Location within the Philippines
|Coordinates||9°21′11″N 123°10′45″ECoordinates: 9°21′11″N 123°10′45″E|
|Max. length||1.5 kilometres (0.93 mi)|
|Max. width||1 kilometre (0.62 mi)|
|Surface area||76 hectares (190 acres)|
|Max. depth||90 feet (27 m)|
|Surface elevation||1,000 feet (300 m)|
Lake Balinsasayao, Lake Danao, and Lake Kabalin-an are part of Balinsasayao Twin Lakes Natural Park, a protected area totaling 8,016 hectares (19,810 acres) created on 21 November 2000 by virtue of Proclamation No. 414 signed by former President Joseph Estrada. It lies within the municipalities of Valencia, Sibulan, and San Jose in the province of Negros Oriental.
The lakes are situated northwest of a narrow mountain ridge, in a caldera formed by four mountains: Mount Mahungot to the south, Mount Kalbasan to the north, Mount Balinsasayao to the east and Guintabon Dome to the west. A normal fault separates Lakes Balinsasayao and Danao while and another fault, the Amlan, is about 1,400 metres (4,600 ft) west of Danao. Four geologic faults also intersect the southern edge of Lake Danao, whose water level is lower than that of Balinsasayao.
Flora and fauna
As a protected natural park home to an expansive ecosystem and biodiversity, Balinsasayao Twin Lakes National Park is one of the major tourist attractions in Negros Oriental. The lake has a rich fish fauna and the surrounding dipterocarp forests are rich in bird life. However, invasive fish species such as tilapia, common carp, mudfish, shrimp, mosquito fish and milkfish have been introduced in the lake.
The Department of Environment and Natural Resources (DENR) through the Biodiversity Management Bureau (BMB) manages tourist activities in the natural park. The bureau allows swimming, sightseeing, mountain trekking, camping, birdwatching, paddle boating in Lake Balinsasayao. The natural park has a concrete view deck, umbrella cottages, a restaurant, a souvenir shop, restrooms, and a visitor center.
Conserving the natural park's flora and fauna is a continuing struggle as surrounding forests are exploited for timber and charcoal production. The uncontrolled cutting of timber by slash-and-burn farmers or kaingineros is reducing the inflow of water to the lakes and causing a fall in water levels. Also, since the lakes are situated near Energy Development Corporation (EDC)'s Southern Negros Geothermal Field in Valencia, the forest surrounding the lakes are under threat from constant geothermal drilling. A co-management plan for geothermal preservation has been drafted by the DENR-PENRO, EDC, and the local governments of Valencia and Sibulan.