Increasing type and number of human activities will impact on decreasing quality of water. Therefore, it is necessary to determine the water quality status of Rawapening Lake regularly to ensure that the water quality remains in its natural condition. The purposes of this study were to evaluate the water quality status and class of Rawapening Lake. The survey was done in the lake during dry season for 3 months (July to September 2016). Water sampling conducted in seven locations. The measured variables were all parameters as specified in Government Regulation No. 82 of 2001. To determine the water quality status was using storet methods. Determination of the water class was by comparing the concentration of all parameters with the standard. Observations indicated that the Rawapening Lake water quality status was in heavily polluted. There were eight parameters exceeding the standard i.e. TSS, BOD, COD, total phosphor and total coliform, Cd and Pb, and H2S. Therefore, it is necessary to decrease them through activities such as not throwing rubbish into the lake, lifting biomass of water hyacinth, picking up peat soil sediments, using environmentally friendly fuels, reducing fertilizers and pellet, reforesting critical lands, limiting mining activities, banning waste disposal directly to rivers.

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Two important issues for establishment of nutrient criteria are identifying which nutrient limits algal growth and determining the concentration of that nutrient enabling nuisance growths. The purposes of this research were: 1) to examine the nutrient (TN, TP, ratio of TN/TP) dynamic in Rawapening Lake spatially and temporally, 2) to identify Nutrient Limiting of Algal Growth in Rawapening Lake, and 2) to determine the nutrient criteria for enabling algae growth in Rawapening Lake. The research was conducted using a survey method in 7 sites from February to August 2016. The result showed that spatially Total Nitrogen (TN) and Total Phosphor (TP) in the lake were not evenly distributed and temporally influenced by the inflow. The development of algae biomass in Rawapening Lake determined ratio of TN/TP. Nutrient criteria as follow: oligotrophic was 5.96 -14.39, mesotrophic was 14. 39 -42.15, eutrophic 42.15 -51.65, and hyper-eutrophic > 51.65. These criteria could be used in designing controlling eutrophication problem by arranging nutrient input from both external and internal sources in order to meet those limit. The benefits of research contributes to the development of environmental monitoring methods to assess the trophic status using more appropriate in accordance with the conditions of the tropics region. It also could be used for consideration in policy direction and orientation of land use in catchment areas in relation to water quality of the lake.

The transport of nutrien causing eutrophication in water from catchment area especially fosforus (P) through runoff is determined by type of landuses, slop, soils type, and land cover (Jeje,2006) . The research was conducted using a survey method. The sampling technique was done by a purposive sampling on any flooding in the rivers that pass through areas with specific land use (settlement, forest, plantations, agricultural fields and rice field). The main parameters were river discharge and the content of nutrients causing eutrophication that was phosphorus (P) in rivers. The P loadingfrom cacthment area to Mrica reservoir was 11,526,706.14 kg/year and the load allocation (LA) was 3,833,587.70 kg/year. The reservoir operational of power generating dan flushing activity were able to manage the LA up to 1,147,329.09kg/year, so the TMDL of Mrica reservoir become 4,980,916.78kg/year. It was concluded that the highest transport of P was from paddy field and then followed by respectivelly agricultural (potato) field, plantation (perhutani) field, settlement area, and forest area.

The water of Lake Rawa Pening is used as a source of drinking water. Indonesian Government Regulation Number 82 of 2001 on Management of Water Quality and Water Pollution Control stated that the water quality of Lake Rawa Pening should meet the quality standard of first grade and be categorized as no polluted water. The purpose of this research was to assess the water quality based on Indonesian regulation and to assess water quality based on international regulations. The quality of water was assessed using a survey method in 7 sites of the Lake Rawa Pening 3 times for 3 months. Parameters measured were all the water quality parameters required in accordance with Government Regulation No. 82 of 2001. The results indicated that there were 13 values that exceeded the water quality standard of first grade. These exceeded parameters were total suspended solids (TSS), biological oxygen demand (BOD), chemical oxygen demand (COD), orthophosphate (PO4), NO3, As, Se, Cd, Mn, Cu, Pb, H2S, faecal coliform, and total coliform. Water quality status of Lake Rawa Pening was categorized as heavily polluted. The water quality of Lake Rawa Pening should be improved by reducing the pollutants entering the lake by restriction of human activities causing lake pollution.