S itu is a stagnant water above the land surface which was formed naturally or sintethically where the situ water came from the soil if the water surface and functioned as the potential hydrology cycle, as well as one of the forestry area. Situ was intended by human called the dam.Sunter I lake is a artificial lake which was purposed for the flood prevention and water sports. Sunter I lake was placed on the South Sunter lake with approximately length of 27 Ha. The water source of Sunter I lake came fnom the natural source and rain water, while the outlet was distributed to the Sunter II lake, Item River and finanly thrown out to the Pantai Ancol. On Sunter I lake, there is no waste exhanstion which came from the industry or the peoples housing. The activity surrounding the lake is water sport, such as Jet Ski and rowing boat, recreation place witf a cafe, hotel, fot Sk'i rental service and flood controlling facility for its' surrounding place.The objective of the analysis of Sunter lake is to observe the water quality by using the IKA- NSF method. This research was implemented for 5 months, from March-July 2004. The water sample collecting on the Sunter I lake were implemented twice, on May 30th 2004 and June 7th 2004. The sample recollecting was implemented on each point, and it was implemented twice. The sample collecting location are 5 point : first point is the outlet, second point is the fishing place, third point is the middle spot, and fourth point is the hosing, fifth point is recreation.The analysis result which was obtained on the Sunter I lake are : turbidity approximately 5- IO NTU. Temperature 28°C-30°C, T)'.)S 39-65 mg/I;- DO 1-3,15 mg/l, BOD 190-339 mgl Nitrat 0,25-0,55 mgl, phospat 0,03-0,083 mg/l, pH 7,2 - 7,4 and E.Coli 180-630 MPN 100 ml. The analysis result which was obtained then will be compared to the the DKI Jakarta governor desicion, on group C numbers 582 year of 1995, The government regulation number 82 year of 1995 Class III, and calculating the water quality by using the IKA - NSF method.The calculation result of IKA - NSF showed the water quality of Sunter I lake included in the middling category because, it's rate is about 51-70. On the first point of the outlet part, the value of 67,1: (middle), on the second point, the dam part, the value of 69,53 (middle), on the third point, the middle spot, the value of 72,28 (good), on the fourth point, the housing part, the value of 70,550 (middle), on the fifth point, the recreation part, the value of 70,9';' (middle). Generally, the water quality of the Sunter I lake is the middling condition because it is support by the proper physical and chemical quality.