After having exploited all feasible sites for big hydro, Sri Lanka has turned to the development of smaller projects. Many streams have been marked as potential for building mini-hydro projects and already about 37 are in construction or evaluation phase, revealed CEJ member Hemantha Withanage. A mini hydro power plant of 0.6MW is being constructed on the Koskulana River, within the 100m buffer zone of Sinharaja Forest Reserve. Sinharaja rain forest located in the South- West of Sri Lanka was declared back in 1875 as a reserved forest in terms of Ordinance No.24 of 1848 (an Ordinance to regulate the felling and removal of Timber grown on Crown Lands of Sri Lanka). In 1978, Sinharaja was recognized as an International Man and Biosphere Reserve by UNESCO. In 1988, it was declared as a National Heritage and Wilderness Area under the National Heritage and Wilderness Areas Act No.3 of 1988 of Sri Lanka. In the same year it was inscribed on the world heritage list of UNESCO. The inscription as a world heritage was justified as ‘Sinharaja is the last remaining relatively undisturbed remnant of tropical humid evergreen forest in Sri Lanka’ and its endemism is extremely high with at least 139 species of endemic plants and its faunal endemism particularly for birds, mammals and butterflies exceeding 50%.  Sinharaja is also an important watershed, as a network of waterways generating from it feed two major rivers, Gin Ganga and Kalu Ganga.

In November 2015, the Public Interest Law Foundation (PILF) through media reports became aware that a 600 Kw mini hydro power plant was being built at the Koskulana River in the Kalawana Divisional Secretariat Area in the District of Ratnapura causing adverse impacts on Sinharaja World Heritage site and the river itself. Upon inquiry PILF became aware that the mini hydro power project was right on the boundary of the Sinharaja World Heritage Site.

The Central Environmental Authority (CEA) had approved the project on the submission of an initial environmental examination report (IEE). PILF’s position is that the irreversible adverse impacts of the project on Sinharaja, is best carried out through an Environmental Impact Assessment (EIA) and not through IEE. EIA is a more in depth study than an IEE.  The organization Environmental Foundation Limited has observed that the IEE report describes the general features of the project area to some extent but never state that the project area is exclusively within the buffer zone of the Sinharaja Rain Forest. EFL has also lamented scarce accuracy in biological survey, like fish species. Also, according to the IEE report, there are no river users along the river bank within the proposed project area, which is incorrect. There are many houses beyond the proposed weir on both sides of the river bank. People explore theses streams for gems and also to catch fish.

The IEE report blames the upstream inhabitants for soil erosion rather than the devastating activities taking place for the plant construction. There will be an unprecedented soil erosion and subsequent sediment load into the stream due to the construction of the weir, excavation for headrace channel, forebay and powerhouse and other infrastructure development activities such as the construction of access roads. The soil erosion resulting from construction of power projects cannot be compared with minor agriculture activities. According to LankaWeb, "The total length of the affected stream stretches (ASS) in the Kukule Ganga including the Kukule major hydropower project is 12.39 km of which 8.18 km have resulted from Kukule Ganga major hydro dam, which generates 80 MW whereas about 4.5 km stream stretches have been destroyed from six mini hydropower plants, which generate only 10.50 MW." This indicates that mini hydropower projects also generate major cumulative impacts as serious as those provoked by large hydro.

The National Environmental Act No.47 of 1980 as amended allows public participation in the decision making process of EIAs and this right is not available for IEEs. During investigations it was observed that the Forest Department under whose control the Sinharaja lies had initially objected to the implementation of the project but had subsequently sent a letter of no objection with no reasons for justification. Also, the IEE report has been submitted to the CEA after the period given for submission in the Terms of Reference. The CEA has granted approval for the project within one day after submitting the IEE report. Another issue taken up by PILF was that the alienation of State land was done in violation of the State Lands Ordinance.  PILF filed Writ Application No.527/2015 in the Court of Appeal of Sri Lanka on 23rd December 2015 challenging the approval process of the project in question. The matter is pending in Court and the activities of the project were stopped based on an undertaking given to Court by the developer on 23rd  December 2015. The project has also been challenged subsequently by Environmental Foundation Ltd. by filing a Fundamental Rights case in the Supreme Court in January 2016.

The capacity of the Koskulana mini hydro power project proposed by Waste Management Water Power (Pvt) Ltd is 600kw. It has a proposed wier (12m length and 2.5m height) across the Koskulana river, a head race channel (86m length), forebay tank, penstock (265m length) and a power house. Electricity generated to be linked to the national grid of 33 kV at Koskulana grid connection point, 2.2 km away from the power house.