental objectives for the catchment.Current Status
Purpose of the plan
The Ord Surface Water Allocation Plan guides how the Department of Water allocates and licenses surface water in the Ord River area to manage the competing demands of irrigation, hydroelectricity generation and the lower Ord environment in the transition to full allocation.
Secures 890 Gigalitres/year (GL/yr) from the existing infrastructure for current and future irrigation demand.
Defines water release rules for the Ord River Dam power station to meet downstream irrigation and environmental commitments while maximising hydroelectricity generation.
Shows when water restrictions for hydropower, irrigation and the environment will apply to manage competition for water in dry periods.
Establishes how the Department of Water will license water use and adjust water licences as irrigation and hydroelectricity demands change over time.
Water availability in the Ord surface water area
The Department of Water will grant water entitlements up to 905 GL/yr from the existing infrastructure in the Ord surface water area. Of these, 865 GL/yr will be from the Main Ord and Carlton-Mantinea sub areas downstream of Lake Argyle. As these entitlements can only be granted because of Lake Argyle’s storage, they are designed to be fully supplied in 95 per cent of years. As of January 2013, 335 GL/yr of this has been licensed to the Ord Irrigation Cooperative to supply its members in the Stage 1 area of the Ord River Irrigation Area. Most of the extra water for irrigation expansion will be diverted from the Ord River within the Main Ord sub area. This includes water to supply the Goomig, Knox Plain and West Bank farm areas in Western Australia and the Keep River Plain in the Northern Territory.
Productivity and water flow regulation in the Ord River of North Western Australia.
Irrigated agriculture expansion into the Goomig Farm Area, the Western Bank of the Ord River, Knox Creek and Northern Territory.
Potential to further raise the spillway on Lake Argyle.
Groundwater investigations on the Bonaparte Plain and Cockatoo Sands areas.
How much water is required for “environmental flows”?
Who “pays” for the environmental flows and for flow to enable recreational use of the river?
What is the “dollar value” of the water, that is the actual cost of the water?
What impact will a changed water regime, resulting from greater diversion of water for the Goomig Farm Area, have on the downstream environment, as well as the ability to use the river for recreation and tourism?
What impact will the lower flows have on the water quality in the river?
When will the changed water regime begin? (Of note is that this will determine the lead-time to implement changes in management for tour operators, farmers and others).
What impacts will lower water levels have on cumbungi and para grass in the Lower Ord?
Will it be possible to simulate flood pulses in the river that are big enough to have an impact on the health of the river system?
What are the sizes and probability of flood pulses that come from the Dunham River catchment?
What impact will lower water levels have on crocodile populations, movement and recreational user safety?
Are the environmental flows meeting the objectives of the lower Ord’s ecosystems and water quality parameters?
Develop an understanding of the environmental requirements of the river downstream of the Kununurra Diversion Dam by:
1. Encouraging well planned research to determine the Environmental Water Requirements and the likely impacts of changed river flows on the riverine and adjacent riparian environment.
2. Monitoring these environments and providing real time feed back that enables management of river flows to be based on up to date information.
Review the Ord River Surface water allocation plan current Water Allocation Plan by:
1. Taking into account the requirements of:
the downstream environment
Stage 1 Irrigation Area.
The Goomig Farm Area.
Proposed irrigation developments, for example as Knox Plains.
Ord Hydro Pty Ltd
2. Ensuring involvement of key stakeholders in the development of the Water Allocation Plan (including the Ord Irrigation Cooperative, Stage 1 irrigators and tour operators who operate in the area).Responsibilities
The Department of Water is responsible for managing and licensing the State’s water resources under the Rights in Water and Irrigation Act 1914 (WA) and is therefore the lead agency for the allocation of water. The Department has a responsibility to ensure local stakeholder involvement in the allocation process.
Water users, including irrigators, Water Corporation, tour operators and recreational users of water and Ord Irrigation Cooperative have a responsibility to ensure that they have input into the allocation process. The general public and other river users complete the list of potential stakeholders that need to be involved in the planning process.
1. Gardiner, H.G. (2000) Ord Land and Water Management Plan 2000. National Heritage Trust: AGWEST.
2. Department of Water. (2013) Ord River surface water allocation plan: ww.water.wa.gov.au/
To prevent further damage to and restore natural riparian areas including vegetation and banks.
To reduce the impacts of stock on riparian areas.
Riparian areas are those close to the margins of waterways and drainage lines, whose characteristics are determined by the presence of water. These areas are important as they act as areas of refuge for animals during dry periods, and often support a highly diverse and fragile ecosystem. Maintaining diversity of these ecosystems is important to ensure that the ability for these ecosystems to adapt to change is not lost.
Riparian land is often highly productive and often plays an important role in the lifecycle of many native animals and plants (Tubman (Ed), 1996). By its very nature riparian land is fragile. Its productivity also makes it vulnerable to overuse and to practices which cause it to deteriorate (Tubman (Ed), 1996).
The importance of the riparian areas of Lake Argyle and Lake Kununurra (and the Lower Ord Floodplain) is emphasised by their listing as Ramsar wetlands. In this context, they are seen as important internationally as migratory bird habitat and must be managed so as to maintain their ecological character (James, 1997).
The main land use in the catchment is cattle grazing. Often waterways are used as the source of water for stock alongside artificial water points. Some of the catchment has been destocked (Ord River Regeneration Reserve) or has access to the river controlled by fences.Current Status
The more uniform river flows, since the construction of the two dams, has altered the location and nature of the riparian areas of the lower sections of the catchment.
There are now four sections with quite different flow regimes that have developed unique riparian areas.
Above Lake Argyle – where the river is still seasonal with flood pulses that maintain a near original riparian zone. This section is also applicable to the Dunham River above the water level set by the permanent flows of the Ord River.
Lake Argyle – where the water level fluctuates; the old riparian vegetation has been drowned and a new shoreline has formed with little or no vegetation.
Lake Kununurra – where the water level is stable; the old riparian vegetation has been drowned and a new shoreline formed with reed beds and a more luxuriant riparian vegetation.
Below the Diversion Dam – there are permanent flows with rare peak flood flows and also, the fresh water/salt water interface is further downstream. New and more luxuriant riparian vegetation has developed in this portion of the Ord River system.
The diversity of plants and animals in all these areas has changed since the construction of both dams. The riparian areas around Lake Kununurra have increased in diversity as a result of having stable, permanent water levels. Plant species within the Ord River catchment have been found to be well adapted to the altered hydrological regimes of the Ord River, with species such as Eucalyptus camaldulensis displaying timed seed fall when river water levels are receding (Petit & Froend, 2001). This may be of importance around the timing for feral animal control especially for pigs. The shorelines of Lake Argyle may have lost diversity as a result of the fluctuating water level.
Weeds are currently one of the primary issues of concern in riparian zones. In areas where there has been disturbance by people or stock, weeds can proliferate. Significantly, there are now areas of mesquite, bellyache bush, rubber vine, parkinsonia and other weeds in the middle and upper catchment. In the lower catchment Mimosa pigra, neem, bellyache bush, parkinsonia and leucaena pose significant threats. (See Section 4.3 - Weeds).
Cane toads have been in Western Australia since 2009 and are seen as a significant threat to the riparian areas as they move through the catchment. There are a number of small populations of feral pigs in some areas of the catchment; however, these numbers are not high enough to warrant a formal control program. Feral cats are widespread and wild dogs are becoming more of a menace as their distribution increases. (see Section 4.1 – Pest and Feral Animals).
Intensive use of the river for stock watering has the ability to cause destruction of riparian vegetation and bank erosion, this is particularly in areas where access to the river is restricted by steep banks and the pressure is increased on areas where access is possible. However, it is not economically feasible to fence off the river completely, as this would mean having to provide artificial watering points and the loss of some of the most productive grazing areas.
It is not necessary to permanently exclude animals from riparian lands, but it is important to control their movement and to manage grazing pressure.
Riparian zones differ from surrounding land in their biology, moisture levels and ground cover. As a consequence, fire impacts on riparian zones vary with the severity and extent of burning in the catchment and stream size. Riparian zones can act as a buffer against fire and as a refuge for fire-sensitive species. However, under some climatic conditions and with the accumulation of dry fuel, riparian areas can become corridors for fire movement.
The impact of possible future change in the water regime on the riparian areas below the Diversion Dam and the aquatic ecology of the lake.
The levels of silt that is moving as a result of stock access.
The longer term effects of dry season fires on riparian areas.
Reduce the impact of use on the riparian areas by:
1. Undertaking literature reviews of past and current management works to identify gaps in knowledge and approaches.
2. Educating the public about the importance of the riparian zone of waterways.
3. Limiting user access to particular serviced access points.
4. Including the riparian areas in an overall river management strategy.
Prevent further damage and modification to the natural riparian vegetation by:
1. Developing and implementing a river management strategy which includes controlling the spread of weeds and feral animals
2. Further developing grazing management systems aimed at reducing the impact of stock on riparian vegetation.
3. Providing alternative watering points for stock.
4. Encouraging fire management practices that reduce the impact of late season fires.
Monitor changes in the riparian zone ecology by:
1. Developing and implementing monitoring systems (both scientific and general observations) to follow changes in the condition of the riparian zone.Responsibilities
The health of the riparian zone is linked to the health of the catchment. Those with responsibilities include the Department of Agriculture and Food, Department of Water, Department of Parks and Wildlife, Land Managers and the Shires of Wyndham East Kimberley and Halls Creek.
1. Gardiner, H.G. (2000) Ord Land and Water Management Plan 2000. National Heritage Trust: AGWEST.
2. Pettit, N.E. & Naiman, R.J. 2007. Fire in the Riparian Zone: Characteristics and Ecological Consequences: Ecosystems.
3. James, R. (1997) A Directory of Important Wetlands in Australia – The Ramsar Convention in Australia – 25 years on: Wetlands and Migratory Wildlife Unit, ANCA.
4. Water and Rivers Commission. (1997) State of the Northern Rivers: Water and Rivers Commission.
5. Land & Water Research & Development Corporation. (1996) Riparian Management - Managing Riparian Land: Editor, Wendy Tubman.
To develop, with community input a flood management plan for high risk and high value areas within the Ord Catchment.
To develop as a priority a flood management plan for Kununurra Township and the irrigation area.
The Ord River is now a controlled river. The Kununurra Diversion Dam was completed in the early 1960s and Lake Argyle was completed in 1973. Prior to this time the Ord River was a seasonal river, drying up during the dry season and flowing according to rainfall during the wet season.
There is a “State Framework for Floodplain Management in Western Australia” and there is a flood emergency plan for the Ord River that identifies agency responsibilities. Flood warning information comes through the Bureau of Meteorology. This information is available at www.bom.gov.au/weather/wa. and is updated regularly.
A number of wet season flooding events have highlighted the need for flood management in current and future developments. Despite the Ord River being a controlled system, localised flooding in Warmun in 2011 and Kununurra in 2014, reached record or near record highs. As a result there is now a flood management strategy for the Warmun Aboriginal Community and in Kununurra the Shire of Wyndham East Kimberley has undertaken modelling work for certain areas and is further considering stormwater management.
Surface water, in and around Kununurra, has a number of discharge points. The townsite of Kununurra discharges into either Lake Kununurra/Lily Creek or the M1 Channel. Shire roads discharge into either Lake Kununurra/Lily Creek, the M1 Channel and various irrigation drains within the irrigation area. Some Crown Land also discharges into agricultural drains and the M1 Irrigation Channel. Mirima National Park normally discharges directly into Lily Creek but in significant rainfall events also runs into shire drains leading into Lily Creek.
The Water Corporation operates the two dams. When wet season flows enter Lake Argyle a stable level is maintained in Lake Kununurra to reduce the risk of flooding of the Ord River Irrigation Area and township.
Flows of the 1999/2000 wet season through the system were up to 1000 cubic metres/second (m3/s). A significant flow down the Dunham River reached about 2,000 m3/s. The Lower Ord is likely to have had flows well in excess of 4,000 m3/s. These flows, for both the Ord and Dunham Rivers, are likely to be the highest flows ever recorded. Further information on peak flows will be available in the near future.
What impacts (positive or negative) does flooding have on the environment?
How do we best manage flood conditions to minimise the impacts on the upstream and downstream users and the environment?
What impact does flooding have on users (for example residents, agriculture, tourism, recreation etc) of the system?
Projects under way
There are a number of projects to reduce the damage of flooding on infrastructure by the Ord Irrigation Cooperative and the Shire of Wyndham East Kimberley.
Minimise the impacts of flood events on water users by:
1. Developing a flood management strategy that includes:
A communication strategy to ensure effective, timely communication between the community and relevant government agencies.
Timely monitoring and forecasting to provide information for action to be taken by the responsible agencies.
Incorporate a coordinated flood management strategy in the planning for the Ord River.
Advocate for appropriate buildings and fences in high flood risk areas through the Shires’ of Wyndham East Kimberley and Halls Creek building approval processes (for example; houses on stumps and no solid fences).
The responsibility for flood management lies with the Department of Water, Water Corporation and Shires. The hydrology information required to monitor flood flows is also the responsibility of the above agencies. Shires need to ensure their flood management strategies are relevant to wet season rain events, are appropriately resourced and based on up to date flood modelling and mapping. There needs to be a high level of collaboration between the Shire of Wyndham East Kimberley and the Ord Irrigation Cooperative to ensure private property and the individual organisations infrastructure is protected as best as possible.
1. Gardiner, H.G. (2000) Ord Land and Water Management Plan 2000. National Heritage Trust: AGWEST.
2. Ministerial Taskforce into Floodplain Management to the Minister for Water Resources. (1998) A Framework for Floodplain Management in Western Australia with a focus on Carnarvon. (1998), ISBN 0-7309-7423-5.