TUNGOG LAKE RESTORATION
MESCOT’s Tungog Lake Restoration Project is a resounding success story for the Batu Puteh community. Completely disconnected from the Kinabatangan River, the Tungog lake is one of only three deep clear-water oxbow lakes within this floodplain, and is a natural sanctuary for more than 180 native freshwater fishes. The 18-hectare (45-acre) lake and surrounding forest also holds economic and cultural significance for the local indigenous people.
Major floods in 2000 introduced an invasive species of South American water weed, Salvinia molesta, into Tungog Lake. The fast-growing Salvinia is known to completely take over and suffocate freshwater lakes, out-competing other plants, choking off oxygen, and killing fish and other aquatic animals. Within two years, Tungog Lake had become completely clogged by an acute infestation of Salvinia. Impacts on wildlife were observed immediately, including the notable absence of the rare Oriental Darter and three native species of otter, all of which had frequented the lake previously.
After two years of intensive research, a removal and maintenance program was developed and implemented by MESCOT and the local communities in 2005, with the support and advice of LEAP and the Alexander Abraham Foundation. This program is a highly labor-intensive process, involving workers and volunteers wading into the leech and crocodile infested waters and removing the weed by hand for disposal on land. However, this process also ensures minimal human impact and involves no chemicals, pesticides or heavy equipment which could negatively impact the ecosystem in other ways. As this lake sits within a relatively pristine forested area, this removal process was chosen after careful study as the least invasive for the ecosystem as a whole.
While both time and labor intensive, the program has been an unmitigated success. The lake has been clear of Salvinia since early 2007, and remains that way due to on-going maintenance efforts involving manually dragging the lake every month to remove any re-growth. Notably, since the clearing, a significant increase in bird life has been observed and otters are again regularly frequenting the lake.
The entire restoration was funded by the Alexander Abraham Foundation – a direct result of LEAP’s work as a bridge between MESCOT and the funder. MESCOT’s next step is to establish a self-sustaining maintenance program for the lake in conjunction with the Eco-Camp operations, after which donor funding can be phased out. Long-term maintenance will be necessary as Salvinia is extremely aggressive and hard to eradicate completely from a system, no matter what the means.