WATER QUALITY IN THREE RESERVOIRS ON THE CITARUM RIVER, INDONESIA Simon Sembiring * *Reseacher, Research Institute for Water Resources Development Jl. Ir. H. Juanda No. 193 Bandung – 40135, Indonesia Fax : + 62-22-2500163 ABSTRACT Three large reservoirs have been built on the Citarum River in West Java over the last two decades. Saguling (completed 1985), Cirata (1988) and Jatiluhur (1967) are the first, second and third reservoirs respectively downstream from Bandung city. Saguling and Cirata were built primarily for hydroelectric power and Jatiluhur primarily for rice irrigation. Subsequently all three are used for industrial, domestic, fisheries, recreation and transportation purposes. Jakarta city, about 130km from Jatiluhur, plans to use the water from this reservoir as its main water supply. It has been known for more than a decade that the water of all three reservoirs is polluted by inflows of domestic sewage, industrial and agricultural wastes. In addition, considerable organic pollution comes from fish farming in the reservoirs. In year 1998 Saguling had 2500 floating cage nets, Cirata 2700, Jatiluhur 720 . A number of pollutants exceed the limits of the official water quality regulation standards of the government of Indonesia, particularly dissolved oxygen, zinc and iron. This paper give some updated information about the level of pollution. Unless the sources of pollution are controlled the effects of it presently seen in macrophyte plant infestation, algal blooms, fish kills and degradation of potable and industrial water will increase. KEYWORDS: Citarum , reservoir ,Cirata, Jatiluhur,Saguling, pollution, water quality. INTRODUCTION The Citarum is one of the main rivers in Indonesia, with a length of about 315km. Three reservoirs have been built in the middle basin between Bandung city and Curug where much of the water flows into an irrigation network. Saguling filled in 1985, Cirata in 1988 and Jatiluhur in 1967. Their original purposes were for rice irrigation for Jatiluhur, and hydroelectricity for the other two. The total power generated is 1350 MW for both industry and domestic use. Subsequently many other functions for the water have developed. Some general features of the reservoirs are in Table 1. The river has a typical discharge of about 50 m3/sec in the dry season and about 280 m3/sec in the wet season, with an annual mean of about 150 m3/sec. Table 1 : Some features of the Citarum reservoirs Jatiluhur Cirata Saguling Year filled 1967 1988 1985 Altitude (m) 115 221 645 Area ( Ha) 8300 6200 5340 Catchment area (Ha) 659.000 603.200 334.300 Volume (x 106m3) 2970 2165 982 Maximum depth (m) 90 106 90 Mean depth (m) 35.8 34.9 18.4 Water level fluctuation (m) 25 20 20 Hydroelectric power (MW) 150 500 700 Original function Irrigation Hydroelectric Hydroelectric Power Power SOURCES OF POLLUTION The major source area of pollution is the upper Citarum basin, which includes the most important polluting area of Bandung city. The major pollutants are domestic sewage, industrial waste, arable agricultural runoff including pesticides, and animal husbandry. In the reservoirs themselves the pollution is the waste from fish farming. Domestic sewage. This type of pollutant involves organic material and so produces excessive consumption of oxygen (as Biological Oxygen Demand, BOD) and excess of the plant nutrients nitrogen and phosphorus that produce algal blooms and macrophyte plant infestations. The population in the upper Citarum River basin (Kabupaten Bandung including Bandung city) is about 6 million people, and in the Citarum catchment as a whole is about 11.4 million. Of this total population, about 64% discharge sewage directly into the river. 32% have septic tanks, and about 4% are said to be linked to the municipal treatment system in Bandung. Direct river disposal alone contributes about 173 tons of BOD per day. Depending on the efficiency of the septic tanks this figure could be up to double the amount (Table 2). For typical sewage this is theoretically equivalent to about 25-50 tons of nitrogen and 5-10 tons of phosphorus per day. Other references give 33.4 tons N/day of nitrogen and 4.4 tons P/day of phosphorus. Table 2: BOD loads for the Citarum catchment Population Municipal Septic tank Direct BOD load BOD load Direct kg/day kg/day 11,352,481 460,000 3,657,553 7,234,928 256,724 172,513 Industrial waste Most of the industries in the Citarum are based on organic raw materials and so BOD, nitrogen and phosphorus are significant. However, the manufacturing industries are also the most important sources of other contaminants such as heavy metals (zinc, mercury, selenium), phenol and cyanide. There are more than 2,500 factories of various industries in the Citarum basin and about 384 are in the upper part. Most are small but their combined pollution load is considerable. The textile and paper industries are the most important polluters, and next in order of importance are the rayon, pharmaceutical, food processing and tanning industries. The total BOD load is about 8 tons/day and the theoretical total nitrogen is about 1 ton/day. Table 3 gives a list of the major BOD industrial inputs for only the largest factories but which produce by far the most pollutants. Table 3: BOD load for each type of major industry in the Citarum basin kg/day Textile 3270 Paper 1841 Rayon 952 Chemicals 736 Communal sewage system 605 Food and beverage 136 Sugar 130 Tanning 82 Paper products 68 Textile chemicals 63 Basic chemicals 44 Printing 15 Mixed industrial estates 13 Single product food 10 Metal working 10 Fertilizer 8.7 Ceramics 5.8 Animal holding areas 5.3 Electroplating 5 Refrigeration 1.6 Pharmaceutical 0.6 Paint 0.14 Carpets 0.1 Arable agriculture waste This is most important for the excessive inflow of the plant nutrients nitrogen and phosphorus. At 1993, the agricultural area in the upper Citarum was 27,976 ha. The annual crop sequence is mainly rice- cash crop –rice. In general the use of fertilizer (urea and TSP) is relative high. Urea application is about 200 kg/ha and TSP 100 kg/ha. According to Iskandar (1993), the pollution load from arable agricultural is approximately 2,800 kg/day for nitrogen and 600 kg/day for phosphate. Fish farming The effects of the type of pollutant are similar to domestic sewage. In 1985 there were about 200 floating net cages in Saguling reservoir. By 1999 this number had increased to 1,900. In 1999 about 1,700 nets were in Cirata and 520 in Jatiluhuluhur (Sembiring,1992) .Based on the amount fish feed needed for each net, the total amount of feed applied is presently about 35,400 tons 12,000 tons and 4,160 tons/year respectively for Saguling, Cirata, Jatiluhur. Approximately 10 percent of the total amount of fish feed is wasted and falls to the reservoir bottomKrismono et al, ,1992). Generally fish feed contains 24-26 percent nitrogen, and phosphor 0,96 percent by weight. So that the nitrogen input from wasted fish feed alone can be estimated as 880 kg/day, 300 kg/day and 104 kg/day for Saguling, Cirata, Jatiluhur reservoirs respectively. The corresponding phosphorus input would be 35 kg/day, 12 kg/day and 4.2 kg/day. The total amount of nitrogen and phosphorus from the fish farming would be much more than this however because it does not consider excretion from the fish themselves. Digestion for this type of basically herbivorous animal is only about 50-60% efficient, so that the inputs mentioned above could be up to 50% greater for the complete farming operation. Livestock waste Waste from livestock husbandry can become an important source of pollution. It is equivalent to domestic sewage in its effect. One cow is equivalent to 5 people. According to Iskandar ,1993) pollution loading to water from animal waste is about 3.3 tons N/day and 0.8 P/day. Total Nutrient Load Estimation of pollution loads to from the main sources entering the Saguling, Cirata and Jatiluhur reservoirs every day is summarized in Table 4. Table 4: Estimation total loads of nitrogen and phosphorus (kg/day) WASTE SAGULING CIRATA JATILUHUR SOURCE Nitrogen Phosphorus Nitroge Phosphorus Nitroge Phosphorus n n Domestic 33,350 4,370 5,800 760 1,450 190 Industry 21.9 - - - - - Agriculture 2,800 600 - - 782 167 Livestock 3,281 812.4 - - - - Fishery 605 24 300 12 104 4.2 -). No. data and very little impact It is very evident that by far the most important input of pollution is domestic sewage. All the other categories combined only amount to 20% of the total nitrogen and about 30% for phosphorus. It is also evident that the industrial inputs are the smallest of the categories. This would be so even allowing for the obvious errors and gaps in the data. Domestic sewage disposal is thus shown to be the first priority for pollution management policy, rather than industrial effluent management. EVALUATION OF WATER QUALITY Evaluation of water quality uses here the water quality standards (PP. No. 20/1990) of the Government Indonesia for: Raw Water Supply (Group B), Fisheries (Group C), Agriculture and Hydroelectric power (Group D). Generally the water quality improves downstream in each reservoir. This is because they function in a similar way as sedimentation ponds for sewage treatment systems. The majority of particulate material sinks to the bottom of the reservoirs. However, over time the lower reservoirs will develop worse water quality. The condition of both Saguling and Cirata is poor because their waters are completely deoxygenated below 5m from the surface. Jatiluhur remains oxygenated to the bottom at present, so the other two reservoirs should also be oxygenated to the bottom if there was no organic pollution.