Journal of Ecological Engineering Journal of Ecological Engineering 2021, 22(3), 99–110 Received: 2020.12.16 https://doi.org/10.12911/22998993/132427 Accepted: 2021.01.14 ISSN 2299–8993, License CC-BY 4.0 Published: 2021.02.01 Water Quality of Gatal Lake, Kotawaringin Lama, Central Kalimantan Desi Susilaning Tyas1, Tri Retnaningsih Soeprobowati1,2*, Jumari Jumari 1 1 Master Program of Biology, Faculty of Science and Mathematics Universitas Diponegoro, Semarang, Indonesia 2 School of Postgraduate Studies, Universitas Diponegoro, Semarang, Indonesia * Corresponding author’s email: [email protected] ABSTRACT Gatal Lake is located in the Kotawaringin Lama District, West Kotawaringin Regency, Central Kalimantan, In- donesia. The government and the surrounding communities use Gatal Lake for recreation, irrigation, livestock, and fisheries. Geographically, Gatal Lake, is close to oil palm plantations and palm oil processing factories that contributed to water pollution, especially the pollutants originating from plantation activities in the form of large- scale use of fertilizers and pesticides. This study aimed to determine the status of the water quality of Gatal Lake, Kotawaringin Lama based on the physicochemical parameters. The samples from five stations were analyzed based on the following parameters: temperature, TDS, TSS, pH, BOD, COD, DO, nitrate, nitrite, phosphate, Pb, Cd, H2S, oil and grease, detergent, and phenol. The study was conducted using a purposive sampling method and determining the status of water quality based on Government Regulation No. 82/2001. The results of the physi- cochemical analysis of Gatal Lake showed that the water quality parameters which exceeded the water quality standards, are BOD (6.94 to 8.65 mg L), COD (9.58 to 15.7 mg/L), and DO (4.20 to 5.10 mg/L), while the pa- rameters that did not exceed the water quality standards for Class I, II, III, and IV are temperature, TDS, TSS, pH, nitrate, nitrite, phosphate, Pb, Cd, H2S, oils and fats, detergents and phenols. On the basis of the STORET method, the water quality of Gatal Lake for Class I, II, and III are included in the highly polluted category, and for Class IV is in the moderate category. Keywords: Gatal Lake, water quality, physical-chemical parameters, STORET INTRODUCTION The surface water quality is a very sensi- tive and critical issue in many countries [Sen- Water is a fundamental constituent in life and er, et al. 2017]. The condition of freshwater in is very important for all needs. Water has an im- Indonesia has always been a threatening issue portant role in various fields including agricul- and a national problem [Soeprobowati et al. ture, horticulture, livestock, fisheries, domestic 2016]. For example, the problem of Rawapen- consumption, industry, energy generators, and ing Lake in Central Java Province is the oc- recreation [Sukmawati, et al. 2019]. Freshwater currence of eutrophication, sedimentation, de- ecosystems such as lakes, reservoirs, and riv- creased water quality, and the blooming of wa- ers are natural resources that play an important ter hyacinths [Soeprobowati et al. 2017, 2019; role in ensuring the availability of water on land. Hidayati et al. 2018]. The same problem also The 2030 Agenda for Sustainable Development occurs in other national priority lakes, includ- recognizes the importance of water quality and ing Lake Toba, Maninjau, Singkarak, Kerinci, includes specific water quality targets in Sustain- Tondano, Limboto, Poso, Tempe, Matano, Ma- able Development Goal (SDGs) 6 [United Na- hakam Semayang-Melintang Jempang Water- tions, 2016]. However, the surface water pollu- fall, Sentarum, Sentani, Batur, [Rahim & So- tion remains a major problem worldwide, caused eprobowati, 2019], even in the small volcano by natural processes and anthropogenic activities lakes in Dieng [Soeprobowati et al., 2017, [Rahim & Soeprobowati, 2019]. 2018, 2019, 2020]. Lake Batur in Bali also 99 Journal of Ecological Engineering 2021, 22(3), 99–110 experiences silting due to the cultivation ac- MATERIALS AND METHODS tivities around the lake, agricultural activities, and the presence of waste both residential and Study Area tourism waste [Sukmawati, et al. 2019]. Gatal Lake (Figure 1) is one of the oxbow This field work was conducted from August lakes located in Rungun Village, Kotawarin- to September 2020 at Gatal Lake (02º23’37.7 “S gin Lama District, West Kotawaringin Regen- 111º25’01.2” E), Rungun Village, Kotawaringin cy. The area of Gatal Lake is 1,500 Ha with a Lama District, West Kotawaringin Regency, Cen- length of 2,000 m and a width of 900–1,100 m. tral Kalimantan, Indonesia. There are five sam- pling stations with different characteristics by The depth of Lake Gatal in the rainy season is purposive random sampling which represent each 6 m, while in the dry season it is 4–5 m [In- activity around the Gatal Lake waters (Table 1 donesia.go.id/kalteng, 2020]. The government and Figure 3). Determination of the research sta- and the surrounding communities use Gatal tions was based on the level of depth from the Lake for recreation, irrigation, livestock, and edge to the middle of the water (horizontal). fisheries. The lake is located close to oil palm plantations and palm oil processing factories, Water Sample Collection and Analysis the pollutants from which can enter the waters (Figure 2). The main sources of pollutants that Water sampling was carried out at each sta- enter to the lake waters are the excessive use tion by the Indonesian National Standard (SNI of pesticides and fertilizers in agriculture and 6989.57–2008) on how to take the surface water domestic waste from local communities. Agri- samples with a lake depth of less than 10 meters. culture is identified as the largest contributor The water samples were collected in 1L clean to pollution for surface and groundwater in the plastic bottles, labeled and then put into a cooler. world [Rahim & Soeprobowati, 2019]. The physicochemical parameters such as temper- Monitoring the quality of surface water and ature, pH, and dissolved oxygen were measured groundwater is very important as a basis for directly (in-situ) in the field and other parameters the management of water pollution. The water were analyzed at the Mutuagung Lestari Labora- quality monitoring process involves determin- tory, Pasir Panjang Village, West Kotawaringin District, Central Kalimantan, Indonesia. ing the sampling points and analyzing the water The results of the physical and chemical characteristics to obtain the correct interpreta- parameter values of the water obtained were tion of the results [Sukmawati, et al. 2019]. The then compared with the water quality standard most frequently used water quality parameters criteria in Government Regulation Number 82 are the physicochemical and biological param- of 2001 concerning Water Quality Management eters. The physicochemical parameters play an and Water Pollution Control. Determination of important role in maintaining the restoration Gatal Lake water quality was performed using system and regulating the water quality [Mus- the STORET (Storage and Retrieval) method liu, et al. 2018]. This study aimed to determine which refers to the Regulation of the Minister of the status of the water quality of Gatal Lake, Environment of the Republic of Indonesia No. Kotawaringin Lama based on the physicochem- 115/2005 concerning Guidelines for Determin- ical parameters. ing Water Quality Status. Figure 1. Gatal Lake, Kotawaringin Lama district, West Kotawaringin regency 100 Journal of Ecological Engineering 2021, 22(3), 99–110 a) b) Figure 2. (a) Oil palm plantations and (b) Palm oil processing factories owned by PT. BGA Group (Source: bumitama-agri.com) Figure 3. The 5 research stations in Gatal Lake, Central Kalimantan Table 1. Geographical position and description of the research stations of Gatal Lake, Central Kalimantan Stations Geographical position Sites description G-1 02º23’52.1”S 111º24’27.3”E Tourism and recreation area G-2 02º23’51.3”S 111º24’26.5”E Local community cage area G-3 02º23’53.2”S 111º24’29.1”E Forest area G-4 02º23’48.7”S 111º24’32.1”E Central lake area G-5 02º22’14.4”S 111º25’43.7”E Inlet area of the Lamandau river 101 Journal of Ecological Engineering 2021, 22(3), 99–110 The STORET method is one of the techniques 2. Class II, water intended for water recreation in- often used in Indonesia to determine the status frastructure/facilities, freshwater fish farming, of water quality based on the US-EPA (United animal husbandry, water for irrigating crops, State-Environmental Protection Agency) value and/or other uses requiring the same water system to categorize the water quality into four quality as the said use. classes (Table 2) [Rahim & Soeprobowati, 2019]. 3. Class III, water intended for the cultivation of Through the STORET method, we can find out freshwater fish, animal husbandry, water for ir- which parameters have met or exceeded the water rigating crops, and/or other uses which require quality standards by comparing the water quality the same water quality as the said use. data with the water quality standards that are ad- 4. Class IV, water intended to irrigate crops and justed to their designation to determine the status or other uses that require the same water qual- of water quality [Rintaka, et al. 2019]. ity as the said use. Determination of the water quality status us- ing the STORET method is carried out according to the following stages: RESULTS AND DISCUSSION 1. Periodically conducting the water quality data collection to form data time series. This study uses the water samples from five 2. Comparing the measurement data of each wa- sampling stations. The coordinates of the location ter parameter with the quality standard value are recorded using GPS (Global Positioning Sys- according to the water class. tem). The results of measuring the water quality 3. If the measurement results meet the water qual- of Gatal Lake, Kotawaringin Lama District based ity standards (measurement results <quality on the physicochemical parameters can be seen standards), then a score of 0 is given.