Iralalaru Hydropower Project in Timor-Leste

After gaining independence, the Government of Timor-Leste (East Timor) called on the Government of Norway for support in the rebuilding and strengthening of the energy sector of its newly-independent nation.

Priority was given to the development of hydropower, and Iralalaru on the Irasiquero River was identified as a potential site where water resources could be harnessed to provide electrical energy. The proposed Iralalaru project is situated in the eastern part of the country near Lospalos, in an area of karstic limestone. It occurs within the last remaining Tropical Dry Forest area of Timor-Leste.

The forest provides a range of habitats and maintains an extensive biodiversity base. Accordingly the area has a high conservation value and has been proposed as a protected area that may cover 620 km2. As part of the hydropower development an Environmental Impact Assessment was required. Since the aquatic ecosystems are likely to be the most seriously affected by hydro-power projects, WRM and ERISS were contracted by EPANZ Services to conduct aquatic ecosystem studies in Timor-Leste as part of an assessment of potential impacts of the proposed development. The specific aims of the study were to evaluate:

  • the distribution of freshwater aquatic species, especially fish, benthic fauna (including aquatic insects, molluscs and crustaceans) and plants, and how the proposed development may affect biodiversity and conservation values,
  • determine the distribution of the newly discovered species of fish, the hardyhead Craterocephalus laisapi outside its established habitat in the Irasiquero River, and how the development may affect this species,
  • within the limits possible, make an assessment of the presence of stygofauna in springs and caves downstream of the Mainina sinkhole,
  • assess the possible conservation significance of the resident aquatic fauna in springs that may be fed by Mainina waters and identify the likely impacts to the fauna from potential dewatering, and
  • identify and assess other potential impacts to freshwater ecosystems arising from the Iralalaru Hydropower Project.

WRM, in collaboration with ERISS, recorded 13 species of macrophyte, over 220 taxa of aquatic macroinvertebrates and 27 species of fish during the survey. The fish fauna included eight species which represent new records for Timor-Leste and 2 species believed to be endemic to the Irasiquero River. In addition, 7 of the 9 caves and 13 of the 21 springs sampled yielded stygofauna.

WRM and ERISS identified the risks to the aquatic ecosystems of the Irasiquero and wider Timor-Leste through translocation.