Thus by the dawn of the twentieth century the first step towards conserving at least part of the Sinharaja had already been taken. Between 1885 and 1907, with the formulation and enactment of the Forest Ordination,, and the establishment of the Forest Department, the forest came under the administration of the Forest Department. In 1907, the forest was again considered for reservation of the time under the Forest Ordinance on the recommendation of Mr. Mendis, a Sri Lanka forester. By 1909, a total of approximately 7,910 acres in the Galle and Matara Districts had been demarcated for this purpose. However, it took almost twenty years before the reserve was finally created. In May 1926, total extent of 9,203 acres was declared a climatic reserve purely for its watershed value. This area was mapped out in 1930.

                   The 1930's also saw the mounting of two more explorations the Sinharaja. The first was John Baker's three-month long expedition which resulted on the flora and fauna of the reserve. This account is a landmark in the history of Sinharaja as it is first example of a systematic study of the forest. The second expedition was made by one of Sri Lanka's foremost zoologists, P.E.P. Deraniyagala who made brief reference to the fauna  of the forest in his annual report as the Director of Museums.