The Kinabatangan Catchment - problems and opportunities for change
Water quality decline
Water quality in the Kinabatangan and its tributaries has been declining since the intensification of commercial logging in the upper catchment from the 1960s and the aggressive conversion of floodplain forests to oil palm plantations in the 1980s. There is still a considerable amount of logging in the upper Kinabatangan catchment. Many areas have been logged repeatedly, seriously impairing the recovery of the forest. These activities contribute to significant soil compaction. With the reduced infiltration capacity of the soil, baseflow is affected. Less water becomes available at the Bukit Garam water supply intake during dry periods and the capacity of the river to dilute pollutants is reduced. This also has an impact on aquatic life and river navigation. The removal of forest cover is also expected to aggravate flooding in the Kinabatangan.
The main pollution sources in the Sg. Kinabatangan catchment are effluent from palm oil mills, pesticides, fertilisers and sediment from plantations, sediment from logging activities and sewage and refuse from villages along the river.
The 20 palm oil mills in the Kinabatangan floodplain produce an estimated 1.08 million tonnes of effluent annually. Many do not meet the Department of Environment effluent standards. Although all mills have waste stabilisation ponds, many of these ponds are poorly maintained or too small to be effective. Some of the waste stabilisation ponds are also inundated during flooding, causing concentrated effluent to be washed into the river. Enforcement by regulatory agencies is still inadequate at present.
Pesticides and fertilisers are widely used in the Kinabatangan area. Fortunately, the river still has a significant capacity for dilution. However, although water sample analyses indicate that the Kinabatangan is relatively clean but many of its tributaries are polluted. The Tenegang tributary for instance has a high organic pollution load. One or more of the mills along the Tenegang may not be effective. Dead fish floating have been observed floating on the water in this river with troubling regularity.
Land clearing for plantations and logging is the main source of sediment in the Kinabatangan River. Without sufficient soil conservation measures valuable topsoil is lost and large quantities of sediment are carried into the river. The failure to protect riparian reserves has led to easy delivery of the sediment to the river as well as riverbank collapse.
Sedimentation has also reduced the quality of water at the Bukit Garam intake. This has made conventional treatment ineffective. A pre-treatment process is now needed before the water can be passed on to conventional treatment.
Domestic waste and sewage
Most villages along the river do not have proper sanitation systems. Villagers either use the river directly or have floating toilets over the river. These practices pose a health hazard because the river water is used directly for bathing, washing and in some cases, for drinking.
A better way
Carrying out land use change with minimal impact to the river system is not impossible. The retention of riparian reserves is one of the measures advocated to protect the Lower Kinabatangan Wildlife Sanctuary as well as the Kinabatangan River. With the emergence of improved technology for managing palm oil mill effluent, waste stabilisation ponds should eventually make way for cleaner production processes wherein effluent can be reutilised. Till then, the ponds will need to be sited well above flood levels. More comprehensive enforcement of environment protection regulations is critical to control pollution from palm oil mills.
Multiple-use requires an integrated approach
Recognising that the Kinabatangan basin accommodates various types of land uses ranging from forestry in the upper reaches to agriculture, urban centres and wildlife sanctuaries in the downstream, besides providing water supply, an integrated approach must be adopted. It is clear that land use management in the Kinabatangan River basin needs to take into account a wide range of ecological, economic and social factors and needs. This will require closer coordination and cooperation among relevant agencies involved in water resources and environmental management.
Report by Josephine Regip
- Water quality data obtained from a hydrological consultancy by IR. G. Balamurugan conducted in 1999.
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Editor, Partners for Wetlands