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Lake Profile

Toba (Danau Toba)

General Information

Description Lake Toba, the largest year-round lake in Southeast Asia, is located in the province of North Sumatra, Indonesia, approximately 176 km to the west of the provincial capital, Medan. It is the largest volcanic lake in the world.
Country Indonesia
Latitude 2° 30' 0" (2.5000)
Longitude 99° 0' 0" (99.0000)


 Toba global index map
 Largest Lakes of the World by Volume (LakeNet Explorer 2004)
 Toba locator map
 Toba Watershed and Adminsitrative Boundaries (LakeNet)
 Lake Basin Management Initiative (LakeNet Explorer)
 USAID-supported Lake Basin Management and Biodiversity Conservation Technical Assistance 2003-2004 (LakeNet Explorer)

Physical Characteristics

Description Toba's origins are tectonic and volcanic. The lake was formed as a consequence of the largest volcanic eruption ever to occur on earth, approximately 75 000 years ago, which ejected some 1 500 to 2 000 km3 of material. Dust and other volcanic material reached as far as Sri Lanka and the Bay of Bengal. At some locations in the vicinity of Lake Toba, tuff layers as thick as 600 m can be found. In comparison, the largest recent volcanic explosion, Mount St. Helens, which erupted in 1980, produced 2.3 km3 of material. Additional eruptions approximately 30 000 years ago created the island of Samosir in the middle of Lake Toba. (Lehmusluoto et al. 1999).

The lake is approximately 90 km long and is situated approximately 900 m above sea level. The lake catchment area is approximately 43% hilly and 30% mountainous, with peaks more than 2 000 m above sea level. Average rainfall is more than 1 500 mm annually, and temperature fluctuates between 19- 20 C.

Of the 202 brooks and rivers that empty into the lake, only 70 run year-round. Studies suggest that the inflow of water into the lake is decreasing. In the period 1920-1932, average inflow was 110 m3 s-1, which decreased to 104.4 m3 s-1 in 1957-1975 and to 90 m3 s-1 in 1976-1988.

Volume 240.00 km3
Surface Area 1,103.00 km2
Depth Maximum depth: 505.0 m
Age 10,000 - 99,999 years before present
Origin Volcanic
Trophic State Oligotrophic
Type Fresh
Catchment Catchment size: 3,658.00 km2
Catchment/surface area ratio: 3:1


Economic Value The unique geographical position of Lake Toba reserves a number of economic potentials for the benefit of the wide range of communities, especially as a source of bountiful fresh water and lust tropical forest which attract the interest of big industries to invest in the areas.
Primary Economic Sectors Agriculture - 64%
Major Cities Medan
Population 517,050 (0)

Watershed Management

Description Administratively, by far the largest part of the Lake Toba water catchment area (87%) is situated in the North Tapanuli District (Kabupaten, or Regency), with the balance divided among the regencies of Simalungun (8.4%), Karo (2%) and Dairi (2.5%). Naturally the North Tapanuli District also houses the largest part (81%) of the total 517,050 inhabitants of the Lake Toba water catchment. The same district has also the highest population density, with 185 people km-2.
Sub-basin Action Plan Developed
Invasive Species Moderate Impact
Other Issues Aquaculture
Point source pollution
Polluted runoff
Watershed habitat alteration
Specific Contaminants Pathogens
Monitoring No systematic monitoring program is in place.

Biodiversity Conservation

Species of Concern


Lake Toba Heritage Foundation - Yayasan Perhimpunan Pencinta Danau Toba
Institute for Environmental Monitoring Studies, North Sumatra
Stone Environmental Inc.

LakeNet Programs

World Lake Basin Management Initiative
Community-based Watershed Management for Lake Toba, Indonesia
Indonesian Lakes Forum Meetings
Lake Toba-Lake Champlain Sister Lakes Technical Exchange
Lake99 Workshop: Managing the Great Lakes of the World, Implementing the Watershed Approach
USAID-funded Technical Assistance
Wastewater Management for Lake Toba, Indonesia
Feasibility Study for the Lake Toba Science & Education Center
LBMI Regional Experience Sharing & Review Workshop for Asia


A Final Report - Community-based Watershed Management for Lake Toba, Indonesia (2,364K)  (PDF) Project Report. Final. LakeNet. 8/31/2001.
Lake Toba: Need for an integrated management system  Agenda. Final. Lakes and Reservoirs- Research and Management. 9/1/2004.
Lakes & Reservoirs: Research and Management, Special Issue edited by LakeNet, Volume 6:3  (PDF) Announcement. Blackwell Science-Asia. 7/31/2001.
Managing Lake Basins for Sustainable Use - Lake Basin Management Initiative Final Report (PDF)  Project Report. Final. English. 2/27/2006.
Toba   (PDF) Experience Brief. Final. 2/27/2006.
Toba: World bank Comments on Experience Brief  Comments. Draft. World bank. 3/22/2004.


ILEC Database
Lake Toba Online
Lake Toba: Need for an integrated management system
Lake Toba-Lake Champlain Sister Lakes Partnership


3/10/2005 - Most lakes' ecosystems in Indonesia under threat
4/23/2004 - Towards a Lake Basin Management Initiative
2/14/2004 - North Sumatra and Asahan Authority to save Lake Toba ecosystem
6/10/2003 - Village heads threaten to quit over Toba pulp mill issue
6/11/2002 - Over 5,000 protest reopening of pulp & paper mill on Lake Toba
3/25/2002 - Environment body slams Lake Toba regreening policy
8/29/2001 - Lake Toba Online and final report for community-based watershed project

Additional Data Sources

Birkett, C., and I. Mason. 1995. A new global lakes database for remote sensing programme studying climatically sensitive large lakes. Journal of Great Lakes Research, 21 (3) 307-318.
Herdendorf, C. 1982. Large lakes of the world. Journal of Great Lakes Research 8:379-412.
International Lake Environment Committee, the United Nations Environment Program and Environment Agency, Government of Japan. 1997. World Lakes Database.

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